6gt
- Thread starter Dthomas3523
- Start date
So not reloading related. But it is 6gt specific.
Mags question. Who’s had the best luck with what mags?
Ive ran the AW mags in my AI and Rukus. But trying another action that doesn’t work with AW mags. So what’s everyone having the best luck with?
Mags question. Who’s had the best luck with what mags?
Ive ran the AW mags in my AI and Rukus. But trying another action that doesn’t work with AW mags. So what’s everyone having the best luck with?
I run the recently discontinued ARC aics mags with mkm followers, never had a hiccup, but I try to keep them clean and out of the shit at dirty matches.
MDT is bringing out any day now ribbed (5 ribs), metal 12 round magazines that are rumored to function flawlessly in 6GT.
Accurate mags are right now the best answer. https://www.shortactionprecision.co...roducts/accurate-mag-308-10-round-regular-mag
I had decent luck with the ARC mags, until I started trying to modify them to hold more than 10 rounds.
That's quite odd on the arc. I have 2 at 10 rounds, 2 with Altus +2 extensions, and one with a419 +4 extension. No issues, other than the spring pressure is very low on the 14rd mag on last round, occasionally passes over last round. I do run mkm followers tho. I stretch the springs always when adding a mag extension.
Same one I used. I stretched the spring. I also did not get anywhere near +4 out of it.
Maybe I did something wrong.
I have not tried the Mk Machining follower.
I did try LRI's expensive billet follower, which from what I can tell made the situation worse.
I cannot put 14 rounds in. It is more like 11 or 12, and the last one or two nose dive and cannot be loaded.
Maybe I did something wrong.
I have not tried the Mk Machining follower.
I did try LRI's expensive billet follower, which from what I can tell made the situation worse.
I cannot put 14 rounds in. It is more like 11 or 12, and the last one or two nose dive and cannot be loaded.
RS14, check out this thread.
6GT Mag Suggestions
I am currently running 6GT with a Bighorn Origin in an ACC chassis and since day one having issues with mags. i have tried 2 x 10rnd 308 mdt poly mags and 1 x 10rnd 308 metal mag. I always had to advance every round in the poly mag and the metal mag was not 100% reliable but for the most part...
www.snipershide.com
My son put me on the MDT Poly.metal 10 round mags. I tried them and they ran flawlessly, loading ten rounds and every round fed perfect from round 1 to round ten. He has same results. He runs them in his Bighorn action and I ran them in my Curtis action.
Currently on back order of course. So, what else is new?
Currently on back order of course. So, what else is new?
If you don’t mind a little longer single stack single feed magazine the Magpuls AICS version works great. I’ve used them to feed everything from 6 BR to 6.5 Creedmoor without any problems. Whenever someone is having problems with their magazine at a match I hand them a Magpul to finish the match. They have ran in everything so far.
I’ve shot 11 matches so far since getting my GT using AICS mags. One 10 rounder , one with atlas +2 and one with Area 419 +4 extension. I’ve had zero issues in matches or at the range with them. I did tune the feed lips on all three mags but just for smoother feeding. P-Mags seem to work well as long as you don’t get the mag hard into your bag or cram the bottom of the mag into a prop. I tried AW mags but couldn’t get them to work with my setup. I also tried MDT mags and they were so bad I sold them the next day.
Impact action in a Foundation stock with Hawkins DBM.
Shot my gt at 510 today. 5-7 mph crosswinds. 5 rounds. Woulda been pretty good had the one not came out of the group! But still pretty happy. Load info
Alpha brass
37.2g 4350
Cci450
Berger 108 bt.
Alpha brass
37.2g 4350
Cci450
Berger 108 bt.
Tried out some RL 15.5:
26" Bartlein M24, 1:7.5" twist @ 1,933 rounds:
Berger 105 gr Hybrid
CCI 450
Alpha non-OCD Brass (6x fired)
+/-0.050" jump
33.0 gr Reloder TS 15.5
Ave MV: 2,758
ES: 6
SD: 2.4
33.5 gr Reloder TS 15.5
Ave MV: 2,798
ES: 9
SD: 6.6
34.0 gr Reloder TS 15.5
Ave MV: 2,835
ES: 11
SD: 4.6
*SD/ES is likely a direct result of barrel heat. Shot quickly with no cool down.
