450Bushmaster.net

What would cause an accuracy decline in my 16” AR15? When I first got it, it would cut bullets with several different loads. Most accurate was 37gr Lil Gun with 250 FTX and 34.5 gr for 275gr Barnes. Now it doesn’t shoot nearly as well with the same loads. It’s not bad, it went from half inch to a little over an inch, but not as good as it was. I have thoroughly cleaned the barrel ( I have not scoped the inside), but that didn’t do the trick. I have a different can of powder now and I’m thinking that that might be the issue. I do not see any damage to the crown. What else should I check? I do not have any factory ammo but I think that might be where I should start

Check your rings and mounts also.....450 Bushmaster has a fare amount of recoil....your scope could be on its way out....I've sent back M A N Y scopes with problems for years 5-6 at a time to Leupold several times a year.....

ASAP.....I don't and will not own a Leupold scope.....

Put a cheep scope on a 450 BM and its only a matter of time before it gives up its ghost ......when I say cheep not necessarily price wise....

Scopes and rings and Picatinny screws torque. That’s the first thing to look at. Second thing would possibly be a change in primers or powder or changes that you’ve made in your crimping method. Another possible source could be your COAL. Another source could be your shooting style may have changed fractionally. But my first bet would be the scope and the rings. Powder does change by lot number. So if you can confirm that you’ve changed powders and these changes correlate to your changes in point of impact, you might have your answer. But I would still suspect the optics and the rings first.

Good, faithful brush and patch cleaning after every use is not always enough. Copper can still build up and take its toll. After a good cleaning of the bore, push a couple of dry patches through and give it the "hairy eyeball" with a borescope from end to end. That will tell the tale. Make sure you check the gas port hole for buildup. Also, give a close look at the muzzle crown. That, along with what has already been covered, should reveal the possible culprit.

Let us know what you find.

Hoot

Cutright wrote:What would cause an accuracy decline in my 16” AR15? When I first got it, it would cut bullets with several different loads. Most accurate was 37gr Lil Gun with 250 FTX and 34.5 gr for 275gr Barnes. Now it doesn’t shoot nearly as well with the same loads. It’s not bad, it went from half inch to a little over an inch, but not as good as it was. I have thoroughly cleaned the barrel ( I have not scoped the inside), but that didn’t do the trick. I have a different can of powder now and I’m thinking that that might be the issue. I do not see any damage to the crown. What else should I check? I do not have any factory ammo but I think that might be where I should start

Update?
You ever find the cause of your accuracy issue?

I think I got it corrected but not sure how. I did a deep cleaning, tightened all the screws ( they moved a tiny bit with the torque wrench. I also had to buy a new can of powder so that may have made a difference too. I had my “best ever” group today with some new Bear Creek Ballistic bullets that I got. I forgot how to post pics here I used to do it with Tapatalk or by somehow screenshotting the pic. When I figure it out, I’ll post it because it’s a one-holed 3 shot group

Cutright wrote:

822D1897-CF72-4E2B-9EA3-EB182E1B02A5.jpeg

OMG! That's a truly noteworthy group. Congratulations on finding the perfect recipe and I might mention, excellent target design.

Hoot

PS: Don't sell that cow!

I figured you’d recognize the target! Thanks. By the way, the crimp grove on that bullets matches perfectly with the crimp tool you made for me

Cutright wrote:

822D1897-CF72-4E2B-9EA3-EB182E1B02A5.jpeg

I'd be tickled with that. What range? I can get "clover" groups at 50 yards with my Bushmaster 20" using Hornady Black but farther out... no way, Jose. What I get is more than acceptable for hunting, which is all I use it for, but I won't turn down better if I can get it.

My reloads are lots worse. Very inconsistent... but I don't get much time to play so improving that situation is an ongoing project. It's hard to develop loads when it's weeks or months between the work. Allegedly, I am "retired" but beyond still farming, there is always some other screaming emergency demanding my attention.