Series 70 colt commander slide won't lock back after last round

[Big Boomer]

I have an older Colt Commander (series 70 I think) that is nickel plated and the slide will not lock back after the last round with any magazine I have (and I have several). Can someone give me a bit of advice on how to cure this? Big Boomer

[JimB..]

When you pull the slide back manually, with an empty mag inserted, does it lock back?

If yes, I’d replace the spring in a mag and see if that fixes it.

[HWooldridge]

What load are you using?

[metricmonkeywrench]

The lock back system on most semiautos is fairly simple. Barring a mechanical issue like the nickel plating keeping the slide/ slide lock from moving freely, weak mag springs or bent tips on the mag followers that is just enough to effect this one pistol all that I believe is left is an overly strong recoil spring or weak reloads that are sufficient enough to cycle the gun but not provide enough momentum of the slide to allow the slide to lock.

[challenger_i]

Being a 1911, and a Colt product, and it refuses to lock the slide after the last round with multiple magazines, it most likely has a worn slide stop. Apparently, the slide stop is not properly engaging the magazine follower.

[TNsailorman]

JimB gave a really good starting poiint in your problem solving. If the slide locks back on all magazines when pulled back and release manually, then move on. Some things to check: First is to identify the magazines that do not lock back when the pistol fires its last shot, if more than one or two does not lock back the check the following: A weak magazine spring(remove and mark a magazine spring from on mag that does not lock back, remove spring mag that does lock back; put the spring from the good magazine into the mag that did not lock back and try. If it works you may have found your answer) , or a slightly bent magazine lip/lips could keep the follower from rising high enough to catch the slide(similiar to the magazine spring; remove the follower and spring and mark each one. Put the follower and spring from a good magazine into the bad maga and try. You now know if that mag has something impeding the follower from rising to the top, most likely bent lips). Check the follower in the same manner and thus you have checked most options for identifying your problem. Just things that could/would cause a failure to lock back. I had a couple of high dollar magazines that everybody raved about and they would jam occassionally. They were new and the only brand that would jam, so I sold them to a fellow competitor and he loved them. Each pistol can operate just a little bit differnet from the next. Good luck on you problem solving. james

[Dave W.]

The magazine follower has a "lip" that pushes up the slide stop to engage it, after the last round is fired. If it happens with several magazines, make sure your thumb is not touching the slide stop so it cannot engage.

Next disassemble a couple magazines, remove the springs and put a couple rounds in the bottom of the mag, then reassemble. If this fixes the problem the mags need new springs.

By hand, with a magazine installed, move the slide to the rear and let it go, check to make sure the slide stop will engage. If not, inspect closely to see why.

Good luck.

[Big Boomer]

Load is 4.8 grs of Bullseye, Lee 230 gr rn boolit, powder coated. Magazines are Kimber, Colt, Shooting Star and a number of others I can't think of right now, all good magazines that work well in other 1911s I have (a Charles Daly and a Dan Wesson). Will try and see if an empty magazine will get the slide to lock back (with chamber empty as well) and get back with you all. Thanks! Big Boomer

[samari46]

I believe you can get a oversized slide stop from Ed Brown. Frank

[Lloyd Smale]

thats a fairly mild load. first thing id try is a 15lb mainspring. most 1911s come over sprung. the commander size guns even more then the 5 inch guns

[JimB..]

Load is 4.8 grs of Bullseye, Lee 230 gr rn boolit, powder coated. Magazines are Kimber, Colt, Shooting Star and a number of others I can't think of right now, all good magazines that work well in other 1911s I have (a Charles Daly and a Dan Wesson). Will try and see if an empty magazine will get the slide to lock back (with chamber empty as well) and get back with you all. Thanks! Big Boomer

I thought the issue was with a single mag. Assuming that the issue is that the slide will lock back manually with a number of magazines, but will not when fired, then I’d change the recoil spring. If you acquired the used gun recently and don’t know what’s in it then I’d start with an 18lb spring and work down as needed.

[Lloyd Smale]

18 would be a tad heavy for that load. most all of my 1911s except my comp guns run 15s light enough for most light loads and ive shot 10s of thouands of full power loads with 15s and never saw wear or damage but keep in mind that might not be the case with cheap import guns. but one of my highset round count 1911 is a colt light weight commander that has had 15s in it for 30 years and it has an alloy frame so if that spring would beat a gun up that one would have been in the trash can years ago. id give a guess as to round count but someone would call me a liar. so lets just say more then a few. by the way i also have the kimber version and althoug it doest have the round count of the colt it still has more then ten average shooters put through one in a lifetime. only consession that need to be made is to lube them every couple hundred round and with a lighter sping like that you should clean them every 500 rounds. my comp guns only use light loads and i usually run a 12 in them. but i wouldnt shoot a full power load through them unless i had to and if im where i might have to they wont be the guns with me. truthfully the only 1911 (if you can call it one) i carry anymore is on rare occasions (fancy go to meeting) gun is my springfield emp 40sw. if mine or my familys life is on the line make mine a glock

[Rich/WIS]

Check the slide and slide stop for wear on the engagement surfaces. If neither show wear, since you have several 1911's, try swapping the slide stops. If that fixes it your slide stop may be out of spec but is an easy replacement. Brownells has a good selection if a replacement is needed.

