failure to lockup

Maybe I'm setting myself up for some abuse here but I've face this problem a couple times so its time to ask for directions.  So with a somewhat new range officer and my cast hand loads, about 1/100 rounds will have the following problem; round will chamber barrel hood against slide face but stop before lockup, The slide will be firmly stopped, can't push slide into battery, cant rack slide, cant engage safety.  So far this hasn't happened in a formal venue, so I drop the magazine and drive the gun forward against a log or something non marring and non important on the dust cover/plug.  A straight reward blow relieves the problem and and everything goes into lockup easily, all else usual from there.

1 What would you investigate or try to avoid this condition? 

2 Say you found yourself with the described failure, live round chambered but not locked, what is the remedial action in an area without scrap timber.

Side note, before everyone runs down my ammo, it drops into chamber freely below level with barrel hood and fires fine with no leading and good accuracy, red dot/ hg68/ lee taper crimp.  (My 9mm loads on the other hand are subject to any criticisms you can level but are a topic for another day.)

Thanks

does the same cartridge chamber without incident after removing?

james r chapman wrote:does the same cartridge chamber without incident after removing?

Yes, really it doesn't even get removed, a tap reward on the slide looses the problem and it goes into lockup driven by the spring no problem.

In my other cast bullet experience if something hangs it will sort of squish in the last bit, which isn't ideal but not a huge problem for bolt rifles.  Or .22's with poor ammunition a tap from behind will get things going.  This may well be that, but it doesn't feel like that.  If it happens again I should remove trouble round and inspect it for clues.

Taper or roll crimp?  How much lead is showing forward of the mouth?  Crimp measurement?

My RO was doing the same thing with 185 JHP, and 185 and 200gn LSWC. I seated a hair deeper and adjusted the crimp a bit and the issue went away. I've been loading several rifle calibers and 9/40 for years, but the 45 is a bit if a different animal.

Use your barrel (out of the gun) as a case gauge to check loaded rounds as you finish them and make sure your case sits under flush of the barrel hood.

I agree with the seating a little deeper and a bit more crimp. But my .02 is that it is very probably the magazine. The RO comes with hardball mags. They may be releasing the bullet too soon. Like I said just my .02 worth.

Len


John Travis explains it all.

http://rangehot.com/1911-magazine-design-wadcutter-magazine/

If the hood is against the slide the round is probably in the chamber. Dropping the rounds in the chamber to test them and they all fit flush with the hood should eliminate ammo problems. I'm assuming it's as closed as it's going to get no gap and the brass not visible. Could be the magazine as Len mentioned. If it happened I would not fire the round, remove it and carefully inspect it. Look for anything , possibly extractor marks. I don't think it's the firing pin but it is a possibility. Check the "problem round" to see if the primer is flush and if not is there a groove made by the firing pin? The firing pin should not extend out of the slide even if the gun is pointed down. There is a spring on the pin to keep it totally inside the slide but it can be full of "dirt" stopping free movement.
 Is the gun stock? Or has it been tinkered with? When closing the gun on an empty chamber sloooowly is there a bump just before it closes? From what I'm reading in your post the problem seems to be something is preventing the barrel from moving up into the locking lugs or there is too much upward force on the barrel therefore stopping forward travel to the point the lugs align and barrel moves up into lock position.

You need to do some analysis and keep records.

Mark your magazines then notice if the problem is specific to one mag. For wad guns I love the round follower metalforms. They typically have the Bullseye style feed lips


Also you need to look at your extractor for proper profile and tension. The 1911 extractor causes more feed problem than folks believe.

Just spit balling here. Could the bullets be creeping out of the case while in the magazine due to recoil? How much crimp are you using?

This gun concerns me.  He describes it as going into battery far enough that the hood contacts the breech face, but won't fully lock up.  If that is the case, the round is fully chambered and something else is preventing it going fully into battery.  Possibly extractor mis-fit, but I would also look for mis-fit upper lugs or a burr on the lugs, burr on the breech face, or something mechanical.  I don't trust that it is ammo-caused.

