1911/Slide Locking Back


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tkcomer
March 26, 2011, 04:00 PM
I bought a used 1911 gun (Stainless Kimber II) in 45 ACP and every now and then the slide locks back with rounds still in the mag. So far, all I've shot are 230gr hardball. What could be causing this?

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Control
March 26, 2011, 05:57 PM
1) Check the tab on the slide stop that engadges the magazine during lockback for copper rubbings. If you see anything, you have bullet noses causing early engagement by hitting the tab early. Is your ammo too long for spec? Or, is your mag out of spec and allowing the bullets to nose forward too much? Have to tried different magazines? You can clearance the area on your slide stop with a fine file if you have experience with that but check your ammo and mag first before filing on the slide stop tab. Go slow.

2) Also check the plunger spring for sufficent tension. Beyond that, make sure there are no burrs on your slide stop plunger or inside of your plunger tube. If you have a weak plunger tube spring, replace it with a good one from Brownells, If you see burrs, remove them.

3) While you have the plunger spring and slide stop plunger out, reassemble the pistol. Place the slide stop in the gun but do not press it into the notch. Let it hang down inside of the trigger guard. Watch your frame as you don't want to scratch it. Rack the slide a few times. If the slide stop swings wildly and with sufficent tension, you may have to refit your barrel link and barrel feet. This is a bad case and I hope this isn't your problem. It usually only crops up on tight fitted target or custom guns.

4) If your slide stop is not dimpled to hold it down propertly, you can dimple it. But be careful! If you don't dimple it in the right place or with the right depth you can ruin your slide stop. You don't always need the dimple but it helps out.

5) If you shoot left handed and the slide is locking back on the dissassembly notch, you need to have your slide stop set up for lefty shooting by properly fitting the retaining tab and perhaps cutting the slide stop pin flush with your frame.

rcmodel
March 26, 2011, 06:02 PM
All good advice.

Also, make sure your shooting grip isn't causing your thumb to whack the slide stop up while shooting.

rc

tkcomer
March 26, 2011, 08:40 PM
Thanks for the info. Just trying to figure out where to start first. I do notice the slide stop doesn't drop down like my Gold Cup when I pull back on the slide to unlock it. The slide stop lays right up against the frame when you do that. You can actually pull it down a little more and “lock” it.

Drail
March 26, 2011, 10:49 PM
The rear surface of the stop that the plunger rides on is machined at a slight angle. On some 1911s the angle causes the plunger to push the stop up (and hold it there) and on some it causes the plunger to push the stop down. That angle can be adjusted with careful file work if you want to be able to "slingshot" the slide. Personally I prefer to adjust and dimple the stop so that it tends to stay down unless I manually push it up into the lockback position. I prefer not to have the slide lock open on empty. As stated early lockback is usually caused by rounds tapping the slide stop lug or thumbs getting under it. It sounds like your plunger may be trying to register in the groove in the slide stop. Look closely at the rear surface of the stop and you can see a shiny line where the plunger is riding up and down. If the plunger is trying to crawl into the groove then the stop is not properly fitted to your gun or the groove is cut a little too deep.

rcmodel
March 27, 2011, 01:11 PM
I do notice the slide stop doesn't drop down like my Gold Cup when I pull back on the slide to unlock it.Dollars to donuts you have a Wilson Shock-Buff plastic dodad on the recoil spring guide.

Take it off and throw it away.
They cause more problems then they cure.

rc

tkcomer
March 27, 2011, 02:55 PM
No plastic do-dads that I can find. The slide stop in the Kimber is slightly stiffer than the Colt. Probably because it is newer and has a stiffer plunger spring. Funny how they cut the frame rail above slide stop. I don't see why that cut is there.

EddieNFL
March 27, 2011, 02:56 PM
Kimber had a batch of slide stops that were out of spec. Rather than fit them properly before shipping, they decided to let the end user figure it out. They should send you a replacement if you call. The one they sent me was out of spec, as well. I fitted both at no charge to Kimber.

SoulLessGinger
March 27, 2011, 03:11 PM
How it "feels" and what you can see with the gun assembled isn't really all that useful.

Have you actually field stripped the gun and inspected the parts?

Make sure it is clean and check the function of the slide stop and plunger spring. With the slide off, see if the mags are still engaging the slide stop with the follower pressed down or a dummy round in the mag.

rcmodel
March 27, 2011, 04:22 PM
Funny how they cut the frame rail above slide stop. I don't see why that cut is there.The cut is there to prevent warrenty frame replacements on down the road a long ways.

1911 frames are known to crack the frame rail right above the slide stop cut with extended use.

It is purely cosmetic, and doesn't hurt anything.
But Kimber knows it can't crack and cause unhappy customers if it isn't there to start with.

rc

tkcomer
March 27, 2011, 04:44 PM
I have a friend that's sort of a 45 guru. He wants me to bring it up and try different mags. He thinks its either that or the bullets might be hitting the slide stop on the inside. Trouble is, the last 100 rounds I put through it, it only locked back once. I hope he can figure it out. I don't want to waste a lot of ammo testing the gun.

Auto426
March 27, 2011, 11:27 PM
Funny how they cut the frame rail above slide stop. I don't see why that cut is there.

Colt started cutting that section of the frame away after some of the very early Delta Elite 10mm 1911's started displaying cracks in that area. It didn't really hurt the gun, and since that little section of rail wasn't critical to the gun's operation Colt simply did away with it. Ever since then it's been standard practice throughout the industry, regardless of the guns caliber.

Rinspeed
March 28, 2011, 10:43 AM
As Eddie said if you call Kimber they will send you a replacement slide stop. After you have it you can take a file to the old for a spare.

bobnailer
March 28, 2011, 11:59 PM
I second the comment about thumb tripping the slide lock during recoil.
I own a Kimber Ultra Raptor II that had the same problem... wasn't the ammo, nor the mags, it was my big, fat, thumb. How do I know? Simple, I switched hands and shot lefty... problem went away.
Bob

makarovnik
March 29, 2011, 03:11 AM
My Thompson 1911A1 GI had a problem with rounds hitting the slide lock on the way into the chamber. It also caused mis-feeds. Would a stronger safety plunger spring help?

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