So I get this "drop-in" 400 Cor-Bon conversion barrel for my Colt 1991A1, and I still haven't gotten it to work.

Am I the idiot, am I missing something really obvious?

First the barrel diameter was bigger than my bushing, so I had to sand/polish it for HOURS to get it to fit.  It wasn't just the end of the barrel or the final half-inch - it was the entire length I had to work on.

Oh well - that was irritating, but a little bit of fitting wasn't the end of the world, and I'd rather have a tight fit than a loose one (so true for many things ).

But when I took it to the range, it fired on the first shot (woo-hoo!), but did not fire on the second shot (boo-hoo).  At first I thought it was a hangfire, and let it sit for a while pointed downrange.  I pulled back the hammer and let it have another one, and it fired.  Hmm - stange.  I was shooting Cor-Bon factory ammo, and I found it unlikely that it was a problem with the ammo.

This happened several times again.  But rather than trying to hit the primer several times, I took out the rounds that didn't fire and examimed them (after waiting for a while on each one, of course).  On one of the primers, there was a very faint imprint of the firing pin, and on another there was none.

Clearly, it is not the ammo, but the gun.

Can any of you tell me what the problem is?  Is it more "fitting" of my "drop-in" barrel that is required?  Is the space between the chamber and the firing pin too great?  What the hell do I do?

Oh - just to add more confusion.  I noticed that the primers on some of the cartridges were "blown out" in that I could look through the primer from the back and see light.  Could some of the pieces of the primer metal perhaps have somehow been blown back into the channel the pin rests in and have interfered with the firing pin?   I find this really unlikely, but I've never really seen that before, so I thought I would mention it.

The other changes I made when I put in the new barrel were:  A stronger recoil spring, a buffer and a full length guide rod.

Anyone have advice?  I bought a drop-in kit because I cannot afford to take this to a gunsmith, and nor do I want to.  If I wanted to do that, I would have done so in the first place, not bought a "drop in" kit.

sounds like you have excessive headspace problems. DONT FIRE IT AGAIN!

Ok cool, got that out, now go visit a gunsmith and get it fitted, please!

Yeah, what Beetle said. The excessive headspace is also what is keeping your firing pin from making full contact with the primer.

See - that's exactly what I was afraid of.  

So not only did I have to spend hours of my time fitting a "drop-in" barrel - but now I have to go pay a lot of money to a gunsmith to get my "drop-in" barrel to work right.

What a crock of shit.  I don't have some kind of a cheap 1911 knock-off, I have an almost brand-new Colt that has not been used very much at all.

I feel so screwed - I wonder if the manufacturer will take their "drop-in" barrel back for a full refund?  The bastards should.

Or am I just being unreasonable?

Its water under the bridge now, but generally you open up the bushing to get it to fit the barrel – not vice versa.

I agree that it sounds like you’ve got excessive headspace.  Absolutely do not fire this pistol again until you’ve got this resolved.  Otherwise, we may have yet another ka-boom thread!

Try this:

With the barrel in the gun and the slide forward, verify that the barrel hood (that’s the square protrusion at the top, rear of the barrel) is touching or very nearly touching the breechface of the slide.

Then, take the barrel out of the pistol.  Hold the barrel with the muzzle end down.  Drop a live round into the chamber.  The rear of the round should go past the hood ever so slightly, if at all.

For comparison, also try the above with your .45 barrel and a live round.  Also, compare both barrels at the same time with live rounds in them – is there a difference in how far forward the rounds are seated?  

IMPORTANT:  A live round in a barrel is potentially dangerous even if it is outside a gun.  If you accidentally set one of those rounds off while in a barrel (say, by dropping the barrel with a round in it), you could definitely hurt yourself or someone else.

Just to be on the safe side: if you’ve got another box of ammo, compare it to the first to make sure you’re not using defective rounds.

Since you’re getting blown primers, it doesn’t sound like there’s anything wrong with your firing pin.  However, it’s still a good idea to also verify that your firing pin projects adequately from the breechface.  

Do this by removing the slide from the frame, then remove the barrel from the slide.  Hold down the firing pin safety and push the firing pin forward with a ball point pen or such.  You should be able to see the firing pin project from the breechface.

I suspect the chamber may have been cut too deeply in the barrel.  If this is true, I doubt it’s fixable.  However, you should be able to get the manufacturer to replace it (defective worksmanship and all that).

Who made the barrel?

Quoted: Its water under the bridge now, but generally you open up the bushing to get it to fit the barrel – not vice versa.

Shows how little I know!    

My thinking was that I didn't want to screw with the bushing since I want to be able to swap my .45 barrel back in there without the bushing being all loose.  

I agree that it sounds like you’ve got excessive headspace.  Absolutely do not fire this pistol again until you’ve got this resolved.  Otherwise, we may have yet another ka-boom thread! Try this: With the barrel in the gun and the slide forward, verify that the barrel hood (that’s the square protrusion at the top, rear of the barrel) is touching or very nearly touching the breechface of the slide. Then, take the barrel out of the pistol.  Hold the barrel with the muzzle end down.  Drop a live round into the chamber.  The rear of the round should go past the hood ever so slightly, if at all. For comparison, also try the above with your .45 barrel and a live round.  Also, compare both barrels at the same time with live rounds in them – is there a difference in how far forward the rounds are seated?   IMPORTANT:  A live round in a barrel is potentially dangerous even if it is outside a gun.  If you accidentally set one of those rounds off while in a barrel (say, by dropping the barrel with a round in it), you could definitely hurt yourself or someone else. Just to be on the safe side: if you’ve got another box of ammo, compare it to the first to make sure you’re not using defective rounds. Since you’re getting blown primers, it doesn’t sound like there’s anything wrong with your firing pin.  However, it’s still a good idea to also verify that your firing pin projects adequately from the breechface.   Do this by removing the slide from the frame, then remove the barrel from the slide.  Hold down the firing pin safety and push the firing pin forward with a ball point pen or such.  You should be able to see the firing pin project from the breechface. I suspect the chamber may have been cut too deeply in the barrel.  If this is true, I doubt it’s fixable.  However, you should be able to get the manufacturer to replace it (defective worksmanship and all that).

