Range Report: CZ527M (7.62x39)

[Netpackrat]

Kewl. I did find an aftermarket firing pin spring, which I have received and installed. Not sure if it was significantly heavier than the original, but we'll give it a shot. The packaging was marked for ".223 bolt face" but it seems to fit just fine.

I also read on some other forum where a guy found that there is a stop on the cocking piece that sets firing pin protrusion (it interfaces with the receiver when fired), and by filing it slightly, he was able to cure his misfires entirely. One thing that is neat, is I found the bolt can be disassembled without any tools. Reassembly is a little trickier, because the keeper for the firing pin spring has to be lined up just right.

Research also revealed that the common thought is that since the CZ is chambered to CIP (European) specs, that the misfires are somehow due to too much headspace with US brass cased ammo made to SAAMI spec. The problem with this theory, is that it is just flat wrong... A CIP chamber is tighter than SAAMI in 7.62x39, and in fact, a SAAMI "go" gauge will not chamber in my CZ. I further learned that the SAAMI specs were based on data provided by the Finns, who had reverse-engineered 7.62x39 for their own military rifles. After the fall of the Soviet Union, CIP created their standard using the correct data provided by the Russians.

[Netpackrat]

Made it to the range this morning with the CZ... Still getting the misfires, so I am going to investigate the firing pin stop next. Also started getting misfeeds again. Given the mediocre accuracy, I can't say as I am all that happy with the way the rifle is working thus far. For what they charge, I expected more than just looks.

[Netpackrat]

Back at it again. I put the original firing pin spring back in, since the aftermarket one didn't make things any better, and I'm not even sure that it didn't make them worse. I got out my dial indicator set, and using a long brass rod, I measured the firing pin protrusion. It looks to be about .065" which should be more than enough to set off any primer. I have a set of CIP headspace gauges on order just to double check to make sure I am not full of shit as far as the different chamber specs go, but I doubt if they are going to tell me anything I don't already know. I did see posts elsewhere that referenced putting a shim washer under the firing pin spring... I may look into that; I suspect a hi-collar lock washer would do the trick nicely. Others have gotten new springs from CZ, but I think my rifle is probably a recent enough build to have the latest one.

I also hand cycled a bunch of ammo through it to further observe the misfeeding... It only happens sometimes, with some brands of ammo. Between the misfeeding and extremely poor ignition, I have concluded that Fiocchi ammo just plain sucks. I observed one misfeed with the Winchester ammo tonight; it's not a matter of the bullet hitting high or low as you might expect, but of the cartridge rim not slipping under the extractor properly when feeding from the magazine (so much for the reliability of "controlled round feeding"). The rounds can generally be chambered with a little force, but this isn't exactly good for the Mauser type extractor from what I am given to understand. I'm still hopeful it will smooth out over time. The Zombie Max and the Hornady steel case that I also cycled through it tonight fed perfectly, so it does seem to be brand dependent, like the misfires.

For shits and grins, since I don't think I had done it yet, I put the trigger pull scale on it. Un-set, the trigger breaks at around 3-3/4lb. That's quite respectable for a factory trigger, but this is a single set trigger. Set, it breaks at a consistent 1-1/4lb, which makes it one of the things I like the most about the rifle.

Oh, and I got a shipping notice for the spare magazine that I have had back-ordered for some time.

So while I am still working the issues with this, I am less frustrated with it than I was when I made my last post. For one thing, it's just so damned beautiful, that it's tough to stay upset with it, and for two, I do have a couple loads that I would happily use for hunting (absent bears- I may have to take it out of state to hunt with it). Third, none of the problems are anything that should be insurmountable.

[Denis]

So while I am still working the issues with this, I am less frustrated with it than I was when I made my last post. For one thing, it's just so damned beautiful...

Glad to hear the little rifle is redeeming itself. I'm sure there's nothing wrong with it that's outside your skills to remedy. Enjoy the tinkering!

[Netpackrat]

My CIP gauges came in the mail today, and the CIP GO gauge will just barely chamber in the CZ, with some force. This confirms what I had already believed to be the case, which is that the Euro spec chamber is actually tighter than SAAMI, so the common theory about the cause of the light strikes is flat wrong.

[Netpackrat]

As I mentioned in a previous post, I found a forum link wherein the poster described trying to solve this problem by adding a spacer/washer behind the spring, to give it just a little more oomph. He evidently calculated that the spacer should end up about 1/10 inch thick, and he made it by starting with a piece of round stock, chucking it up in his lathe, drilling down the center, turning down the OD, and then finished it off by cutting off a washer of the exact thickness required. Pretty neat.

