Thread: ZKK-600 7x57 Hard to chamber

I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

Originally Posted by Tentman

I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

After a blast through the solvents and brass brushes for the 6th time I can now pick up and feed just fine, but the bolt up/down to lock and unlock is still far to stiff, almost like the bullets to far forward if that makes sense ?

I’m about to resize some factory ammo and see what that results in otherwise I’m thinking somethings askew with the neck/throat as there isn’t really anywhere else, I can see the chamber 100%and I’m confident where the “body” of the case is is 100% Spick and span but the neck obviously is a bit hard to get a really good look at without a bore scope handy

Originally Posted by Tentman

I don't "buy" the mismatch theory, CIP (Euro) and SAMMI (US) specifically work to "harmonize" critical dimensions, and in any case PPU is Euro.

Looking at the cases pictures I wonder if there is a lump of something on the chamber wall in the area of the case body. A Headspace guage is cut away in this area so might have chambered ok and told the GS that it was within spec. It wouldn't necessarily have highlighted a chamber anomaly.

After a blast through the solvents and brass brushes for the 6th time I can now pick up and feed just fine, but the bolt up/down to lock and unlock is still far to stiff, almost like the bullets to far forward if that makes sense ?

I’m about to resize some factory ammo and see what that results in otherwise I’m thinking somethings askew with the neck/throat as there isn’t really anywhere else, I can see the chamber 100%and I’m confident where the “body” of the case is is 100% Spick and span but the neck obviously is a bit hard to get a really good look at without a bore scope handy

Firstly, pulled a random PPU from the box, disassembled and gave it a resize in the older Lee die set and sent it through twice painted up with no projo

1# no contact
2# no contact

Bolt is still extremely stiff on lock and unlock….

Maybe I need to get in the locking lug and dig around with a pick ? The pressure has to be interference somewhere.

shiny as a brass bell in there !

Originally Posted by Billymavs

Firstly, pulled a random PPU from the box, disassembled and gave it a resize in the older Lee die set and sent it through twice painted up with no projo

1# Attachment 264983 no contact
2# Attachment 264984 no contact

Bolt is still extremely stiff on lock and unlock….

Maybe I need to get in the locking lug and dig around with a pick ? The pressure has to be interference somewhere.

Attachment 264985 shiny as a brass bell in there !

In the photos there seems to be a bright mark on the forward corner of the rim and, maybe, some brass particles on the bench. Might be worth having a good look at the extractor to see if it is dragging and shaving brass.

Originally Posted by grandpamac

In the photos there seems to be a bright mark on the forward corner of the rim and, maybe, some brass particles on the bench. Might be worth having a good look at the extractor to see if it is dragging and shaving brass.

The rim is from me being a spoon and dropping it on the shed floor before getting it in the gun, brass filings are from todays other fun job or re braising and tidying up a couple of P14 bands