The Unofficial P64 Resource Forum

Not sure if this has been asked, but are the slides usually interchangeable from frame to frame, or do they require some slight modification?

I bought my first p64 around 2017, and wanted to keep the firearm original, or at least not irreversibly modify it. I really like the gun, so I got the 18 lb Wolff hammer spring to tame that double action a bit and figured I'd get the recoil spring pack as well, and ordered some wood grips from Grips4u (beautiful workmanship, fit without modification. The hammer spring is fantastic, and the grips are as well. Really suits this firearm. I haven't changed the recoil spring yet.

Anyway, long story long, I got to thinking I might want to experiment with adding more modern sights, so I purchased a spare slide on ebay so that I wouldn't have to worry about mucking up the original one. Tried fitting it on my gun and it fits, but it seems like it's scratching up the slide rails and frame, i found tiny slivers of metal, and it stops about 1/8-1/4" out of battery unless I push it (not a lot of force, just needs to be helped home). I took a pair of calipers and took various measurements of the internal dimensions, and while there is some variance, it's in the hundredths of a mm range. I can't for the life of me figure out why it doesn't want to fully go back into battery without help.

2nd p64, should be arriving to my ffl sometime this week. This one I plan to cerakote and modify a bit, with the plan being a slide milled for Novak night sights and a slide with a red dot that I could interchange freely. I have seen this done on Makarovs. The p64 I have now, will remain as relatively stock.

Sorry for being long-winded. Any input is appreciated.

I have swapped slides around quite a bit on two different guns and 5 different slides experimentally (both newer and older versions) and have only had a few slight issues.

Sometimes they can be a little tight like you mentioned and go into battery a little hard if you ride the slide forward instead of dropping it hard. The issue doesn't seem to be in the rails but rather on the bottom inside area where the hammer rides, especially as it meets the safety barrel. A little bit of Lucas assembly lube with moly helps and it breaks in pretty quickly. Some slides tend to get really beat up at the point where this bottom rail inside meets the safety when the hammer is slamming it. It can get peened over a little and deformed even on matched serial number guns.

Once I had an issue with the disconnector not fully going up to allow the trigger to operate in double action on a swapped slide. It did work fine in single action though. A teeny-tiny bit of stoning on the forward angled edge of the disconnector solved the issue. I have heard that this can sometimes also be an issue with ammo having a rim at the high side of the thickness tolerance.

Finally I highly recommend that if you put in a reduced power mainspring (hammer spring) that you bump the recoil spring at the same time. The hammer springs were made extremely heavy on these to fire the hard primers of submachinegun 9x18mm Makarov ammo. Since the hammer spring works in concert with the recoil spring it is actually helping quite a bit with the recoil. Lowering the hammer spring will likely be overwhelming the recoil spring and allowing the slide to really slam into the takedown lug on the trigger guard pretty hard. It tends to do this anyhow I have found and gets much worse with a reduced hammer spring. I put in the 22lb Wolff spring in both my shooters and almost wish that they would make a 24lb one too. I'd like to try one if they did.

The recoil spring is a very simple swap. Make sure that the tight end goes in first and is hard to slide down the barrel the whole way -don't put the bigger side on first. Also, be sure the ends have been ground flat on both sides and not just clipped. There are older Wolff recoil springs floating around that weren't ground and they can be a smidge too long. This will cause extremely difficult reassembly and if you do manage to get the slide on like this good luck ever getting it off again. There are a few threads on here bemoaning this issue.

There aren't too many folks active here anymore. It's nice to have someone else to talk to in this forum.

Good luck

First off I'd like to say thank you very much for your detailed reply.

I usually run a dab of Hoppe's gun grease on the slide rails--I'll have to look up the formulation as it's not printed on the tube but I have found it to be superior to oil for sliding parts.

I may have found the culprit. There is a small deformation at the bottom of the right slide rail, not at the rear as you mention (although that is good information to know), but in the front. Leads me to believe during disassembly perhaps someone lost grip on the slide after lifting it out of position and it slammed forward. Just a theory. I should be able to get to it with a jewellers file and we'll give it another test fit. I did not think to take pictures/ make a mental note of the scratches and bluing wear prior to testing the newer slide, so I am not sure which ones, if any, were actually caused by it vs prior use. Something to remember in the future.

As for the hammer spring working in conjunction with the recoil spring, this is useful information, and makes perfect sense.

I just got the springs last Tuesday and installed the hammer spring that day, I haven't fired it, just tested the feel of the trigger pull, so I shouldn't have caused any issue. I fully plan on using the 22 lb recoil spring (it is flattened on the flared side and I ordered directly from Wolff so I do believe these are the newer style springs), but I didn't install it because it came with a new firing pin spring, which I intended to use on the replacement slide, but decided to wait while I troubleshoot the failure to return to battery issue and didn't want to mix and match the new and old springs.

It is a shame there isn't much traffic here anymore. These are fantastic little pistols, both aesthetically and functionally, and a great platform for tinkerers and amateur 'smiths. I have been a lurker for a few years and have learned quite a bit from this place. It really is the only place I've been able to find comprehensive discussion on this particular firearm. Often seem to be late to the party on these kind of things.

Nevertheless, I am grateful for your response and experience. Can't say I'll be able to offer much in the way of knowledge, but I am glad at least to discourse with someone of similar interest.

I remember now that I had a slide once that was dropped and it caused the rear corner at the rail to be a little tiny bit tight. It didn't take much to get it back into spec. I took some 240-grit sandpaper and wrapped it around a popsicle stick and gently worked the obvious (under magnification) bump out. A jeweler's magnifying visor from harbor freight is a big help here. Then I bumped it up to 400, 600, 1000 grit to smooth it all back. A popsicle stick is nearly the perfect size for sandpaper backing in the rails.

If you really look inside these there is a whole lot of tooling marks. The machining is pretty crude so even a home gunsmith can work inside them without fear of making the scarring any worse.

There are some really good videos on how to take the slide apart and and the frame too. I suggest you get a pair of surgical locking forceps for working in the slide. If you push the firing pin forward with a brass dental pick you can grab the tip of the firing pin with the forceps at the breach face and hold it there so that the safety barrel can be pulled out. I put shrink tube on the ends of the forceps to protect the firing pin from getting scratched up. Do this last step of pulling the safety in a big ziplock bag until you learn how to hold your hand at the end to catch the detent pin and spring which will likely come flying out once the safety is yanked. Be sure to position the safety halfway between safe and fire so the detents don't hang up before pulling it out sideways. Once you take it apart it is obvious why this needs to be done.

Might as well take the loaded chamber indicator out and clean the goop out of there too. If you smack the slide down on a block of wood the little clip that holds it will fly down with momentum and free the LCI. Do this maneuver in an open cardboard box with the block of wood inside until you learn how the pieces will fly out and how to hold them when doing these steps so they can't escape.

I have never lost any parts permanently but I have spent some time on my hands and knees searching for them. Now its gotten so I'm pretty good at taking this gun apart and it is not hard at all except for the trigger guard which takes a lot of force and a helper to drop the pin in. The videos help with disassembly and reassembly.

Locking forceps and dental picks are really helpful for working on a P-64.

I grabbed a cut-a-way from Centerfire Systems some time back with the idea that having it gave me a ready supply of spare parts should the need arise.
https://www.dropbox.com/scl/fi/mqfaoyh1 ... zkeoe&dl=0

The barrel is bulged which is likely why it became a "Szkolna" marked example and was modified. The firing pin was welded to the breach face so I had to free that up to get the slide apart.

All of the other internal parts are serviceable as replacements.