CZ 527 in 7.62 x 39

RKG

NES Member
Joined
Dec 7, 2005
Messages
3,993
Likes
959
Location
Boston
Feedback: 0 / 0 / 0
I am not an expert with the CZ rifles, so take the following with a grain of salt:

I bought one of these a while ago and, like most folks, started off by shooting a bunch of the cheap, Russian, steel-cased ammo. Functioned flawlessly.

I then bought some factory brass cased ammo (PMC) for the brass and, also like a lot of folks, found that nearly half the rounds suffered light primer strikes. The issue has to do with minor, but apparently significant, chamber dimension differencess between the CZ's CIP chamber and ammo based on the SAAMI chamber.

My solution was to insert a 0.030" spacer on top of the shell holder when I installed the RCBS (SAAMI) sizer die. Effectively, this leaves the rounds fire formed in the CIP chamber except for that portion of the neck that is more than about 30 thou forward of the shoulder. I'm pleased to report that every single round functioned flawlessly this morning.

Load data follows:

Code:
7.62 x 39 Chrono Data										
										
Date:	8/28//2017 - 70F - HSC					Date:	8/28//2017 - 70F - HSC			
Gun:	CZ 527 18-1/2" 1:9 Carbine				Gun:	CZ 527 18-1/2" 1:9 Carbine			
Round:	7.62 x 39 mm Russian				Round:	7.62 x 39 mm Russian			
Load:	123 gr. Hornady PSP COAL: 2.192"			Load:	123 gr. Hornady PSP COAL: 2.192"			
	25.5 gr. A-1680						26.0 gr. A-1680			
										
1	2201	Mean:	2248			1	2336	Mean:	2314	
2	2226	Max:	2311			2	2336	Max:	2338	
3	2227	Min:	2201			3	2307	Min:	2251	
4	2274	ED:	110			4	2338	ED:	87	
5	2311	SD:	44.10			5	2251	SD:	37.29	
6		CoVar:	1.96%			6		CoVar:	1.61%	
7						7				


Date:	8/28//2017 - 70F - HSC					Date:	8/28//2017 - 70F - HSC		
Gun:	CZ 527 18-1/2" 1:9 Carbine				Gun:	CZ 527 18-1/2" 1:9 Carbine		
Round:	7.62 x 39 mm Russian				Round:	7.62 x 39 mm Russian		
Load:	123 gr. Hornady PSP COAL: 2.192"			Load:	123 gr. Hornady PSP COAL: 2.192"		
	26.5 gr. A-1680						27.0 gr. A-1680		
									
1	2353	Mean:	2378			1	2408	Mean:	2400
2	2363	Max:	2415			2	2399	Max:	2421
3	2382	Min:	2353			3	2421	Min:	2377
4	2415	ED:	62			4	2377	ED:	44
5		SD:	27.29			5	2397	SD:	16.15
6		CoVar:	1.15%			6		CoVar:	0.67%
7						7			

Note: PMC Brass, sized 0.030" shy of shell holder, to avoid light primer strikes with factory SAAMI ammo.  Worked:									
function was 100%.
 
Nice could you not just neck size the rem brass after fireforming?

You could argue that that is essentially what I did.

True "neck sizing" (as opposed to "partial sizing"), while it does not set back the shoulder-to-neck junction, might tend to restore the shoulder angle to the die's dimension. In point of fact, the discrepancy between the CIP chamber and the SAAMI chamber involves the shoulder angle, versus a linear dimension. By backing out the die, I tried to insure that he die would leave the as-fire-formed shoulder angle untouched. Sort of an experiment, but so far it seems to have worked.

I should observe that, when firing loads for chronographing purposes, I do not shoot for accuracy, but I do hang a target to help avoid shooting the chrono. At the end of the 20 rounds fired for data, I had more or less a ragged single hole in the cardboard. And that is with some fairly crude open sights. Nice little rifle.
 
Back
Top Bottom