As people are rapidly finding out, many manufacturers are relying on the reamer maker to build the reamer to the SAAMI spec, and then are finding that it is otherwise. Even reputable barrel makers like Lilja have been caught in the practice by reamer makers. Your bolt failures fall FAR outside the norm, and make anyone who has AR experience very suspicious of a bad bolt/extension interface.
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6.5 Grendel v .300 Blackout
- Thread starter Flex686
- Start date
As people are rapidly finding out, many manufacturers are relying on the reamer maker to build the reamer to the SAAMI spec, and then are finding that it is otherwise. Even reputable barrel makers like Lilja have been caught in the practice by reamer makers. Your bolt failures fall FAR outside the norm, and make anyone who has AR experience very suspicious of a bad bolt/extension interface.
The part where you specify whether you headspaced the now-Grendel chamber to the .264LBC bolt...
The problem with your inference is that I "specified" no such thing. After the second bolt failure, the rifle's headspace (and feed ramp and barrel extension) was checked with <b>BOTH Les Baer AND Alexander Arms bolts</b> and was already within SAAMI specifications.
Indeed that was initially my suspicion and why I sent the rifle back to the builder to be checked (see above).
Further, the builder built a nearly identical sister rifle, different only in color and caliber, .223 Rem. No problems with that rifle, only the Grendel.
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Which makes it even more likely that you have a bolt/extension issue. But treat it how you feel most comfortable. History says that this kind of an issue is related to a bad extension.
Broken bolts can only come from 3 things really:
1) Bad bolt. This included bad metallurgy, bad heat treatment, bad machining, etc.
2) Bad barrel extension or a combination of tolerance stacking between the bolt and barrel extension.
3) High pressure.
Since the VAST majority of Grendels have never broken a bolt, and since the vast majority of users are shooting factory ammunition (just like virtually every other factory caliber), high pressure in factory loads is apparently very rare. (The exception in the Grendel MIGHT be old Les Baer Grendel 123 Sierra ammunition, which many users reported was fairly hot.) High pressure in Wolf Grendel loads would be incredibly unlikely, in light of the data that many users have discussed regarding velocities.
So if you are 100% sure that your bolts are good and your extension is good, the ONLY thing remaining is your pressure creator, your ammunition.
Since WOLF is known to be a mild load, you really have a conundrum.
I would STILL believe that you have a bad extension, or have an extension/bolt tolerance stacking issue, with both measuring correctly separately, and with the gun closing on go/no go gauges, (which I am willing to bet is the ONLY method your gunsmith used to test your tolerances). It only takes a few thousandths of machining error to create a tolerance issue with the bolt and extension surfaces. A few thousandths will create unequal loading on the lugs and bolt breakage.
OR.....you might have a cursed rifle!
1) Bad bolt. This included bad metallurgy, bad heat treatment, bad machining, etc.
2) Bad barrel extension or a combination of tolerance stacking between the bolt and barrel extension.
3) High pressure.
Since the VAST majority of Grendels have never broken a bolt, and since the vast majority of users are shooting factory ammunition (just like virtually every other factory caliber), high pressure in factory loads is apparently very rare. (The exception in the Grendel MIGHT be old Les Baer Grendel 123 Sierra ammunition, which many users reported was fairly hot.) High pressure in Wolf Grendel loads would be incredibly unlikely, in light of the data that many users have discussed regarding velocities.
So if you are 100% sure that your bolts are good and your extension is good, the ONLY thing remaining is your pressure creator, your ammunition.
Since WOLF is known to be a mild load, you really have a conundrum.
I would STILL believe that you have a bad extension, or have an extension/bolt tolerance stacking issue, with both measuring correctly separately, and with the gun closing on go/no go gauges, (which I am willing to bet is the ONLY method your gunsmith used to test your tolerances). It only takes a few thousandths of machining error to create a tolerance issue with the bolt and extension surfaces. A few thousandths will create unequal loading on the lugs and bolt breakage.
OR.....you might have a cursed rifle!
Broken bolts can only come from 3 things really:
1) Bad bolt. This included bad metallurgy, bad heat treatment, bad machining, etc.
2) Bad barrel extension or a combination of tolerance stacking between the bolt and barrel extension.
3) High pressure.
Since the VAST majority of Grendels have never broken a bolt, and since the vast majority of users are shooting factory ammunition (just like virtually every other factory caliber), high pressure in factory loads is apparently very rare. (The exception in the Grendel MIGHT be old Les Baer Grendel 123 Sierra ammunition, which many users reported was fairly hot.) High pressure in Wolf Grendel loads would be incredibly unlikely, in light of the data that many users have discussed regarding velocities.
So if you are 100% sure that your bolts are good and your extension is good, the ONLY thing remaining is your pressure creator, your ammunition.
Since WOLF is known to be a mild load, you really have a conundrum.
I would STILL believe that you have a bad extension, or have an extension/bolt tolerance stacking issue, with both measuring correctly separately, and with the gun closing on go/no go gauges, (which I am willing to bet is the ONLY method your gunsmith used to test your tolerances). It only takes a few thousandths of machining error to create a tolerance issue with the bolt and extension surfaces. A few thousandths will create unequal loading on the lugs and bolt breakage.
OR.....you might have a cursed rifle!
Add to your list-out of square receiver. If the barrel extension is not held square with the bore of the receiver only some of the bolt lugs will catch the thrust.
