Question for Gunsmiths????? (Taurus Rifle)

[rbertalotto]

I have a Taurus Thunderbolt (Colt Lightning clone) that I'm rebarreling from 45LC to 38-40.

I pulled the barrel from the receiver....(That was fun! They glue them on and a heat gun was needed to break the bond)

I measure the threads on the barrel tenon and it is .780 X 25TPI.......I can't cut 25TPI but I'm willing to guess it is metric and is 1mm pitch............What say you?

Now I need to find that big box of change gears I stored away about 15 years ago........Hope I have the correct change gears to cut these threads.....

[Mescalero]

Can of worms!

[Mescalero]

I would at least invest in a metric TPI guage.
Or would that be tpm?

[rbertalotto]

All set.........Changed the gears in the lathe and cutting the 1mm threads.........easy peasy!

I made a test tenon to be sure. A much better fit than the factory barrel. In fact, Taurus had the tenon tapered. Almost like a pipe thread! And a real sloppy fit. Shows to go ya, the rifle was super accurate even with a terrible barrel fit and a horrible chamber.......

But it had huge amounts of blow back to the point that you needed to wear a welders mask to shoot the darn thing. The chamber was so proud I took a piece if 45LC brass and wrapped a layer of electrical tape around it and it easily chambered! With a bit more room to spare. No freak'n wonder I was getting blow by!

But this is one reason they never chambered rifles back in the day in 45LC.....to get them to feed you had to make the chambers quite oversized. All these lever action and pump rifles are much better served with a bottlenecked case like the 38-40 or 44-40.........

[rbertalotto]

I'm starting another thread on rebarreling this Taurus Thunderbolt. But here are a few preview pictures of what the factory barrel's chamber was like.....

Talk about unsupported case! If this was a 1911 with a feed ramp like this, it would be criminal...


Here is a 45LC case wrapped with electrical tape:


It fit in the chamber with room to spare:


The barrel was glued in with some type of "pipe dope"...

[Mescalero]

Good idea on the tenon,
when I re-cut the treads on the python barrel, I did a tenon first.

[Mescalero]

I wrote treads?????????????
I meant threads

[piller]

I am not a machinist at all, and I could probably make it as sloppy as the original.

[Ysabel Kid]

Looking forward to the pictures of the progress on this project!

[Rusty]

This sounds really interesting. I' ve been looking into the .38-40 lately it looks like a really good choice. Now just to find sumptin to shoot it in.

[1894c]

I wrote treads?????????????
I meant threads :shock: :roll:

it's ok no one is going to mark or grade your grammar...you're project and your "tread" really has my interest...thanks for sharing... :)

[soon 2 retire]

I would at least invest in a metric TPI guage.
Or would that be tpm?

Millimeters per thread.


Bob in Friday harbor

[Sixgun]

This is an interesting thread------one to learn from Surprised the gun was as accurate as it was from the factory. That baby ought to smoke in the 40 caliber.---------Sixgun

[rbertalotto]

Yup, the 38-40 is a great cartridge for Cowboy Action.........Like the 44-40 they feed nicely, easy to load for and brass is readily available and no more expensive than 45LC. And it is a "Proper" cartridge for the rifles we shoot. 45LC was rarely (if ever) chambered in CAS type rifles.

If you are shooting Black Powder, there is zero blow-back. The thin walls of the 38-40 seal the chamber and there is nothing to clean but the barrel after a day of shooting.

Accuracy is fantastic on the number of rifles and revolvers I have chambered.

Because it is a relatively low pressure round, it lends itself to barrel liners. An old shot out lever action can easily be lined and chambered to 38-40.

38-40, what's not to like!

[.45colt]

Another Great post Roy, Thank You. when they first came out I olmost pulled the trigger on the Taurus but after reading alot of info from SASS about them not being reliable I held off. I bet the bottleneck case solves that and can't wait to see how Your's ends up.

[Mike Hunter]

Epoxy or Loctite on threads is nothing new, most major manufactures have been using them for a while.

The tapered threaded shank is interesting though, Colt used to do that on their Single Actions; never saw a reason for it, and a real PITA to cut correctly.

I suspect the reason that Winchester didn’t make any of their rifles in .45 LC is more of a proprietary thing and not a ctg design thing. Back in the day, Winchester made as much or more money on their cartridge sales as they did rifle sales. Winchester seldom chambered a rifle in a cartridge design that was not Winchester developed, hence the W.C.F. designations i.e.. 38 W.C.F, 30 W.C.F. etc.

The electrical tape on the .45 case is interesting, but not overly relevant at this point, lot a variables; thickness of the tape, was the case made to SAAMI specs, hardness of brass etc. Best thing to do is take a chamber cast and measure the chamber and compare to SAAMI. The camber needs to be slightly oversize for several reasons: easy feeding and extracting, proper release of the bullet.


V/R

Mike

[olyinaz]

A much better fit than the factory barrel. In fact, Taurus had the tenon tapered. Almost like a pipe thread! And a real sloppy fit. Shows to go ya, the rifle was super accurate even with a terrible barrel fit and a horrible chamber.......

But it had huge amounts of blow back to the point that you needed to wear a welders mask to shoot the darn thing. The chamber was so proud I took a piece if 45LC brass and wrapped a layer of electrical tape around it and it easily chambered! With a bit more room to spare. No freak'n wonder I was getting blow by!

Egads!!

I can't wait to see the finished item.

