how to shorten your headstock...

M

mike in co

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while i have about a 1.5 inch bore thru my headstock, a 20 inch bbl is about as short as i can go( 3 or 4 jaw to my spyder).
this would be good if i was only doing br rifles, but alas there are other guns in my future.
one of my first projects is to take a std ar15 match bbl and shorten to 16-18 inches. hardware available for 16, but really want 18". ( this is a "shot out " high power bbl). not having jackie's tooling, the first thing that came to mind is to take off the chuck and replace it with a spyder,,,saves 2 inches easy. so ordered some parts. while waiting brain was spinning.....

my rear spyder is on pretty square...what if.....taking jackies lead.....i built a tool that fit inside the spyder and further reached into the head stock ? turned an od to fit the id of the outboard spyder( just over 1 inch long, turned an od that just clears the id of the outboard end of the head stock..about 3 inches long, 3/8's thru hole, and then bored the inside end with a 1 id hole, .5 deep.

remember how jackie actually uses two tools to hold the bbl in the outboard end of the headstock, one for the muzzle end and another for the breach end while setting up the muzzle end.
well the 1x.5 hole holds either a bbl bore pilot or a muzzle od tool. to keep it all concentric, the pilot and muzzle tool are both machined in place. they are turned to fit the hole plus a setscrew hole, and then installed on the "adapter/headstock shortener", dialed in in a chuck and then turned....22 pilot. 6mm pilot. 30 pilot...could all be turmed on one tool..just in steps.

finished the pilot and threw in a bbl ...in a 3jaw......indicated plus or minus a half(.0005) on the od......not bad....
i can now do this bbl(in a 4 jaw) while waiting for the other spyder parts.

mike in co
 
i did not run it. there are three diameters involved.
5 or 6 inches at the chuck end...maybe a slight taper.
threaded at the outboard end
and a larger diameter in the middle between the two.( larger than the threaded section...maybe smaller than chuck side)

as recieved the middle section was pretty dirty, and may have some rust...not sure. i have tried to scrub it clean but still get residue when i push thru a shop towel.

i do not have a deep hole gage to measure the middle section..and it is rough.

considered line boring.....sliding bar thru a support on the outboard end from the tail stock and /or a chuck side bearing/support.
i can dial in the headstock shortener, large flat face bolts on the spyder, shortener sticks out enought to put an indicator on.

the muzzle end pilot made significant improvement on how the 3jaw held the bbl.

mike in co


off to volleyballl be back after 10mst
 
You could make a barrel extender from an old axle that extends the barrel into the rear spyder. Have the end that connects to the axle threaded onto a collar. Have the collar long enough to slip over the barrel with set screws to hold firmly. may need 2 sets of 4 set screws like a mimi spyder.Brass screws may be best.

For the AR, you may want to remove the barrel extention and make a collar to screw on the rear of the barrel.

Several possibilities.
 
Remember, it is one thing to make a device to hold the barrel. Joel Pendergraft has shown his; which is somewhere in the archives.

It is quite another to indicate in the muzzle that is deep within the headstock. I can't think of a way. You *can* use a tapered rod w/ bushing that sticks out significantly at the back, & make front & back adjustments to the barrel with front & back measurements on the rod (then finally indicate in the eventual neck/bullet portion of the barrel with a dial indicator), but that is not quite the same thing. I'm comfortable with it, you may not be.

So before you write off between centers & come up with a way to hold the barrel in the headstock, be sure you are comfortable with a method for indicating in the barrel.

FWIW
 
MY PLAN IS TO KEEP THE MUZZLE FROM FLYING ALL OVER THE PLACE, JUST CLOSE NOT PERFECT.
my plan is to keep the breech end out where i can get at it. the long reach indicator will get me at the throat.
i have 3/4" plate mounted to a backing plate, this gave me another 3 inches or so over a 4 jaw chuck. the plan is to use 5/16 threaded rod in four place for a headstock spyder.

i did get a 1" boring bar, and may discuss with jackie on boring thru the headstock.
i think someone missed that i have already shortened the outboard end with a internal spacer from my spyder on that end.
mike
 
I used a face plate for turning between centers and made a spider to replace the chuck.
The setup is actually two spiders, one in front and one in back. I can mount a barrel that is just shorter than 18" with this setup.
It is not hard to make the spider just a bit of your time.
The toughest part was making the brass pointed screws for the spider.
Hope this helps
 
"MY PLAN IS TO KEEP THE MUZZLE FROM FLYING ALL OVER THE PLACE, JUST CLOSE NOT PERFECT"

Here's an idea, and it was one recommended at a gunsmithing course. Just take a roll of masking tape, and wrap a tape bushing around the outboard end of your barrel that will slide snugly inside your spindle. It works reasonably well if all you want to do is keep if RELATIVELY centered.
 
ok guys
i will have an inboard and an outboard spyder for most bbls, but when i go to 18" or less i have an inboard spyder in place of the chuck and a 3" spacer in the outboard spyder that moves the bbl support inboard of the actual spyder.

mike in co
 
Joe,
I would recommend copper inserts over brass like Gene Bukys made for me. Very easy, just put your set screws in a collet and drill them to the size of your copper material. Press them in.
Butch
 
You're right Butch, that's what I used..........copper. It was actually a piece from an old electrical ground beside a broken off telephone pole. I just used the wrong word in my post.
Thanks!!
Joe Cowan
 
the outboard spyder has xfine threaded brass, the inboard will be 5/16-24 steel with copper inserts.
thanks
mike
 
I am about to start out making the spiders for my colchester lathe, are there any photographs on this site showing ddifferent set ups?

Cheers

Remmy700:cool:
 
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