26" Bartlein M24, 1:7.5" twist @ 1,933 rounds:
Berger 105 gr Hybrid
CCI 450
Alpha non-OCD Brass (6x fired)
+/-0.050" jump
33.0 gr Reloder TS 15.5
Ave MV: 2,758
ES: 6
SD: 2.4
33.5 gr Reloder TS 15.5
Ave MV: 2,798
ES: 9
SD: 6.6
34.0 gr Reloder TS 15.5
Ave MV: 2,835
ES: 11
SD: 4.6
*SD/ES is likely a direct result of barrel heat. Shot quickly with no cool down.
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I am an idiot. Yes, post edited. 34.0 gr was 2,835 FPS. No pressure signs.
Mines got a tad over 1900rds with DTACS and 4350 but I’m running mine at 2770fps. Since I only shoot one day matches I’m gonna see how far it’ll make it.
I'm at 1850rds through my first 6GT barrel and it's still shooting great. I've already got another barrel, but I'm going to try and hold off on pulling my first one as long as I can as I'm curious how long it'll make it?
I've never run it real fast (2750-2900fps), but shooting longish 112gn Match Burners hasn't allowed me to jump as much as I usually like to so IDK? I was used to jumping 100 thou with my 6CM, but with the GT anything more than 10 thou off the lands puts the bullet's bearing surface below the shoulder/neck junction (which I'm not totally convinced actually matters).
I ran the first 1500rds through it at 50 thou off with the bearing surface well past the shoulder/neck junction (with the base of the bullet about at the start/bottom of the shoulder), and it shot great, no issues. I've loaded the last few hundred rounds longer, keeping the bullet's bearing surface above the shoulder/neck junction to see if it shot any better... and it seems to shoot the same (I almost think my vertical was a little better downrange with more jump and the ass of the bullet deeper in the case but IDK?).
I've actually been slowing it down to make it easier to see impacts on plates inside 600 yards, and other than my SDs opening up a little (still in the single digits), it's shot great at 3 different charges/speeds with no load development (Shooters World Precision Rifle):
34gr / 2850fps / SD~3 / 50 thou off
33gr / 2804fps / SD~4 / 10 thou off
32.5gr / 2760fps / SD~6 / 10 thou off
I've never run it real fast (2750-2900fps), but shooting longish 112gn Match Burners hasn't allowed me to jump as much as I usually like to so IDK? I was used to jumping 100 thou with my 6CM, but with the GT anything more than 10 thou off the lands puts the bullet's bearing surface below the shoulder/neck junction (which I'm not totally convinced actually matters).
I ran the first 1500rds through it at 50 thou off with the bearing surface well past the shoulder/neck junction (with the base of the bullet about at the start/bottom of the shoulder), and it shot great, no issues. I've loaded the last few hundred rounds longer, keeping the bullet's bearing surface above the shoulder/neck junction to see if it shot any better... and it seems to shoot the same (I almost think my vertical was a little better downrange with more jump and the ass of the bullet deeper in the case but IDK?).
I've actually been slowing it down to make it easier to see impacts on plates inside 600 yards, and other than my SDs opening up a little (still in the single digits), it's shot great at 3 different charges/speeds with no load development (Shooters World Precision Rifle):
34gr / 2850fps / SD~3 / 50 thou off
33gr / 2804fps / SD~4 / 10 thou off
32.5gr / 2760fps / SD~6 / 10 thou off
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I have a 120fb 24" 6gt, the 112 shoots small at 10k jump, it's a relatively small window as 7k and 13k jump open up to half moa or slightly bigger. I'm running at 2905 with 36.3gr H4350. It's a hunting/varmint barrel so really not concerned with life. 4 my other 6gt barrels are 169fb, this barrel and the womans are the only ones I have with short fb. Idk if being below the neck matters much, but I just don't like it personally. I'll usually take a long freebore as I found the jump windows are larger the further you get away from lands, although the precision isn't quite as tight as close, however a much more forgiving stable load you can shoot for a long time without retuning.
