ACTUAL CONFIRMATION if CZ-527 7.62x39 Mags work for 300-221 rounds?

[este]

I've read over and over varying reports that while the 527's 223 mags need the sides cut to allow for the 300 bullet to sit properly, that the 7.62x39 version's magazine will work for the 300-221 bullets without cutting.

Personally, I think it's bullshit because the x39 case is shaped radically different from the 223 case. I would think the feed lips would be different at the minimum.

I also read that the 527 can be made to take 6 rounds vs 5 by shaving down the follower. Can anyone also confirm this?

I'd like to set the record straight so first hand only, Thanks

[amafrank]

I personally have slotted mags for the 527 .223 mags in order to get them to feed 300-221. I've not tried cutting down the follower for an extra round though so I can't make any comments on that. I looked all over for a 7.62X39 mag to try but never could get my hands on one so no help there either. I can see that the width of the 7.62 mag along with a feedlip issue may make them not work with the 300. The 7.62 is wider and the feedlips may not hold the smaller round ????

Frank

[este]

Frank, thanks I appreciate that. I have no issue cutting the 223 mag sides, although I will look for a way to patch them so as to not have visible holes for dirt and dust. I know I could make them 3 round but I don't want to do that.

The mag follower saving to get 6 rounds was a guy here, but he never elaborated.

Right, the feed lip width is the obvious issue with the 7.62mags. I just don't understand how I've read multiple places that it works. It would seem to me that if you bent them in, it's likely the bolt won't catch the case anymore or be iffy at best. I have a 7.62x39 and a 223 case in my hand right now, it definitely would need to be modified.

[kurtz]

300 Whisper in a un-modified CZ 527 7.62x39mm Magazine....


[IMG][/IMG]

[este]

Ahhhh...... Ok, I see. How well in there is that round? If you jiggle it will it pop out?

It doesn't appear to be right, but looks like it could work. I'll have to think about that some.

[kurtz]

not much holding it in.....I probably wouldn't use it like that, just posted a pic of what it looks like un-modified....

I mill the ribs out of the 223 mags and they work fine....was working on a mandrel to press the ribs out but never got around to finishing it...

the 7.62x39 mag goes to a 7mm wildcat built on the CZ x39 action....

[IMG][/IMG]

[IMG][/IMG]

Drops right in, no mods needed to mag....

[este]

Kurtz,

That 7mm looks very cool. Thanks for sharing that.

A mandrel to press them sounds like a great idea. I wonder if it could be done cleanly or not? Seems to me that with the mag welded together it would be tough to properly press that. I'll think about that a bit though. It's definitely a good idea if it can be done. How far did you get?

Having seen it, do you think there is enough material for bend the feed lips on the x39 mag over to hold a whisper round properly?

[kurtz]

Originally Posted by este

A mandrel to press them sounds like a great idea. I wonder if it could be done cleanly or not?

sure, with a correctly made tool and enough pressure....

Originally Posted by este

Seems to me that with the mag welded together it would be tough to properly press that.

the weld shouldn't make a difference, the overlap next to the rib should help serve as a guide...

Originally Posted by este

How far did you get?

If I had a bunch of these mags to do I would of made it further along....since I only had four or five to do I just milled them....

disassemble a mag, hold it with the baseplate opening up....my plan was to make a two piece magazine holder that would surround the mag and keep the walls from pushing out...the tool/mandrel would be pushed in the mag from the baseplate opening with a hydraulic press...the tool would need to be stepped.......on either side of the rib would need to be the full mag opening width (to keep the tool centered in the mag body) and then step down to the new desired rib height...

I made some real rough tools out of hardwood and aluminum to do the same thing to 20 round straight AR mags to push the rib out for 300 Whisper loads (aluminum AR mag vs steel CZ mag, the CZ tools would probably need to be all steel) The AR mag tools worked good, so I would think the CZ tools would work as well....but for the AR it's pretty easy to de-rib PMAGS...

Originally Posted by este

Having seen it, do you think there is enough material for bend the feed lips on the x39 mag over to hold a whisper round properly?

Viewed from the top, the distance between the feed lips taper from .365 at the rear to .378 at the front....the lips could probably be squeezed together enough to hold a whisper case, but it'll fit pretty sloppy in the mag body....I haven't compared the seating depth of the two mags to see if there is a difference......I'm probably gonna stick with milling the .223 mags....

[este]

Well, 223 Mags it is then.

If you don't mind, I'm going to borrow your idea for pressing those out a bit. I think aluminum billet would work for the mag body, but probably steel for the tapered pressing piece.

FWIW, the 223 mag lips on my mag here are .325 at the bottom of the taper and .338 at the top. So, yea, .050 wouldn't be a ton to turn in, but it would be tough to get it at the right height.

[kurtz]

got around to pulling both rifles out of the safe at the same time....

the .223 mag is .475 wide...

the 7.62x39 mag is .517 wide...