1:9 16inch carbine length and 62 grain 5.56 NATO

[Seedy]

Hey folks! I have a RRA LAR-15 16inch carbine length gas port with 1:9 twist. I just picked up some Lake City "Penetrator" 62grain steel core ammo. This is the same NATO marked, green tipped stuff our soldiers shoot.

Am I going to have issues with bullet stability? I've read I can expect "keyholes" and tumbling at 200M... I bought the ammo to plink with so I don't plan on going "long range" with it.

Has anybody else played with heavier bullets in 16 inch carbine length gas port 1:9 twist barrels? Thoughts, experiences?

 

[89hits]

You will not at that grain weight. Anything heavier, maybe, maybe not.

 

[LOKNLOD]

You'll be fine with 62-gr. in a 16" 1:9. It'll probably handle up to 68 or 69-gr. without trouble, but that will likely be the upper edge.

 

[ez bake]

It depends largely on barrel quality.

We've hashed out the barrel twist / bullet weight argument a lot on this site and many others, and it really comes down to barrel quality almost as much as twist rate.

Barrels made to tighter specs (and chambers that are closer to or even just a hair under SAMII specs seem to almost always break the "1/9 twist is only for lighter bullets and 1/7 is only for heavier" argument.

Case in point - I've got a 1/7 Noveske in only 14.5" and it shoots everything from 45gr to 75gr with no problems. My old M&P15 had a 1/9 twist and could do the same thing.

Both were more than accurate enough between 100 and 230 yards (that was the max range I had at the time).

I've seen only two looser-tolerance 1/9 barrels produce a key-hole on paper at 100-150yds with heavier (and I can't remember if they were 69gr or 75gr) bullets, but I've yet to see a decent-quality barrel do it.

 

[Spooln-Rex]

My dpms...... anyways, it likes the 62 grain stuff just fine. which is the same deal except its a lite contour barrel but 16" 1X9 twist. i usually shoot 55gr just cuz its easier to get ahold of. but i can run 62's just fine out to 300yds. i havent ever bought anything heavier though been wanting to try a 69gr or 75gr just to see how they act.

 

[mike_pinto]

I think what you are asking is about the steel core, right? Yes, they will become unstable at distance. They are nose heavy. The green tip 62's were not made for shooting distance. Can it be done? Yes, but I wouldn't count on it.. Also, never shoot steel targets with that stuff. It will make the owner of the target very upset!

 

[Seedy]

Excellent info. Thank you all for the responses. Yes, it is the "steel core" that I had read had issues at distance. I had already considered the "steel target" issue too, I suppose this would also preclude me from shooting it at indoor ranges!

All in all....for the price (about $0.45 per shot) I think it will "plink" just fine If I get somewhere where I have 200M+ range I'll make sure to grab some lighter ammo though.

EZ-interesting to note that you have found that there is enough difference in tolerances in supposedly the "same" barrels to effect the stability of heavier bullets at longer ranges.

FYI-I got the ammo as "loose bulk" from Sportsworld. It is about $45 for 100 rounds.