I'd think a 105 will tune in with another half grain +-, 105s usually have shot around 2920-2950 in my barrels, but using H4350.
I don't know why they tested a 105amax, pretty sure that bullets been discontinued for near a decade. The 105hyb has less bearing than an 107smk and is lighter, I'd say you're max would be half way between the 107smk and 103vtac.
YMMV, but I'm done with chasing speed, now I'm chasing slow lol... I think for me the goal now is actually finding the slowest load that shoots that I can (while staying supersonic out to just past ~1250 yards and having enough case-fill so that SDs don't go to shit).
I guess I'm really just treating the GT as a "Dasher without the headaches", and at middle-of-the-road Dasher speeds, mine has been shooting great.
If I'm honest I think I lost a little something going from 33gr/2804fps to 32.5gr/2760fps... 33gr/2804fps was hammering and allowing me to see what I needed to with impacts at closer distances, but I figured I'd try to back it down a little more since less powder equals less recoil.
That said, I'm starting to think the magic recipes have more to do with case-fill than speed. But there also seems to be something magical about the Varget/SWPR burn-rate powders as compared to slightly slower powders like H4350/RL15.5... so there's that.
As far Varget and Varget-alikes like SW Precision, N150/N140, etc... does anyone know which one at the same charge weights, has the highest load density to yield the most case-fill..? I think that might be worth a little further experimentation...
And if I ever come across some H4831 I might try some of that as I should be able to fill up the case with no problem and still end up with slower speeds, but IDK if that'll lose some of the magic I've been getting with the faster SWPR (where everything shoots and yields single digit SDs without really trying).
Lastly, does anyone know if anyone has ever done a recoil comparison with different powders..? While recoil is a little softer with my 6GT and 33gr of SWPR versus my 6CM and its 41gr StaBall load, it's also "snappier" and less of a "slow push" type of feel (kind of like the difference between a 9mm and a .45ACP).
I'm wondering what would feel softer: ~33gr of Varget/SWPR versus ~38 of H4831..?
I guess I'm really just treating the GT as a "Dasher without the headaches", and at middle-of-the-road Dasher speeds, mine has been shooting great.
If I'm honest I think I lost a little something going from 33gr/2804fps to 32.5gr/2760fps... 33gr/2804fps was hammering and allowing me to see what I needed to with impacts at closer distances, but I figured I'd try to back it down a little more since less powder equals less recoil.
That said, I'm starting to think the magic recipes have more to do with case-fill than speed. But there also seems to be something magical about the Varget/SWPR burn-rate powders as compared to slightly slower powders like H4350/RL15.5... so there's that.
As far Varget and Varget-alikes like SW Precision, N150/N140, etc... does anyone know which one at the same charge weights, has the highest load density to yield the most case-fill..? I think that might be worth a little further experimentation...
And if I ever come across some H4831 I might try some of that as I should be able to fill up the case with no problem and still end up with slower speeds, but IDK if that'll lose some of the magic I've been getting with the faster SWPR (where everything shoots and yields single digit SDs without really trying).
Lastly, does anyone know if anyone has ever done a recoil comparison with different powders..? While recoil is a little softer with my 6GT and 33gr of SWPR versus my 6CM and its 41gr StaBall load, it's also "snappier" and less of a "slow push" type of feel (kind of like the difference between a 9mm and a .45ACP).
I'm wondering what would feel softer: ~33gr of Varget/SWPR versus ~38 of H4831..?
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I don't believe H4831 will hit the minimum pressure threshold to seal the case before reaching 105% case capacity. I've been using H4350 and am planning on working up Varget due to the carbon issues I've been having with H4350.