Thanks for all your advice.  It sounds a lot like what I wanted to try to figure out myself before going to a gunsmith.

Who made the barrel?

Briley.  

As with other "drop-in" barrel, they DO say that it may require "minor fitting" - I just didn't realize that meant taking it to a damn gunsmith, and I also thought that since I have an original and very new Colt, the amount of fitting would be minimal.  

Maybe the lesson here is that there is no such thing as "drop-in"

Thanks again to everyone for all your advice.

Just out of curiosity, pull your firing pin out of the gun, I've seen them fracture diagonally, and cause erratic strikes (depending on whether the front half was forward or back when struck by the rear half.  ed

DK-Prof:

While I’ve never actually handled one, I’d think a Briley would be a decent barrel.

However, I’m still thinking you probably got a defective barrel.  Excessive headspace shouldn’t be an issue with a drop-in, even if it does need a bit of fitting.

I agree with your desire to be able to reinstall the .45 barrel if you want.  However, a better way to achieve this would have been to get a second bushing for the new barrel (unless of course the original bushing worked OK to begin with).

Nothing’s ever easy!

DK-prof, sounds like the barrel hood is extended 1-2mm too long. If you have a caliper, measure the original barrel's hood space and compare it with your new barrel. If it's too long, just file a little off the end (Not More Than 2mm). That adjustment should cause the chambered case to sit closer to the firing pin when discharged. Also, next time don't file the entire barrel for proper fit. (to much time consuming), just file the inside of the bushing.      

......I respectfully disagree with 199. Do Not Use A Live Round to check for headspace. This type of measurement can and should only be conducted  with an empty shell/case.  You will get the same results. LOS

I had the same prob with my Para P12.  Bought a new match grade barrel from Para Ordnance that was supposed to be a "drop" in part.  No way would it fit.  I couldn't get the slide to lock in all the way.  After messing with it for a couple of days, and since I am not a gun smith, I called Canada for some advice.  The tech rep at Para Ordnance told me there is no such thing as a drop in barrel.  It has to be smithed  to fit properly.  After a trip to my local pistol smith, and $28 later, it fits and works great.  I don't consider that too large a price to pay to get it done right.

Next time buy the book from Wilson Combat that has step-by-step instructions on customizing a 1911.  It will pay for itself in no time.

Quoted: DK-prof, sounds like the barrel hood is extended 1-2mm too long. If you have a caliper, measure the original barrel's hood space and compare it with your new barrel. If it's too long, just file a little off the end (Not More Than 2mm). ...

I agree that if only the hood is too long, filing it down should solve the problem.

However, I’m thinking that if any of the other dimensions are off, then trimming the hood might run the risk of the locking lugs on the barrel and in the slide not matching up correctly.  

After all, these lugs apparently are matching up correctly now.  Trimming the hood will obviously move the barrel back a bit relative to the slide.

I have no idea how much slop is available between the barrel and slide lugs for doing something like this before problems arise.

Quoted: ......I respectfully disagree with 199. Do Not Use A Live Round to check for headspace. This type of measurement can and should only be conducted  with an empty shell/case.  You will get the same results. LOS

I truly appreciate your diplomatic way of disagreeing with me.  

My concern is that the .400 Cor-Bon is a bottlenecked cartridge which, I suspect, headspaces on the case shoulder.  

If so, having fired the round in a condition of excess headspace could result in the fired case being fire-formed to the chamber.  Such a case would give a false reading.

Perhaps we could compromise by suggesting an unfired round which has had the bullet pulled?  

Check the fit of the barrel inside the slide, note the fit of the locking lugs and barrel hood.  If the barrel hood is that long, I don't think it would go into battery at all.  You want to be sure that filing the hood down will actually help matters.  If the locking lugs are already properly mating, all you will accomplish is to create a gap between the breech face and the barrel hood.  Use a magic marker on the barrel mating surfaces, and note where the ink has been rubbed off.

It does sound like excessive headspace is the problem.  Whether you can fix it yourself without sending the barrel back is the question.

Another rule of thumb re: filing the barrel down vs. the bushing. "Always modify the cheaper part."

Quoted: ......I respectfully disagree with 199. Do Not Use A Live Round to check for headspace. This type of measurement can and should only be conducted  with an empty shell/case.  You will get the same results. LOS

Don't bother using an empty shell case either, unless it has been resized and trimmed to proper length.  Spent casing expand which would give you false reading as well.  Take it to a professional.  Spending some extra cash now will save you from having to spend a lot of extra cash later and possibly having some fingers sewn back on.

223REM

So many variables. But I think it's something pretty minor actually. Maybe a weak Mainspring? I think it's the barrel hood length more than likely.

There is one more alternative.  Leave your .45 as a .45.  Conversions are at best....iffy....and at worst...well ....now you know.  Don't feel too bad, we've all been suckered into this kind of thing.  As a rule, the only conversions that work are those made by the same manufacturer as the original firearm.