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Groove dia. in CZ527

Ambrose
What's the groove diameter in the CZ527 in 7.62x39? I have bullets in .310, .311, and .312--wondering which might shoot the best.
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4 comments

Date Votes
  • mbsams
    load some and test some - best way to see what works best in yours.
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  • tsr1965
    Ambrose,

    Measure the bore yourself, by slugging it. It is easy to do. For that bore diameter, get yourself a 36 caliber ball meant for a muzzleloader...it is PURE LEAD(extremely important!). Lube the bore good with a quick spray of Break Free, CLP, WD-40, Tri-Flow, or something similar. Drop the ball in the breech end, and use a wooden dowel and hammer to tap the ball thru the bore...the soft lead will form to the bore perfectly, and you will be able to get the measurement you are looking for.

    Best
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  • beantownshootah
    Supposedly bore diameter on the CZ guns is .311"

    Of course you can slug it to find out the true bore diameter, but ultimately the empirical test is the best test.

    In other words, no matter what the bore diameter is you're still probably best off trying different bullet types to see which gives the best groups in your particular gun.
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  • jonk
    Bore diameter is more crucial for cast lead bullets. I've had .311 bores that actually shot a particular .308 best. The jacketed material is much more resiliant.

    On the other hand, 1/1000 over nominal bore diameter won't cause pressure issues unless you're at max loads, thinking of the .312.

    So I'd try them all and see what does best.
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