To figure strength of the lugs use the width X the length X the number of lugs(7) times the yield strength(170-180K psi). The problem with bolts is the lugs are not attached to a solid piece of metal. The recess of the bolt face removes some of the strength since the wall the lugs are attached to is so thin. Thinner the wall the less strength. On a 5.56 where the wall/web is as thick as the lugs are wide it doesn't lose any strength. That is why a 5.56 bolt is so much stronger than the 6.8 or Grendel. If you consider the recess is .125-.135 deep taken away from the lugs that are .275-.277 long and the web is 50% or less of the width of the lugs the bolts are apx 25% weaker than a 5.56 bolt. A 6.8 or 6.5 has more bolt thrust due to the larger diameter of the cartridge on top of the bolts being weaker from thinning of the web.
ETA- The lugs next to the extractor are missing half of the web which reduces the strength of the .125" length part of the lug by 50% compared to the other 5 lugs. Thats why most bolts break the lugs next to the extractor. The thrust surpasses the yield and the tensile strength of those 2 lugs.
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An out of square receiver is another possibility, and I should have mentioned it. That essentially creates the same situation as a bad barrel extension, with thrust on the lugs produced unequally. I would have hoped that any competent AR smith would have squared the receiver and Nukes seems fairly convinced his guy knows what he is doing, so it never crossed my mind. Even good smiths don't have an easy way to check the barrel extension once its installed by the barrel maker, so I tend to lean that way, especially with all the cheap, high volume barrel extensions being made today.
Nukes, what company made the reamer that was used on your barrel?
Do you have max OAL measurements for it?
Who made your barrel again?
I suspect it was a compilation of bad extension, out of spec chamber, bad bolts, etc....
Do you have max OAL measurements for it?
Who made your barrel again?
I suspect it was a compilation of bad extension, out of spec chamber, bad bolts, etc....
<u><b>IF</b></u> I remember correctly, Pacific Tool & Gauge. I do not have the measurements. For a reputable tool maker, I would expect adherence to the SAAMI specifications. After all, this rifle was ordered and manufactured more than a year after the SAAMI specs were published.
Krieger barrel 20" 1-8.5.
http://www.saami.org/PubResources/CC_Drawings/Rifle/6_5 Grendel.pdf
Krieger barrel 20" 1-8.5.
http://www.saami.org/PubResources/CC_Drawings/Rifle/6_5 Grendel.pdf
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If the reamer manufacturer was PT&G, it is HIGHLY unlikely that you have a SAAMI chamber. PT&G has apparently been carrying on their own campaign to change the Grendel chamber, and has been supplying a reamer that is their version of the .264 LBC chamber. They have done this to multiple different manufacturers, including Lilja and apparently Satern. They even openly bragged about it to a member here.
If your gunsmith doesn't have appropriate measuring equipement for that typle of measurement, it is highly likely that he took PT&G at their word that they were supplying a Grendel reamer, when in reality they were not.
I believe there were 2 different types of reamers being sent out by PTG. One was a compound throat Grendel type but was undersized. The Grendel spec calls for all diameters + where most reamers say +- .001. The reamer that caught Satern was a undersized Grendel type. That made all of the throats short.
The other reamer that Lilja had seemed to be a 264 style chamber, what PTG now calls the Grendel II. I know a few manufactures who say they hate the Grendel chamber because it is so tough to get and keep the throat centered on the bore. Who's to say they didn't order a 264 reamer thinking no one will ever know the difference? PTG tried to get me to use a 6.5 chamber with a parallel freebore but .5 degree throat angle around 2007. That would be half 264 type chamber and half Grendel chamber. He didn't hide it, just said he thought it was better. I could tell he didn't want to grind a Grendel chamber or couldn't back then because Bill didn't want to release his design. I know there's a lot of animosity between some companies, I heard it first hand. Companies blamed each other for bad product and a few different companies ended up stuck with the cost. Anything is possible and only those involved really know. There's only 2-3 reamer makers in the country that will grind carbide production reamers. If you piss those guys off you could have a tough time getting reamers and barrels made. I hear Manson is making some carbide reamers now, that's a good thing.
I passed these revelations on to our gunsmith. He confirmed that he used a PTG reamer on our rifle.
He also said that Alexander Arms came to their gunsmithing school and AA oversaw the use of their own factory reamer. Our gunsmith had a broken Les Baer bolt on his own rifle chambered using the AA factory reamer.
He concludes, as he did previously and as I reported, that there is a bolt problem—apparently more frequently with Les Baer bolts than with AA bolts.
He also said that Alexander Arms came to their gunsmithing school and AA oversaw the use of their own factory reamer. Our gunsmith had a broken Les Baer bolt on his own rifle chambered using the AA factory reamer.
He concludes, as he did previously and as I reported, that there is a bolt problem—apparently more frequently with Les Baer bolts than with AA bolts.
300ACC for is for morons, the like that wear skinny jeans, drive a prius and watch american idol. It has ALWAYS been a niche catridge with a narrow performance envelope. Mass marketing targeting mouthbreathers does not change physics. 100% Hype and unless your running SBR + Can, pretty fucking pointless. Spend $400 on a M92 7.62x39 Pistol and you have 300ACC performance out of a cheaper, more reliable and capable design.
6.5G and 6.8SPC II are both great canidates for those that cant step up to .308 case and larger or want to do it cheaper and don't need the range/energy that .260/6.5CM give you. Problem is you are either stuck with cheap shitty componets, or expensive high end ones. There is no middle ground for building a good shooting, inexpesnive 6.5G/6.8SPC.
I would rather have .308/6.5CM/.260 at the end of the day. Ammo is similar priced but has much better energy/range.
