The full auto Colt Single Action Army.

[KurtM]

Long ago, I used to help out a friend of mine in a rather well known Gunsmithing shop in Aurora Colorado. A guy came in one day with a real nice second gen Colt Single action in 45 Colt. He stated something was wrong with it as it would go full auto! RIGHT!!!!! So I grabbed a few 45 Colt rounds and headed back to the test tube with absolute surety that this guy didn't know shit! Dropped in 4 rounds, lined up the first one, eared the hammer back and let her fly. Way faster than it could even take to explain it emptied all 4 rounds. Two went into the test tube, one bounced off the side of the test tube and tumbled into the back cinder block wall sideways and one went right on through ricochetted off the ground and hit a dumpster out back. Cyclic rate probably around 650 rpm, not as fast as a Glock, but darn impressive for a "Single Action"!
Now I was absolutely stunned! But I don't want to spoil the guesses so WHAT HAPPENED?

 

[OK Corgi Rancher]

Something had to be forcing the hammer back to full cock before you could get your finger off the trigger. Ruptured case venting backwards??? That's the best I can do.

Now I want to know...

 

[KurtM]

Well, God Damn!! A learned man!!!
The firing pin bushing had fallen out! Look at a Colt and there is a big old bushing insert where the firing pin comes through the frame. That had fallen out at some time, so upon firing the primer, now unsupported, would blow out of the back of the case blowing the hammer back and of course under recoil your finger is pinning the trigger back! As I was unloading the empty brass I noticed all the primers were blown out!

Historical aside, John Garands first design was primer actuated but he found it was too violent for sustained use. So yeah full auto single action!!!

 

[Catt57]

Now that's unique.

 

[OK Corgi Rancher]

(***Rushes out to gun room to remove firing pin bushing from Colt SAA so I can try this.***) (***Shit...I don't have a SAA.***)

I would've never believed that could happen if someone brought me their SAA and said that had happened...

 

[KurtM]

And exciting, and a bit surprising and a bit of mixing quick Crete to plug up the holes in the cinder blocks.

 

[KurtM]

Trust me I thought the guy was a dweebazoid, until the fucking gun started stuttering!!!

 

[adamsredlines]

That had to be a tad exciting to hold on to

 

[KurtM]

Actually my thought at the time was "I hope I don't bend his front sight on the test tube" THEN it was WHAT THE ABSOLUT FUCK????

 

[CS Boomis]

So, any idea where the blown primers ended up? Best case I can come up with is they’d launch over your head off the hammer face.

 

[KurtM]

Several were down inside, the rest, who knows! Not in me is all I can say.