Thread: ZKK-600 7x57 Hard to chamber

Originally Posted by John Duxbury

For clarity - is it feeding cartridges with difficulty from the magazine, or just hard to chamber - close and open the bolt on? (Or both?)


First thing you do - is shoot it. If the empty case then extracts normally - try then and rechamber one of the fired empty cases. If it goes in with ease, then you will have a slightly have an out of spec chamber. This is fine, just means you need to reload after "fireforming" your brass in the rifle.

If it extracts with ease, but then is difficult to chamber the empty, means you probably have a slightly out of round chamber. (To prove this, it will chamber better, if you keep turning it around till it "fits" again.)


If you have issue with feeding from the mag, you can look at the usual suspects -

Mag spring too strong.(Try running a cartridge out of the mag with the floorplate dropped (held in your hand) a cm or so lower, to weaken the spring. If it goes in alright then, you need a weaker spring.)
Or, change followers with a Mauser and see if it feeds better.

Examine - Slide a cartridge forward slowly and see where its going wrong. Some might feed ballistic tip spitzer bullets well but not rounder nose soft points. You will have to see what it is doing. Is it releasing too late from the mag, it the bullet face planting on the side, or top, of the chamber.
Rough feeding ramps, you can smooth/polish with a stone or fine file. Smoothing only, you dont want to change any angles yet...not until you absolutely have to and you have to know exactly what you are trying to achieve.


NOte: There is no "mismatch between Euro and US cartridge specs" for this cartridge. Anyway, the rifle was made in Czechoslovakia, the Sellier and Bellot is made in Czech Republic and the PPU is made in Serbia. All European. (There is however, a difference in extractor groove depth on some old 7x57 PPU cases. Some older Highland/PPU cases will not fit standard shell holders and could be contributing to a difficult chambering.)

A video would be helpful to see what going on.

Where I’m at now is just very stiff locking and unlocking of the handle, at the moment that is my focus as the magazine spring can be dealt to later.

I made some progress today and now have it feeding in and out to an acceptable standard, just forceful up and down on the bolt to lock and unlock.

It seems to feed and lock the fat nose S&B far better than the longer PPU rounds, although it still is to tight with the S&B for comfortable use and that is only after a massive amount of cycling rounds in and out all evening.

I have tried all other things suggested thus far, and I am at a loss as the results are contradicting.

I’m tempted to just get it re reamed and checked and specd by someone who knows these well, it owes me peanuts so far….

Prehaps it was just a Friday afternoon rifle ?