That sounded like kind of a laborious process to me, and oh yeah, I don't have a lathe in my shop. So I summoned forth the spirit of WECSOG, dug around in the stuff that I DO have, and came up with a couple of #10 hi-collar lock washers, such as would be used under the 10-32 screws holding a modular rifle stock to a receiver adapter. Just happened to have them.

My first step was to grab each of them in two pairs of needle nose vise grips, and bend them until they were flat washers with no spring to them. Next, since the ID was too small to actually fit over the firing pin, I stuck them on a tapered alignment punch, and pushed them up the taper using a small diameter piece of steel tubing. This took some trial and error to get a good fit. Once spread to fit the pin, the OD was too large to fit inside the bolt body. So I put them back on the tapered punch, and reduced the OD with a 1" belt sander until they would fit inside the bolt body (Of course, I did all these steps to each washer one at a time, in case you wondered).

Slid the new spacers onto the firing pin, and measured the total thickness of them together. This ended up being .105" (using my inaccurate dial caliper though...), which is pretty dang close to what the other dude used. Reassembled the bolt and slid it back into the rifle, and all seems well. My biggest concern was that the spring would fully compress at full cock, and there is still some space between the coils, so all should be well. Here's a picture of the bolt components showing the spacers slid part way down the firing pin:



I won't really know if this helped any until I can get it to the range again. With luck that will be Sunday morning, otherwise later next week. Looking over the thread I linked, I don't even know if it helped the guy who made his with a lathe, since he never posted a follow-up in that thread.

[HTRN]

and oh yeah, I don't have a lathe in my shop

Well now you have a reason to buy one!

Past reasons for buying tools I have used: It was on sale, I had too much money in my checking account, the sun was up, the sun was down, I just felt like, etc.

[Netpackrat]

No room, plus will hopefully be between shops in the near future.

[Netpackrat]

While I am not done fucking around with this, and in fact I think I am far, far from that point, I am ready to make a pronouncement.

Do not buy this rifle. If you want a bolt action in 7.62x39, buy the Savage instead. The CZ is light and handy, I suspect more so than the Savage, and it is very pretty, but it has too many issues for a rifle that cost me $700. I think I have conclusively demonstrated that blaming the problems on the US made brass case ammo is bullshit, particularly given the number of rifles in this caliber that will happily eat any ammunition you feed them. And as far as accuracy goes, I frankly expected better. I have tried many brands of ammo, and this is a 2moa gun at best. It may be that there is more to be had with handloading, but I'm not going to expect that much. Maybe it will still surprise me.

As one might have surmised from the above, I did make it to the range with the CZ again today. The good news first... I had no misfires with any of the 12 rounds remaining of Winchester JSP that I ran through it. I haven't been able to find any more of that yet, so that's not really enough data to say whether that represents an improvement. The two 5 shot groups I fired with this ammo measured about 2" and 2.5" respectively. It may be that I need to clean it again. I still experienced some misfires with the Hornady Zombie Max and the PMC brass case I fired next. And speaking of the ZM ammo, most of it took a fair amount of force to chamber... The ammo was a tight fit and still had misfires, so I think I can put to bed for good the theory that the misfiring is due to SAAMI spec ammo fitting loosely in the CIP chamber. Though as far as I'm concerned, I already established that is BS with my headspace checks.

There is likewise little excuse for misfeeding in a bolt action rifle that feeds from a single stack magazine. As mentioned previously, the rim isn't slipping under the claw extractor properly. At this point I will probably never buy another rifle that features so-called "controlled round feeding"... I have never had this kind of trouble with one of my push feed rifles. When the CZ misfeeds a round, the bolt can be withdrawn slightly, and then the cartridge will push feed forward, but I am given to understand that actually chambering a round in this manner is very bad for a Mauser type action. The gunsmith who threaded it says that maybe the claw needs to be re-beveled. Maybe over the next winter when he is less busy I will hand him the rifle and a bunch of ammo, and see what he can do with it.

On the plus, once I was done firinng for groups from the bench, I looped up and shot a bunch of rounds kneeling, and I was able to keep them well within an area the size of a deer's vitals. While it is not as accurate as I would like, it is still accurate enough for hunting within the limitations of the cartridge. Never mind that there are AKs that are more accurate.

[Kommander]

Never mind that there are AKs that are more accurate.

Ouch. Well thanks for taking one for the team, I am sure we will all stay far away from this rifle.