Colt commander problem.

[mike6161]

I bought a colt combat commander series 70 in 38 super last year and I am having a problem that I can’t fix. It was in great shape on the outside but on the inside it had rust on the frame and trigger I fixed the rust and put a new trigger and beavertail safety on and it shot beautifully. Then I was at the range when I noticed my groups were all over the place I checked my sights and the rear sight came off in my hand it was just sitting on the slide and would move every time the gun went off. A gun smith put it back on and it worked perfectly. Then I took it to the range a month after that and it wouldn’t put them on the target to save its life. I put it in a rest to take me out off the equation and brought the target in to 25 feet when I shot off 5 rounsd it was all over the target I took it apart and everything looked fine the barrel locked tight and the sights are still on. I used deferent Mags and it still wouldn’t group.
So what do I do know. Do I need to take it back to the gun smith and what would cause it to not group.

 

[bannockburn]

mike6161

I had a number of Colt Combat Commanders from the '70's in .38 Super (though they weren't called Series 70; that was for the full size Government models), and I sometimes encountered a similar problem. Back then the supposed explanantion for this was that the barrels were made such that the case headspaced on the rim and not the case mouth. Since rim dimensions could vary somewhat between different ammo manufacturers, accuracy might at times become erratic and inconsistent. One solution was to get a Bar-Sto barrel which headspaced on the case mouth, and have it fitted to your gun. I believe Colt eventually switched over to this manner of headspacing as well sometime ago.

 

[mike6161]

Thanks bannockburn.
so I just need a new barrel?
I didn't think a headspace problem would make the group size a foot wide but that makes sence becouse I use a lot of difference cases.

 

[GIJOEL]

Before you buy a barrel, is the barrel/slide/bushing locking up tight? I would give everything a very close look and make sure everything is locking up and operating properly. What ammo where you firing? Have you used that brand before? Are you using handloads? Problems are rarely random, start simple.

 

[Old Fuff]

Field strip your pistol, and remove the barrel.

Drop one of the cartridges you are shooting (no matter what it is, factory, handload, whatever) and push lightly on the base.

The head of the cartridge should stay even with the end of the barrel hood. If it drops in further you have one of the old style barrels. If it doesn't then look for the solution to your problem elsewhere.

 

[1KPerDay]

Stupid question: how would a rimless/flush rimmed semi-auto cartridge headspace on the rim?

 

[CMC]

It cant headspace on the rim it is rimless

 

[Old Fuff]

The .38 Super cartridge isn't rimless, it's semi-rimmed. In the original Colt .38 Automatics the rim headspaced the cartridge, but in the 1911 platform the only contact between the rim and barrel is at the hood, and this doesn't always work.

I'm not at all sure that a headspace issue is causing the lack of accuracy, but it could be - and it's easy to check without going to the considerable cost of buying a new barrel.

 

[1KPerDay]

Duh... I didn't even read the 38 super in the first post. Never mind.

 

[rcmodel]

I agree it it very likely a headspace problem due to older Colts head-spacing on the .38 Super semi-rim. Since it was based on the much older .38 Auto case, the semi-rim was carried over.
The only other ACP with a semi rim is the .32 ACP.

By the time the .380 ACP, & .45 ACP came along, they had figured out a rimless case was a better way to fly.

The .38 Super case only has .022" difference between case body and rim, and combine that with sometimes sloppy chamber jobs, and differences in factory ammo length & rim dia and you got headspace problems.

Colts .38 Supers always had a reputation for very poor accuracy until some genius finally figured out the reason, and started head-spacing on the case mouth like the .45 ACP & 9mm Colts.

Once that was done, the .38 Super is as accurate as any other pistol caliber.

rc