primers backing out....need help

[Mako]

Rooster,
As you know I suspected your primers from the very first posting (and I still suspect them).  Most people don't realize what actually happens to a primer when a cartridge goes off.  In fact there have been several weapons systems including the original Garand design that used a primer "set back" to unlock the action of a semi-auto or automatic action.

Adirondack Jack actually explained it very well, if you have a low pressure load the primer may sit proud of the case base after it is all over. In a firing sequence the force of the firing pin usually pushes the case forward until it bottoms out on the head space feature, in the case of most revolvers it is the rim.  Then the propellant goes off and the first thing that sees pressure is the primer because the burning begins right at the flash hole.  The primer gets pushed back by gases flowing back through the flash hole even before the case gets set back.  In the case of a narrow  long firing pin like we have on our Conversion Pistols and Open Tops the firing pin is enveloped by the primer cup. The thinner cups like Federals deform easily and tend to grab on to the firing pin.  Sometimes the protrusion is so great or the firing pin has sharp features on it that it even pierces the primer.  If the Firing pin is broad and has limited penetration like the big conical designs you see on Colt Gen 1  SAAs, and the primer cup material is thick enough it may even push the hammer back slightly as the primer sets back, at the very least it has a very broad angled penetration into the primer.

If the load has enough pressure the case will set back to the breech face under recoil and the primer will be pushed back at least flush or further if the firing pin has enough surface area to push it to full pocket depth. With the thin long firing pins like we have on the pistols in question the primer gets pushed flush to the face of the rim by the breech face but usually no further by the firing pin which just penetrates into the primer .  A ring of material like the edge of a crater may be upset and be extruded into the firing pin hole in the clearance around the skinny firing pin.

Upon attempting to cock for the next shot the firing pin may stick in the primer if it is very deep or if the firing pin is distorted.  The case is now wedged between the breech face at the firing pin hole and the back of the cylinder.  The primer is either proud or flush with the rim and a crater rim of upset material is sticking back against the breech face or actually into the firing pin hole.

I had an Open Top lock up on me to the point I had to remove the barrel to free it.  After removing the barrel and cylinder the fired case was just hanging there still stuck on the firing pin and had to be pulled off.  After this I replaced the firing pins.  The firing pins were actually deforming, they were bent and mushroomed a bit.  The primers were pierced or sticking on almost every shot.


When these pistols or modifications were originally designed they were still learning about the dynamics of centerfire  primers.  19th century primers were sometimes hard to set off and they thought they needed a small cross section and good penetration.  With the 1873 Mason design they had already switched to very broad conical shaped firing pins.  With our modern primers which move very freely in the primer pockets and with the thinner cup materials we now suffer because of the needs of the 19th century. If this wasn't the case there wouldn't be any market for Bill English's "Happy Trails" replacement firing pins.

I hope he doesn't mind but I'm including a picture from his site showing some firing pins (I added the credit info), his are the two on the far right.

http://www.thesmithshop.com/openfire.html

If it is firing pins you can always call him and he can help you with your problem.   (401) 921-0147

The best to you and a happy Thanksgiving,
Mako

[Cuts Crooked]

where would one look to find a bushing?

Check with a gunsmith. I can't find them either and don't have to equipment to do the work, but a good smith should be able to acquire and install one pretty easily. (Unfortunately the smith who fixed my Remington is no longer in buisness.  )

[Fox Creek Kid]

where would one look to find a bushing?


I still have oodles of Heathen loads for this I will try a handful and compare

Lil Rooster, look at the breech face of the revolver. Is there raised metal there that looks like it has flowed toward the center? ALL breech faces will peen on ALL revolvers as it's inevitable due to the headspace. That is why all Colt, S&W & even Rugers have recoil plates. No, they are NOT easy to install nor make. It takes a professional revolver smith to do it. The "Big Three" I mentioned will do it for you. With clones you're SOL. I only know of one gunsmith in the country who makes & installs them on clones & that is John Hooper in CA. I had to have two installed on two Open Tops that were locking up as what happens is that the soft primer metal will flow into the cratered breech face and will lock it up until it cools & contracts. It's less apparent when shooting smokeless loads as the "dwell" time is less in the recoiling cartridge case and it hits the breechface faster & harder thereby "freeing" itself on the rebound recoil impulse. Some people have merely stoned the breech face raised burrs back flush after reaming out the FP hole a frog hair with a proper sized drill bit BY HAND. I think Driftwood Johnson once said that's how he solved his.

[litl rooster]

Lil Rooster, look at the breech face of the revolver. Is there raised metal there that looks like it has flowed toward the center? ALL breech faces will peen on ALL revolvers as it's inevitable due to the headspace. That is why all Colt, S&W & even Rugers have recoil plates. No, they are NOT easy to install nor make. It takes a professional revolver smith to do it. The "Big Three" I mentioned will do it for you. With clones you're SOL. I only know of one gunsmith in the country who makes & installs them on clones & that is John Hooper in CA. I had to have two installed on two Open Tops that were locking up as what happens is that the soft primer metal will flow into the cratered breech face and will lock it up until it cools & contracts. It's less apparent when shooting smokeless loads as the "dwell" time is less in the recoiling cartridge case and it hits the breechface faster & harder thereby "freeing" itself on the rebound recoil impulse. Some people have merely stoned the breech face raised burrs back flush after reaming out the FP hole a frog hair with a proper sized drill bit BY HAND. I think Driftwood Johnson once said that's how he solved his.

   I did find a small burr on the flash shield around the vent hole. On one of them, if there was one on the orther I could not feel it with my finger.  Just the same I took a stone to them both and cleaned them off.   The Toy store was packed Wed. morning as the "blackgun" buy'n frenzie continues, so I was not able to stay any longer to get different primers to try.   I am going to go head and order the better firing pins and try them.
   I like to thank all of you that have responded to this.

[w44wcf]

Lots of good info from the pards.   One other possibility. If the chambers are not smooth, upon ignition, the case locks momentarily in the cylinder, allowing the primers to back out to the recoil shield.  Smooth chambers will allow the cartridge case to back out and reseat the primer.  An interesting test would be to put a very small amount of case lube on the outside of a cartridge case, fire it and see if the primers reseat.

w44wcf

[Fox Creek Kid]

...An interesting test would be to put a very small amount of case lube on the outside of a cartridge case, fire it and see if the primers reseat.

w44wcf

Ballistic lab tests have proven that lube in the chamber of a firearm TREBLES rearward case thrust. Always remove any trace of lube from the chamber(s) before firing as to allow the brass to expand against the chamber walls w/o a lube film between the case & wall.

[Mako]

FCK is correct, this is definitely hazardous in high power rifle cartridges.  It may not be an issue with the lower pressures we see with BP, BUT remember we are talking about "relatively" thin wall cylinders.  I think his warning should be heeded.

I've seen some nasty ruptured cases in machine guns where the gunners were lubing the chambers or the cartridges themselves trying to keep  worn out barrels in service.  It had the opposite effect they ended up with separated heads and the rest of the case stuck in the chamber.

So once again, I'd think more than twice about what FCK said.

~Mako

[w44wcf]

FCK, Mako,
Thank you. I should have mentioned that this practice was not to be used with high pressure rifle loads. It is not an issue with the low pressure b.p. revolver loads we are talking about here though.  It is a way of determining if there is an issue in the finish in the chambers.

w44wcf