Rifle twist vs bullet question

[joker1969]

I have a KAC SR-15 with a 1/7 twist and was wondering if hand loaded 55gr bullets would work OK. My rifle shoots 855 rounds very well but i have heard some EXPERTS at the range tell me that a 1/7 twist will over stabilize 55gr pills. What say y'all.

 

[ArchAngelCD]

A 1/7 twist probably won't over stabilize a 55gr bullet. My 1/9 twist will shoot 45gr bullets well and some shooters told me the same thing.

The only way to really know is load up a handful and shoot them.

Welcome to the forum...

 

[cfullgraf]

No problems shooting 55 grain bullets in a 1-7 twist AR-15.

 

[joker1969]

Thanks for your input. I loaded 270 55gr. BT FMJ rounds using LC 5.56mm brass
and 25grs. of IMR 4064 per my Speer manual # 14. My COL was 2.215. The salesman @ my local gun shop who sold me the IMR 4064 told me that it was spherical. NOT!! It was extruded and a PIA to meter through my Dillon 650. I'm new to reloading rifle rounds and was surprised that I was only able to load 270 rounds using 1 pound of 4064. Is that typical??? I'll let y'all know how the 55gr BT FMJ worked out as soon as I get the time to hit the outdoor range.

 

[Reloadron]

Thanks for your input. I loaded 270 55gr. BT FMJ rounds using LC 5.56mm brass
and 25grs. of IMR 4064 per my Speer manual # 14. My COL was 2.215. The salesman @ my local gun shop who sold me the IMR 4064 told me that it was spherical. NOT!! It was extruded and a PIA to meter through my Dillon 650. I'm new to reloading rifle rounds and was surprised that I was only able to load 270 rounds using 1 pound of 4064. Is that typical??? I'll let y'all know how the 55gr BT FMJ worked out as soon as I get the time to hit the outdoor range.

Well figure it this way, 1.0 pound of powder = 7,000 grains so with 25 grain loads I see 7,000/25=280 so what you are getting seems normal to me.

As to the 55 grain bullets with the 1:7 twist?

I recently fired some 55 grain Nosler ballistic tip boat tails in one of my AR rifles (Colt Target 1:7 twist). Powder was N135 25.2 grains, case was 1.750" and OA Length was 2.260. The rounds were originally loaded for my 1:12 bolt gun. Average velocity over the chronograph (from the AR) was 3180 FPS. What I got at 100 yards was pretty consistent key holes. However, that same Colt AR with a 1:7 twist has fired other 55 grain bullets just fine. I guess it just depends on the loads. Crapshoot 101.

Ron

 

[mdm]

I've shot a lot of 55 gr HPFB with 23.8 gr of VihtaVuori through a couple of Colt 1:7 barrels. Groups with iron sights are about 1.5" at 100 yards with nice round holes in the paper.

 

[Reloadron]

I've shot a lot of 55 gr HPFB with 23.8 gr of VihtaVuori through a couple of Colt 1:7 barrels. Groups with iron sights are about 1.5" at 100 yards with nice round holes in the paper.

Yeah, so go figure? I was seeing my groups as scattered in a 12" square and about 4 of every 5 were keyholes. That same rifle shot other 55 grain bullets just fine. Those same loads from the same lot shot sub MOA from my custom bolt gun with a 1:12 twist. I never understood the why of it, just beats the heck out of me. Never bothered to try yet another AR with a 1:7 twist. Anyway, if there is a rhyme or reason to it I guess it escapes me.

Ron

 

[taliv]

almost all of my ARs are 7 twist. almost all of my ammo is M193 or handloaded 69g or 80g SMK or 75g OTM or 100g FMJ.

they all shoot fine in 7 twist. but... i have seen a few wacky situations where one barrel just did NOT like one particular bullet. no explanation.