68gr Hornady Poor Accuracy

[Pripyat]

I then made up 4 with 24.5 gn varget.



Velocities:
2716
2725
2753
2731

Interestingly the group could have been better.. all four shots were made in under a minute. That black border on the red dot was wreaking havoc on my eyes.

 

[joem1945]

I have a AR that I fooled with for 2 years to try to get it to shoot. Bullet weights from 62, 65, 68,69, 75,77's. Groups would vary from 2" and up to 16". Finally cut a new crown and that fixed it, groups .750 @ 100 yds from a rest, no wind.

 

[Pripyat]

I'm going to do a little more testing out to 200m with these projectiles. Hopefully whatever projectile I find shoots well in the 18" AR will also do well in the 20" bolt gun. I would really like to standardize on something.

Primers are flattened slightly with the 24.5gn load. Going to try partial full length sizing and see if the pressure goes down any. Otherwise I'll probably start backing off in small increments.

The rifle feels completely different. I feel like I don't experience as much mechanical feedback due to the action after the gun discharges.

I guess this issue has been resolved. One last question - Since the issue had something to do with bullet stability do I need to worry about the bullet becoming unstable after some speed has died off downrange?

 

[morcey2]

. One last question - Since the issue had something to do with bullet stability do I need to worry about the bullet becoming unstable after some speed has died off downrange?

The bullet will be at its least stable as soon as it leaves the barrel. As it slows down, it actually becomes more stable up until the point that it gets to the trans-sonic zone. Then all bets are off. As it starts to transition from supersonic to subsonic, a nice smooth match bullet can destabilize and start to tumble.

Matt

 

[Pripyat]

It's definitely the 68 grain projectiles. Loaded up 5 rounds with 24.5gn varget under 68gr HPBT. 4 grouped a tad over 1.5". The fifth was a flyer - If you count the fifth you get 3.7" at 100m.

Next group was 5 shots 55gn Sierra BK. .66" at 109yd.

I started out with heavier projectiles because they had a higher BC and my main objective with this rifle is accuracy for paper punching and playing around at the range out to 200m. I may just stick with the lighter projectiles for now..

 

[ttnkountze]

1:9 is too slow for many of the long bullets. I like 1:7 for the heavies.