Taurus Thunderbolt, .45 ACP!

[RBHarter]

On 2 occasions I've very nearly cost myself a lot of money .
For many years I had a sign over the bench and a lable on the tool box " keep it simple stupid " , " clean and lube before you fix something thats not broken " .

Sometimes that's a hard lesson to learn , I can't tell you how many $500 dollar jobs I didn't do because of an hr of shop time and $3 worth of solvent and lube .

 

[Ian]

Range time today, electricians tape holding the magazine tube to the barrel until I shorten it to match the shortened, rechambered barrel.

Still having some feeding issues as a result of substituting a 3/8" shorter cartridge for the one for which the mechanism was designed. The magazine, metering stop, and lifter worked pretty well with up to ten cartridges in the magazine, but any more than that and any additional cartridges were too difficult to worm into the oversized tube.

Good news is the lockup is absolutely solid, the firing mechanism works well, and it shoots just fine.

The feeding jam is due to the lifter being kicked out from under the cartridge too soon by the bolt. That causes the back end of the cartridge to drop down and jam the nose up against the roof of the chamber. I'll investigate milling some metal off the bolt to change the timing of the lifter drop. Ideally I'd extend the little fin on the bottom of the bolt face and change the angle slightly to help "scoop" the back of the rimless .45 ACP case up a little higher, a little sooner, but that's not going to happen for several reasons all relating to the multiple functions of that fin (for one thing it bears against the bottom of the barrel and keeps the bolt nose from kicking up under bolt thrust loads) and my lack of metallurgical knowledge. I'll try to make it feed just by modifying the action of the lifter.

I'll also investigate buying a chrome-moly tube to make a smaller diameter magazine tube so the cartridges are easier to load through the gate.

 

[Ben]

Ian,

I would say you've got your hands full.
But, knowing you, I figure in the long term that you'll ultimately win on this one.

Ben

 

[fiver]

you'll need a spring too, and a new follower.
the follower would be the easiest since you can make that yourself on the lathe.
I'd also explore a brass tube, even if you have to make a sleeve for it to fit tight in the frame.
that way you can solder the tube into the sleeve if necessary, and it's about 16 times easier to machine.

 

[Ian]

Spring, follower, end plug, and bushing at the frame. No big deal on the lathe work. I can braze, epoxy, or weld the bushing steel to steel. I could hot-water blue the chrome-moly to match the deep blue factory gloss finish. Or I could use Krylon....

I may be screwed on modifying the lifter, looks like in the drawings the locking bolt thingy rides the lifter and pushes it down. Will have to take it apart and study some more.

 

[Ian]

Tore it down, removed and reshaped the lifter ramp (part the bolt rides on the way forward to push it down) to move it as far forward and delay the lifter lowering as much as possible, no help. Can't take metal off the bolt without weakening it. Can't weld up the cartridge stop on the lifter to stop the cartridge further forward because then the lifter would eject the live round out of the action due to the bolt raceway inserts being too short to stop it. Can't lengthen the inserts due to a number of factors.

So I decided to shorten the mag tube, put it all back together, drift in some dovetail sights, and enjoy it the way it is. It feeds fine if the muzzle is lowered while chambering a round. In all it's better than it was when I first got it because it doesn't ruin an expensive piece of brass every time it's fired, and it doesn't spray the user's face with hot powder and gas.

 

[fiver]

hmm trying to remember.
but it might be easier to raise the top of the lifter [or just the front half] to hold the cartridge up just a titch longer.


remember what I said about the cartridge being part of the inner workings on these older rifles...

