Spiral scratches on bullets?

[siconic]

I am hoping someone can help. I am not even sure its a big deal, but I am trying to get a sub moa group, and the scratches may very well be one factor in not acheiving that goal. Its a new build, 20" BCA barrel, AA upper, DPMS lower. The feed ramps on the barrel lug line up with the upper.

I also have dinged cases, and I adjusted the gass block to "perfect". I suspect heavy extractor spring. Not really a big deal, but it would be nice to eliminate.

I will add the pics when I can. Apparently I cant on the mobile site.

[A5BLASTER]

How many scratches?

If only 2 then it could be sharp edges on the extention.

If more like the same amount of the rifles bore then it could be the rifling.

[siconic]

I dont think its the rifling, I should be 0.08 off the lands. It could be 2 spirals though, and they are well past the ogive, almost to the case neck... would polishing the feed ramps help?

The dings I was mentioning are on the neck, in case it was not clear.

[A5BLASTER]

I dont think its the rifling, I should be 0.08 off the lands. It could be 2 spirals though, and they are well past the ogive, almost to the case neck... would polishing the feed ramps help?

The dings I was mentioning are on the neck, in case it was not clear.

It couldn't hurt for sure.

Dents in the case neck could be from the case hitting on its way in to the chamber, maybe double check the rounds are feeding smoothly from the mags your useing.

[siconic]

The dents in the neck I think are from the brass deflector on the upper. Not 100%, but there is brass color on the deflector as well. I think its "over extracting" and really throwing that brass out.

The spiral scratches on the bullets, so close to the case necks, could that be from the feed ramps? Just seems so weird to me for some reason.

[Bigs28]

Case necks hitting the extractor and denting is normal. You can put a soft pad on the deflector if you want to minimize it but i don't worry about it and let my resizing die take care of it.

[Sticks]

Welcome to the Horde.

The barrel might be the first problem with the accuracy, then who built the upper and if they bedded the barrel in the upper.

Followed by what ammo you are shooting.

Top that all of with the optic, mount, and your abilities.

Few more details and we should be able to get this figured out.

[HercMaster]

How deep are the sceatches, and how close together are they? This could narrow down your search and let you know if indeed you are hitting the feed ramps and suggest you polish them. I just built a 6.5 with a dual charging upper and a 20" Heavy SS barrel, both from Bear Creek. I did true up the upper with my Wheeler Lapping Tool. With Hornady Black 123gr EDLs I an getting sub Moab @ 100yds and also with a new load using the Lehigh 110gr CC, 30.2GR 2520, WSR primer, new Starling brass trimmed 1.510", chamfered with VLD tool (prevents any shaving of bullets) with a COL of 2.250", This load was worked up to starting with 28.4gr of 2520 and two days ago gave me a 10 shot .581 group. This is my 3rd BCA barrel, they are all sub moa and I couldn't be more pleased with their guality!

I build all my own ARs and only use a silver based antisieze compound. I have been working with and building ARs for near 40 years and do nor recommend using anything other than a high quality non copper based antisieze. Using a copper based compound wIth steel (stainless included) and aluminum sets you up for galvanic corrosion and will destroy your upper in a very short while!,

[rabiddawg]

A5 you still got that popcorn maker?

[bj139]

Case necks hitting the extractor and denting is normal. You can put a soft pad on the deflector if you want to minimize it but i don't worry about it and let my resizing die take care of it.

If your case necks are hitting the extractor you sure do have problems.

[Kswhitetails]

If your case necks are hitting the extractor you sure do have problems.

heh. I bet he means deflector. Good catch there, Bj.

[siconic]

So, the upper was built by me. I am not gunsmith, but I was a machinist, so I understand how import fit and finish can be, especially for accuracy. That being said, I lapped the upper, bedded the barrel using blue locktite (dont judge, lol), used proper torque, and used non-copper antisieze for the barrel nut.

My loads are handloads, ladder tested CFE223 from 29 to 32.2 under 123 gr SST, Hornady brass, AR Comp Primers, and a COL of 2.248. With that combo 31 gr CFE223 was the best group.

As far as my skills, I was an Amry Infantry Soldier and I consistently scored expert every time. They sent me to SDM school, so there is that. I figure its like riding a bike. I know I am rusty, its been 10 years since I shot a rifle regularly, but I should be able to shoot MOA groups pretty easy, even being rusty. That being said, I know what to look for, and I am pretty sure any group over 2" @ 100 is not my fault, lol.

2 Target pics; 1 is a 15 shot group,3 inch target, 25 gr 8208 XBR under 123 gr sst, fireformed AK brass, CCI Large rifle, @ 100 yards. Good group, way to slow. 2nd pic is a 1 inch target, 5 shot group, 29.4 CFE223 under 123 gr SST, Hornady brass, AR Comp Primers, and a COL of 2.248. Other than the flyer it looked pretty good and disregard the writing, I was ladder testing 8208, and started to see over-pressure signs, stopped and re-used the target. My group with the 31.0 grains of cfe 223 looked similar without the flyer.

The other pics are my troubleshooting issues.

[siconic]

[imaguy3]

I wouldn't worry about those dents in the case mouths... heck I've dropped brass after sizing on my garage floor and it did that. I just run it back through my sizing die and they turn out fine.

I also don't think the scratches on your bullet are going to cause any accuracy issues.

[siconic]

What could be causing those scratches though? I am just OCD, so if I can eliminate them, I would like to. BUt I cant imagine at 100 to 300 yds it would, but what about out to 700?