Holy Smokes! NAS3 .308 Outer Limits.

[Russ-T]

Hey All!

Working on the next round of testing for the humble .308 using the NAS3 cases.

(2) Separate tests:

110gr TTSX
212gr LRX Borerider

These, I believe, are the outer limits of the cartridge's super sonic range.

Initial powder calibration tests below:

110gr Barnes TTSX
Accurate LT-30
COAL 2.735

I will generally do (5) shots to calibrate the powder / bullet combo in GRT.

The results were astounding:

This produced a 3/4" group with (5) shots covering (5) grains of powder differential. WOW!
This one is going to shoot!

Next, the heavy side with the strangest bullet. (.308 Super)

Barnes 212LRX Borerider
VV N550
COAL 3.375". Yes this fits into the standard SAAMI 308 Chamber*

The (Super) combo was almost exactly what GRT modeled. This is usually the case with the VV powders and GRT.

Peaked at 2798 fps.

I did not look for accuracy for this load. The 212LRX needs 1:8 twist to stabilize.

Knowing that this will work, I will def be building a long action .308 with an 8-twist barrel


Ladder tests to come with the 110gr TTSX.

Up, Up and AWAY!

 

[rockchalk06]

Impressive.

I had some amazing results using the Sig 7.62x51 stamped pull down from AR. Found 400 pieces of it.

3200ish with a 130 TTSX in a 20" Seekins using Varget
2900ish with a 180 TB in a 24" Tikka using Power Pro 2000-MR.

Both stacked amazing and held tight out to 600. The 130 kinda loses its mustard at that distance but it is accurate.

I forgot about the 212 LRX. That might be worth grabbing a bunch to see what my Seekins can do.

 

[Earnhardt]

OK…now this thread is cool as hell!

 

[Greatgrandad]

Hmm, the pics aren't showing for some reason.

 

[wvbearhunter]

Check my thread on these. I was pushing the 195 TMK to 2775 in 308 with the nas3 and the 175 eld to 2804. I can push both faster but the accuracy fell off.

 

[MSU Marksman]

I understand that the draw to these cases is allowing higher pressures, but how exactly are you determining how much powder to load and if you are approaching over pressure?

 

[bamban]

I really need to try those cases to see how much more I can push the 124 HH out of my 26 inch 308 bolt gun.

 

[Russ-T]

I understand that the draw to these cases is allowing higher pressures, but how exactly are you determining how much powder to load and if you are approaching over pressure?

I use GRT for load work ups. The velocity is the measure for pressure levels. Once the powder calibration is done, the load work ups are always spot on.

For the NAS3 (and Peak Alloy) cases, I have no other measure for the pressure ceiling. They don't show the normal signs of overpressure. ie: primer flattening and elector swipes.

 

[Russ-T]

I really need to try those cases to see how much more I can push the 124 HH out of my 26 inch 308 bolt gun.

View attachment 765456

I am amazed at how accurate they shoot at such high velocities

 

[xsn10s]

I understand that the draw to these cases is allowing higher pressures, but how exactly are you determining how much powder to load and if you are approaching over pressure?

IMO without actual pressure reading equipment, it's just a best guess. I think it was 45-70 over at snipershide that did the best write up on how to read pressures while shooting hybrid cases. He watched flattening primers and primer flow into firing pin hole to guesstimate pressures. He also checked headspace to make sure he wasn't getting recoil lug set back. Even with a strain gauge is just an educated guess.