Pre-B magwell smithing info

[noway]

So basically do this *before* cerakoting?

[Earl Keese]

So basically do this *before* cerakoting?

Yes.

[M1A4ME]

Missed a (way) earlier post/question on metal left after the filing/metal removal is complete.  Sorry.  Still figured pictures might answer any future questions.

Pre B CZ 85 still nasty/dirty from it's previous location/user.  The magazine would only go in so far before binding up on the rear of the frame near the top of the frame.



I did remove some additional metal from the two posts in front of the grip screw holes as I didn't want the mag brake pressing against the back of the magazine and holding it in the frame (mags. are supposed to drop when you hit the mag release button, you know.)  You can't see much difference, if any.  Doesn't take much clearance to make things work.  The frame is upside down on a towel.  The shiny area inside/back of the frame near the towel (top of the frame) and closest to the eye (bottom of the frame) as well as about midways down the frame on the front of the two posts the grip screws thread into (removed metal from the front of those, where they press against the magazine brake, to make sure the magazines would drop free when the release button was pressed.



I took the parts out of my pistol, filed, sprayed with carb cleaner (it was nasty inside anyway) prior to doing a fit check and then I'd file some more and do another carb. spray blow out and fit test.  I repeated till I got it right (clearance plus enough to make me feel good about the cerakoting not causing issues if it builds up any at all).  Then I sprayed it good with rem-oil (carb spray or brake cleaner strips all the oil off the metal surfaces and rust is ever ready to jump in and cause you problems).

Edited to add:  Got another opportunity to replace some photobucket nonsense with pictures from imgur and had to modify the text describing the pictures a little bit (hopefully to make it more clear/easier to understand).

[srREXed]

Why grind out the frame instead of just modifying the magazines themselves?

I've done many a magwell fitting and opening up for other purposes. But to make a magazine fit, I've always made the changes to the least expensive item. The mag. Please tell me what exactly I'm missing, and why the shape of a magazine can't be changed instead of the shape of the inside of pistol frame.

Thanks.

[Earl Keese]

Why grind out the frame instead of just modifying the magazines themselves?

I've done many a magwell fitting and opening up for other purposes. But to make a magazine fit, I've always made the changes to the least expensive item. The mag. Please tell me what exactly I'm missing, and why the shape of a magazine can't be changed instead of the shape of the inside of pistol frame.

Thanks.

The magwell is too shallow front to back at the top under the sear cage. 5 minutes with a file and it's good. The later mags are nicer and less expensive than the early mags. The idea is to make the gun compatible with readily available mags, not to make all mags compatible with the one gun.

[srREXed]

5 minutes with a file has done some horrible things... But I see the point if you're going to be running a lot of mags through the gun. Unless it's really worth it to grind out the frame in a diy manner instead of doing it right, the overall cost vs. just getting a handful of pre b magazines. I'd think guys like us who work on the bench would be more prone to this compared to the guys who just shoot and don't have the ability to refinish the gun after removing the excess material.

So how many of you have done this? Can I see a few photos of your results? Thanks Earl.

[M1A4ME]

Any metal removal can be a disaster, if you don't do enough fit checks during the removal process.  I went through about 1/2 can or more of carb cleaner blowing the metal filings out of my CZ 85 frame to do regular fit checks with the magazines.  I used two magazines also.  A standard 16 round Mecgar and a larger capacity Mecgar (like I said, I'd bought several and wanted to be sure they worked, too).

When it would slide in/fall out like the MecGars worked in the CZ 75 Compacts I figured two or three more light strokes and then on to other stuff prior to the cerakoting (just in case the cerakoting might build up enough to cause decreased clearance issues).

Same on the night sight installation.  I'd file a little off the angled sides of the front sight and then try to push it in, then more filing, try it again.  Finally I'd get close enough to figure I could get it in without damaging it and get the locking screw loctited into it (this was on the CZ 75 Compacts and the CZ 75 SA, but the idea is the same, slow with frequent checks is a good way not to remove too much metal).

[srREXed]

Well now we're just talking basics of hand fitting components. Takes a second to screw up and a lifetime to get right.

Can I see some photos of your work on the pre b magwell?

[noway]

Have been working on my pre-B for about 1/2 hour now, and limited progress. I can run the mag in from the top, slide-side down, but when I insert it from the magwell, still hanging up.

Most of my DIY projects seem to turn out this way, even following the good advice here...

Finally have the mag going in, but doesn't drop freely yet. Been filing for hours now, six inch single cut Bastard file.

[incogneato]

This is good to know... thanks for posting!

[briang2ad]

Have been working on my pre-B for about 1/2 hour now, and limited progress. I can run the mag in from the top, slide-side down, but when I insert it from the magwell, still hanging up.

Most of my DIY projects seem to turn out this way, even following the good advice here...

Finally have the mag going in, but doesn't drop freely yet. Been filing for hours now, six inch single cut Bastard file.

BL:  preBs are ALL over the map, and when you THINK all you need is some filing at the top and bottom of the rear, it might not work at all.  I did a little filing and my 88 ejects the old cz USA 16 round pre b LEO mags - they SHOOT out. They hang up in my 84. The other generic pre b mags now fit nicely, but they are a bit snug in the 84. But, the 84 ejects the AT 84 mags like a champ but the 88 pre B almost can?t take them.  Again, it?s a crap shoot and there are various places in the mag well that can be a problem.  Never assume any home project will be simple.

Update:  After MUCH work, I've optimized PreB and AT 84 mags in the 88 and that is ALL I can do.  The 17 rounders are a WHOLE nother animal, and I will stop at ejecting PreB mags healthily.  I've removed MUCH steel in the top rear and I'm not even close on the 17 rounders. 

[mbliss57]

This has been a good learning thread. I bought 2 16 round pre B mags last week for my new to me CZ 75 pre B. $100 shipped.   I did not do the research ahead of time when I bought the Pre B CZ75 to realize  how expensive they were.
This would be a decent alternative but after reading the entire thread I am not so sure it is all that straight forward.
I think will stick with the I have for now.  Thanks for posting this information.

[briang2ad]

This has been a good learning thread. I bought 2 16 round pre B mags last week for my new to me CZ 75 pre B. $100 shipped.   I did not do the research ahead of time when I bought the Pre B CZ75 to realize  how expensive they were.
This would be a decent alternative but after reading the entire thread I am not so sure it is all that straight forward.
I think will stick with the I have for now.  Thanks for posting this information.

Rest assured - it is NOT straightforward.  I did a BUNCH of sanding and filing and it is only a marginal improvement, and will NOT take MecGar 16s or 17s.

[Walt Sherrill]

briang2ad:

I thought I posted this earlier, but it didn't show up...

Did you use Dykem or something similar (permanent magic marker will work) to help identify any like areas where the fit is too tight?  If you didn't, it takes some of the guesswork and arm work out of the process.  Here's a link.  Skip the ads.

\ https://www.youtube.com/watch?v=ueQQdnMCDLw

[Walt Sherrill]

Somewhere here on the forum, maybe in the home gunsmithing area, there is a pretty detailed explanation of what needs to be done, along with a graphic showing exactly where material needs to be removed from the grip frame.  I've found it before, and I think it's still out there.   

Anyone know WHERE that "how-to" guide is to be found?

(Search functions in all of these gun forums work in unexpected ways -- and they almost never work as I would expect them to work.  )