6.5G and 6.8SPC II are both great canidates for those that cant step up to .308 case and larger or want to do it cheaper and don't need the range/energy that .260/6.5CM give you. Problem is you are either stuck with cheap shitty componets, or expensive high end ones. There is no middle ground for building a good shooting, inexpesnive 6.5G/6.8SPC.
I would rather have .308/6.5CM/.260 at the end of the day. Ammo is similar priced but has much better energy/range.
Another possible path comes to mind. Wait for Desert Tech's MDR, a bull pup semi-auto available in .308, and suppress it.
Desert Tech MDR: a different breed of bullpup
Desert Tech MDR: a different breed of bullpup
Every cartridge is a niche cartridge. There is not a single caliber, or round that can do it all. Sure some are pretty flexible and some are really limited.
Same goes for firearms not one can do it all.
Same goes for firearms not one can do it all.
Interesting reading here. I first forayed into the Grendel three years ago. Build one and shot it for awhile but moved on to different things since I was going crazy trying everything. I've learned alot more and am more refined in what I want. I've had a dozen or so large frame AR's in .260, .243 and .308. They were great and shot very well but for me just to heavy for anything other than prone shooting. I want to hunt with my AR so something in the AR15 frame was necessary so I built another Grendel. My new one is all billet with the Spikes enhanced lower with all the cool stuff and an ambi side charge upper. JP captured spring and a LUTH-AR stock make it the sweetest shooting AR I have ever shot. It weighs in at a total of 10lbs with the 4-16 Vortex Viper HS-T scope. It has a 20" Satern Liberty barrel which was the one they had issues with early on. Since it is new I'm sure they have it all figured out. It is by far as accurate as any rifle I have ever owned. Below the pic shows a .20 3 shot group with the 123 Amax at 2410 FPS during my load workup. I have since duplicated groups similar to this with 5 round groups. More impressive to me is I shot this load out to 710 yards dumping a 25 round mag on a 18" ISPC steel target without a miss. I did not take it farther because I ran out of elevation so I have to buy a 20 MOA mount. It is hard for me not to be impressed with this caliber and rifle since I don't consider myself to be a highly talented shooter.
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The problem with the Les Baer bolts was using 8620 and bad metallurgy. 8620 is more unforgiving, especially with the small dimensions of the AR15 bolt, and is what prompted the military to look at different tool steels for the M16 after bolt longevity became a problem for the 5.56 NATO. The original cartridge that the AR15 was chambered for and what all the dimensions were based on is the .222 Remington, which is rated to 50,000 psi MAP by SAAMI.
When you analyze all the critical dimensions for the AR15, especially strengths of the barrel tennon, everything makes sense based on that .222 Remington. It then becomes understandable why they specified certain barrel steels, bolt metallurgy, the HPT/MPI shot peening process for bolts, Carpenter 158, etc. 5.56x45 was generating average operating pressures much higher than .222 Remington, and the critical dimensions of the rifle simply weren't engineered around 5.56x45.
There is a lot of talk about just using a .308 versus the Grendel. I've owned a bunch of AR10's, and regularly shoot them throughout the year. After having had two .260 Remington's in AR10's and the Grendel's, I don't own anymore .308's. The only thing .308 has going for it in my experience is ammunition availability, but I never shot any factory ammo through my AR10's for two reasons:
* Most .308 factory ammo was inappropriate for my uses.
* The ammo that did interest me doesn't run well in gas guns.
Same thing with my .260 Remington AR10's, but there is no ammo that is meant to run in them, and I strictly hand load for .260. My 22" .260 Rem AR10 upper weighs more than my entire 16" Grendel with scope and magazine at 8.6lbs. I could build a super lite .260 Remington, and probably will, but it still won't have 36 factory loads that work for it, and we're looking at literally only 200yds of supersonic reach difference between my 22" .260 Rem and my 16" Grendel, which is still supersonic out to 1318yds.
Like I mentioned, I do a lot of shooting from positions. I'll be on target much faster than you can with a .308 all day long with the way a little lightweight carbine handles. You might say, "Use a muzzle brake." I steer clear from brakes because of the ill effects in close quarters and those around me, as I do a lot of shooting with people to my left and right.
I also just ran the numbers again for a 12" .308 vs. an SBR Grendel, with the 123gr A-MAX or SST vs. a 155gr .308 A-MAX with .435 BC at 2400fps, which is favorable for the .308 Winchester from a 12" gasser. Most people are in the mid 2300's with 12" pipes in .308 Winchester. I ran the 12.5" Grendel at 2320fps. 14.5" Grendel's have been in the 2420fps range on the high end with factory A-MAX, but average in the 2350fps range.
Anyway, trajectory-wise, they are almost identical out to 600yds, but the Grendel has less wind drift from the start. After 600yds, the Grendel SBR is flatter. Energy on target is very close if you look:
6.5 Grendel 12.5" Barrel 123gr 2320fps
.308 Winchester 12" Firebreather 155gr A-MAX .435 BC 2400fps
Then when you figure the Grendel has roughly half the recoil of that .308, it starts to make a lot of sense. Barely under .308 performance in terms of on-target energy, but half the recoil, better supersonic reach, lighter weight system, ammo is actually designed specifically for the AR15, more ammo capacity per weight, less wind drift...I didn't just come to this conclusion by running the numbers, as I have 5 years of time on target with it now.
My .260 Remington spends a lot of time at home, while the Grendel has been getting more time than my 5.56 blasters. I would never have guessed that when I started dabbling in the Grendel.
When you analyze all the critical dimensions for the AR15, especially strengths of the barrel tennon, everything makes sense based on that .222 Remington. It then becomes understandable why they specified certain barrel steels, bolt metallurgy, the HPT/MPI shot peening process for bolts, Carpenter 158, etc. 5.56x45 was generating average operating pressures much higher than .222 Remington, and the critical dimensions of the rifle simply weren't engineered around 5.56x45.
