question/concern about 1-9 AR barrel

[kritos666]

I have a question about shooting heavier bullets in a 1-9 barrel. My main bullet is 69gr, which is great until the wind picks up. I had a few 75gr bullets and tried those on a windy day (8MPH avg. 13MPH gusts). Shooting at 500 yrds. My 69s just couldn't buck the wind. I've worked up a load for 77gr SMKs and have pretty good results. I haven't yet chrono'ed them yet. The gun is stabilizing the 77's just fine, my load workups were at 200yrds. I don't have a 300yrd range.

Am I risking any type of damage or undue wear on the barrel using 77gr bullets ?

Any input would be helpful.

 

[MitchAlsup]

Re: question/concern about 1-9 AR barrel

No barrel damage will take place other than the std wear and tear that is already taking place (as long as the pressures are not excessive.)

What altitude are you shooting at?

 

[kritos666]

Re: question/concern about 1-9 AR barrel

875~ for load testing

2250~ for actual distance work (in woods shooting across small valleys)

thanks for the reply !

 

[MitchAlsup]

Re: question/concern about 1-9 AR barrel

875 and hot with 77gSMK will probably work in 1:9 barrel.
875 at 0dF with 77gSMK probably won't.

 

[kritos666]

Re: question/concern about 1-9 AR barrel

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MitchAlsup</div><div class="ubbcode-body">875 and hot with 77gSMK will probably work in 1:9 barrel.
875 at 0dF with 77gSMK probably won't.</div></div>

assuming your saying at 0 degrees F, what would you say would be a rough cut off don't bother below X degrees? I believe the temp was 65F. I don't remember the other environmentals. I would have to consult my log book which I don't have on me.

I take it the colder/denser air would require a higher twist to stabilize?

 

[MitchAlsup]

Re: question/concern about 1-9 AR barrel

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kritos666</div><div class="ubbcode-body">assuming your saying at 0 degrees F, what would you say would be a rough cut off don't bother below X degrees? I believe the temp was 65F. I don't remember the other environmentals. I would have to consult my log book which I don't have on me.

I take it the colder/denser air would require a higher twist to stabilize? </div></div>

Your rifle will tell you. Basically 1:9 in 224 is good for 69-71gr bullets over the entire set of atmospheric conditions at sea level.

The overturning moment is 20% greater at 0dF than at 100dFsimply because the air is 20% thicker (22% = 100dF/453dR).