153 grain ATIPs

[232593]

Any of you running 6.5 CM AR10s use 153 grain ATIPs? If so how much neck tension do they like? What powders do you use?

Reason I ask is I ran some factory Hornady 147 match ammo and it would appear that my SP10 likes heavier bullets.

 

[Bantam1]

I shot some with Reloader 26 using .002" tension in a bolt gun. No issues but the 135 Atips shoot a lot better for my rifle.

 

[232593]

I shot some with Reloader 26 using .002" tension in a bolt gun. No issues but the 135 Atips shoot a lot better for my rifle.

Ever try them in an AR10?

 

[Bantam1]

I do not own an AR10 type rifle.

 

[Frank Green]

I haven't tried them in a AR10 but have loaded for a AR10 in the past in 260 Rem.

Load your ammo just like you would a bolt gun. I was running about .004" to .005" neck tension. No issues.

Watch your twist rate for the 153's. I'd say 7.5 twist minimum. Hornady says they will fly out of a 8 twist but it better be an honest 1-8 twist barrel. It's very common with button rifled barrels for the twist to vary and not be true/accurate.

You get on the ragged edge of twist stability and you can see accuracy issues and guys blame the bullets at times and it might not have anything to do with the bullet.

The 150SMk bullets are really nice as well but those for sure need a 1-7.5 twist barrel.

Later, Frank
Bartlein Barrels

 

[232593]

honest 1-8 twist barrel.

Seekins SP10 meet that criteria?

 

[Frank Green]

Seekins SP10 meet that criteria?

That's the question for Seekins.

I want to say Seekins was using Rock Creek button rifled barrels Unless they are making they're own now? If button rifled barrels... again the button rifle barrels tend to vary on uniformity of the twist. If the button hits a hard spot or a soft spot in the steel usually the button will slow down on the twist rate... it could speed back up to what it's suppose to be doing but if either case happens you either end up with a non uniform twist or a barrel with a negative twist. If that happens... then the barrel is more temperamental as to what it will like shot thru it.

I've seen button barrels that started out as a 8 twist at the breech end but by the time you get to the muzzle end... the twist ended at 8.75. That's a negative twist and those barrels wouldn't shoot any 105 or 107gr type bullet if they're life depended on it.

Size uniformity can be another issue with button barrels because button rifling induces stress into the material. When you contour the barrel and especially where the contour makes drastic changes.... during turning the bore can relieve itself and it will typically open up. The last you want to see that happen is at the muzzle crown.

Does this happen to every button barrel? No but it's more common than you think. Also some button makers are trying to help guide the rotation of the button. The twist is built into the button. Button rifling is a swaging process. It doesn't remove the material it displaces the material.