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Thread reducer bushing

aimtite

Plastic
Joined
Nov 8, 2016
Hi everyone.

I have been a long time reader and follower of this great forum and finally decided to join.

I work as a data architect but my favorite hobby is metal working and gunsmithing.

I am amazed about the knowledge shared on this entire forum.

If this is ok I would like to ask a couple of questions...

I want to fabricate a bushing to convert 1.060x16 action threads to .9x20 threads for a quick barrel swap system in a Remington 700 bolt action.
This reducer will have a shoulder that will hold the recoil lug in place and it should be strong enough to torque it down to 100ft-lb or so.
I am planning to make this with a piece of stainless steel I already have. The shoulder portion will be 1.3" in diameter and around .2" long.
I will make a barrel nut for .9x20tpi in order to torque down the barrel at 40ft-lb after headspacing. This is not different than the popular
savage system, just reduced to a smaller thread for small caliber quick swap.

my questions are:

A) Would the 1.060x16 allow me to torque to 100ft-lb?

B) What would be the best way to torque down the bushing with a simple design and w/o cutting too many slots or holes?
I do have a lathe but not a mill :-(

Many thanks.

E.
 
Never handled a Savage with a barrel nut, is .9 the Savage thread size? A thin wall threaded bushing that size kind of scares me, maybe if I made a sample first it would not bother me as much. Is there a reason not to make long 1.060 threads and make a special nut to fit. You could use a simple clamp to catch the nut and rig it up to be used in conjunction with a torque wrench, you would need to figure out the offset of your wrench and multiply by a factor to get the exact torque but that is easy.
 
Where did you come up with 100 ft-lbs? You don't need that much. I'd suggest making the recoil lug integral to the bushing (you don't need a mill to do that) and then Loctite the bushing in at 50-70 lbs. Barrel really doesn't need much more than 30-40 lbs to stay in place and you'll have less distortion. make a "wrench head" that will leverage the integral recoil lug for install. all doable with a lathe and hand tools.
 
Where did you come up with 100 ft-lbs? You don't need that much. I'd suggest making the recoil lug integral to the bushing (you don't need a mill to do that) and then Loctite the bushing in at 50-70 lbs. Barrel really doesn't need much more than 30-40 lbs to stay in place and you'll have less distortion. make a "wrench head" that will leverage the integral recoil lug for install. all doable with a lathe and hand tools.

Agree. 100 ft-lbs is totally unnecessary and the integral recoil lug will be a stronger unit.
 
I was going to come back with making the recoil lug and bushing one piece but 2 guys were smarter than me and thought of it right off. I would have suggested making a large flange on the bushing and milling the excess away, not sure what the others were thinking but they must have some sort of plan.
 
Many thanks for your prompt replies and new perspectives.
Let me try to answer every question.

Never handled a Savage with a barrel nut, is .9 the Savage thread size? A thin wall threaded bushing that size kind of scares me, maybe if I made a sample first it would not bother me as much. Is there a reason not to make long 1.060 threads and make a special nut to fit. You could use a simple clamp to catch the nut and rig it up to be used in conjunction with a torque wrench, you would need to figure out the offset of your wrench and multiply by a factor to get the exact torque but that is easy.

Savage has two shank sizes with the smallest and most common in many rifles being 1.0625x20 tpi. My adapter is for a Remington 700 that is very similar diameter at 1.055x16tpi but with different threads. The .9x20 inside diameter is a custom dimension that is the estimated minimum to create a bushing that is thick enough to hold a new barrel while the outside diameter fits the Remington 700 1.055x16 tpi. I thought about the wrench and I have a savage wrench that would work in smooth
surface designed for the old smooth barrel nuts but I am afraid the shoulder might not be wide enough. I also though about a couple of keys in order to use a spanner wrench. I do have the action jig to install and remove barrels that is a given.

