PDA

View Full Version : Reverse taper barrel



JRB
07-15-2013, 07:07 AM
My buddy just got a BR Hall barrelled action, with a reverse taper barrel, this is the first time I have seen this
What is the reason for it? from action threads out about 1 inch than down to 5/8 and tapers to .900 at the muzzle.
Does this set up have a standard barrel channel in the stock?
Jim

JRB
07-16-2013, 09:56 AM
Any one seen this before?
Hope its not a bad experiment, can post some photos if that will help
Jim

Dave S
07-16-2013, 10:29 AM
I am currently shooting a Gene Davis built 40X with a reverse taper barrel on it. I agree, it does look different, but boy does it shoot. As far as the barrel channel goes, I have mine in a McMillian stock that previously sported a "bull barrel" and have "gaposis" all the way down the barrel.. It gives new meaning to "free-floating" ;)
Try it before you change anything and see how it shoots...

Dave

JRB
07-16-2013, 10:48 AM
Thanks Dave,
What is the reason for it? or what does it achieve?
Jim

Dave Shattuck
07-16-2013, 12:52 PM
Can't tell you why, but it has something to do with the harmonics. All I know is: on both my Sporter and Heavy gun I have reverse tapers, and just like with Dave S, mine shoot great. Plus, with the heavy I was told and found that setting the tuner required a lot less effort, and ammo. I started at "0" going out one revolution at a time while shooting 2 shots per setting until I had my 10-shot group, then continued doing this for only a very short time, like maybe into the third 10-shot group. After that I went back to "0" and fiddled with it for a while ending up at "3", then shot it for an entire season. At the end of that season, and after reexamining that first test target, I decided to try turning it out 4 turns to "103" and am still shooting it there. How easy was that?

Bill Myers did both of mine. I had him cut the reverse taper onto an already good shooting Lilja which was on my Sporter that I'd been shooting for 6 years and immediately saw an improvement. So, naturally when it came time to rebarrel my Suhl I gave Bill a call, only this time had him talk barrel to the maker to give instructions on how he wanted the taper.

As Dave S said, don't touch a thing until after you've shot it for awhile, and my bet will be, after finding out exactly what you've got you'll stick with it as is. As for the barrel channel, so long as it's not making contact, that's all that counts.

Dave Shattuck

Fred J
07-16-2013, 02:07 PM
Some of the higher agg's, have been shot with the Benchmark Reverse Taper barrels. If you have one, shoot it and keep it clean.

Charles E
07-16-2013, 02:28 PM
See

http://varmintal.com/a22lr.htm#RVBBL (http://varmintal.com/a22lr.htm#RVBBL)

Just to understand, read above & below, as well.

Here's a link that takes you to the beginning of RF

http://varmintal.com/a22lr.htm

But the whole topic is of interest, you might just want to read Varmint Al generally...

crb
07-16-2013, 02:39 PM
A reverse taper can also help make the bore taper all the way to the muzzle. When I first started messing with rimfires I was using some real old cheap Anschutz blanks I was getting from Numrich. They are 1.20" straight cyl when you get them. When you slug them you can feel that the bore is parallel until near the muzzle where there is some significant choke you can feel. Once you have the slug pushed beyond the chamber in these old bbls the bullet slides along with almost no resistance.

Eventually I turned the 1.2" down to .825". Since this was a 40X I left a short section at 1.2" for a torque shoulder to bear against the recoil lug. Much to my surprise I could feel a distinct restriction at the torque should when pushing a slug down the newly turned bbl. This opened my eyes to what is happening inside the bore when we are carving on the OD of a bbl.

Charles E
07-16-2013, 06:16 PM
Much to my surprise I could feel a distinct restriction at the torque should when pushing a slug down the newly turned bbl. This opened my eyes to what is happening inside the bore when we are carving on the OD of a bbl.Or if, as I suspect, the barrel had been fit to the action, the distortion, or part of it, was caused by the 40+ foot-pound of torgue used to fasten it. This happens in CF as well as RF, but in CF, the distortion is *usually* in the chamber, not the rifled portion of the barrel.

There are several compromises one can make to eliminate this in RF, but they all involved more effort in changing barrels.

However, yes, depending on how you turn down a barrel, you can affect the dimensions, or even the straightness. 4Mesh, who no longer posts to BR Central, use to get 1.400-inch o.d. (unprofiled) barrels from Shilen & turn them down himself. This for CF rifles. He said that when he turned them down, the material coming off was a gray dust, not "chips." Obviously, not much heat buildup with his technique.

We're kinda going beyond what a hobbyist machinist can be reasonably expected to do, here...

crb
07-16-2013, 07:39 PM
Or if, as I suspect, the barrel had been fit to the action, the distortion, or part of it, was caused by the 40+ foot-pound of torgue used to fasten it. .

This was before I reinstalled the newly turned bbl. I needed to find the tight spot in the choke as the bore was a bit loose in the last 1/4" or at the muzzle.

What I did to eliminate the tight feeling was turn off the shoulder and run threads all the way out. Then I bought a nut from Pacnor and used that to tighten the bbl to the rec.