There is a lot of talk about just using a .308 versus the Grendel. I've owned a bunch of AR10's, and regularly shoot them throughout the year. After having had two .260 Remington's in AR10's and the Grendel's, I don't own anymore .308's. The only thing .308 has going for it in my experience is ammunition availability, but I never shot any factory ammo through my AR10's for two reasons:
* Most .308 factory ammo was inappropriate for my uses.
* The ammo that did interest me doesn't run well in gas guns.
Same thing with my .260 Remington AR10's, but there is no ammo that is meant to run in them, and I strictly hand load for .260. My 22" .260 Rem AR10 upper weighs more than my entire 16" Grendel with scope and magazine at 8.6lbs. I could build a super lite .260 Remington, and probably will, but it still won't have 36 factory loads that work for it, and we're looking at literally only 200yds of supersonic reach difference between my 22" .260 Rem and my 16" Grendel, which is still supersonic out to 1318yds.
Like I mentioned, I do a lot of shooting from positions. I'll be on target much faster than you can with a .308 all day long with the way a little lightweight carbine handles. You might say, "Use a muzzle brake." I steer clear from brakes because of the ill effects in close quarters and those around me, as I do a lot of shooting with people to my left and right.
I also just ran the numbers again for a 12" .308 vs. an SBR Grendel, with the 123gr A-MAX or SST vs. a 155gr .308 A-MAX with .435 BC at 2400fps, which is favorable for the .308 Winchester from a 12" gasser. Most people are in the mid 2300's with 12" pipes in .308 Winchester. I ran the 12.5" Grendel at 2320fps. 14.5" Grendel's have been in the 2420fps range on the high end with factory A-MAX, but average in the 2350fps range.
Anyway, trajectory-wise, they are almost identical out to 600yds, but the Grendel has less wind drift from the start. After 600yds, the Grendel SBR is flatter. Energy on target is very close if you look:
6.5 Grendel 12.5" Barrel 123gr 2320fps
Code:
Range Velocity Energy Trajectory TOF Drift
(yards) (fps) (ft-lb) (MILS) (sec) (MILS)
0 2320 1470 0.00 0.0000 0.00
25 2279 1418 -0.54 0.0326 -0.06
50 2238 1368 0.07 0.0658 -0.12
75 2197 1319 0.11 0.0996 -0.18
100 2157 1271 0.00 0.1341 -0.24
125 2118 1225 -0.17 0.1692 -0.30
150 2078 1180 -0.37 0.2049 -0.36
175 2040 1136 -0.59 0.2413 -0.42
200 2001 1094 -0.83 0.2785 -0.49
225 1963 1053 -1.08 0.3163 -0.55
250 1926 1013 -1.35 0.3549 -0.62
275 1889 974 -1.63 0.3942 -0.69
[b]300 1852 937 -1.91 0.4343 -0.76[/b]
325 1816 901 -2.21 0.4752 -0.83
350 1781 866 -2.52 0.5169 -0.90
375 1746 832 -2.83 0.5594 -0.97
400 1711 800 -3.16 0.6028 -1.05
425 1677 768 -3.50 0.6471 -1.12
450 1643 738 -3.84 0.6922 -1.20
475 1611 708 -4.20 0.7383 -1.28
[b]500 1578 680 -4.57 0.7854 -1.36[/b]
525 1547 653 -4.95 0.8334 -1.44
550 1516 627 -5.34 0.8824 -1.52
575 1485 602 -5.74 0.9324 -1.61
600 1455 578 -6.15 0.9834 -1.69
625 1426 556 -6.58 1.0354 -1.78
650 1398 534 -7.02 1.0885 -1.87
675 1371 513 -7.47 1.1427 -1.96
[b]700 1344 493 -7.94 1.1980 -2.05[/b]
725 1318 475 -8.42 1.2543 -2.14
750 1293 457 -8.91 1.3118 -2.23
775 1269 440 -9.42 1.3703 -2.32
800 1246 424 -9.95 1.4300 -2.42
825 1224 409 -10.49 1.4907 -2.51
850 1202 395 -11.04 1.5526 -2.61
875 1182 382 -11.61 1.6155 -2.71
[b]900 1163 369 -12.20 1.6795 -2.80[/b]
925 1144 358 -12.80 1.7446 -2.90
950 1127 347 -13.43 1.8107 -3.00 Still supersonic
975 1110 337 -14.06 1.8778 -3.10
1000 1095 327 -14.72 1.9459 -3.19.308 Winchester 12" Firebreather 155gr A-MAX .435 BC 2400fps
Code:
Range Velocity Energy Trajectory TOF Drift
(yards) (fps) (ft-lb) (MILS) (sec) (MILS)
0 2400 1982 0.00 0.0000 0.00
25 2351 1902 -0.58 0.0316 -0.06
50 2302 1824 0.04 0.0638 -0.13
75 2254 1748 0.09 0.0967 -0.20
100 2206 1675 0.00 0.1304 -0.26
125 2159 1604 -0.15 0.1647 -0.33
150 2113 1536 -0.34 0.1998 -0.40
175 2067 1470 -0.56 0.2357 -0.48
200 2021 1406 -0.79 0.2724 -0.55
225 1977 1345 -1.03 0.3099 -0.62
250 1933 1285 -1.29 0.3483 -0.70
275 1889 1228 -1.56 0.3876 -0.78
[b]300 1846 1173 -1.84 0.4277 -0.86[/b]
325 1804 1120 -2.13 0.4688 -0.94
350 1763 1069 -2.43 0.5108 -1.03
375 1722 1021 -2.75 0.5539 -1.11
400 1682 974 -3.07 0.5980 -1.20
425 1643 929 -3.41 0.6431 -1.29
450 1604 886 -3.76 0.6893 -1.38
475 1567 845 -4.12 0.7366 -1.47
[b]500 1530 805 -4.50 0.7850 -1.57[/b]
525 1494 768 -4.89 0.8346 -1.66
550 1459 732 -5.29 0.8855 -1.76
575 1425 699 -5.71 0.9375 -1.86
600 1392 667 -6.14 0.9907 -1.96
625 1360 636 -6.59 1.0453 -2.07
650 1329 608 -7.05 1.1011 -2.17
675 1299 581 -7.53 1.1581 -2.28
[b]700 1271 556 -8.03 1.2165 -2.39[/b]
725 1244 532 -8.54 1.2762 -2.50
750 1218 510 -9.07 1.3371 -2.61
775 1193 490 -9.62 1.3994 -2.72
800 1170 471 -10.19 1.4629 -2.83
825 1148 453 -10.78 1.5276 -2.94
850 1127 437 -11.38 1.5936 -3.06
