Good fast powder for 77gr SMK out of 10.5" AR?
- Thread starter Formosan
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I don't for a 10.5" but I got good velocities out of my 14.5" with TAC and 77TMK's.... .223 Wylde Chamber, I think I worked up to 24.5gr of TAC safely. I forget what it did out of my 14.5" but it ran around 2775-2820fps out of my 18.5"
Not sure if someone has ran maybe a faster powder ... something like AA2230 (have not tried it myself)
Obviously whatever you're doing, make sure you work up your load. 24.7gr was the max for NATO pressures, SAAMI was 23.9 or something like that.
Ditto for me on TAC. I've run up to 24.8gr with a 77 SMK with no pressure signs in my 18" Savage MSR. Didn't grab chrono data for that load but at 24.3 I'm getting MV of right about 2750
I did pressure testing up to 24.7 I think. Decided to back off from that. My 18" runs suppressed and it was getting super gassy and you could tell it was recoiling harder, and shooting hard lol. Velocity also peaked for me there, so went with 24.5. Its a great powder
How far do you shoot your 10.5? Any reason not to shoot a cheap 55g instead of a 77g? I was shooting 53 v-maxes at p-dogs around 1k this morning. 5 to 5.5 mils of wind. I never hit one that far, but I was kneeling shooting off a tripod also. I cracked a bunch of them standing with the tripod from 100-400 though. The 53 v-max is ok out to 500-600 if the wind is steady. A little gusty turns it into a crap shoot quickly.
I've recently chrono'd 24.5gr of Tac with the 77gr smk through the 18"woa and it was averaging 2780 I think.
I'd like to shoot up to 200 yards on feral hogs with the 10.5" CHF PSA FN barrel.
How small of a group am I likely going to see if I work up a load of 77smk?
Not exactly what your looking for but here is a seating depth test with 55VMAX and H4895 out of my 10.5" DD Govt barrel. You can see the speeds on those 55VMAX and they shoot lights out.... 5 shot groups @ 100yds avg around .5" with the optimal seating depth at .3".... Load development was all done from the bench with bipod and rear bag and a Gen1 Razor HD scope. I dont have the speeds for those 77xx/8208XBR loads but the 77's just werent as accurate as the 55 VMAX's..
My ever-present GP truck gun is a 10.0"/10.3"/10.5" M4 carbine with an M4 can attached. TAC at 5.56MM NATO pressure works very well under the 77GR. SMK in 10" class barrels. It is fast (2450 FPS from 10.3" MK18 w M4 can) and its accurate, on par with 77GR. SMK OTM based BHA MK 262 MOD 1 factory load. But I swapped over to the 77GR. TMK for better terminal performance on varmints/predators/hogs/whitetail. The non yaw dependent TMK yielded a big step up in 5.56MM terminal performance over the yaw dependent SMK with almost the same MV/accuracy. Ramshot/Western publishes data for both .223 & 5.56MM NATO pressure. Barnes also publishes both sets of data for use with their 0.224"TSX/TTSX bullets fired from several barrel lengths including the 10.5". HTH
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What velocity is that getting you? I'm running that under a 75gr and am getting 2660-2680 out of an 18".
IMR 8208 XBR produces good MV with low ES/SD along with a very high level of thermal stability. It is the propellant I use for my best LR 5.56MM accuracy loads. SWA produced an outstanding 5.56MM pressure 77GR. SMK OTM load over 23.8GR. IMR 8208 XBR in new LC brass. A 5.56MM 77GR. SMK over 23.8GR of IMR 8208 XBR handload is approx 80 FPS slower than the MAX published 5.56MM NATO TAC load. But it is a couple 0.1s more acccurate. Interestingly, the MV of the SWA load was within just a few FPS of the outstanding 5.56MM BHA AMU 77GR. SMK load (approx. 2744 FPS from 18" SPR with M4 can attached at 80F).
I shoot quite a lot of 5.56 77 SMK ammo. For year round reliability I find that 24.3 grains TAC is the top load in the .223 Wylde chamber and 7 twist LC brass. Any hotter and hot weather will blow some primers. Velocity is 2750 in 18" barrels. No idea how folks are getting reliability from hotter loads?? I sure never could do so.
We started developing our own 5.56MM pressure TAC loads well before any data was published. The load we settled on was only 0.1GR. off the published data when it was finally released. First and foremost, any MAX 5.56MM NATO pressure load (62,366 PSI) will wreck even new LC 5.56MM brass primer pockets in as little as 2-3 firings. I fire mine 2X and leave the brass where it falls. I don't use once-fired MG brass for MAX 5.56MM NATO loads. And all my chambers are 5.56MM NATO except for the 18" SPR which has a CLE MATCH 5.56MM chamber which appears to behave just like a 5.56MM NATO chamber for me in regards to pressure. I have heated my MAX TAC loads to 135F and no primers backing out. Your chamber might be a bit on the tight side. Also, LOT to LOT variation of TAC or any other propellant is not to be ignored. It may be zero, it may be 3%, or anywhere in between. 24.3GR. of your LOT of TAC may well be MAX in your barrel.
