help please! does anyone out there know how to alter new style barrels to fit pre-855000 s/n receivers! i have; lathes and a mill! and know how to use them. but i haven't had any luck finding any info on this! original barrel was already dammaged when i bought it. besides i am a lover of 16's and absolutely gorgeous wood, and it was both. thanks!
If youhave a optical caomparator or thread gauges in both 55 degree and 60 degree Vee, check the threads.
I believe that the early barrels used a 55 degree vee thread, that is why the current 60 degrees can be re-ground to fit. THIS IS MY OPINION. CHECK IT OUT!!! I don't have ability to confirm. there maybe something in the 1963 year American Rifleman magazines, for that is the year the change over occurred.
Hope this helps. What wrong with the old barrel?
Ok, speaking as an old machinist, here is how you do it. Check the older barrel and new barrel threads with a thread gauge to determine the lead or threads per inch. An optical comparator will certainly do the job but few people have access to one. If the leads are the same, you are in good shape. Other wise, forget it.
Then turn a metal plug that fits snug into the chamber and sticks out a few inches. Chuck the old barrel into a four jaw jaw chuck and dial in the plug for concentricity. Also run the indicator along the plug that sticks out. This will ensure the barrel is paralell to the ways and headstock. Grind a good 60 degree threading tool and mount it into the tool post. Put your compound rest on 29.5 degree angle. Set you tool bit using a thread center gauge against the plug.Set your quick change gear box for the lead of threads. Run the lathe very slow and engauge the half nut. Stop the lathe after the tool advances over the threads. Do not cut metal yet. Using the cross slide and compuond rest, move the threading tool until it fits into the V thread. Use a white peice of paper under the tool to check for light. This is the most accurate way to do this. Once the tool is set, make note of the dial settings and back it out. Move the tool to the end of the barrel and move to the settings you had. Now you are ready to clean up the threads. Remember you don't want to cut deeper. You just want to create 60 degrees instead of 55. It's really simple if you are a skilled machinist and you have the right equipment.
thank you so mutch for this vital information! it is the same no. of threads per inch. so it must be the 55deg. i will follow your instructions to the letter! and i know how hard it is picking up the original threads. so i'll probably get ole eagle eye, my last teenage son to help me with that part of it. thanks again, and good wishes for you and yours!
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