New 6mm Advanced Rifle Cartridge
- Thread starter Gtscotty
- Start date
Running a CAT Noah which is low back pressure. So I kept the same gas block setting as unsuppressed.
Ok thanks, appreciate the feedback. I have a PVA Osprey 18" 6 ARC Rifle +2 barrel and I still need to test it out with a good clamp on gas block & some factory ammo (108gr eld-m) but I keep getting short stroking with my handloads (N140 and 2000-MR pushing 107-109 grain bullets near max book loads) paired with 3oz buffer weight and sprinco std power white spring.
The barrel's gas port measured out to 0.093" which seems a bit conservative to me given the short dwell time but we'll see how the testing with factory loads goes. By comparison Proof is using a 0.096" port on a 18" with rifle +1.
Since I don't want to run a reduced power spring I'm considering drilling out the port to about 2.5mm (0.098") if it still short strokes on factory ammo with the clamp on gas block. Josh at PVA has been great at getting back to me and advised me to do the above testing before drilling anything, it just seems like the gas port is way to small for unsuppressed use.
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Headspaced rubber city bolt. I tried the 3 piece rings that came with it and also a JP one piece ring. Had short stroking with both. I also was originally using the bolt in a radian enhanced carrier and tried switching to a rubber city nitrated carrier to match the bolt and still no difference. Also swapped uppers from vltor MUR to san tan tactical billet
I’ve shot a good amount of TAP. Velocities are similar to all the other Hornady loads. I haven’t gotten them to shoot as well as the ELD-M, -X or Black. I think 1.5 to 2 moa at 100yds. if memory serves, where I see .75-1 moa with the other loads.
I never saw 0.75-1 MOA with those. Black was probably the best and 1.2 5 shot group. The more you shoot with them all, the wider the spread until they too are 2” groups
Looks like I won't bother with buying any TAP then. Should get my GFR in today. I haven't been this excited about a semi auto ever. I'm going to mount my zco 420 on it, any reason I would need a cantilever mount? I have a standard Badger COMM 1.54 mount for it and would really like to not have to buy another mount.
It’s not a mono receiver your gonna need a cantilever
420:
Also. Someone should buy my nib stratomatch 20” Steal at $2900.
18” PROOF CF 1:7.5”
1/28/24
46F 88% 29.70in
Hornady Black 105gr BTHP
2942, 2527, 2532, 2521, 2546
2530, 2535, 2552, 2533, 2547
SD 16 ES 59 1.2”
2542, 2523, 2533, 2539, 2539
2560, 2550, 2550, 2480, 2551
SD 21 ES 80 1.5”
8/21/24
67F 47% 30.22in
Hornady 108 ELDM Factory
2483, 2500, 2493, 2491, 2526
2495, 2477, 2513, 2485 SD 12.5 ES 39.7
2474, 2478, 2507, 2511, 2483, 2509, 2510, 2504, 2495, 2471 SD 15.1 ES 39.5 1.4”
9/4/24
72F 40% 30.36in
Hornady 108 ELDM Factory
2504, 2506, 2480, 2472, 2445
2505, 2492, 2488, 2480, 2463
2498, 2517, 2511, 2513, 2510
2479, 2511, 2487, 2508, 2494
SD 18.5 ES 72 2”
1/28/24
46F 88% 29.70in
Hornady Black 105gr BTHP
2942, 2527, 2532, 2521, 2546
2530, 2535, 2552, 2533, 2547
SD 16 ES 59 1.2”
2542, 2523, 2533, 2539, 2539
2560, 2550, 2550, 2480, 2551
SD 21 ES 80 1.5”
8/21/24
67F 47% 30.22in
Hornady 108 ELDM Factory
2483, 2500, 2493, 2491, 2526
2495, 2477, 2513, 2485 SD 12.5 ES 39.7
2474, 2478, 2507, 2511, 2483, 2509, 2510, 2504, 2495, 2471 SD 15.1 ES 39.5 1.4”
9/4/24
72F 40% 30.36in
Hornady 108 ELDM Factory
2504, 2506, 2480, 2472, 2445
2505, 2492, 2488, 2480, 2463
2498, 2517, 2511, 2513, 2510
2479, 2511, 2487, 2508, 2494
SD 18.5 ES 72 2”
I was getting a .4m high POI change from the 108s out of my suppressed 16” Proof.
Accuracy was not as good as the 108s, the TAP was 1-1.2 moa.
I'm getting less than 3/4 MOA with the lots I have in a 20" Proof carbon barrel. Typically around .55-.6. Good accuracy all the way to 1000 yards so far. It was stupid impressive at my local range at 600 yards. I really enjoy the rifle.
I hope when I start loading I can match it or exceed it. Velocity has been 2680-2690 as the barrel broke in. It started around 2640-2660. SD around 13, ES in the 20's for the small amount I tested.
Wow, those are pretty good velocity numbers, I would have expected something in the low 2600's for a 20"
I have an 18" that I'm about to run some factory 108 eldm's through and will post my results here once I get to the range.
Since I handload I will likely try to clone this factory load so I will pull a few apart to take a look at the powder, primer, etc..
.6-.7 out of my 16” Proof. I’ve noticed that every 100-150 rounds I need to run a snake through it because it’ll open up to around 1 moa.
I’ve gotten some stupid good groups from some cases of the same lot.
This is from a scope tracking test:
106 ATIPs shoot phenomenal too, but I only shot one group to see what the POI offset was because I don’t a lot of them.
T
That’s pretty incredible for factory ammo. Mine likes 103 ELD-X like that but hand loads.
That’s the best group I’ve gotten, definitely not the average. I usually will do a tracking test and check zero on paper, so I don’t usually shoot a lot of groups at 100.
I need to start hand loading. I kinda want a boltgun 6 ARC too and chase a bit of velocity.
Mine does right at 1 moa with the factory 103 eldx. Somehow the POA/POI is the same as the factory 108 ELDM.
My factory 108s are running 2525 fps out of a suppressed 16” Proof.
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If you don't handload (which tunes the ammo to the gun) if you have a set type of ammo you can tune the gun to the ammo. In other words you can tweak barrel harmonics by changing the barrel nut torque. Start at 47 ft-lbs (or torque spec listed by handguard manufacturer) then test groups at +/- 10 ft-lbs from there. You can also tweak barrel harmonics with a tunable muzzle break or shims with a non compensator flash hider (edit, just saw that you are using a can so this latter option wouldn't apply to you).
Some people are running 6 arc bolt guns for PRS due to less recoil than 6 dasher, etc. while still being able to use the high BC 6mm bullets....they don't care about the slight drop in velocity compared to dasher b/c most people running the dashers aren't running max loads anymore.
Not 100 yard groups but here is some 108 ELD factory ammo at 550. Only 4 on the small steel as I dropped one off the plate not holding the wind and then held wind and shot the other 4. 5 on the IPSC though. I a pretty happy with the factory 108s.
4500-6000 rounds of match barrel life, no recoil, small primers, only consumes 28gr of Varget every shot... 2750fps with a 109-110gr pill is no slouch. Never had problems hitting long ball targets with it.
Damn I was only getting 2540 and mild pressure with 108’s and 27.3 of Varget 18” gasser. Great accuracy though.
27.3 2535, 2543, 2540, 2546, 2544 SD 2.2 ES 6.4 0.7”
Pretty sure that’s bolt gun data LedZep referenced, and Hornady data only has it at 2650fps in 24” so he might be running a longer barrel
MDT seems the lowest profile and nicest on my delicate hands.
I think most folks are running area 419 or MDT mlok arca rails but there are a ton of solid options out there.
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