To troubleshoot I would take barrel out and see how ammo drops into chamber; is it flush, lower or higher than hood? Put barrel in slide with top of slide facing down. Put barrel in battery; does barrel move/rock side to side, front to back? Look at where hood fits into slide by holding up to light; is thete gap on sides or at breech face? Does link freely move/rotate back and forth? Is bushing too tight on barrel?
Put gun together without recoil spring and hand cycle slowly; does it cycle smoothly? Do same thing with dummy round; does it feed smoothly? Extractor; slide a dummy round under extractor; does it have slight resistance or require effort?
Hmmmmmmm.
Jon

I'm thinking we need a little more info. Just exactly where is it jammed? I assume it is far enough so that the safety looks as if it can be used but not far enough to engage. I assume the disconnecter is down low enough that the trigger is still disconnected. The OP did not mention the type of primers. I had a batch of CCI that had a few in each 100 that were large enough in diameter they would not fit in the primer tube of my Dillon 650. He might want to get a few boxes of Federal primers to see if the problem continues. Burrs may cause the problem but not 1 in 100. Unless something is creating a burr to the point it gets large enough to cause the problem then with the action of getting the gun to shoot it is sheared off and starts to form again. The slide stop pin to lower lug relationship is my guess if everything else is OK. That slight "bump" just before the lugs engage about 1/4" before the complete forward travel of the slide is an indication of improper fit.

On reflection factory ammo hasn't caused problems so I tested a group of my ammo dropping them in the chamber and managed to sort out some that sat tall of the barrel hood.  I measured overall length vs non problem, calipers indicated no significant difference. 

Then I got out my reading glasses and a flashlight.  On very close inspection rounds that did not seat flush had a very small lead burr just ahead of the case, and I mean small.  So the hypothesis now is I had almost but not enough flair on my case mouths when seating, or the seating die body was eliminating the flair too soon (more likely due to the scale of burrs).  Anyhow next time more flair, and let the crimp die alone do the crimping.  I was probably less than a 1/4 of a die turn from no problems.

To confirm this tried loading a round in the barrel and slide without the receiver.  Turns out the last bit of head space is eliminated as the barrel rises into lockup. A problem round I identified would allow the barrel and breech face to contact, but would require a push to get into lockup, where as non-problem and factory ammo did not.

 the seating die body was eliminating the flair too soon

   I had to open the inside diameter of a seating die to cure the problem, even tho i seat and crimp in separated dies.

Merick wrote:On reflection factory ammo hasn't caused problems so I tested a group of my ammo dropping them in the chamber and managed to sort out some that sat tall of the barrel hood.  I measured overall length vs non problem, calipers indicated no significant difference. 

Then I got out my reading glasses and a flashlight.  On very close inspection rounds that did not seat flush had a very small lead burr just ahead of the case, and I mean small.  So the hypothesis now is I had almost but not enough flair on my case mouths when seating, or the seating die body was eliminating the flair too soon (more likely due to the scale of burrs).  Anyhow next time more flair, and let the crimp die alone do the crimping.  I was probably less than a 1/4 of a die turn from no problems.

To confirm this tried loading a round in the barrel and slide without the receiver.  Turns out the last bit of head space is eliminated as the barrel rises into lockup. A problem round I identified would allow the barrel and breech face to contact, but would require a push to get into lockup, where as non-problem and factory ammo did not.

I have had this same problem (and some others in my league) with a certain cast bullet company. It seemed that some of the castings had a front driving band that was a few thousands bigger than the rest of the bullet and when crimping it would squash a bit of lead around the crimp area, unless one looked close this would be overlooked. Casting from several other companies would work fine but not ones from this company. It didn't matter how the bullets were crimped, when or if a Lee FCD was used, the cartridge would hang up and stop the slide from going fully into battery by about anywhere from 1/8" to 1/16". To make matters worse the more someone would push the slide forward to seat and fire the round the more a ring of lead would build up in the chamber. At some point the slide was stuck fast with a round in the chamber and the slide not being able to go into battery. It would take some persuasive pounding to force the slide open and remove the unfired round.

Guns with sloppy over-sized chambers didn't have any problems feeding these rounds and never had a problem but with a tight properly chambered gun they would jamb up and stop the slide from going into battery. I could have seated these casting deeper and solved the problem but being lazy I didn't want to change my seating die. I ended up giving a couple thousand  of these bullets away to a guy with a sloppy chambered gun. He couldn't have been happier as was I for solving my problem.


Virgil