CZ527 .223Rem Slender chamber

[mematyi]

Dear Fellow Varminters!

I have an interesting question(at least for me) to you! I recently got a NOS CZ527 Varmint rifle, with the older 1:12" twist. It is an '03 year, and has British proof marks.

Breaking in was done with S&B FMJ 100pack bulk ammo, that brass I am planning to save for reloading. In the first 30 rounds, it literally had  almost zero copper fouling.

I noticed that all rounds went in the chamber quite tightly, one or two had to be really pushed to close the bolt handle.

I inspected the fireformed brass, and came up with this sketch. 

The "F" means fireformed, "FL" is just a check of my Hornady dies screwed all the way down.

What seems to be interesting for me is that the case neck is very normal, the body-shoulder junction diameter is right on the minimum, but the case web diameter is way under the minimum chamber dimension. I did check it with multiple fired brass.

I could not measure the headspace length, but I've tried numerous range pickup brass and none of them could be chambered in it, so I guess it is short lengthwise, too. 

I do think that it is actually a benefit, not a Con as I'll be reloading for it anyways, but it is strange how it passed the proofhouse.

 

Is it a common thing, or I got a Lemon?

[Andrew]

Dump the brass. I find bulk ammo of any kind is made quickly to sell cheaply. A poor brass mix, or not sufficient annealing, will not let you draw much conclusion as to 'fireformed' dimensions.  I have the same vintage CZ223 and have shot my handloads loaded on new FL sized brass with no issues. ~Andrew

[gunner]

just curious , i have a 527 cz but how can you tell the year of manufacture etc ?? 

[mematyi]

Thanks for the reply!

I know that the Bulk ammo does not have the nicest brass, but it seems like both SB and GGG brass have half-decent consistency, certainly usable for a factory gun. Not quite Lapua standard but usable for a non-benchrest gun.

It seemed that it was the COAL that made chambering very hard, it has a jam COAL of about 2.233" with 55gr ball fmj ammo, as I had no malfunction like this since then.

I wish my remington would have at least half this tight chamber.

 

 

The year of manufacture is stamped on the barrel, right side for me, "03" mark.