Nas3 308 direct comparison to Sig Hybrid 308
The Sig hybrid cases formed to 308 and fired measure 57.2-57.74gr H2o with spent primer.
The Nas3 case with spent primer installed measures 57.64gr H2o
So I loaded identical ladders for both cases.
Gun is 16" 308Win 8 twist mid gas, with Law folder, Suppressed KRG R30T, & Larue mags. Vortex viper pst2 2-10
Baseline for clean bore shots FGMM 175's x 3 = 2389fps
Powder for all loads is PP2000, primers cci#34, & all loads seated to 2.860"
169smk
Sig Hyb...............................Nas3
48.9 x 5 = 2567 SD 6.7/ x 5 = 2536 SD 7.5
49.3 x 5 = 2592 SD 4.1/ x 5 = 2563 SD 5.0
49.7 x 5 = 2623 SD 3.2/ x 5 = 2577 SD 5.1
50.1 x 1 = 2639 / x 1 = 2589
177smk @ 2.860"
Sig Hyb...............................Nas3
48.1 x 5 = 2528 SD 3.2/ x 5 = 2482 SD 3.5
48.5 x 5 = 2544 SD 3.8/ x 5 = 2506 SD 5.8
48.9 x 5 = 2574 SD 2.8/ x 5 = 2527 SD 5.9
49.3 x 1 = 2592 / x 1 = 2545
Case dimensions after firing.
Sig Hyb @.200 line = .4735", case length = 2.020", & H2o = 58.58gr
Nas3 @.200 line = .4753", case length = 2.0215", & H2o = 60.68gr
All shot @100y bi-pod/bag prone.
Guns favorite load was in Sig Hyb with 177smk
Interesting though that when the Nas3 hit that same speed it also shot a .800" group.
For 308 bolt gun I only loaded Nas3 cases.
ARC CDG with 26" 10 twist PVA barrel & first shots with Diligent Defense Enticer Sti. Jury still out on the can, always shot this braked.
174 ELDM - VT @2.950
PP2000, Rem 9-1/2 mag
48.2 x 5 = 2780 SD 7.6
48.6 x 5 = 2813 SD 9.9
49.0 x 5 = 2845 SD 5.1
Berger 200.2x @2.960
Vit N550, Rem 9-1/2 mag
46.8 x 5 = 2636 SD 2.9
47.2 x 5 = 2667 SD 15.3
47.6 x 5 = 2689 SD 10
Nothing great in the accuracy dept. First time with Can, powder, case, & primer in the bolt gun. 174's were all about 1" & 200.2's were 1.2-1.8" No primer craters or heavy bolt with any of these.
Thoughts on these Nas3 308 cases so far:
TLDR version. For the AR there pretty good & that's what I'll be using them for. Not usable in the ARC CDG.
Neck tension on the 308 cases is pretty good & consistent. I used Imperial dry neck lube and after seating finished with a Redding taper crimp just to close up the small flare. No added crimp.
Head space is Hot dog down a hallway for these 308's like it is for the 5.56. I had .009 - .012" head space with these & this can and did cause problems for the bolt gun. Unfortunately the ARC CDG is their only action that does not have adjustable firing pin protrusion. I had a few that wouldn't fire. Add .0012 HS to -.006 primer depth and that only leaves about .010 pin strike on my CDG.
Case head size. Norma Brass = .471", Sig Hyb = .4685", Nas3 = .4665"
The ARC CDG did not extract a single one of the Nas3 cases. It pulled them partially out of the chamber and then the extractor just let go so I had to drop the mag every shot. The CDG runs the Sig Hyb cases flawlessly.
Case volume. The Nas3 end up at plus 2 gr over the Sig Hyb when fired. They expand width @.200 line & length adding 2gr & it shows in the velocity on the comparison ladder. This kind of confounds Gordon's since it wants fired capacity & based on that Yuge 60.6gr fired capacity I could go hotter than I did. Looks to me like they need about +.6gr to equal the Sig hyb even though they start at same H2o.
Reloading - Just don't!! For one thing without any rhyme or reason about 3/4 of the 308 case heads will spin after firing. The 5.56 don't do that.
Also the Nas3 neck thickness is .001" thicker than my Norma brass. Think about that, it's steel. I tried a collet neck sizer on a 5.56 Nas3 and it laughed at it. I also tried a .2245 mandrel in the 5.56 Nas3 to reduce neck tension a bit for bolt gun. The fucking thick ass steel necks are so strong it pulled the case head off trying to pull the mandrel out (Graphite lube). Also galled the mandrel. I had to make a mandrel from Nickel brass & that worked acceptably to at least ensure consistent tension.
On a positive note, these 308 Nas3's ran perfect in my AR. On the lighter charge weights in the comparison ladder I got bolt lock with the Nas3 at 30-40fps slower than the Sig Hyb that did not lock back. This tells me they are easier to extract.