875 1108 423 -12.01 1.6607 -3.17 No longer supersonic
[b]900 1090 409 -12.65 1.7290 -3.28[/b]
925 1073 396 -13.32 1.7984 -3.40
950 1057 385 -14.01 1.8688 -3.51
975 1042 374 -14.71 1.9403 -3.62
1000 1028 364 -15.44 2.0128 -3.73Then when you figure the Grendel has roughly half the recoil of that .308, it starts to make a lot of sense. Barely under .308 performance in terms of on-target energy, but half the recoil, better supersonic reach, lighter weight system, ammo is actually designed specifically for the AR15, more ammo capacity per weight, less wind drift...I didn't just come to this conclusion by running the numbers, as I have 5 years of time on target with it now.
My .260 Remington spends a lot of time at home, while the Grendel has been getting more time than my 5.56 blasters. I would never have guessed that when I started dabbling in the Grendel.
LRRP, c'mon man. I've seen a bunch of your posts and they've all been spot on. This one though, this one is reaching like a mofo. If you want to compare the efficacy of an SBR in 308 to one in 6.5G then at least note that you're using a shit projectile in the 308. The whole velocity thing is also BS. POF has chrono'd factory 178's at an AVERAGE of 2311fps. Getting 2400 out of a 150 or 155 is EASY. That isn't even a hot load. Hell, I almost exclusively run the 1.370" (surprisingly shorter than the 185 grainer) 190 gr Berger Hunting VLDs at 2285fps in my 12" 308 and it demolishes anything the 6.5G would put out of a 12.5" barrel at 2325.....and my complete 12" 308 weighs a hair over 7 lbs. We both know that ain't heavy for any rig putting 1600 fpe on a target at 500 yards. Using the 190 gr I can out shoot a 12.5" shooting a 123 gr Scenar with .527 BC at 1000 yards - that would include elevation & wind drift (with 10mph full value from 3 o'clock) as well as energy on target. The versatility of the 308 in terms of the variance in projectile weight in the context of a hunting application really can't be touched by the 6.5G.......... Unless you're dead set on using .435 BC projos in your .308 of course.
The 6.5G is a bad ass AR15 chambering though....I think I prefer it in a 14.5" or 16" midlength to get all the value I can out of it...
The 6.5G is a bad ass AR15 chambering though....I think I prefer it in a 14.5" or 16" midlength to get all the value I can out of it...
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I agree with this. Comparing SBR .308 is sort of cherry picking the data. Most powders are not even close to burning out which is why building a .308 gun under 16in is reserved for fools.
Also, .308 Case, not .308 is what we be talking about. .260/6.5CM blow .308 out of the water at range. Lets compare two 18-20" 6.G and 6.5CM and see what the number gods say?
LRRPF52 has "been there, done that", including humping the M249 and running the M240. He's competed at the highest levels of International long range competition, (think Finnsniper, if you are familiar with it).
And he did compare the .260 and the Grendel, note that he points out the difference in supersonic flight is only about 200 yards.
The comparison is valid, because you are talking about rifles that have significantly different recoil reactions. The .260, 6.5 CM, and 6.5 Lapua all have signficantly more recoil than the Grendel does in a much lighter rifle. None of them have any significant number of factory loads that will run in them, while the Grendel has ammo from AA, Hornady, Precision Firearms, and Black Hills, all of which will run in the gas guns.
Try running factory .260 or 6.5CM loads in a gas gun and you are asking for issues.
Thanks for the history lesson captain obvious. I know who he is and pm with him a good amount. There are alot of people on this forum who have humped a saw or 240, and much much more. Thats not going to impress me.
If you actually read the data he posted, its a bullshit, straw man argument (sorry LRP). Anyone who has BTDT, knows that SBR length .308 case rounds plain fucking suck. They are ballistically anemic and half the powder is burnt outside of the barrel. The 6.5G is not a SBR round, its a mid to long range round. The same as .260 and 6.5CM. The difference is the .308 case rounds do it faster, with more energy and with better bullets. Let me know how that works out trying to push 142gr SMK's and 139GR scenars out of your 6.5G @ mag length.
Recoil is a TRAINING issue. While the .260 and 6.5CM have more recoil, its nominal. They are also usually pushed out of heavier guns and with modern muzzle breaks, its a moot point. For anyone to take advantage of the benefits of these rounds, they are already going to have the fundamentals down where recoil is NOT an issue. 6.5CM &.260 are pussy fart rounds. Much less recoil than .308, which is considered mild by itself.
