Extractor Marks on AR15

[Mbaysinger89]

I'm loading for a 20 Prac. When I was sizing I was feeling roughness in the shell holder and noticed I was getting extractor marks on the case rim. I'm new to loading for AR so I'm not sure if this is normal. Does the extractor have burrs that need polished, just run with it, something in the loading procedure?

Brass is Lapua, BCG is Aero.

 

[Josh1978]

Typically extractor marks or swipe, are often the beginning signs of high pressure. Have you had an opportunity to chronograph any of the rounds you have loaded?

 

[Mbaysinger89]

Its on every peice of brass from 3200 fps with 22.5 gr Benchmark and 35 Bergers that didnt fully form the new brass to this barrel, to 25.8 gr at 3750 that is just starting to knock a little round off of the primers. No ejector swipe or mark, nothing close to flat primers.

 

[Josh1978]

3750 sounds like a lot. I checked my loading book for 5.56 and it shows Max loads at 3200 FPS. I loaded some Hornady 52gr BTHP using Benchmark. I went up to 24.0 gr which should be something like 3100 FPS. I haven’t had a chance to go shoot them and see what the chrono. says.

Hopefully someone with more experience will chime in. There are guys in here that have been loading longer than I have been alive, and I’m in my 40’s. Lol

 

[SporterII]

52 SMK at 3500 in my 24” bolt gun raised my eyebrows. IMHO you are way over pressure. Long throat saving you.

 

[Mbaysinger89]

20 Practical fellas. Not 5.56. Shooting 35 gr pills. Should be roughly the same velocity as a 35 gr in 5.56 with a little less powder due to the tighter bore.

 

[Josh1978]

I don’t know why I was thinking 5.56. Man I have been struggling today. Lol

 

[308sako]

Mbay... what you are seeing is the rough edges of the tooling from the extractor, and your initial thoughts of that being the culprit are correct. If your loads are indeed reasonable and all other performance aspects are in line, then look to taking the rough edges off and that issue should resolve itself.