Oly

[Griff]

Well... the 1st .45 Colt chambered levergun was the Winchester (USRA), mdl 94AE in 1985. Followed by Uberti in their 1873 clone in 1986. And, yes, it probably was a cartridge design issue why the .45Colt only a handgun chambering until the modern case standardization came into being. I believe it was Malamute that posted some pictures of his collection of .45Colt cases showing the progression from the folded rim of the balloon head cases with their relatively small, weak rims to the modern web case with an extractor cut. Since the Colt SAA and Remingtons of the day used an ejector rod pushing from the inside of the case for extraction, the case didn't need an extractor groove, nor a particularly strong rim. Rim strength didn't become an issue until S&W & Colt used swing-out cylinders and star extractors around the turn of the 20th century. Even then, an extractor groove wasn't necessary, unlike a what would be needed with a extractor claw.

[rbertalotto]

Thanks Griff! That was great!

A point about the barrel threads........The barrel had tapered threads but the receiver has perfect straight threads. With measuring, it looks like only a few threads were holding the barrel to the receiver............Nice!

[Mike Hunter]

Griff

Think it was more of a proprietary concern than a case design concern. … Not invented by Winchester.

Remember the Henrys and 1866s that Winchester produced, all chambered for the the 44 Rim fire ctg, very weak head. The same with the 22 RFs today, generally there no issues with bolt mounted extractors.

As to the threads, not a comfortable feeling.

V/R

Mike

[44-40 Willy]

If it was a proprietary Winchester thing, then why didn't Marlin or Whitney Kennedy or another levergun maker jump on the a 45 Colt chambering and have that market? I'm leaning towards the weak rim theory myself.

[Nate Kiowa Jones]

I have a Taurus Thunderbolt (Colt Lightning clone) that I'm rebarreling from 45LC to 38-40.

I pulled the barrel from the receiver....(That was fun! They glue them on and a heat gun was needed to break the bond)

I measure the threads on the barrel tenon and it is .780 X 25TPI.......I can't cut 25TPI but I'm willing to guess it is metric and is 1mm pitch............What say you?

Now I need to find that big box of change gears I stored away about 15 years ago........Hope I have the correct change gears to cut these threads.....

I don't know this for sure but I suspect Taurus gets there T-bolt barrels from Rossi. Rossi may even make the whole gun for them all along. There are many similarities in how they are made. The pre-2000 Rossi 92 barrels were also .780 x 25tpi. The current ones are .745 x 25tpi.

All set.........Changed the gears in the lathe and cutting the 1mm threads.........easy peasy!

I made a test tenon to be sure. A much better fit than the factory barrel. In fact, Taurus had the tenon tapered. Almost like a pipe thread! And a real sloppy fit. Shows to go ya, the rifle was super accurate even with a terrible barrel fit and a horrible chamber.......

But it had huge amounts of blow back to the point that you needed to wear a welders mask to shoot the darn thing. The chamber was so proud I took a piece if 45LC brass and wrapped a layer of electrical tape around it and it easily chambered! With a bit more room to spare. No freak'n wonder I was getting blow by!
But this is one reason they never chambered rifles back in the day in 45LC.....to get them to feed you had to make the chambers quite oversized. All these lever action and pump rifles are much better served with a bottlenecked case like the 38-40 or 44-40.........

I don’t know for sure but I think the reason they never chambered a levergun for the 45lc is because of the old balloon cases not having a rebated rim. Without the rebated rim the extractors doesn’t work too well.
About the 45lc rifles and the severe blowback with the down loaded CAS ammo.
The reason the problem is more common with the 45lc rifle is because the makers all use the maximum SAMMI (Sporting Arms and Ammunition. Manufacturers’ Institute) specs when they ream the chambers for the gun. They do this so the gun will more likely cycle with a broad spectrum of ammo's. This is why semi-auto pistol with match grade barrels are finicky about the ammo they will run. The match grade chambers are tight.

I did warranty work for EMF back when they sold Rossi rifles. Over the years the EMF folks have had me do chamber cast on various rifles. but not just the Rossi, because the customer insisted the chambers were bad.
Most recently, they had a feller send me a 92 and a 73 for this reason. He insisted the chambers were too big on both. I cast both guns and both guns were within SAMMI. He still insist that they are bad, that SAMMI spec are not correct and the industry should do something about it.


This diagram shows both cartridge and chamber dimensions. Note that unless noted all diameters are +.004 and there .200" inside the chamber the nominal is .4862. if you add .004 to that the chamber can be as large as .4902 and still be in spec. Notice the max bullet dia. .456. Modern 45lc bullets run to only about .454 max with the majority at .452. The current ammo specs don't fill the chambers like the old balloon case ammo. I suspect this change came about when Colt went to smokeless proof guns, about 1900. Reducing the bullet size for the higher pressure smokeless ammo would help prevent damage to the older BP proofed guns



This 45lc blowby in the rifle problem has been going on for so long now I believe the IMR folks came out with their Trailboss powder just to combat this. A good book charge of Trailboss and a 250 grain bullet crimped well in a Win or Starline case seems to be the solution for some folks. Win or Starline cases are somewhat softer brass than most of the others. Some folks only neck size their once fired rifle brass. For BP, there are some folks using 44-40 brass blown out to 45 and claim it works well. 44-40 brass is really thin.

[rbertalotto]

Steve,

Thanks for taking the time to post this great info.....Much appreciated!