[JimB..]

18 would be a tad heavy for that load. most all of my 1911s except my comp guns run 15s light enough for most light loads and ive shot 10s of thouands of full power loads with 15s and never saw wear or damage but keep in mind that might not be the case with cheap import guns. but one of my highset round count 1911 is a colt light weight commander that has had 15s in it for 30 years and it has an alloy frame so if that spring would beat a gun up that one would have been in the trash can years ago. id give a guess as to round count but someone would call me a liar. so lets just say more then a few. by the way i also have the kimber version and althoug it doest have the round count of the colt it still has more then ten average shooters put through one in a lifetime. only consession that need to be made is to lube them every couple hundred round and with a lighter sping like that you should clean them every 500 rounds. my comp guns only use light loads and i usually run a 12 in them. but i wouldnt shoot a full power load through them unless i had to and if im where i might have to they wont be the guns with me. truthfully the only 1911 (if you can call it one) i carry anymore is on rare occasions (fancy go to meeting) gun is my springfield emp 40sw. if mine or my familys life is on the line make mine a glock

Don’t disagree at all, just suggest starting at 18 because I don’t know anything about his gun. The recoil spring isn’t to protect the firearm from so-called battering, it’s to get the slide back into battery. 18lbs will almost always get that done. 15/16 works most of the time, but again I don’t know the gun and don’t want to put him in a spot where he makes a change that has no effect. He can always lighten it up once it’s working. Of course none of this matters if the slide won’t lock back when manipulated manually, in that case it’s probably the slide stop.

BTW, I love the commander size 1911, they point so well for me that I would have no qualms about running one without sights. But, I’ve never had a lightweight commander. Really need to address that deficiency sometime soon.

[Gtek]

I have seen a few over the years with high round counts that appears to have been thumb released to battery verses sling shot load. The notch in slide was worn and intermittent on capture after last round or the slide stop may be just worn out. If you do look into a new part check into an aftermarket with a .200"-.201" pin, it can help this and lockup. I built years ago a SS topped 4.25" slick top and it is still cherished and close!

[Big Boomer]

Yesterday I emptied every 1911 magazine I have, 2 Novaks, a Kimber, a Colt, two Shooting Stars and a gaggle of other magazines, some unmarked, some with only assembly numbers on the base. They all worked correctly and fed great in two other 1911s but not one would work in the Colt in question. Insert empty magazine, pull back on slide, slide tries to catch when released but moves right on over the magazine into battery. I think I have a pistol problem, not a load or magazine problem. The 4.8 gr. load of Bullseye shoots great in all the 1911s, including the Colt (I think I mentioned the other 1911s are a Chas Daly and a Dan Wesson). I have an extra new stainless steel slide stop/release and safety lever that I'm going to try today and see what happens. Thanks all for for the info and suggestions. Big Boomer

[JimB..]

Yesterday I emptied every 1911 magazine I have, 2 Novaks, a Kimber, a Colt, two Shooting Stars and a gaggle of other magazines, some unmarked, some with only assembly numbers on the base. They all worked correctly and fed great in two other 1911s but not one would work in the Colt in question. Insert empty magazine, pull back on slide, slide tries to catch when released but moves right on over the magazine into battery. I think I have a pistol problem, not a load or magazine problem. The 4.8 gr. load of Bullseye shoots great in all the 1911s, including the Colt (I think I mentioned the other 1911s are a Chas Daly and a Dan Wesson). I have an extra new stainless steel slide stop/release and safety lever that I'm going to try today and see what happens. Thanks all for for the info and suggestions. Big Boomer

Good job troubleshooting, and yes it’s the gun, specifically the slide stop.

[45DUDE]

If the slide will lock back manually I have to go with slide stop. Sometimes people install a buffer on the recoil spring that prevents lock back. Mine will work with 4 grains of bullseye and a 230 lead. If you have another 45 swap slide stops. On the last shot the empty mag pushes the slide stop up to lock position.

[Big Boomer]

Got another problem. Got a new stainless steel slide stop and safety. The new safety went in but now it locks things up. So does the new slide stop. Just won't seem to work. I can get both in but they lock everything up. At a loss for what to do next. Big Boomer

[JimB..]

You need a gunsmith. Most parts in most 1911s need to be fit to the gun.