Amazing my gas guns have no problem running .260 or .308. My SR25 will not choke (and neither will my SCAR), nor any of the .260 guns I have built. Using SW and Copper Creek Factory loads, I have zero ammunition related issues, other than it is fucking expensive. Poorly built homebrew guns or guns that are not tuned to the loads being shot are the issue. The same issue is with 5.56 class guns as well. Almost every gun on the market is under/overgassed to common M193/M855 loads.
My .260 out of a 20in barrel stays supersonic to 1575yds at sea level with 123gr Scenars. Could easily push more range with a longer barrel. The difference is, after about 500 yards, the .260/6.5CM are going to have less drift, more speed and more energy down range, while being able to do it with higher BC pills. If shooting paper, rocks or steel is your thing, than 6.5G is fine out a grand. You probally wont be able to see the splash, but oh well. If you actually hunt people or animals, than the .308 case rounds are on a whole nother level.
Never mind, you're so far off the OP questions that its just useless.
For the OP.....The Grendel will do anything supersonic the 300 BO will do, and will do it further out. The 300 BO shines as a subsonic load, particularly suppressed.
That's it in a nutshell.
For the OP.....The Grendel will do anything supersonic the 300 BO will do, and will do it further out. The 300 BO shines as a subsonic load, particularly suppressed.
That's it in a nutshell.
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I was responding to a post, that YOU also decide to interject into.
You are just regurgitating what I said on the last page.
Yes, except I recognized how far off topic we were and quit, something you apparently are incapable of accomplishing. So go on and have the last word!
Now I remember why I never posted after joining almost 4 years ago. To much phallic wagging going on, too little actual help.
Now I remember why I hope people like you continue to refrain from contributing bull shit.
Clearly, the OPs initial questions had a significant number of responses. In the mean time, there were other ludicrous notions flung about (4.5 lb 6.5G SBRs, recoil impulse based on cartridge without taking into account the multitude of ways that could be managed, energy, weight, and external ballistics compared to AR10 cartridges with cherry picked data, etc) that deserved a response. If no one does, then some poor fuck who comes along reading this shit will think what you and some of your buddies are suggesting holds merit. Since it doesn't, appropriate responses were made.
Clearly, the OPs initial questions had a significant number of responses. In the mean time, there were other ludicrous notions flung about (4.5 lb 6.5G SBRs, recoil impulse based on cartridge without taking into account the multitude of ways that could be managed, energy, weight, and external ballistics compared to AR10 cartridges with cherry picked data, etc) that deserved a response. If no one does, then some poor fuck who comes along reading this shit will think what you and some of your buddies are suggesting holds merit. Since it doesn't, appropriate responses were made.
No, actually, not one single appropriate, reasoned response. You and those like you love to wag, but can't discuss without accusing everyone else of "cherry picking" or "stacking the deck" etc. You all act like liberals who love to yell and shout about how the right does it wrong, but can't actually deal with facts. If LRRPF had picked a 175 or 190 out of an SBR, you would have screamed about how heavy bullets shouldn't be shot from SBR's. He picked the most reasonable bullet to do so, and you wag about how he cherry picked the wrong bullet and how the powder in a .308 can't be used in such a short barrel. BS. You knew nothing about what powder he used. He chose to use a reasonable velocity out of a short barrel, in comparing to SBR's, that's all. He may have gotten that velocity using pistol powders, for all you know.
Go back and read MY posts and tell me how I'VE been posting anything of the sort. I simply pointed out that his comparison was valid. SBR vs SBR, reasonably comparable bullets, etc.
You guys all need to go back to school and learn some manners, and how to debate in an adult world, using adult language, not gutter talk. Your credibility flies out the window the first time an "f word" pops up. As I was taught at a young age by a wise man, "Those who cannot distinguish between good and bad language, or find the distinction unimportant, are unlikely to think carefully about anything else!" I'm becoming convinced that there are too many here that fit that description.
Cry me fucking river Iceman. The comparison using a .435 BC .308 projo was in no way legitimate compared to a .510 BC .264 AMAX/SST - especially when there's a laundry list of projectiles that would exacerbate the issue of a 308 clearly outperforming it in an SBR. I can easily post the data, but I don't have to. Anyone can run the data through any of the available programs out there and clearly see the difference.
Read your posts? You just carried on about the .260 vs 6.5G above - not the 308 vs 6.5 in an SBR. You didn't point out shit being legitimate other than the 200 yds of difference between supersonic range of a 260 and 6.5, but rather immediately fell back to how awful recoil is in 308-case calibers. WTF are you taking about?
I didn't say shit about powders btw.
As to your "wise man" quote..... that shit is gayer than cum on a mustache.
Read your posts? You just carried on about the .260 vs 6.5G above - not the 308 vs 6.5 in an SBR. You didn't point out shit being legitimate other than the 200 yds of difference between supersonic range of a 260 and 6.5, but rather immediately fell back to how awful recoil is in 308-case calibers. WTF are you taking about?
I didn't say shit about powders btw.
As to your "wise man" quote..... that shit is gayer than cum on a mustache.
From your post its apparent you would be an expert on that, at least!
Your language relegates you to the group of troglodytes that anti-gunnies wish to smear all 2nd Amendment proponents.
Holy shit, how about actually reading the thread before spouting off.
The comparison was an SBR Grendel to the American Standard .308 in an SBR of equal length. The OP asked about a 300 BO vs a Grendel, so we've moved ahead with the assumption that he was referring to SBRs and have moved ahead accordingly. Therefore, it's a legit comparison here.
