bbl instl: usgi 03 bbl onto a 03 usgi recvr

M

mike in co

Guest
ok taking off the original bbl was no issue, but installing a replacement bbl is a challenge. these bbls are pre-fit by uncle sam, and there are matching witness marks on the bbl and the recvr.
i have installed several mauser bbls with no issues, but i cannot get the witness marks within about a 1/4"( which means the extractor cutout is not lined up .
i have done all my installs with vise jaws, not a full blown bbl vice.

so do i spring for a bbl vice, or have any of you had issues installing a usgi bbl in a 03 recvr ?

(cut a unique set of jaws to fit the od of the bbl ?..i do have a lathe)

thanks
mike in co
 
Get a barrel vise

If you ever do any barrel work it's a must.

Just as I've said that, a friend of mine who is a professional shooter and lives 160km from a small country town, uses only a bench vise, (where he clips the receivers) and a plumbers self tight tooth grip wrench to unscrew the barrels. He leaves all the wrench marks on, except if he cuts his hand on them later he may file the top of them while all is back in the stock. He shoots some 40-60 rounds three times per week culling, but he has no cleaning gear of any kind whatsoever and he claims, that he'd never cleaned a single barrel in his entire life. However, I've personally witnessed that he is able to make 99% of clear head shots up to 300M.

Shoot better
Peter
 
mike,
The barrels are mil spec'd meaning any GI armorer doesn't have to thread/fit/chamber the Bbl to each & every receiver.
They vice it up & put three gorilla's on a 6ft cheater pipe to witness the bbl on the receiver.
They are installed with enough torque as not to loosen in combat.

You could set the bbl back & ream it to headspace with approx 1/3 less torque to the witness mark-
 
dan,
do the square threads distort ?....whats got me confused is how easy the old came off..it was tight, but no cheater bar to get it off.....i do think you are right on the three gorrillas......
mike in co
 
Are you restoring an original? If not, then if the headspace is okay when you tighten it up, cut a new extractor clearance. Mausers have it all cut off.
 
Wrong on the 3 Gorilla Idea

The Enfields were torqued to headspace, but to the best of my knowledge the 03's were not. Take the time to measure the shank on both barrels. I have pulled and replaced about 10 03 barrels in the last couple of years. While most line up on the witness marks, there are variations.

If you have 10TPI, and the barrel is .25" from the witness marks and extractor groove matching up, how many thou is that? -

The rifles themselves were manufactured in different plants, i.e. Springfield and Rock Island Armories, and Remington, and the barrels were made in several other places. Manufacturing tolerances existed even in the early twentieth century and if you have one item at the high end and one at the low end of tolerance, you stand a chance of getting in trouble.

Furthermore, you have no idea whether or not the barrel you pulled had had the shoulder set back. About two years ago, I pulled a barrel from a Rock Island 03 that had a shim between it and the receiver. It headspaced on a Springfield with out the shim. I believe the barrel was a WWII replacement.

Torque the hell out of it if you want, but that is not the smart thing to do.
 
Mike

If the witness mark is on the reciever ring, probably between .005 and .006 compresion. depending on a reciever ring a little over 4" circumference.
In theory, the square thread will not close the chamber up or induce outward presure on the reciever ring like a V thread as you tighten it, but pulling that much after make-up seems a little extreme. Well, more than a little extreme........jackie
 
thanks for the help guys.
yes this is a restoration.
the old bbl has the shoulder pushed back and up from installation. the square threads have certainly had a load put on them and are a little distorted. i guess i will make a set of jaws for this bbl, maybe spring for a real bbl vise, and then if all else fails take a couple thou off the shoulder of the bbl.

we did have a thread on calulating cut for rotation..i'll go search for it.

i'm selling the old bbl and the stock it was in. when i bought this there was a copper mine in the bore. since i was selling the bbl, i wanted to be able to tell the buyer just how good the bbl is. i shot it sunday with a WAG load.( 47 4064/sie 168.)..shot two 5 shot groups...0.64 and 0.9 not bad for a 1942 gi bbl!

mike in co
 
got a bbl vise and still no luck getting any closer to matching witness marks. chucked up the bbl, thru the headstock, dialed in the chamber and took a small clean up cut, but still not go. several small cuts and close enough to try the bbl vice and recvr wrench. cycled it a couple times, and then hit it hard a couple times, and a match, bolt cycles well but will not close on a dummy round, so its short chambered....reamer time.

question on the reamer....we are talking about 20 thou or so.....so solid or floating pilot ?? or as some have said, no pilot ??

finish reaming only...

thanks again
mike in co
 
Mike

I would use a standard spec solid pilot reamer, they generally have a generous amount of clearance on the lands, so the reamer would follow the originol chamber.
Either that, or rent a regular spec reamer with a live pilot, and just leave the pilot off, insurring that the reamer will follow the originol chamber for the few thousanths you have to go in with the shoulder........jackie
 
What Jackie Said

And a couple of questions? Was the bolt stripped when you tried it? If so, you may also have to set the cone and the extractor slot back. The extractor may bottom in the slot, and if the cone has not been set back, it may impact feeding. Did you feed the dummy round from the mag? mike
 
no, a bolt assembly was used, none of the other items are issues. no not from the mag( its not installed). i believe the whole reason for the witness marks is to line up the frt sight and the extractor grove.
hopefully just chambering, and then assembly.

mike
 
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