Alterations to 1911 Slide Stop

[Snowdog]

A bit of history, I have a Rock Island Armory 1911 in 10mm that has a slide that locks back on a magazine with rounds remaining. This happens only with "real" 10mm, not the typical .40S&W Long stuff. With the mild loads, it's reliable.
Buffalo Bore, Underwood and handloads will often cause the slide to lock back, perhaps every 1 in 4 rounds. Simply releasing the slide (with the slide stop) or racking the slide loads the next round.

So far, I've changed out the recoil spring with something heavier (I forgot what), replaced the firing pin stop with an EGW flat bottom FPS with small radius bevel and a heavier main spring.

It feeds, fires, extracts and ejects wonderfully and it's accurate to boot. It's just the issue with the slide locking back on a charged magazine that keeps it from going with me during hikes.

The problem is about the same now as it was before.

I was thinking about purchasing an additional slide stop and make some alterations that prevent it from locking the slide. I know this a radical option, but I need this pistol to be reliable.

Punching paper with it was wonderful, leaving perfect holes (powder coated 145gr SWC over 10gr of Power Pistol, standard WLP) right where I wanted it. It's a great pistol other than this issue.

So, what can be done to a 1911's slide stop that will prevent it from engaging the slide? I think I have decent idea of what, but there's a wealth of knowledge here that I think could come in useful.
I won't be using the original stop, but an extra from Brownell's or some such.

 

[drband]

What kind of magazine are you using? Is the magazine fairly new? Does it lock back early with all magazines using full power 10mm?

It sounds like it could be a mag issue more than a slide stop issue.

Also, with the slide stop removed, check the plunger & spring... does the slide stop plunger move freely and have good tension from the spring? My son's SR1911 had an issue with the plunger tube that prevented the SS plunger from moving freely, causing premature lock back...

 

[JTQ]

First thing I'd do, if it were my gun, is to shoot it left handed to make sure it isn't my grip that is hitting the slide stop and causing it to engage. It's much like the issue with righties hitting the slide release on SIG's and keeping the slide from locking back.

 

[Snowdog]

Thanks for the replies.

Drband, I'm using both the stock magazine that came with the pistol as well as two 9-round Tripp Research magazines. The problem happens with all three. I can check the plunger today to see if all seems well. I had not checked it.

JTQ, you know, I hadn't thought of that. I'll give that a try and see if it's my grip. I haven't had the problem with my other 1911s in .45acp shooting warm loads, but even they don't bark like the hot 10mm loads do.

 

[reddog81]

I'd just spend $20 on a new slide stop and see if that one works. If it has the same problem I'd start by modifying the new slide stop and see if you can get that one to work.

Keep the old slide stop in the RIA box so you have it for later if needed.

 

[larryh1108]

Some have tried putting a dimple in the slide stop where the plunger contacts it.
This prevents it (slide stop) from jumping when you are shooting high recoil rounds.

 

[Drail]

Are your magazines clean and dry (no oil in them)? If high powered rounds are jumping forward in the magazine you might try a Wolff extra power magazine spring. I run them in all of my semi autos - feed reliability is enhanced greatly. I would also check this - remove the slide, reinsert the slide stop into the frame. Now lock in a magazine loaded with the rounds that are causing the slide stop to lock open in the middle of a loaded magazine. How close is the nose of the top round to the lug on the slide stop? Now check it with every round by removing the top one. Slide the round fully forward and fully back in the magazine and check for contact with the slide stop. If they are very close you can file back some of the lug to get more clearance. This is a problem that a lot of competition shooters run into. You know how they ultimately solve it? By grinding off ALL of the lug so the gun will never lock back on empty. The only way to lock the slide open is by manually pushing the stop up with your thumb. I still have a couple of my old race guns modified to never lock open. Cartridge noses cannot physically reach the slide stop. Problem solved. There are a number of gunsmiths that will modify your slide stop like this. I learned many years ago to count my rounds so I never shoot the gun dry. 1st Rule of competition - NEVER shoot the gun dry. If you do you will always be beaten by some guy who counts rounds and reloads before his gun goes empty. Trust me.