Gunsmithing flat sided case neck cause ??

[banshee sws]

i have a FN spr 308 that , is flattening the case neck , at the mouth, on one side only, 5 out of 10 fired cases; new factory load, or handloads doesn't matter.

rifle barrel is factory FN 20" fluted; coned breach, extractor cut, etc.,

(just giving as much info as i can here)

for the life of me I cannot figure out why it's doing this

no hard extraction, shoots well , accurate rifle

i used a BRIGHT light to inspect the bore, chamber, areas, nothing unusual that i could see

IDEAS ??

thanks in advance

 

[gamma]

Re: flat sided case neck cause ??

This is usually caused by a heavy ejector spring. If you have a very strong ejector spring it can bash your cases hard against the side of the side wall of the chamber and action as it ejects. The cure for this is a lighter spring.

 

[banshee sws]

Re: flat sided case neck cause ??

possible -

corrrected for FN action , it has a fixed blade ejector

no spring, lol i am too used to remington 700's

i was running my rifle pretty hard today, fast bolt manipulation
but then i had others that i was easy on, and i bet those were
the ones that have NO mouth deformity

interesting ....

 

[Badshot308]

Re: flat sided case neck cause ??

I thought the SPR had a fixed blade ejector. If that's the case, the the shooter determines how hard the case ejects when they pull the bolt back. Is it possible the cases are hitting a scope turret or mount? That type of action though usually ejects more sideways than up.

 

[banshee sws]

Re: flat sided case neck cause ??

it does have a fixed blade ejector, that is another option ,it hitting something on the way out

i may get my son to video tape me running it, and just see whats up

good idea sir

 

[Badshot308]

Re: flat sided case neck cause ??

On my MLR which has a spring loaded ejector, it occassionaly appears to not eject fully and leaves the 338 Lapua case laying in the action. What I found was really happening, was that the relatively high upward ejection of the case was causing the case neck to hit the scope turret and bounce it right back into the action. Having your son video tape it, may find a similar issue. In your situation, the case neck stiking something and getting deeply dented.

 

[nashlaw]

Re: flat sided case neck cause ??

George, sorry I did not get back to you earlier about the case issue. I was at work and could not get to the phone.

I had a .223 that did the same thing. It was a Remington, but the ejector spring was stiff enough to bang the case on ejection.

You may have to back off on working the bolt. I know that is a hard thing to do for a man of your substantial dimensions.

 

[neeley205]

Re: flat sided case neck cause ??

My FN does this too when I rip the bolt open really hard. Doesn't do it under normal firing situations.

 

[BradfromND]

Re: flat sided case neck cause ??

Check your scope turret to see if there are any signs of brass. My Sako 7 STW wrecked cases from the case mouths hitting the windage turret once ejected. No more target turrets on that gun.

 

[customshooter]

Re: flat sided case neck cause ??

2nd that