@CK1.0 N150 is probably the bulkiest of which you listed. I'm my ladies rifle I tested 107smk with N150 and 32.7gr is running 2940 and shoots well, I need to back off to. Mid 2800 and see if it still shoots there. That's a 26" 7tw 120fb chamber. Her barrel has always built pressure sooner than my other 237 bore HH pipes, but mine are all 7.5tw. In my experience in the 6bra, ts15.5 was bukier and produced slower velocity than varget. N555, Rl23, SW4350 are all 1-2gr slower than H4350 in the gt.
I am testing N555 with 115 DTACs. Good case fill and some decent speeds. Looks like 2860 is going to be a good place to run them with 37.6 grains of N555. I am not seeing any issues with carbon but I have not run past 150 rounds before cleaning either. We have had good luck with RL16, RL15.5, H4350, N150 and Varget and they all work. The best numbers so far though have been with N555. Recorded 51 rounds with SD of 4.3. I have not been able to accomplish that with any other powders so far.
"Minimum pressure threshold to seal the case"? WTF lol? That's beyond my expertise, please explain...
If you don't have enough chamber pressure combustion gasses will leak down the brass. It looks like soot on the shoulder and body.
My experience is slower burning powders feel softer, less snappy, than fast burning powders.
This is untested and only GRTs guesstimates for H4831 with my case volume (44.1) and 27” barrel and 112 MB loaded 20K off the lands.
GRT says 38 grains should theoretically yield 2836 fps with 104% case fill and 86% burnt propellant. It would take over 45.1 grains at 120% case fill to get 100% burn.
My experience with anything much less than 90-93% burn and ES starts to suffer. I do believe the numbers would change slightly with actual testing, and would be surprised if it was a winning combo. If you try it report back. I have a jug of it and tried some in my 22 GT without much luck. Now that the barrel is broke in I might look at it again for $h!ts and giggles.
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I agree that generally slower powder feels softer, but since one needs more of it to match the faster Varget/SWPR stuff (that lets one get away with using lighter charges), IDK what the net recoil "feel" would end up being as compared to each other...
I'm pretty much sold on trying to live in the 2750-2800fps range, that's all the speed I'm looking for. I feel like I might be able to get there with H4831... but what @Cascade Hemi mentioned about the soot and chamber not sealing is a little concerning lol.
Next time I drive by my LGS I might see if I can score a pound for experimentation purposes... I guess if it doesn't work in the 6GT I can use it with my 6CM barrels.
Does the H4831SC "short cut" have any advantages over the regular H4831 or vice versa (does the regular cut provide more case-fill)? I've never used it before.
The N555 is very soft on recoil and cool burning. Our rifles are almost identical and my barrel is much cooler after a 10 shot string than hers running 33.4 grains of 15.5. And my 37.6 grain load of N555 is 103% case fill and 100% powder burn. Barrel life calculator estimates accurate barrel life just short of 3k rounds.
The N555 looks like good stuff for sure too. I've read some things about it and It's interesting stuff in that it's a new formula/compound that offers the power boost of double-base powders without all the unwanted heat, and yeah, supposedly cooler burning than the usual suspects like Varget and H4350.
I guess what I'm wondering is: since I'm not looking for a lot of speed, would I be better off running a slower powder that's better at filling the cases up, versus what I'm doing now, which is maybe teetering on the line before things go to shit, where I'm getting below 80% case-fill?
I really shouldn't complain, it's not like the difference between an SD of 3 versus a 6 is holding me back, but since I've decided that slowing things down is working better for me, I'm just wondering if there's a better way to do it.
I guess what I'm wondering is: since I'm not looking for a lot of speed, would I be better off running a slower powder that's better at filling the cases up, versus what I'm doing now, which is maybe teetering on the line before things go to shit, where I'm getting below 80% case-fill?
I really shouldn't complain, it's not like the difference between an SD of 3 versus a 6 is holding me back, but since I've decided that slowing things down is working better for me, I'm just wondering if there's a better way to do it.
