View Full Version : 69 GR Sierra HPBT 9 Twist

10-11-2012, 2:47 PM
Will the 69 GR Sierra HPBT stabilize with a 16" 9 twist barrel? It's a AR. Thanks James

10-11-2012, 2:49 PM
I have not try that combo before. I shoot 1:8 with all the heavier bullets ... Tagged

10-11-2012, 2:51 PM
1 in 9" will stabilize up to 73gr or so. I shoot the same bullet and twist. Works fine.

10-11-2012, 2:59 PM
1 in 9" will stabilize up to 73gr or so. I shoot the same bullet and twist. Works fine.

What type of groups are you getting @100yds and what loads do you use?

10-11-2012, 5:13 PM

10-11-2012, 5:33 PM
I get very good results with 69gr SMKs from an 1/9 18" barrel; consistently under 1 MOA. Loads make a huge difference. I'm using 23.8 gr of TAC, YMMV.

I get acceptable results with 77 gr SMK, also. Close to 1 MOA. They knock down steel with more authority at 400-500 meters.

10-11-2012, 5:37 PM
Thanks for the replies. A person that works at my range said they were too heavy but I thought not. I was blowing primers and I read somewhere that CCI 400's were not good with heavier bullets. I was using 23.5 grs of RL 15.
Thanks James

10-11-2012, 6:27 PM
1:9, 24" PSS no issues with 69 SMK or ~73, however some of its best 100 yard groups were made with 52 Gr SMK

10-11-2012, 7:33 PM
Those bullets will work perfectly fine. 25.3gr Varget will work pretty good, but always work up your own loads.

10-11-2012, 8:16 PM
Yes, a 69 grain Matchking will stabilize from a 1:9" barrel. These are from this afternoon, 69 grain Sierra Matchking HPBT, 24.5 grains of Varget. Shot from a 1:9 twist 22" barrel (stock Savage 10 FP). I've even had good results with 75 grain Matchkings, I haven't shot anything heavier than 75's. Zero was at 100 yards.

Edit: I just did the calculation, the 400 yard group should actually be 0.47MOA.


10-11-2012, 8:58 PM
Thanks for the posts but I just need postings related to AR 15s and not bolt guns. James

10-11-2012, 9:00 PM
I've shot them over H322 and TAC through my 20" 1/9 Savage 10FP also. I generally got groups at 100yrds in the .6" to 1" range. I've since switched to the Sierra 53g SMK for the bulk of my target shooting which group a little better and cost me a little less.

Bolt V AR won't make a significant difference for stabilization. In this case so long as the pressures they're being loaded to are equal the platform the barrel is mounted to makes very little difference once it's fired.

10-11-2012, 9:20 PM
Just to be clear; it is not the weight of the bullet but the length (it's actually a bit more complicated than that) that determines how fast a bullet must spin to be stabilized. Generally bullets with a similar weight have similar weight distribution so you can make generalizations, but it won't always work. You can stabilize a heavier flat or round nose bullet than longer vld or solid brass bullets of a same weight. In addition the speed of the bullet effects how fast it spins, so the same bullet fired from a longer barrel (or a bigger powder charge) will spin faster and therefor be more stable. A 1:9 Remington 700 with a 26" barrel and maxed out load will stabilize a heavier bullet than a 16" AR with a light factory load.

10-11-2012, 9:23 PM
No prob in 20" Stag.