RF Barrel Choke

B

bob3700

Member
All right, everything that I have read indicates that RF bbls shoot their best when the muzzle ID is smaller than the breech end ID of the bbl.

There are gunsmiths that actually taper lap the bbl ID to achieve this result.

If various articles are correct, bbl makers like Anschutz etc. manufacture their bbls with this muzzle choke in them.

Now here is my question. If bbl choke is so desirable, why not just install an external bbl band at the muzzle and squeeze the inner bore down with that. It will cause a restriction/choke at the muzzle and this would seem to be desirable for a lead bullet application.

I have slugged bbls (centerfire) that have such bands on them and you can feel the restriction in the bore.

Just looking for some interesting discussion here.

Bob
 
bob3700 said:
All right, everything that I have read indicates that RF bbls shoot their best when the muzzle ID is smaller than the breech end ID of the bbl.

There are gunsmiths that actually taper lap the bbl ID to achieve this result.

If various articles are correct, bbl makers like Anschutz etc. manufacture their bbls with this muzzle choke in them.

Now here is my question. If bbl choke is so desirable, why not just install an external bbl band at the muzzle and squeeze the inner bore down with that. It will cause a restriction/choke at the muzzle and this would seem to be desirable for a lead bullet application.

I have slugged bbls (centerfire) that have such bands on them and you can feel the restriction in the bore.

Just looking for some interesting discussion here.

Bob
Click to expand...

Bob,

It has been tried with mixed results.

Current thinking is the lapping should taper the bore to the crown, and the crown should be perfectly round. The idea being to swage the bullet down the barrel, (no loose spots) and make it perfectly round before it is escapes the muzzle. Hopefully, this allows the bullet to spin true, and go to sleep, without cork screwing to the target.

One sign of cork screwing is when you change from shooting 50 yards to 50 meters. If you have to adjust windage that ain't good!!

Tony
 
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By shrinking a band on at the muzzle, you can of course tighten the bore. If you extended
this past the muzzle, it would also become a fixed tuner. Should you get lucky with your
numbers on the first pass, you will have a killer. Done well, it might even look like one piece
with the barrel
 
tonykharper said:
Bob,

It has been tried with mixed results.

Current thinking is the lapping should taper the bore to the crown, and the crown should be perfectly round. The idea being to swage the bullet down the barrel, (no loose spots) and make it perfectly round before it is escapes the muzzle. Hopefully, this allows the bullet to spin true, and go to sleep, without cork screwing to the target.

One sure sign of cork screwing is when you change from shooting 50 yards to 50 meters. If you have to adjust windage that ain't good!!

Tony
Click to expand...
tony thanks for the corkscrew tip, here I mistakenly thought sighting in at 50yds then meters if looking at a clock the shots went left at meters the scope was canted left of 12:00 and right of 12:00 canted right, here i thought 1 minuete of cant = .090 difference from 50yards to meters. tony thanks for the tip that's one awesome tip. it's great when secrets of shooting by the top shooters are given to us awesome thanks, martin
 
Hi Guys,

As some of you may know, I've been going through the process of working up a good tune for Bronson (my new Anschutz BR-50) and having finally acquired a Hoehn tuner, did while at the gunsmith a couple of weeks ago - ask him to 'slug' the barrel for me - purely out of interest. Interestingly, the gunsmith I mention has again recently won an RF State title here so he is definitely someone that I'll listen to.

Importantly and as Bob has alluded to - Anschutz do a pretty good job becasue when the bullet was pushed through my (heavy match) barrel - it was tight in the first six inches from the breach - loosened up in the middle and then became noticeably tighter in the last four inches to the crown. That said - my gunsmith had no interest in lapping my barrel and believes that the crown is the key and as Tony correctly suggests, perhaps more attention to ensuring a clean, round crown (at 11 deg) is important.

As to 'corkscewing' - I think that the imprint (hole) the bullet makes on the paper will tell you the 'real' story. For me - using Eley Match - they're clean and perfectly round so not sure that I subscribe to the theory - not at least from what I've seen but I'm always open to learning something new.

Allow me to wish you all a Happy and safe Thanksgiving

Cary
Downunder
 
Foster,

Yes, I level my rest, rifle, and the target. I also bed my scope in the rings, so the scope is centered to the bore and has an equally amount of adjustment available in each direction. I don't think I have a cant problem, but I'm willing to learn how to fix it if I do.

I too have been lucky enough to have had some good shooting Anschutz rifles. If they shot well because of the choke, or inspite of it, I don't know.

Tony
 
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