The reason for the .9 diameter is because I have a few calibers some from older rifles that I didn't use for a few years and few different models and shank designs so I want to be able to use them in a universal shank and unique rifle. They all are small cartridges and calibers so there is plenty of shank diameter for them to be accurate. I can also create a step thread so I will be able to keep a wider profile at the front of the chamber with a larger diameter nut if I want.
For the nut I can use any standard nuts or use a 12 point stainless nut that I can thread to .9x20. I hope this makes sense.


Where did you come up with 100 ft-lbs? You don't need that much. I'd suggest making the recoil lug integral to the bushing (you don't need a mill to do that) and then Loctite the bushing in at 50-70 lbs. Barrel really doesn't need much more than 30-40 lbs to stay in place and you'll have less distortion. make a "wrench head" that will leverage the integral recoil lug for install. all doable with a lathe and hand tools.

To be honest I think I read that torque value somewhere from someone doing something similar but you are right 100ft-lbs might be too much.
I like the idea of integral recoil lug! But how do I cut the lug part w/o a mill? I guess I could offset the chuck in both axis and even could use
the tool holder to do some minor milling very slowly but what do you have in mind? Also the lug will have to indexed but should be easy by shaving a few thousands from the back until final torque down. The wrench head will not be a problem as I would use a lug with straight drop so will torque like a regular hex nut.
I agree 30-40 is more than plenty for a rifle barrel. Never had one walking even with less torque.

If you don't mind sharing how to cut the lug this could work really well. Remember I am not a metal worker by trade just a hobbyist so a lot of the stuff I learned has been by trial and error, lots of them! lol

But I feel I am at a point where I can try new things with some direction from people way more experienced than I.


Agree. 100 ft-lbs is totally unnecessary and the integral recoil lug will be a stronger unit.

Yes I think 70lb with locktie like suggested above will do it and with the integral lug it will be a lot stronger.

I am also bedding the rifle and providing a strong bed thick and fully supported so I don't think a large recoil lug is needed. Just enough to do provide a good
anchor.

This is the thread that inspired this idea...
http://benchrest.com/showthread.php?80688-Rem-700-switch-barrel-project


bushing-0.jpg


bushinginstalled-0.jpg
 
I was going to come back with making the recoil lug and bushing one piece but 2 guys were smarter than me and thought of it right off. I would have suggested making a large flange on the bushing and milling the excess away, not sure what the others were thinking but they must have some sort of plan.

Yes that could work and it would be a lot stronger as above suggested.
If I leave enough in the flange I can certainly get it indexed no problems.
I even thought about creating a larger diameter all around as it doesn't interfere with the scope mount but it will create enough space to engage
as recoil lug. That would save me the indexing and milling but I will have to remove some extra material from the stock and will look a little funny.
Maybe I give these ideas a try before cutting it straight. In this case I think a few holes for a spanner type of wrench would make more sense don't you think?

I just want to know ideas to cut a straight clean lug w/o a mill. I am saving for a mill but I don't have one yet. :-(

Many thanks for all the suggestions.
 
With no mill I can think of 2 solutions borrow a mill or if you are handy with a hack saw and file install the oversize bushing hack it of to rough shape and file it to size after it is installed. With a good vice and technique you could do something to be proud of. You plan on your driving holes being in the area that gets hacked off and all is good.
Another thought on trimming the excess of the lug is mount the receiver on your lathe and put a cutting tool in side ways and scrape the excess off round. I did that with an 1917 Enfied receiver to put a scope mount where the sight ears had been. Hacked the ears off and used the lathe like a shaper. Finished it in one lunch break at the shop I was working at.
 
I like the idea of keeping things integral.
What I am going to do is to try a dummy simply oversized like 1/8 with a slot where I can seat on top of a piece of hardened steel
that is anchored to work as recoil lug, all bedded.
Pretty much like the axis but instead of the cut being on the receiver simply do the slot on the bushing. If I don't like this test
then I will proceed to cut another one with a long lug to be indexed.
The good thing is I have quite a few factory tuperware stocks so I can play with the bedding too and if the result is not rigid enough
I will just put the stock on the trash.
I have to test the material, if the steel is not too hard I might be able to use the tool post slowly mill out the material.
I don't mind the elbow grease but I prefer to have the machine work for me.
At some point I need a mill and I will also ask a friend to see if I can stop by his shop to mill the final version if needed.
I will keep everyone posted about my prototype in case anyone else find this useful in the future.

