Is there a shop that can do a DPP cut on an SP-01 without blocking the extractor pin?

[paltrypoultry]

I'm looking into getting a CZ 75 SP-01 manual safety cut for a DPP.  Does anyone know of a place that can do that, but far enough back on the slide that you can still remove the extractor without removing the optic?  Thanks!

[trgt]

Springer Precision has a nice milling cut that not only places the DPP cut behind the extractor pin, but still leaves a little bit of the rear end of the slide untouched such that the DPP is captured between the front and rear of the milling area. Sorry for late response, just happened to see this, left a comment in case still helpful to you, or perhaps another later. 

[paltrypoultry]

Thanks for the reply.  Springer actually did that exact cut for me.  I'm gonna write out my whole saga on this for the sake of other people searching for options.

 

First I got an EGW dovetail mount, since I figured I'd see how I like CO and the DPP before I commit to cutting a slide.  I installed it using their directions and the #6-32 screws they sent with the mount.  The optic came loose from the mount while zeroing.  I figured maybe I applied the loctite (blue) badly so I started over, cleaning everything well and making sure I did the loctite right.  It came loose again.

 

I looked harder at what was going on and noticed that on the top of the DPP, the screw holes are countersunk.  The screws EGW shipped didn't have angled heads, so very little of the screw was contacting the DPP, which I figured was probably the problem.  I couldn't find the right screw for sale anywhere, because the DPP factory screws are M4, so the countersink angle on the optic body is 90 degrees, but the EGW mount holes are #6-32, and you can only find screws angled 82 or 100 degree in non-metric threads, not 90.  Anyway, I emailed EGW and they immediately replied that they're starting to use new screws for DPPs, and they shipped me out some, which turned out to be the exact unicorn screw you need for this: #6-32 with a 90 degree angle.  I have no idea where they source them.

 

I reinstalled with those screws and this held up for awhile, maybe 500 rounds, and then I noticed that my impacts were off, and I saw that the whole mount had started shifting in the dovetail.  I decided to just get the slide cut.  Not to throw shade on EGW here, their customer service was great and it's possible I dorked up the install of the mount into the dovetail somehow.  I was just ready to move on to milling rather than mess with it more since that was my long term plan anyway.  One thing I'll say though is that the dot does end up pretty high with the mount, which was a tough transition for me, coming from irons:

 

EGW dovetail mount height: https://i.imgur.com/P7EU3Hj.jpg

 

I emailed CGW, CZC, Springer, and Primary Machine asking if any of them could do a DPP cut while keeping access to the extractor.  CGW said no.  CZC said maybe but they'd need to get the whole gun in their hands to confirm the hammer would clear.  Primary Machine said they didn't cut customer slides anymore (though I guess they do again now?).  Springer said they could do it, and just needed the slide and the optic, so I sent those off to them.

 

Springer turned it around super fast, I think it was like two weeks total from when I mailed it to when I got it back, and it was a reasonable price. They shipped it back with the optic installed.  The first thing I noticed was the cut was exactly where I hoped, like you say, leaving access to the extractor pin, but also leaving some material at the back, too.  The second thing I noticed was that they didn't use the factory DPP screws that I sent them, which I thought was interesting.

 

I zeroed it, and shot a couple matches with it and then at the end of the 2nd match, I noticed one of the screws had started backing out (I'd put witness marks on them after my first problem with the EGW mount).  I think it'd been about 400-500 rounds total.  When I got it home I took the mount off and found that they'd tapped the screw holes to #6-32.  This is why they didn't use the factory screws.  I think maybe they did that so that they could use the screw holes in the DPP base as recoil bosses, since they didn't cut any of the other recoil bosses a DPP can accept (see pic):

 

https://i.imgur.com/jbrW7uK.jpg

 

Anyway, I think the screws they used are #6-32 with a 100 degree head, so I don't think they were getting as much abutment against the top of the optic as they should (as they would with a 90 degree head).  So, I just used the #6-32 / 90 degree unicorn screws that EGW sent me and reinstalled it.  I used blue loctite and 12 in-lb.  That held up for 1000-1500 rounds and I thought I'd finally solved it, until a screw just started backing out again the other day.  I did some experiments to find an amount of red loctite I could use and still be able to remove the screws without applying heat, and reinstalled with that, and 20 in-lb (which I felt safer doing since there's hardly any loctite on the threads).  I shot 200 rounds with that and so far so good, but time will tell.

