AR15 and scratched ammo

[fchavis]

I've noticed that the bullets of chambering rounds get scratched up on my ar15. The corners left on the feed ramps by the receiver's lug grooves put scratches in the copper jackets, and I can't help but think this degrades accuracy. My rifle shoots just fine, but is it capable of better with more symmetrically uniform, unscratched ammo? Does anyone recommend rounding those corners very slightly? I just mean at the top, outside face of the feed ramps. This should not affect lock-up or overall integrity. I don't think I have ever seen an auto-loading rifle that wasn't a little hard on ammo, what with the forces involved, but is there a way to minimize this on an AR? Is my description clear enough?

Thanks

 

[IndianaBoy]

Imagine how drastic the scratches are that are left in the bullet by the lands in your barrel.

Cosmetic scratches from handling or chambering are insignificant.

 

[Conqueror]

I have the same "problem" and have wondered the same thing. A little too scared to try it on my custom $300+ barrel though.

 

[fchavis]

wow, I can't believe that didn't even occure to me, but in fairness, rifling marks are symmetical.

 

[Onmilo]

One thing to consider is whether the scratches are caused going into the chamber or coming out.
People see scratches on the bullets when ejecting live cartridges from the chamber and on many occasions the scratches are caused on the bullets by ejecting the live round.

I wouldn't worry too much about this unless your rifle is shooting six inch groups at one hundred meters.

 

[fchavis]

Nah, I've certainly got no complaints with accuracy, its just something I have been wondering about. Thanks for the thoughts.

 

[jayp]

I've wondered about this too.

I'm new to the AR 15 world; just took my Bushmaster M4 out for it's 1st shootiing session. Chambered bullets that were ejected without firing had slight but noticable scratches. I think this is normal.

 

[HOLY DIVER]

wellcom to the club jayp!

 

[Whitman31]

I posted this same question some months ago, I got a lot of garbage back saying that the scratches won't do a thing to the accuracy of the round. I did get one good response telling me that the scratches were from the barrel extension cutouts for the bolt lugs. The extractor lifts the nose of the shell up against them only when removing a live round, not when chambering. If you open the bolt slowly and use your finger to keep the round pointing down the barrel and not tipping up, you'll see the scratches aren't there.

So, whether or not this effects accuracy, it's only happening to the live rounds you eject. I tend to believe this has to have some effect on the flight of the bullet. The grooves left from the lands are significant, but symmetric.

This is all opinion and I have no facts to back any of it up...

 

[jayp]

wellcom to the club jayp!

Thanks. Glad to be part of the Black Rifle world

 

[P-32]

Let me tell you what happened to me about 3 weeks ago while firing a 600 yard practice match with my AR. At 600 I use 80 gr. SMK's loaded .015 off the lands. These rounds have to be loaded one at a time as they won't fit a mag and it's slow fire. I use a sled in place of a mag. I throw the round in the ejection port and close the bolt when ready to fire.

Once in awhile a round lays in the sled wrong and when the bolt closes the round gets dinged. Normally I will have a extra 600 yard round for the once in awhile misfeed.

On this day I was shooting the last 20 round string for record out of 60 rounds. I loaded a round and saw I had a stove pipe. I extracted the round and saw the bullet was dinged worse than I have seen it before. I could see an imprint from the bolt clearly in the side of the bullet with a couple of deep sharp dents and I could see lead. I had only enough ammo left to finish the match. I thought to myself the bullet won't make it but I loaded and shot it any ways. I shot it knowing it would either loose the jacket and be a miss or if I was lucky be a flyer.

The shot left the rifle and my target went into the pits. OK, I at least hit paper. It seemed the guy in the pits took longer than I expected. I thought bad thoughts. The target came up and......it was a 10. I finshed with a 190 out of 200 so the ten ring had been hit before.

I proved to my self it is the Bullets with damaged bases that don't fly right.

 

[EdLaver]

Minor scratches wont hurt anything at all. It wont hurt the round, bolt, or the barrel. Now if you have to use the forward assist to chamber it, then you might have a problem. The only time I have ever had to use the forward assist on any AR was with my DPMS AR when I fed it Wolf ammo. Never used it again after 5 rounds, I gave the remaining boxes I had to some kids shooting a .223 bolt at the range.