 

[Ian]

The lifter lifts the cartridge until the body hits the bolt guide inserts and at that point it looks like this, the lifter is perfectly positioned for the cartridge to slip right into the chamber (and it will literally fall all the way in if the muzzle is tilted down about 45⁰). If the lifter would stay in that position as the bolt came forward another 1/4 inch or so it would be perfect, but the shorter ACP doesn't get far enough into the chamber before the lifter is bumped down out from under the back end. No real way to fix it. The rim on the Colt case positions the back end up even higher on the lifter than the ACP, but actually stopped the lifter sooner and didn't line up as well as the ACP does initially. If the rifle was strong enough I'd consider trying to make it a .45 Winchester Magnum because that would be about perfect for feeding, but not going to even try that. As it is I'm running a 20K psi cartridge in a 14K psi gun.

 

[RBHarter]

Rimless Schofield ? 1.1 case length , 14kpsi . Same MV as the ACP .

 

[Joshua]

Rechamber it to 45 Win Mag?

 

[JonB]

Dang, how did I mess this thread?

 

[fiver]

yeah I got to thinking about the rim and the rails some last night.
the cartridge length,, etc.
re cutting to win mag would help for sure,,, but god help anyone that tried running a factory load through there.

the cowboy case might work if the rim would catch the rails before the lifter dropped off, but then again the front of the case might not be held up just yet and you'd end up with a nose down jam.

the problem here is the round has to come back to that stop to get into position to be chambered by the lifter.
unless you can figure a way to make or build up some feed rails that are supporting the case as soon as/by the time the bolt moves forward tripping the lifter down your not gonna get this to work quite right.

all the tipping downward is doing is compensating for the length change in the cartridge, a set of rails would do the same thing.

 

[Joshua]

re cutting to win mag would help for sure,,, but god help anyone that tried running a factory load through there.

I was thinking about that this morning. If you cut a Win Mag chamber .050” short, it could be safe. Call it a 45 Win Special.

I’m only half joking with this next statement. If we all went through our scrap piles and sent Ian every piece of 308 family, 30-06 family, and x57mm family brass we had, he’d have enough donor brass to last a lifetime!!!

Then all he would need was a convertible Blackhawk, and give it the same treatment.

You just let us know. I’ve got a SFRB with your name on it.

Josh

 

[RBHarter]

If it's not filled from the colts rim you might get away with the Schofield in those short Hornady cases .

Everyone hates them but nobody wants to turn loose of them ......

 

[RBHarter]

Maybe after I get done with the blown neck 06' cut back and used up for 358 Win ....... I too have small lots of mismatched Mauser lineage brass .

 

[Ian]

Ugggg. I tried working out a spring wire scoop of some sort to help the bolt pick up the cartridge, but that's going to be tough. Any sort of spring-loaded side rails will interfere with the weak and mechanically-disadvantaged lifter mechanism.

So, if I weld up the lifter stop and re-grind it, and drill/tap the receiver for two threaded studs that will extend the slide rails forward and make an elevation stop for the cartridge (and ejection stop for spent cartridges), it might work better. I studied the lifter ramp some more and it turns out there is more room than I thought to extend it forward.

 

[Ian]

Discretion being the better part of valor, I shortened the magazine tube, touched up the bluing, got it properly attached, drifted some sights into the dovetails, and went back out in the beautiful afternoon and abused some steel plates with half a coffee can of mixed loads that I've been accumulating for years. It cycled and ate everything without a bobble as long as I dropped the muzzle slightly when racking in each round.

It holds 16+1 rounds loaded at near max OAL and 17+1 of my universal zombie whacker load which is 1.208". I had zero issues with any of the different loads cycling and lifting from the magazine (even stuffed to maximum capacity) and zero ejection issues. There is absolutely no recoil so I have no concern with RN .45s chain-firing in the magazine unless the rifle is dropped really hard on the butt.

Good enough for me!

 

[Ian]

A final photo just for the heck of it.

 

[Cherokee]

Nice conversion Ian. I always wanted to try one of those in 32-20 but never found one within my price range. Sounds like you have got it under control and it should give you some fun times.

 

[Brad]

OK Ian, how fun is it to shoot? Little recoil, accurate enough to hit cans or steel plates. Easy to load ammo.

Sounds like a great way to consume some ammo while having a hell of a lot of fun.