"The 6.5G is not an SBR round"??? WTF??? What is an SBR round? Was the Grendel not designed for the AR15???? Yes. Has the Grendel not be ran out of 10.5 barrels reliably from its inception? Yes. It's in no way the same as the 260 or Creedmore in respect to a 10.5"-14.5" barrel. The Grendel utilizes faster powder, making it more efficient in the shorter barrels.
He never said ANYTHING about people having problems with hand loads tuned to the gun. He referenced the problem with FACTORY loaded ammunition in a gas gun.
And a 123gr Scenar out of a 20" Grendel at Sea Level can be expected to stay supersonic to 1250 yards. That's a 275 yd difference. Still in line with the comparison.
For heavens sake. Even Marine Grunts have to score to a certain level on the ASVAB to hold specific 03xx jobs. Can we not enforce an IQ level on this board using a common test?
Like this shit. Lets at least enforce some reading comprehension.
Sub 5lb Grendel. Why the hell not. If someone wants to spend their money trying to see how far they can push the platform and cartridge in a specific direction, why the hell is that ludicrous??? Because you deemed it so??? On what merits? Lay them out and lets have a real conversation.
If someone doesn't understand the basics of physics in that less weight means more recoil, they're not ready to be building their own rifles. Plain and simple.
Some of us enjoy what little bit of hearing we have left and so choice to stay away from muzzle brakes. That and I just can't look at myself in the mirror as a man after using a muzzle brake on something smaller than a mag caliber. (That being said I don't have physical limitations to that degree after my service, that prevents me from taking the recoil.)
Again not cherry picked data, it's relevant to the subject at hand. If you have other data that blows that comparison away, please share it.
No one is claiming the Grendel blows away the .308. All we are saying is the Grendel will meet 90% of the needs that the .308 fulfills in a lighter platform. Can the .308 be pushed further yes.
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Where did the OP say ANYTHING about SBR's? Where? You can't just change the variables in an argument because it suits your position.
The fact is, the majority of shooters are morons and ignorant. They do NOT know shit about ballistics or that the 300 is a SBR optimized round.
You are just reaching for shit to argue about now. Supersonic doesn't mean shit if it has no energy behind the round.
If you want to get into a dick measuring contest about ASVABS, we can have a go. 17, half drunk and running on 2 days of no sleep I pulled a 96 out of my ass. I work with Navy and Marine personal everyday.....not impressed.
as·sump·tion - a thing that is accepted as true or as certain to happen, without proof.
Google is your friend.
https://www.google.com/search?q=def...rls=org.mozilla:en-US:official&client=firefox
SBR length barrels have been the topic from the beginning.
A Grendel is NOT an ethical hunting round at 1200+ yards , and neither is a .308, nor is a 260/Creedmore . That being said I wouldn't want to be on the receiving end of any of them at that range.
So what exactly was your point???
Oh was it that the .308 is a larger projectile and must have more energy at the same velocity.
Time for a physics lesson. KE (Kinetic Energy) = mV^2 (mass * (velocity^2))
So lets look at a 6.5mm 140gr projectile and a .308 178gr projectile at 1700 fps.
The 6.5mm projectile has 525 ft*lbf of energy as opposed to the .308's 667 ft*lbf.
The .308 looks like it has an edge. However, it's not as much as you think. The .308's larger projectile is a structurally stronger projectile due to it's larger cross section Area. Therefore, it'll require more energy to open on game reliably. Black out Hunters have learned this first hand.
Therefore the difference here in energy is negligible assuming the right bullet was selected for the task at hand.
There's a little more to it than ballistics and mass, but you're almost there buddy.
Edited: To reflect a 178gr projectile as opposed to the 172gr projectile.
Google is your friend.
https://www.google.com/search?q=def...rls=org.mozilla:en-US:official&client=firefox
SBR length barrels have been the topic from the beginning.
A Grendel is NOT an ethical hunting round at 1200+ yards , and neither is a .308, nor is a 260/Creedmore . That being said I wouldn't want to be on the receiving end of any of them at that range.
So what exactly was your point???
Oh was it that the .308 is a larger projectile and must have more energy at the same velocity.
Time for a physics lesson. KE (Kinetic Energy) = mV^2 (mass * (velocity^2))
So lets look at a 6.5mm 140gr projectile and a .308 178gr projectile at 1700 fps.
The 6.5mm projectile has 525 ft*lbf of energy as opposed to the .308's 667 ft*lbf.
The .308 looks like it has an edge. However, it's not as much as you think. The .308's larger projectile is a structurally stronger projectile due to it's larger cross section Area. Therefore, it'll require more energy to open on game reliably. Black out Hunters have learned this first hand.
Therefore the difference here in energy is negligible assuming the right bullet was selected for the task at hand.
There's a little more to it than ballistics and mass, but you're almost there buddy.
Edited: To reflect a 178gr projectile as opposed to the 172gr projectile.
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I grabbed my laptop when I came in to take a shit because I couldn't find my cell phone. Usually I play candy crush. Anyways I figured I'd hop on the Hide and see what's happening. Not much. I saw this thread was #2 (how fitting) in line from the top, so maybe something productive has happened since I left it alone. Nope. At least I got a couple extra turds out in the time it took me to read this that otherwise wouldn't have been waited on.
Still waiting to see where the OP said or refferenced ANYTHING out SBR's.
I'll be waiting...............
So you disagree with the assumption most people here to include myself have made.
Alright so shall we compare a 20" Grendel to a 20" BO?
