I finally had a chance to taper a couple of 54.18 pulled barrels and took them out today for testing.
Pictures of the guns, and the targets will follow up, Paul will be posting them for me, since I still don't know how to do it.
The first gun tested is a Match 54 build in 1971 with a 1407 ultralight trigger mounted in a Mc Millan thumb hole Silhouette stock. First I pulled the barrel and cut a taper starting at .750" at the muzzle and tapered to .870" at the receiver end, original dia. was .900" all the way. It is still in the original length of 21 1/2" long but I re-crowned it with a match 11 1/2 degrees crown. Then the trigger was converted to 2 lbs. Sweet, and a pain in the neck ( I was told it could not be done ) then the stock was inletted and pillar bedded. By the way the top strap of the thumb hole will be cut out, and re- finish to make it legal for hunter class. The gun shot several one bullet hole groups at 50 yds. with 3 different kinds of ammo. Then I moved to 100 yds. and the first 5 shots group was .506 with Ely Club Extra with the EPS bullet. I was so impressed that I decided it was good enough for that gun.
The second gun tested was one of my own 1712, I pulled the Lilja barrel off, and installed, the pulled 54.18 barrel, re contoured to .715" at the muzzle to .800" at the receiver end ( original Dia. ) by 21 1/2" long, also original length, but re-cut the crown to 11 1/2 degrees, and dropped in the original Pharr stock. This barrel also shot a one hole group at 50 yds. with several brands of ammo. By the time I got to the 100 Yds. it was 12:30 temperature 102 and the mirage was horrible, I still manage some pretty damm good groups, the best again with Ely Club Extra with the EPS bullets.
All said, what I intended to prove, is that cutting a taper on and existing straight barrel, when done with the right machining process, will not change the original accuracy of the barrel.
In other words a 54.18 MSR can be converted to a hunter class rifle for less than half of the cost of re-barreling.
If you have a good shooting straight bull barrel, I can guaranty it can be tapered without a change in accuracy.
Pictures of the targets and guns will follow.
Evelio.

Here are the pictures that Evilio ask me to post.

Target


Anschutz 1712



1971 Anschutz 54

Dang! Nice toys! And another myth down the tubes!

Very interesting, Evelio.

Working in aerospace as a metallurgical engineer for over 25 years, in an environment where the tolerances of turbine engine components are very tightly controlled, I've learned that the keys to eliminating residual stresses and distortion during machining, which, in the case of rifle barrels can lead to a drop in precision, are as follows:

1.- Use of very light cuts (depth) at relatively high rpms and modreate travel.
2.- Use of a high coolant rate, preferably with oil-based coolants.
3.- Use of proper cutting tools for the job.

It all boils down to avoiding deformation at the microscopic level (aggressive machining has been demonstrated to deform the grain structure of metals) through the use of light cuts and to minimize heat-induced distortion by residual thermal stresses throught the use of light cuts and proper coolant flow.

Regards,

Joaquin

Joaquin
You are absolutly correct, as you see from the barrel dimensions, I only removed .120" starting at the muzzle end, which translate to .060" cut, not much actually, I also used a lot of coolant, and back up rollers right in front on the cutting tool, and .003" per RPM feed rate.
Evelio.