My slide came back from Galloway Precision, and the 507k look like a perfect match for the P239. The window looks plenty big, and the optic fits snugly on the slide.

It's an interesting gun to put an optic on. I like it.

Did you take a pic before you mounted the optic ? Curious about Galloway's work ? It looks like they just planed the crown off the slide....no ?

From another thread I contacted several shops to do slide millwork for an optic for my old school P series guns. No one could do these - all were focused on newer stuff like the P320 series.

Just went to Galloway's site - could not tell exactly what they would charge. How much was the service to mill the slide if you don't mind? I'm guessing a P220 slide should be in the same ballpark. Thanks.

quote:

Originally posted by Genorogers:
Did you take a pic before you mounted the optic ? Curious about Galloway's work ? It looks like they just planed the crown off the slide....no ?

I was wondering the same

The slide came back with the optic installed. I removed the green dot, and unfortunately Galloway Precision milled away the area for the locating projections.

I am sure they could have included those nubs, I will call them on Monday. Otherwise looks good.
Cost was $160 plus shipping.

I believe in one of their videos Galloway says that the location nubs are really not needed. Says that by applying Locktite along with tightening the screws are all that's really needed. I'm very intertested in how this works for you. For the price IMHO it's a win,win.

As long as the optic is adequately fenced front and rear, you can get away without recoil bosses. Some cuts are not super fitted and that could be an issue. Asking the screws to hold the optic down on the slide while also holding the optic in place longitudinally under recoil can be troublesome. The screw ends up engaged with the slide where threaded in and with the optic only at the head (no threads in the optic body) so you end up with leverage over the screw shaft.

Total clearance is .005", front to back. Later today I will reinstall the optic and check the gap at each end.

quote:

Originally posted by Bulldog7972:
I believe in one of their videos Galloway says that the location nubs are really not needed.

True, in the sense that an "interference fit" is typically cut to the specific size of the optic you send in with the slide. If you ever need to replace the optic you can assume a like-for-like change will be good enough but what if you change your mind, or in the long term the optic you originally chose is no longer available? As an example, Holosun has many models with the same footprint as the Trijicon RMR but in my experience the Holosuns are slightly smaller front to back than the RMR to the point an interference fit now has some slop. Not a good place to be, putting all that load as sheer forces on the mounting screws that aren't meant to take that much sheer force. Optic mounting solutions that provide / use the recoil lugs provide far more flexibility IMO. I won't have another slide milled using just an interference fit.

Are the existing iron sights usable?

quote:

Originally posted by SIGfourme:
Are the existing iron sights usable?

Barely, but the front sight is too low. I believe it was sitting just at the bottom of the window.

quote:

Originally posted by ah3:

quote:

Originally posted by Bulldog7972:
I believe in one of their videos Galloway says that the location nubs are really not needed.

True, in the sense that an "interference fit" is typically cut to the specific size of the optic you send in with the slide. If you ever need to replace the optic you can assume a like-for-like change will be good enough but what if you change your mind, or in the long term the optic you originally chose is no longer available? As an example, Holosun has many models with the same footprint as the Trijicon RMR but in my experience the Holosuns are slightly smaller front to back than the RMR to the point an interference fit now has some slop. Not a good place to be, putting all that load as sheer forces on the mounting screws that aren't meant to take that much sheer force. Optic mounting solutions that provide / use the recoil lugs provide far more flexibility IMO. I won't have another slide milled using just an interference fit.

This right here is a good post. I'm a red dot newbie and I learned something important going forward.

I remounted the green dot, and found that the Holosun is within .001" clearance against the slide on the forward end. So under recoil, if the screws give that .001", the body of the optic will be take most of the force.

Next slide I get a slide milled, I will check on the type of fit.

This message has been edited. Last edited by: c1steve,

I heard back from Eric at Galloway Precision. He states the the "locating stud" depth is not consistent between Holosun optics using the same footprint:

"I mill for them yes, but there is no such thing as recoil lugs. They are location studs only. If the studs see any recoil the screws are not tight. I french the optic into the slide for a tight fit and apply blue loctite so the screws stay tight creating the correct clamping force across the bottom of the optic plate like any bolted part does. On the 507k I do not do the location studs due to the different patterns I have seen them come with and varying pocket deep of the stud.

I do them for burris/vemon, rmr, rmrcc, jpoint, rmsc optics as they are consistent, but not needed for anything other than location for battery removal. The 507k does not have a need for removal of a bottom mounted battery but is snug in the milled pocket we create regardless if removed."

The overwhelming likelihood is that you're fine either way. There is a lot of debate about these things and I will agree with Galloway that the 507K recesses are very shallow. Noticeably shallower than those on the Shield RMSc that the 507K footprint is based on.