Thanks.
 
I just want to know ideas to cut a straight clean lug w/o a mill.
Many thanks for all the suggestions.

Make the bushing from bar stock that is about 1/2 inch larger diameter than the receiver.

Set it up in a 4 jaw chuck offset so that the center of the threads is 1/2 the receiver diameter from the edge of the bar.

Then bore and thread the internal threads, turn the od and thread it, then part off, leaving an offset flange.

Two hacksaw cuts will establish the sides of the finished lug, and two more cuts will remove most of the excess material to each side of the lug.

Then use the lathe as a shaper to finish the lug.

That will be easier to do if you thread a mandrel to screw the bushing onto. It will also allow you to face the rear of the lug to achieve indexing of the bushing.
 
Switch barrels have been done on Remingtons for a long time. Seems to me that pining the lug to the receiver and then installing barrels with a bump would be the way to go. If the receiver is blueprinted prior to the pining and you will not need to torque the barrel too tight. Seems a lot of work for a risk of miss-alignment between barrel and bolt.

jmo

rsal
 
Switch barrels have been done on Remingtons for a long time. Seems to me that pining the lug to the receiver and then installing barrels with a bump would be the way to go. If the receiver is blueprinted prior to the pining and you will not need to torque the barrel too tight. Seems a lot of work for a risk of miss-alignment between barrel and bolt.

jmo

rsal

hi,
I do have other actions setup as you described. This is a bit different.
The barrels are already cut and threaded with different threads, some smaller, so the reducer is a way to adapt them to be used in the same action.

Thanks.
 
Make the bushing from bar stock that is about 1/2 inch larger diameter than the receiver.

Set it up in a 4 jaw chuck offset so that the center of the threads is 1/2 the receiver diameter from the edge of the bar.

Then bore and thread the internal threads, turn the od and thread it, then part off, leaving an offset flange.

Two hacksaw cuts will establish the sides of the finished lug, and two more cuts will remove most of the excess material to each side of the lug.

Then use the lathe as a shaper to finish the lug.

That will be easier to do if you thread a mandrel to screw the bushing onto. It will also allow you to face the rear of the lug to achieve indexing of the bushing.

Thanks. I am cutting the slot first in a dummy and if this doesn't work then I will try the above.
I had planned on a mandrel to both shave in the back in order to index and truing the front of the bushing if needed.
 
No CNC. All manual work. The key to this integral lug working is to time it to the action while the bushing is still in the lathe before cutting off. fit the action and torque it and you will probably have to face the bushing to get the lug to line up with the bottom of the action. No different than getting the flats on an octagon barrel or stamping on a re-used factory barrel to line up before chambering.
 
No CNC. All manual work. The key to this integral lug working is to time it to the action while the bushing is still in the lathe before cutting off. fit the action and torque it and you will probably have to face the bushing to get the lug to line up with the bottom of the action. No different than getting the flats on an octagon barrel or stamping on a re-used factory barrel to line up before chambering.

It the lug is left thick, it can be faced on the rear (receiver)side after cut off. 1/16th removal would give a full turn of travel.
 
Yes, but it would be a lot easier to face the bushing before it is cut off. Otherwise you have a tenuous four-jaw setup on the lug or make a threaded mandrel to hold it. Everything being done in one setup would be the way to go to ensure perpendicularity.
 
Agree with wesg and gzig5, that would be best. However you do it, manual lathe would be easier than CNC since the receiver thread starting point is not "known" and impossible to measure to within 1/2 degree.

With a CNC part it would have to be "clocked" after it was completed. It you had 2.25 or larger bar stock, the threads could be centered, leaving a full diameter flange to be shaped after cut off.
 








 
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