Another query about twist ....

[Gothmog]

I have an Armalite AR15 with a 14.5" barrel whose accuracy is indifferent at best ... apparently twist is 1:9 (standard Armalite, I am led to believe).
The rifle hates UMC 55 gr but performs ok (not great) with Winchester 55 gr or Malaysian ball. American Eagle 62 gr gives slightly better results with the gun but still nothing to write home about.

Should I be trying a heavier bullet (68gr) or perhaps reloading to find what it likes?

 

[Westicle]

if you pick up some federal gold medal let me know where you got it from, want to try some heavier stuff also.

I get good results with russian wolf 62gr..... call me crazy but my ar15T loves the stuff.

 

[Gothmog]

if you pick up some federal gold medal let me know where you got it from, want to try some heavier stuff also.

I get good results with russian wolf 62gr..... call me crazy but my ar15T loves the stuff.

I'll keep an eye open for it ... I am told wonderful things about some kind of Federal 68gr .223 ammo which Sixstar promised to bring back from Del Selin's one day soon, perhaps that is it.

In the meantime, I have 1000 pieces of Hornady 68 gr BTHP which I can reload and shoot, but I'd sure like to hear if anyone else is having the same issues and how to fix them. All the reading I've done suggests that 1:9 is ok with 55 gr but not the best ... and heavier bullets will work, up to a point (ie - 69 gr max), but hopefully someone here has some clues or answers for me.

I was at Dlask's today and he showed me a heavy barrelled AR with a 1:9 twist which shot 55gr very accurately, and I own a 16" barrel with the same twist which is also compaible with that bullet weight, so perhaps its the combination of the shorter barrel with that twist, or maybe my assumptions about the twist rate of this barrel are incorrect ....

 

[Gothmog]

1/9 will shoot 69gr SMK very well.

On the other hand, what do you mean by being "bad"? Twist rate is not the only factor, maybe the barrel, maybe it is the dimension and concentricity of the chamber, maybe the headspace, maybe it is the operator, maybe it is the stars in the heaven, maybe the target moved........don't blame the twist rate yet.

Hi GT, I don't believe I used the word 'bad', but this rifle shows indifferent results with 55 gr ... As you point out, it could be operator error, but I don't suffer the same issues when shooting other AR's, some with the same twist rate, but barrel lengths of 16" or 20".

As I have used this rifle a fair number of times I think we can discount the moving target theory. As to the more technical possibilities (headspace, concentricity) I will check them if I cannot find any other obvious explanation, but they are indeed a potential issue. The question I would have in this case is why the change in accuracy with different ammo if it is a barrel dimension issue?

I am hoping there is some simple answer to this and that perhaps someone else has experienced this and can offer help. I suppose one other thought is that this rifle may be a different twist than assumed, perhaps a 1:7 ... Armalite do not mark their barrels with the twist rate but are supposedly a standard 1:9.

 

[juliet lima]

if you pick up some federal gold medal let me know where you got it from, want to try some heavier stuff also.

Sparrow was sooooo impressed with it at yesterdays match that he gave away his last four boxes...

...after I binned two matches from primers falling out of live rounds, two got jammed in the lug recess and one under the trigger mech causing serious havoc on the line. It was my own fault though as I though I'd use up the last of the Federal Premium 55grain BTHP after zeroing with Lima's White box 55grain the night before. Besides the above make sure you have glasses on (which I did) when slamming the bolt home on two unpopped primers and looking at the ejection port.

jl

 

[Gothmog]

I picked up a few hundred rounds of 62 grain Winchester White Box and tried them out in this rifle recently ... problem apparently solved.

Now, where to find more?