 

One thing I noticed when reinstalling it this last time is if I hold it up to a light, there's a tiny bit of gap in the front (the screws are in the back).  I didn't look for this before, so no idea if that's how I got it from Springer or if it happened when I re-installed or re-re-installed:

 

https://i.imgur.com/O1vUSMo.jpg

 

Anyway, I haven't contacted Springer about it yet, so no shade to them.  I was really happy with price, the location of the cut, and how fast they turned it around.  I also really liked how they put it absolutely as low as you can go on a non-shadow (notice the FPB plunger spring rides up against the DPP itself).  If I were going to do another one, I'd probably start with them again, but ask them if they could leave dedicated recoil bosses and tap the screws to M4 to allow using the factory screws.  If it comes loose again I'll reach out them for other ideas.

 

Hope this helps someone.

[trgt]

I can add some color to your question, I've had many CZ slides done at Springer.

 

My first slides he did with original delta point were positioned at the rear of the slide, he did mill screw bosses at that time to help capture the optic. Next ones were milled forward that required the extractor pin be cut down under the optic. Third time around we discussed and he was able to get the optic captured in the cut between extractor pin and material left at end of slide. That captures the optic so well (notice the radiused cut front for the optic, its not just hogged out) the raised screw bosses I don't think were necessary to prevent any front/rear movement. The screws then just hold the optic down.

 

With regard to screws, my first slides returned from Springer got #5-40 not the factory ones. I was surprised as well, he said its what his CNC was set for, also maybe to get more threads that the factory screw which are only the tip. Later he moved larger #6-32. In both cases I was provided with button top style, maybe easiest for him to buy at first. I just sourced my own machine taper head 6-32, and suggested to him that folks might like that better. So sounds like that's what he's providing, but I doubt any magic on the angle 90 vs 100 degrees, gonna get whatever the screw companies are cutting.

 

###

 

I've not any any problem with retention or loosening, will give you my 'tips' FWIW after 7 years shoot slide ride optics on CZ, its been years since I've had any issues:

1) Make sure the threads on screw and hole are SUPER CLEAN. Acetone or other, I use microfiber tip swabs that will fit the hole to make sure no oil/grease/residue

2) Blue loctite or VIbra-tite VC-3 (secret-sauce #1) to help secure the screw. Blue is good until it loosens at all, then it must be thoroughly cleaned off and reapplied before tightening again. VC-3) I currently prefer, can be reused or retightened as its more a 'gummy' hold vs cement like lock that is gone once hold is broke. 
4) DO NOT use red lock tight, you are risking your optic with a thread locker that requires heat in order to release the bond

5) (secret sauce #2) Only reuse screws two or three times before replacing with a new screw. Screws work by stretching and holding item with that tension. These small screws can give up that tension / stretch at some point. I'm not a materials specialist to know what that point is, but earlier on with first few optic (the original delta point that needed to be removed to replace battery), I would get screws that at some point would never hold. Once I figure out to replace the screw problem solved.

6) I witness mark the screws (small dot edge of screw, small dot on optic), so I can easily see if something has moved. Have a hex key in case to tighten, mainly on new installs settling in.

7) (secret sauce #3) I noticed more issues destroying optics with 124gn vs earlier shooting 147gn, I switched back to polymer guide rode from a any of the metal ones on CZ to give me a bit of a shock buff / softer hit. If you see how peened the metal rod ends getting in the gun, you know something going on, again I don't know how to measure but this change has also helped with the 124s.

 

 

Edited February 1, 2022 by trgt

[paltrypoultry]

Interesting.  I think it might have been a comment from you in another old thread I turned up searching here that pointed me at Springer for this cut.  It seems like a 90 degree screws should hold better since a 100 degree can't make nearly as much contact with the optic, and that does line up with my experience too (Springer-provided 100 degree screws held for 500, EGW-provided 90 degree screws held for 1000-1500).  I'd like to be able to replace the screws if I need to, but I can't find those unicorn #6-32 90 degree screws anywhere.  In the future I'd much prefer a cut using M4 for a DPP though, for that reason.

 

Re: red loctite, too late!  I've got red on there now, but I think it's an amount small enough I can remove it without heat.  I started thinking about it after watching Dave Dawson talk about it:

 

https://www.youtube.com/watch?v=6Hoqqp9mE60&t=260s

 

Interesting re loads.  I'm using a 135pf 125gn load, but I'm probably going back to my old softer 147gn load for other reasons anyway.  Though I do want the optic secure enough I can shoot whatever load and not think about it.

 

Do you ever shoot the matches at Richmond?