Accurizing a 7.62x39 CZ527

[Pyrocat]

Since it's difficult to find long range where I shoot (max is 600m), I bought a CZ527 in 7.62x39. According to computations, shooting a 7.62x39 123gr SP out of it at 600m is very close to shooting a 175gr HPBT .308 at 1200 m in terms of drop and wind drift. So, why not trying! The rifle isn't that expensive at all so risk was limited.

My big issue is that the particular rifle I bought isn't accurate at all in the first place... At best 3 MOA at 100m indoors with bipod, sandbag and scope.

After a bit of experimentation, I think it's a point of contact issue with the stock because I think I see two "modes" in the groups and it jumps back and forth to one another. I tried deburring the stock, it helped a bit but it's not stable.

Has anyone experience in accurizing a CZ527 ? I'd be happy if I can get 1.5' but 3'+ is clearly not acceptable... I saw on the QC plot that it was approved with a 50 mm group at 50 m on a 3 shot test :| It's my fault to have accepted the rifle without testing but I was totally trusting CZ until then...

 

[KnowNothing256]

I haven't accurized mine, but ammo made a drastic difference for me. I started with just steel-case Russian milspec surplus, and it was more of a pattern than a group. Switched to Hornady Black and it immediately turned into a sub-MOA gun.

Have you tried several different ammo options?

 

[Pyrocat]

I tried both Gecco and Sellier Bellot which were the only two I could source. Same results with both (30x 5 shots group each).

I'd like to handload but gunsmiths here only offer Partizan cases... not to mention the difficulty to source some correct powders for the caliber :-/

 

[spife7980]

Being in France it may be difficult to have access to good ammos, I wouldnt consider either of those two brands you mentioned to be accuracy oriented.

 

[Pyrocat]

+1 indeed

And things got worst with the ammo shortage :-/

I designed a pillar bedding part for the rifle but haven't ordered it yet. If/when I order it, I'll post an update here.

 

[supercorndogs]

You could bed the action and see if it helps.

 

[Chickentoast]

Mine shot red army standard both fmj and hollow points <= 1moa. Try it if you can find it, cheap also.

 

[Pyrocat]

You could bed the action and see if it helps.

Bedding was my first idea but the mailman decided otherwise

Instead of purchasing the Bedding compound again, I decided that a massive steel block glued in the stock would be a more decisive solution but that's WIP...

 

[Chickentoast]

View attachment 8118840
Bedding was my first idea but the mailman decided otherwise

Instead of purchasing the Bedding compound again, I decided that a massive steel block glued in the stock would be a more decisive solution but that's WIP...

Before bedding mine, I made some action screw washers out of business cards and put them inside the stock, effectively lifting the stock away from the action. I think 1 in back and 3 in the front gave enough float for the best groups.

 

[supercorndogs]

View attachment 8118840
Bedding was my first idea but the mailman decided otherwise

Instead of purchasing the Bedding compound again, I decided that a massive steel block glued in the stock would be a more decisive solution but that's WIP...

Sometimes actions that needed bedded need it because there is a hump in them. When they have a hump in them, they don't like be bolted to steal block.

 

[KnowNothing256]

I mean, before you start modifying the rifle, I would look at ammo. I understand your factory options aren’t great, but I would try to get something better or handload, even with marginal brass, before I’d assume bedding is the problem. Agreed with @spife that those two ammo brands don’t inspire confidence, and my 527 was distinctly displeased with the budget stuff I tried.

 

[Pyrocat]

I mean, before you start modifying the rifle, I would look at ammo. I understand your factory options aren’t great, but I would try to get something better or handload, even with marginal brass, before I’d assume bedding is the problem. Agreed with @spife that those two ammo brands don’t inspire confidence, and my 527 was distinctly displeased with the budget stuff I tried.

Currently I can only get Sellier Bellot which is considered as cheap training ammo. Gecco is better but not anything close to match ammo.

Handloading I only found Partizan cases which I was told is crap (so I didn't buy them because they're expensive as well) and suboptimal Vita powder. So I'm waiting for a better opportunity that doesn't require applying for an import license :-/

From the tests with the wooden stock I have some good hope that I can improve group size. I see that it's going from distinct POI to another. So I have like 3 shots 1' then suddenly the POI moves on the side or up/down for another 3 shots and so on. And it seems that it's the contact between the stock and the action, not the stock and the barrel.

The rifle was "cheap enough" for me to experiment a bit with it. I have a spare stock as well on the side.

Instead of going to expensive gear, I wanted to start this time with a more basic setup and to machine some parts myself as an exercise (not touching the action-barrel part for obvious safety reasons). I believe it's a good way to learn hands-on experience. I have two other rifles that were 0.5' out of the box so I wanted something "different" this time