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Remington rolling block

gappmast

Cast Iron
Joined
May 13, 2007
Location
California
I'm installing a barrel on a Remington rolling block with 12 TPI square threads. Are these truly square threads or is there a small angle on the sides. Any impute would be appreciated.
 
Thanks for the replies. With a little digging I found that Brownells sells a tool bit which will save me grinding one.
 
I have cut one square thread for an M1870 Trapdoor Springfield and picked up an M1903 and a Garand thread while rebarreling them. The tools I ground from HSS blanks. Not much different from other grooving or thread tools but they are a true 90° thread form and you do have to hold the dimensions. Give your lead screw and half nuts a very good cleaning before you start. A nominal 60 production thread can wander a tiny bit to and fro on the thread dial, but the square threads have to track pretty much dead nuts. Hey it's what we do. Take your time, feed straight in with the compound, and good luck with them. A blade micrometer is best to check your progress proceeding with light cuts.
 
I have cut one square thread for an M1870 Trapdoor Springfield and picked up an M1903 and a Garand thread while rebarreling them. The tools I ground from HSS blanks. Not much different from other grooving or thread tools but they are a true 90° thread form and you do have to hold the dimensions. Give your lead screw and half nuts a very good cleaning before you start. A nominal 60 production thread can wander a tiny bit to and fro on the thread dial, but the square threads have to track pretty much dead nuts. Hey it's what we do. Take your time, feed straight in with the compound, and good luck with them. A blade micrometer is best to check your progress proceeding with light cuts.

It sound like it would be a good idea to use the same number on the dial for each pass.
 
I have cut one square thread for an M1870 Trapdoor Springfield and picked up an M1903 and a Garand thread while rebarreling them. The tools I ground from HSS blanks. Not much different from other grooving or thread tools but they are a true 90° thread form and you do have to hold the dimensions. Give your lead screw and half nuts a very good cleaning before you start. A nominal 60 production thread can wander a tiny bit to and fro on the thread dial, but the square threads have to track pretty much dead nuts. Hey it's what we do. Take your time, feed straight in with the compound, and good luck with them. A blade micrometer is best to check your progress proceeding with light cuts.

A square thread will work on an M1, and many have done it, but it is actually a 10 tpi stub ACME thread. Same with M14. 14-1/2 degrees per side.
 
OK actually measured my rolling block barrel tenon
0.9675 major dia
0.924 minor dia
1.461 overall tenon length
0.581 turned down to minor dia.
now there are some details that have to be cut
best to get a barrel stub from Ken Womack.
see attached photo
rollinblockIMG_0081.jpg
 
How did this turn out? I have a line on a #1 rolling block in .43 Egyptian in really poor shape that I am thinking of converting to a .50 caliber inline muzzle loader. Was it hard to remove the barrel? Is there enough meat in the receiver to cut out the square threads and replace them with V threads?
 
How did this turn out? I have a line on a #1 rolling block in .43 Egyptian in really poor shape that I am thinking of converting to a .50 caliber inline muzzle loader. Was it hard to remove the barrel? Is there enough meat in the receiver to cut out the square threads and replace them with V threads?

Simple and polite answer is no not practical
 
Can't prove it but I suspect that the square threads are there for engineering reasons. With square threads the breech pressure is reflected parallel to the bore. With 60 degree threads half of the breech force is trying to open up the receiver ring.
Converting to a muzzleloader or even bushing with a Grade 2 or 5 bolt and then chamber for a straight cartridge to use as an igniter should work. YMMV.
Maybe use a 209 adapter or chamber to use a 209 directly. The metallurgy on those is not fancy. Refer to Accurate Arms reloading manual for pressures for RRB's.
Probably 18 Ksi...
I've only seen one RRB destroyed by pressure but it blew out the receiver ring. Good place to tread lightly.
 
Just my opinion, but I think the square threads were a manufacturing benefit. The precise depth of the threads doesn't matter in terms of the barrel and receiver clocking up properly. The threads are milled, and sharpening the cutter can be done by grinding either the OD or the face. If the OD, a simple depth adjustment puts you back in business. Likely you could grind the face multiple times before an adjustment would be required.

A V thread has to be reset to the proper pitch diameter to maintain timing of the barrel and receiver. It's also a more fragile cutter that likely requires sharpening more frequently.
 
Oh, BTW, you can't generate a 'perfect' square thread internally even by milling with the cutter inclined to the lead angle. It's always going to have angled (actually curved) sides to it. But as Kendog notes regarding an M-1 (I didn't know they were ACME, probably aught to look close at the extra Kreiger in my shop cabinet), close enough ...

An ACME thread might be millable with an inclined cutter. I'm not sure. They can not be done by conventional thread milling. Only a single point cutter or a tap will generate the proper form.
 
Oh, BTW, you can't generate a 'perfect' square thread internally even by milling with the cutter inclined to the lead angle. It's always going to have angled (actually curved) sides to it. But as Kendog notes regarding an M-1 (I didn't know they were ACME, probably aught to look close at the extra Kreiger in my shop cabinet), close enough ...

An ACME thread might be millable with an inclined cutter. I'm not sure. They can not be done by conventional thread milling. Only a single point cutter or a tap will generate the proper form.


I guess that I don't see why you couldn't cut truly square threads. What am I missing?

squarethread.jpg


-Ron
 
That was in context with milling the threads. Sorry. Single pointing, or tapping will do it. Milling, with a round cutter obviously, results in the leading and trailing teeth going out of bounds of the helix of the thread. Similar to how running a piece of wood across a table saw at a slight angle to the plane of the blade results in a cove cut instead of a wider straight sided groove.
 
That was in context with milling the threads. Sorry. Single pointing, or tapping will do it. Milling, with a round cutter obviously, results in the leading and trailing teeth going out of bounds of the helix of the thread. Similar to how running a piece of wood across a table saw at a slight angle to the plane of the blade results in a cove cut instead of a wider straight sided groove.


Thanks, that makes sense.

-Ron
 
I'll pipe up with a gotcha that I ran in to with a Swede Rolling Block, in that it had half height threads. Same square form, just not as deep.

The Swedes bought a lot of Rolling Block actions direct from Remington, and made a lot more under license.

The real deal is simply to match it to what the receiver is threaded!
 








 
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