May be a silly question

R

Ramsh00ter

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I have an early 40X (single shot) that was converted years ago to PPC with a Sako Extractor.

I have a bunch of barrels from my Panda and Teddy BR guns.

Not knowing the thread details of the Remy compared to the Panda, would it be possible to change/modify the 40X to the same thread/tenion as the Panda?

I was thinking, if I replaced the bolt with cone faced aftermarket bolt, the take off barrels could be used for Squirrels and turf poodles without going cutting the tenion off and starting over?

With all the talk about the treaded insert over in the BR section, this could be an interest possibility?

Anyone ever try this?

Randy
 
I did this a couple of years ago.

A friend had a custom Remington 700, and a couple of take off barrels from his Panda that he wanted to use on the Remington.

Now, don't laugh, but I did this, and it worked.

I trued one of the barrels up in my lathe, and set the lathe to thread 16 tpi. I then kicked the half nut in, and caught the thread about 1/3 the way up. I then simply established a 16 pitch thread on the tenon. By the time I got to the correct depth,, (remember, the 16 is deeper than the 18), it didn't look half bad, maybe a little "hairy", but unless you knew what I did, you would have thought someone had just used a dull tool to thread the tenon.

I then established a counterbore to fit the Remington bolt nose, (it looked like a counterbore with a big bevel), and machined a spacer to take up the difference in the thread lengths.

It tightened right up, and the thing is probably still together to this day. Since this was just a Sunday "fun gun", he wasn't too particular, but the thing shot pretty darned good.

I know this sounds dumb at first glance, but it worked just fine. Plenty of metal left on that thread. I would do it again in a minute......jackie
 
That's the dumbest post I've seen on Benchrest.com. Someone is bound to get hurt and hurt someone else. Shame on you Jackie. Don
 
Don

The object of the thread is to secure the barrel in the action.

A 1.062 16tpi threaded on a material with the same tensil and yeild as 416R will hold aprox 20 tons of pull. The thread established on the previoius 18 tpi still has about 80 pecent of the parent metal as compared to a regular 16tpi.. The bolt thrust of a typical 6PPC is in the 12,000 psi range. This is not any where near what it would take to compromise the thread.

Don, I consider your reaction as typical "knee jerk". Just what do you think will happen?? Give me some actual figures based on thread strength and bolt thrust......jackie
 
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It doesn't take much thread to hold a barrel on. If you can torque it tight without stripping the thread it probably will NEVER shoot loose. Not really up to benchrest standards though... :D
 
Dennis

Never said it was to "Benchrest Standards". But then, this was not a "Benchrest" Rifle.

Tell you what, Dennis. I bet you have an old Panda Barrel laying around. If you have a spare moment, chuck it up and do exactly what I described, and tell me what you think of the thread. It will surprise you how "normal" it looks.......jackie
 
I concur with Don...but would be interested in seeing the calculations that brought you to 80 % of 20 tons (force)....

Moreover, His original question is to modify the action, not the bbl.

Jackies method would be less strong, going the other way....16 to 18, as 18 is less deep.

I think you would have to machine the action to a larger ID until the threads were no longer visible, thread to 18tpi and fit a heli-coil (cu$tom made) Face off the action or shim to get the correct headspace.

Your action would lose strength, but this can be calculated, since there are numbers available on that steel, helicoils etc.

A thread over thread connection could only be quasi-calculated from an engineering standpoint...imho.

A better idea would be destructive testing. Over-thread a junk tennon of the same material, and a tube of the same action material and treatment, and pull it apart with a 60 ton enerpac thru-hole jack...record the pressure, calculate the force.......then make assumptions on strength.

Ben
 
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Ben

Since we do this sort of work all of the time, I have every thing in my shop to perform a distructive test.

I could take a piece of 4140 about a ft long, and thread the inside of one end to a standard 1.062 16 thread, and thread the other end for a 1 3/8 nut. I would then take an old HV barrel, cut it off short enough to put a 1 1/8 thread on it. I would screw them together, and place it inside one of my Hollow Ram Jacks. I have a 30 ton, a 60 ton, and a 100 ton. The 60 will be fine.

I can take the pressure up to 5000 pounds,which will represent 30 tons.
.

I could then take an old unlimited blank that is threaded for my Viper,, and establish a 16 thread over the 18, and thread the other end for a nut. I could then screw it into the "action" assy, place this assy into the same hollow ram and see if it will take the 30 tons......jackie
 
OK, Here issome Hard Data

Heck, that didn't take long.