For thermal stability, I use IMR 8208 XBR in 5.56MM. MAX 5.56MM NATO IMR 8208 XBR rounds cooled to -10F were only 18 FPS slower than rounds heated to +135F. MAX 5.56MM NATO TAC rounds varied by 118 FPS from -10F -+135F.
For thermal stability, I use IMR 8208 XBR in 5.56MM. MAX 5.56MM NATO IMR 8208 XBR rounds cooled to -10F were only 18 FPS slower than rounds heated to +135F. MAX 5.56MM NATO TAC rounds varied by 118 FPS from -10F -+135F.
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IME, I found TAC to be too temperature sensitive. I had two good loads, one at 23.4 and one at 24.5gr, both hammers. The 24.5 was a little less admirable in the ES/SD area, but it was smoking fast. Both loads started dropping 20-40fps when I went from 85 to 65 degrees. For me, thats just too much.
I'd love to use more TAC as I like it, but its only use for me was for precision, so I traded it for XBR 8208...which is, IMO, one of the best .223/5.56 AR powders out there.
This is REALLY great info. Really cool to see you do the temperature testing like that.
Have you worked up what would be considered 5.56 NATO max with XBR 8208?
I'm running 23.5gr now and feel like I could push harder with it. I've tested up to 24.0gr. On my OCW 24gr had a POI that was substantially different than 23.8, which could indicate a node, but I was comfortable pushing higher than that.
AFAIK, there is still no published 5.56MM NATO load data for IMR 8208 XBR. Damn shame. Several of us worked up the 77GR. SMK (not the longer 77GR. TMK) over IMR 8208 XBR in new #41 primed LC cases with COAL of 2.255" in 5.56MM NATO chamber barrels. We came to a consensus that 24.0 appeared to be the absolute MAX. So we backed it off to 23.8GR. just to give us a little safety margin for error. To help confirm this, I pulled the SWA 5.56MM 77GR. SMK load down (below). Sure enough, it was loaded with the 77GR. SMK w/o cannelure in new LC brass with 23.8GR. IMR 8208 XBR. It was one of only a handful of factory 5.56MM 77GR. SMK OTM loads I felt were capable of 0.5 MOA or better accuracy from an accurized AR. The mag-length BHA 77GR. SMK AMU load is another. Prior to using IMR 8208 XBR in their load, SWA stated that they used H4895 which is also a very good propellant. But the long grains don't run thru most powder throws well. And ES/SD with IMR 8208 was slightly lower than with H4895 (below). I ran a quick thermal stability test on several propellants and factory 5.56MM loads about 8 years back (also below).
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The highest velocities I've run in my MK12 clone were with TAC; however, the temperature sensitivity was a no-go for me. Varget has historically been my go to in that rifle, but it's slow. I was getting about 2,625 fps with 77 SMK at its top end accuracy node. I'm finalizing loads now using 8208 XBR under a 77 SMK and am getting better velocity. 23.5 grains of 8208 is giving me 2,717 fps and about 0.6" groups at 100 yds.
I've got a 12.5" carbine I'm also working up loads for with this combo and it's shooting 2,522 fps with 23.9 grains of 8208. 1-1.1" groups are what I'me seeing with that combo.
I haven't tried 8208 a 10.5" gun yet, but I did try some of my Varget loads and if memory serves those were at 2,200 fps. I'm guessing 8208 will run somewhere around 2,350-2,400 fps given some other velocity data I have with that rifle.
I've got a 12.5" carbine I'm also working up loads for with this combo and it's shooting 2,522 fps with 23.9 grains of 8208. 1-1.1" groups are what I'me seeing with that combo.
I haven't tried 8208 a 10.5" gun yet, but I did try some of my Varget loads and if memory serves those were at 2,200 fps. I'm guessing 8208 will run somewhere around 2,350-2,400 fps given some other velocity data I have with that rifle.