I can't say this with 100% certainty, but it seems the numbers are more consistent and lower with a better case fill. We tested a bunch of powders and bullets due to poor availability and wanted a #2 and #3 set up. The 33.4 of 15.5 is in the 90% case fill area and will get higher single digit SDs for 20 plus rounds compared to the sub 5s I have gotten with the N555 and heavier bullets. (110 Atips and now 115 DTACs). Some of the research we did in other disciplines talked about case fill of 96% or higher, so we went down the rabbit hole and looked at case fill. Again, not saying I can prove it 100% but it sure does seem like there is something to finding a powder with a burn rate that allows for good case fill. In our testing, they all worked and we were able to produce tiny groups and good numbers - but the N555 has provided the best numbers so far and super consistent performance.
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Here's something hopefully someone can help with: when talking case capacity, what/where is considered 100% full?
Is it when/where powder reaches the bottom of the shoulder, the point where powder is compressed, or is it less a percentage of total water capacity?
Does anyone know what the case capacity for 6GT is supposed to be (ballpark, obviously Hornady vs Alpha will differ slightly)?
Is it when/where powder reaches the bottom of the shoulder, the point where powder is compressed, or is it less a percentage of total water capacity?
Does anyone know what the case capacity for 6GT is supposed to be (ballpark, obviously Hornady vs Alpha will differ slightly)?
CK
GRT calculates it by physical limits. The length of the case, bullet OAL, the COAL. The shorter the COAL the more bullet is in the case. So the 100% fill is dependent upon free bore available and bullet jump. The deeper the bullet the smaller the volume available.
The other part of the equation is the density of the powder being used. I know GRT used to get it from the manufactures before the owner died. It’s also something that can be tweaked in the program but I’ve never messed with it.
I’ve had two 6 GT barrels chambered with Alpha reamers using Alpha brass. 45.1 grains water is what they averaged by my measurements.
GRT calculates it by physical limits. The length of the case, bullet OAL, the COAL. The shorter the COAL the more bullet is in the case. So the 100% fill is dependent upon free bore available and bullet jump. The deeper the bullet the smaller the volume available.
The other part of the equation is the density of the powder being used. I know GRT used to get it from the manufactures before the owner died. It’s also something that can be tweaked in the program but I’ve never messed with it.
I’ve had two 6 GT barrels chambered with Alpha reamers using Alpha brass. 45.1 grains water is what they averaged by my measurements.
^^^^ quick load is similar. My Alpha brass holds just over 46 grains of water. By my eye 100% case fill is somewhere around the case body / neck junction, maybe just above. At 103% powder is slightly below neck / shoulder junction.
Interesting…
This might partly explain why my gun was shooting great even while having the base of the bullet fairly deep into the case… since doing that shrinks available case volume, it may have had the effect of pseudo upping my case-fill.
I think with the next batch of rounds I make for my current barrel I’m going to go back to jumping 50 thou while keeping my lower 32.5gr charge to see what I get… I’m curious to see if my SDs shrink or not, or if the MV changes much…
Sorry I'm on the road to the PRS final and don't have access to my log for exact numbers but with the cleaning method used here round one would be around 55-60fps slower than my average and shot two is around 40 fps faster than that and by shot three I'm back into my normal ES range.
Here I cleaned with Patch out and accelerator only and used a bronze between bore treatments.
2850fps from 32gr is pretty sweet.
Is the bearing surface of your 108/109s below the shoulder/neck junction running a 60-65 thou jump?
I’m wondering if my bullets are just long (112 Match Burners) or is my chamber short too (SAAMI/Proof prefit)? Because 60-65 thou off would probably put the base of my bullets below the start/bottom of the shoulder (though I’m not necessarily convinced that matters lol).
Ideally more jump usually work better for me in 6CM, so I’d like to jump as much as 100 thou if I could, but that’d put a whole bunch of bullet deep into the case (which again, might not matter).
If your smith is local he can add free bore to your barrel and shouldn't need to put it into the lathe or even remove the barrel from the action...this is something you can do yourself as well...if you trust yourself to do it.
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IME I’ve found that is you have sufficient neck clearance, like 5-6K, you can run the bearing surface below the neck/shoulder junction without a problem. If you only have 2-3K I find I may start to get doughnuts at the neck/shoulder junction after a few firings.
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