Here is what I came up with in the last couple of hours. I found a piece of 1 3/8 commercial heat treat 4140, (we made some coupling bolts from it a while back), which is about 110,000 tensil strength. I bored and threaded one end for a standard 1.062 16 tpi, just like a Remington Action. I treaded the other end to accept a 1.375 12 tpi nut. (I have plenty of these laying around).

I took a HV barrel that has a 1.062 16tpi on it, and cut it to about 8 inches, and then threaded the cut off end for 1.125 12 tpi. I then screwed the pieces together, and placed it inside my 60 ton hollow ram jack. I took the jack to 2000 psi, 3000, 4000, and then 5000 psi. (that represents 30 tons on the jack). The threaded joint was not compromised at all.

I then took an old unlimited barrel that is threaded for the Viper on my Rail Gun, which is 1.062 18 tpi. I cut the barrel off to 8 inches, and put the 1.125 12 tpi on the cut off end. I then established a 16 pitch thread on top of the existing 18 pitch thread, exactly the way I explained it in my first post on this thread.

I then screwed the two pieces together,and inserted them into the jack. I repeated the pressure test, starting at 2000 psi, and going all the way to 5000 psi, stopping after each 1000 psi to check the thread joint.

Guess what. At 5000 psi, the "16 tpi over the 18 tpi" thread was not compromised at all. That threaded joint, which would be identicle to a Remington Action with my "goofy" idea, withstood 30 tons of pressure with no ill affects.

Now, a typical Rifle sees about 13,000 psi at the bolt face. If you do the math, you will see that the actual "tonnage" that is exerted on the threaded joint is miniscule compared to what I just subjected this threaded joint to.

So, here is my question, since I was called a fool for even suggesting such a thing. Where is the big "safety" issue??.

I have a friend that can take some pictures of these parts I made, I will get him to post them.

It sure is good to own a Machine Shop......jackie
 
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It would seem that if your old benchrest barrels are chambered in calibers that are PPC diameter and smaller, and you are not rechambering them to a larger diameter case, that converting them to use Gene Beggs' differentially threaded bushing (nominal .940 tenon OD) would do the trick. It would also have the added advantage of letting you play with barrel indexing.
 
Good on you Jackie...

I would bet if you machined away half the threads leaving about 3 or 4 it would still hold...
 
Wow!...that was fast Jackie. I knew you had the jacks, so well done!

OK, I'll do my part......

OK, based on the PPC case, .4423 at the bolt face, the thrust is about 1986lbs (f), so your safety factor is greater than 30.21 to 1

So, I'd say based on your test the overthread on the bbl from 18 to 16 is reasonably safe.

I was hoping to see it separate at some higher force though..I wonder what that force is?

I've stalled a 60 to enerpac with 16mm B8 all thread.........It's amazing what the thread strength is on a good piece of steel.

Jackie,

Back to his question, Is there any was to fit a heli-coil to an action?

Ben
 
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Ben

After we take the pictures, I will just put it back together and hit it untill it pops. I have a suspicion it will be at about 35-40 tons.

As for studs used with hollow rams, we generally use a 1" B-7, (alloy all thread), for the 30 ton, a 1 1/2 for the 60 ton, and a 2 inch for the 100 ton. The B-7 has a nominol tensil at about 125,000 psi,........jackie
 
damn its great fun having jackie on these boards!

oh and we all have the opportunity to learn at the same time.

thanks again jackie

mike in co
 
Hey Guys

I deal with this sort of stuff all of the time. Threads, pulling studs, installing large bushings and bearings with hydraulic jacks, straightenning very large shafts with straightenning rigs of our own design, (the largest has a 800 ton jack hanging off it), and practicle applications in the real world of Industry. Understanding tonnage, and how to apply it, is a everyday thing for us at my shop.

In all honesty, I had a pretty good idea exactly what the out come of my test would be, but since I was, more or less, called a moron by a good friend, I felt like I had to put forth the effort to build a test rig, with dimensions as close to an action assy as possible, and offer some actual proof.

Building this stuff is no big deal, I doubt it took me two hours to get the whole thing assembled. This just happens to be a test that you can perform without any opinion to mix up the results. You build it, subject the parts to the tonnage, and witness the results. Either the parts will take the abuse, or not.

As sood as I can get in touch with Geramo, who has a nice video camera, I will post the pictures of the actual test rig.........jackie
 
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Jackie

I did not call you a fool or a moron. What I said was that it was a dumb idea and I stand by that. Now what if the 700 has been reworked and the thread is oversize? What about the length of the thread? Not everyone has the skill you have. Don
 
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