OP,
Just want to put the bug in your ear about the 77GR. TMK bullet's terminal performance at 5.56MM velocity. It kills hogs/whitetail VERY well even when fired from a little 10" M4 (exit wound on 175lb. razorback below). Since it is a longer bullet, I have to reduce the propellant charge a bit under what I normally use under a 77GR. SMK bullet to keep pressure under control. The 77GR. SMK is a yaw dependent/non-expanding/fragmenting bullet which requires approx. 2200 FPS impact velocity to fragment. The 77GR. TMK is a non yaw-dependent/expanding/fragmenting bullet that requires approx. 1900 FPS impact velocity to over-expand/fragment. Bottom line for me: I use SMKs to shoot paper/steel targets but I use TMKs to shoot flesh & bone targets. And I have also seen some very nice 5.56MM terminal performance with 5.56MM 70GR. TSX, 5.56MM 75GR. Gold Dot, and 5.56MM 62GR. Lehigh CCCu loads. HTH
Just want to put the bug in your ear about the 77GR. TMK bullet's terminal performance at 5.56MM velocity. It kills hogs/whitetail VERY well even when fired from a little 10" M4 (exit wound on 175lb. razorback below). Since it is a longer bullet, I have to reduce the propellant charge a bit under what I normally use under a 77GR. SMK bullet to keep pressure under control. The 77GR. SMK is a yaw dependent/non-expanding/fragmenting bullet which requires approx. 2200 FPS impact velocity to fragment. The 77GR. TMK is a non yaw-dependent/expanding/fragmenting bullet that requires approx. 1900 FPS impact velocity to over-expand/fragment. Bottom line for me: I use SMKs to shoot paper/steel targets but I use TMKs to shoot flesh & bone targets. And I have also seen some very nice 5.56MM terminal performance with 5.56MM 70GR. TSX, 5.56MM 75GR. Gold Dot, and 5.56MM 62GR. Lehigh CCCu loads. HTH
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5.56MM 77GR. TMK from 10 [email protected]
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That's great info, thank you.
I had always thought the terminal performance of 77smk mushroomed and not yawed.
There are some gel videos on youtube and one by AR15.com showing it expands fairly well even at low velocities. They tested out of an SBR IIRC.
Ive recently settle on IMR 8202 as my long range load for my 18" SPR because of the exact points you posted. But now i can no longer source any of this excellent powder and have used up the last of my bottle.
My second powder choice is AR-Comp, which i have to accept a slightly lower MV and less consistent SD/ES. Im down to a pound and i half.
So my third choice is to settle for a big bottle of Ramshot Tac until all this blows over. Good enough for shorter work.
The 77GR. SMK OTM based BHA MK 262 MOD 0/1 cartridge was designed to be a Hague compliant accurized 5.56MM round. In other words, the bullet can not expand so as to cause undue trauma on the battlefield. The U.S. did not sign the Hague Treaty but we abide by it under organized warfare conditions. The 77GR. SMK OTM bullets must penetrate then yaw at sufficient impact velocity to cause the bullet to rupture into small sub-projectiles (fragmentation). Below is a direct comparison of the 77GR. SMK with the 77GR. TMK both fired at 5.56MM velocity from the same 10" M4 with M4 can. I fired an M193 round just to prove that they do not normally fragment from a 10" class barrel such as was used in early Vietnam in the CAR-15. Note the lack of expansion in the small open tip of all (3) SMK OTM bullets. The TMK does not need to penetrate then yaw to over-expand then fragment. It starts destroying tissue virtually on contact with flesh & bone which is referred to as having little to no neck on the wound. HTH
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OP,
You may loose a little accuracy with a TAC load over an IMR 8208 XBR for an LR load. But the difference will only be a few 0.1s MOA. 77GR. SMK OTM over 5.56MM NATO TAC loads will group very nicely out to as far as you want to stretch it. 5.56MM NATO TAC load group below was fired at 750yds. with an 18" 1x7.7 SS Krieger/CLE chamber barrel with M4 can attached. Groups with that 5.56MM TAC load are virtually identical to the groups fired with factory BHA MK 262 MOD 1. There is only 1 FPS difference in the MV between the 2 when fired from the 18" SPR with M4 can I use (2825 FPS VS 2824 FPS 5 shot average at 80F). But just the different barrel heat combined with varying OAT as the day warms up/cools off will give the TAC load & the factory BHA MK 262 MOD 1 (which also uses a spherical propellant) a bit of vertical stringing. Just as you are thinking, an IMR 8208 XBR load will greatly reduce, even virtually eliminate any vertical stringing caused by differences in propellant burn rate due to temperature variation.
You may loose a little accuracy with a TAC load over an IMR 8208 XBR for an LR load. But the difference will only be a few 0.1s MOA. 77GR. SMK OTM over 5.56MM NATO TAC loads will group very nicely out to as far as you want to stretch it. 5.56MM NATO TAC load group below was fired at 750yds. with an 18" 1x7.7 SS Krieger/CLE chamber barrel with M4 can attached. Groups with that 5.56MM TAC load are virtually identical to the groups fired with factory BHA MK 262 MOD 1. There is only 1 FPS difference in the MV between the 2 when fired from the 18" SPR with M4 can I use (2825 FPS VS 2824 FPS 5 shot average at 80F). But just the different barrel heat combined with varying OAT as the day warms up/cools off will give the TAC load & the factory BHA MK 262 MOD 1 (which also uses a spherical propellant) a bit of vertical stringing. Just as you are thinking, an IMR 8208 XBR load will greatly reduce, even virtually eliminate any vertical stringing caused by differences in propellant burn rate due to temperature variation.
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