Flat spot on case necks after fire

[Trevor300wsm]

I mounted my scope on a new rifle I got last night and started sighting in this morning. The rifle is a 6.5x47 Lapua built on a Defiance action by Todd Bettin. I zeroed the rifle at 100 and decided to shoot a couple groups. I fired 12 rounds. As I was collecting my brass I noticed that all 12 rounds (spent) had a small flat section on the case neck. It's shallow and is only on the tip. Any idea what could cause this? A flat spot in the chamber? It is not from the brass hitting the ground, as they were ejected onto the grass. This is a new one on me, however this is a new rifle that I am not familiar with yet. Here is a pic.

 

[WRM]

Re: Flat spot on case necks after fire

I'd imagine that it really flings the brass out?

I suspect it is the ejector pushing the mouth of the case against the inside of the action just prior to ejection out the side port. Extract and eject an empty case slowly and watch where it is hitting to know for sure.

Cheers,

Bill

 

[Trevor300wsm]

Re: Flat spot on case necks after fire

Ok Bill I'll check it out. I didn't think it would have that much force upon ejection to press it that hard against the side.

 

[Mark Walker]

Re: Flat spot on case necks after fire

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WRM</div><div class="ubbcode-body">I'd imagine that it really flings the brass out?

I suspect it is the ejector pushing the mouth of the case against the inside of the action just prior to ejection out the side port. Extract and eject an empty case slowly and watch where it is hitting to know for sure.

Cheers,

Bill </div></div>

Yep. I have had to trim ejector springs in the past so this was eliminated.

 

[Tripwire]

Re: Flat spot on case necks after fire

That loud metallic click you hear when you move the bolt back enough to withdraw the case neck from that portion of the chamber is the case mouth smacking the inside of the chamber wall. Your ejector spring is doing it by over forcing the empty case towards the ejection side. That's your dent....

To prove it, hold your thumb or finger in there to keep the brass coming straight back and it won't dent anything.

If it bugs you then trim the ejector spring like Walker suggests.....

 

[pjparker]

Re: Flat spot on case necks after fire

+1 for the other posts on ejector springs.

Your ejected empty cases are hitting something on your rifle, either in the motion of clearing the ejection port or pivoting on the extractor and hitting the exterior or your rifle - possibly also your scope turret knob.

And yes, there is enough force in that little spring to do it.

Paul

 

[BK7saum]

Re: Flat spot on case necks after fire

+1. Youve got your answer.

 

[Fuzzball]

Re: Flat spot on case necks after fire

The dent is harmless.

 

[johndoe]

Re: Flat spot on case necks after fire

I have a 700 Remington that does it on a random base even if
I work the bolt the same way?

 

[Tomekeuro85]

Re: Flat spot on case necks after fire

Yea I had those too and eventually figured out/assumed it was the ejector bumping them on the inside of the action when the leave the chamber... but obviously they'll be gone with resizing.

 

[mdmp5]

Re: Flat spot on case necks after fire

totally benign scenario. some of my case mouths look like 1/2 moons they get clanked so hard against the receiver. the sizer ball straightens their ass out.

 

[jagged77]

Re: Flat spot on case necks after fire

I have this situation happen with a Rem 700 in .223 - only with Rem brass however, seems to be ok with Winchester. It is annoying as if I want to use a Lee Collet neck sizer sometimes, unless I'm careful, the mandrel of the collet can dent the case mouth and ruin the case. I shall get around to trimming the spring one of these days.

 

[InTheWeeds]

Re: Flat spot on case necks after fire

Same things happens to my brass coming out of my AR30.. Nothing to worry about- its comes out when you neck size them..

 

[djtjr]

Re: Flat spot on case necks after fire

It's the ejector just use an expanded when sizing and you. Wil be fine

 

[samnev]

Re: Flat spot on case necks after fire

Not a problem. The case is hitting somewhere on your rifle when is being ejected. Not at all uncommon. I've seen cases ejected from SIG 556's that lookm like someone stepped on the case mouth.