The BO would nominally run supersonic projectiles similar to the Grendel's in mass and velocity.
With Mass, Velocity, and bullet construction being the same the Grendel projectile is more effective, per the structural properties I stated above.
The design purpose of the Blackout was subsonic use, with ability to use lighter projectiles at supersonic velocities. Since the design plan was subsonic, and longer barrels increase the probability of supersonic rounds, even when subsonic are desired, there aren't a lot of rifle length BO's built. Subsonic rounds are developed based on short barrel velocities. Take a 950 FPS sub and put it in a 20" barrel and you are going to have a supersonic round, irregardless of its a 9mm, 45, or BO.
Thus when discussing BO's, the general assumption is that you are talking SBR. The BO's raison d'etre is subsonic use. Why would anyone want to take that away by using a rifle length tube?
So when you say compare and contrast the BO and the Grendel, the immediate assumption of any knowledgeable person is that you are wanting to discuss their use in SBR's. Nothing else makes sense.
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Iceman you are wrong. The whisper was a subsonic round but the owner being a I know best guy sold the round short, buy trying to keep the whisper a whisper. Then along comes the copycats who changed it to use 223 brass. They found out if you put in a 115 to 125gr bullet you get AK performance without having a frakking AK. Fast forward to the blackout they are pandering to both groups the fast and the quiet. Some who run the blackout will never run suppressed and some will never shoot supersonic intentionally. Lol some big money guys do not even hand load. Not all factory subsonic ammo is the same speed. Some is made for the 16 inch crowd while some is made for handguns and the SBR groups.
Thank you for saving me from having to type this out.
Its like, "God Created the Earth, and on the 6th day....He created the .300 Blackout ACC." around these dipshits.
Assumtion as in taking a question and creating a whole nother topic/cherry picked disscussion out of it?
NO one was comparing a 20" gren to a 20" BO. It was related to the Gren/.308 cased sidebar. Once again, using cherry picked datat points knowing that one option is not used in that configuration beacuse of poor performance is intellectually dishonest.
Go back, Read the OP 10 times. The tell me what about it screams SBR? Has the OP even said ANYTHING else in this thread that would indicate that?
Still waiting..........
No sir, you go back and tell me where it says anything about the .308. It doesn't!
The conversation drifted into comparing the SBR Grendel that was being discussed with the American Standard .308 in an SBR length.
You previously declared the majority of shooters to be "morons". Looks to be the pot calling the kettle, black.
Oh and it's assumption, not assumtion. And that's what assumptions are for, narrowing down the scope of the analysis/conversation.
Guys, have any of you done ANY research on the round. AAC was determined it had to be subsonic, they wanted it subsonic, they developed it subsonic, they're a freaking suppressor manufacturer, they wanted an ultraquiet round. No way is the supersonic version quiet! They included a parameter that allowed the use of supersonic rounds, and specced that it should match, at a minimum, AK 7.62x39 performance, but the purpose of the round was subsonic.
Most of the subsonic commercial rounds will go supersonic in barrels over 16", heck, maybe all of them do. Most are right at the margin in 14" barrels.
To believe that anyone considering a BO would not be considering it in an SBR is ridiculous, the whole thing was patently developed for SBR use. It was developed for self defense and close contact "high speed, low drag" type situations, though most people will never use it for either.
I've heard lots of these conversations from living people, and no one I've ever heard has said, "I'm looking for a 20" (or even 18") BO." At a maximum they are looking for a 16" because they don't want to wait for NFA approval. The VAST majority want a 10" so they can put a suppressor on it and use it while maintaining a reasonably short profile. Even then it pushes past M4 length. With a 16" barrel and suppressor it pushes to M16 length! Not once have I seen a 18" or longer barrel in any store. A quick online search shows nothing longer than 16", with lots of 9", 10" or similar options. I'm sure someone can go find a longer rifle and then say "I told you so", but the truth is that it was developed for SBR's up to 16". While most qualify SBR's as being under 16", because of the NFA guidelines, there is no real difference between a 15.9" SBR and a 16" carbine.
So, regardless of what the OP stated, in virtually everyones mind a BO is an SBR, or at least most of the manufacturers agree that 16" is the upper limit that people seem to want.
Are u fucking retarded or are you just trolling me?
Read the fucking post I just made.
THE 308CASE/6.5G WAS A SIDEBAR.
Stop trying to change the subject.
If you care about my spelling, it means your arguement is so weak you are grasping at straws. If you want to come type for me like my cute secretary, I'll pm you an address.
What has AAC created other than a million dollar marketing campaign? You are either room temp IQ or have some sort of cognitive disorder. I don't know wheather to get pissed or feel sorry for you.
Do you have a point, or do you just want to insult everyone? The Whisper was a perfectly good niche cartridge. AAC broadened its scope, taking it into a market that was asking for options. They copied the Whisper, and added a supersonic load that people could use when it fit their needs.
The point is that any conversation about it begins and ends with 16" or shorter barrels, thus the discussion about SBR's.
The BO is ONLY unique in its SBR and subsonic capabilities, otherwise its just a 7.62x39 in a 5.56 blanket.
At this point, though, everything is pretty much useless to the OP. Hopefully he can sort through and get the information he needs.
PS--My last official IQ test put me short of Benjamin Netanyahu's, but in front of Bill O'Reilly, so I think I'm Ok there. LOL
As far as cognition, I deal everyday with something like 2 to the 20th power variables several times an hour. I've yet to be sued for making a mistake doing that for the past 20 years, so I think my cognitive powers remain relatively undiminished as well.
Sorry to disappoint you on both counts.
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