Question on brass. 300 prc box ammo

[Decker]

Question on my brass, shooting eldm 225 box ammo

Shooting some more today and I’m struggling to shoot better than 1.5moa at 100. Started to look at my brass and I notice the black carbon around my necks, further investigating I notice this ring along bottom.
Went back and looked at first box of ammo I shot. Have the ring and carbon build on them too. 60 rnds down barrel so far.
Thoughts? Pressure issues, chamber issues?

 

[Mojave]

What is the rifle?

 

[Decker]

What is the rifle?

300 prc custom build I had done.

 

[Decker]

Here is the primer side. There could be nothing wrong and I’m over thinking this.

 

[dieselchessy]

Nothing looks off to me. Ring at bottom in brass is normal, case web.
Carbon around necks looks normal to me. Sooty powder, softer load maybe.
Primers look fine.

 

[IrkedCitizen]

Shoot a 10 or 20 shot group and see how large it is.

How are you supporting the rifle? More specifically the buttstock while shooting? A 300prc shooting 225gr bullets is substantial recoil.

 

[waspocrew]

Looks totally normal to me. I’d try different factory ammo - your rifle may not care for the 225 ELDM.

 

[Decker]

Shoot a 10 or 20 shot group and see how large it is.

How are you supporting the rifle? More specifically the buttstock while shooting? A 300prc shooting 225gr bullets is substantial recoil.

Was shooting 5 rd groups
Using a a bag to support the rear and bipod to support the front. I have the Xlr carbon butt stock on Xlr mg chassis.
I dont feel recoil is to bad. But rifle does jump on the shot.

 

[Decker]

Looks totally normal to me. I’d try different factory ammo - your rifle may not care for the 225 ELDM.

That’s my next step, just wanted to double check and make sure there wasn’t other issues before spending bunch of money on other ammo.