M70 EW cratering primers

I started with 142 ABLR. Then I started over with regular 140gr Accubonds. Used some US869 with no luck. Went to the N570 and is magic in this gun. The Gevelot brass is actually lighter, with more capacity than W-W brass.

The cratering started slowly. But at higher loads. That is why I believe a combo of a weak spring and a sloppy hole.
 
Ruger007 said:
I started with 142 ABLR. Then I started over with regular 140gr Accubonds. Used some US869 with no luck. Went to the N570 and is magic in this gun. The Gevelot brass is actually lighter, with more capacity than W-W brass.

The cratering started slowly. But at higher loads. That is why I believe a combo of a weak spring and a sloppy hole.
Click to expand...

I always heard that the Gevelot and Metalverken was a heavy brass compared to local offerings, I am very surprised to hear otherwise. It was very popular because it was cheap and apparently good stuff, Higginson sold tons of it.
BB
 
I'd bet dollars to donuts that you're wrong.

Why would pressures increase the more rounds fired through said rifle....unless there is/was a restriction.

400 grit silicon carbide lap the chamber/leade/bore & your issues will be non existing until you fire enough ammo to build up a CARBON RING AGAIN.

My Gradient Lens bore scope tells no lies.

Not my first rodeo....either.
 
So I did another cleaning. Bore scope showed some minor carbon at the end of the chamber. Twist with a brush took it out.

Took the firing pin out and gave it a cleaning again. Put back in with no lubricant at all.

Back at the range. 5 rounds each of 67 and 67.4gr N570 140 Accubond with the CCI250 primer. Also 5 of each of the same with Federal 215 primer.

Shot the CCI first,. Blanked the last shot of the 67.4gr. All cases had a slight cratering. Very minor.

The Federals all went off with no issues. No cratering at all. But speed increased by 40fps across the board.

CCI had far better accuracy with less ES.

Perhaps I have a bad batch of primers?
Still want to change the spring. If only I could find a new style spring.
 
There seems to be a bunch of different springs like you say. I'm pretty sure I could compress this spring enough with bare hands to get the spring retainer out.
 
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