Tight spot in Ruger Bisley barrel...

[Dusty Wheeler]

Howdy!
I have an Ruger SS Acusport Bisley .45Colt/.45ACP that is leading badly just ahead of the forcing cone.  I've enlarged the chamber mouths to a uniform size and cut a Taylor throat in an effort to cut the leading down but to no avail.  I'm looking for suggestions as I haven't bumped into this problem before.  Many thanks!

[gunnut69]

The lead in for the thread is likely the problem, a tight spot in the barrel. these tipically occur under the barrel threads and are caused by excessive tightening of the barrel in the frame.. I'd give Ruger customer service a call and get their input. It's really caused by over tightening of the barrel so a manufacturer defect. It can be lapped out, sometimes, but that's no usually a good nor easy to accomplish task.. It requires removing the barrel and casting a lead lap in the bore.. One might also consider 'fire lapping' but since I've not done that for this type problem I can't say for certain. The best and simplest resolution would be to allow Ruger to correct their mistake..

[Dusty Wheeler]

I'll give Ruger customer service a call.  Thanks.

[Nobade]

That ain't the problem. The Taylor throater cuts the barrel like a rifle throater, and there can't be a tight spot there any more. What you need to know is what diameter the Taylor throater cut the barrel to, what diameter the cylinder exit holes are, and what diameter your bullets are. Ideally the cylinder should be .001" or a little more than the throat cut into the bore. And the bullets should be the same as or just a hair bigger than the cylinder. That way there is always a gas seal. If anything isn't right - i.e. bullets too small, cylinder smaller than barrel, etc. that can allow gas to blow past the bullet it's going to lead.

One thing to realize is if you send that gun back to Ruger with a Taylor throated barrel they'll change it back to a factory barrel and charge you for it. It's not in their spec. 

[gunnut69]

I've not used a 'taylor' throater I guess but pistol throats don't extend very far into the bore. The compression caused by Ruger's heavy handed barrel tightening can cause distorsion of the bore to the fromt of the frame.. I suggest slugging the bore to check the tightness under the frame in the bores of the barrel.. If it's to tight the only really good fix is a barrel replacement.. i.e. customer service.

[Nobade]

The Taylor throater does the same thing as a rifle throater except you pull it from the muzzle end. The whole point is to cut far enough up into the bore to remove any constriction present.  (It works with the nifty Brownells revolver throating kit, you just have to buy the cutter.)

[gunnut69]

If the throater you're refering to is a forcing cone cutter then I have used one!! But the forcing cone is cut to a very specific depth, guaged with a plug guage and doesn't nearly reach the front section of the part of the barrel shrouded by the frame.. The leading in a revolver can come from several causes with mismatched throat diameters in the cylinder and bores a common one.  If the bullet is swaged down in the bore ny a constriction it's being swaged back up will cause gas leaking and the blowby will create gas cutting of the lead bullet and the leading problem. Another cause of leading can be too hard a bullet alloy used with light loads, the bullets aren't fully swaged to a tight seal and the blowby causes the leading. If an expandable plug guage or a tight fitting patch shows a tight spot under the part of the frame the barrel screws into then that's likely the problem. As I said it can be lapped out but barrel replacement is the best course..

[Nobade]

No, it doesn't work like a forcing cone cutter. The forcing cone is not changed. It cuts to groove diameter (supposed to anyway) just like a rifle throater. The idea behind it is exactly like a rifle's throat - give the bullet a straight start into the rifling. It is cut a lot deeper into the bore than the forcing cone, up past the torque shoulder of the barrel to eliminate any constriction. And of course, as you said, bullet fit is still critical or it's going to lead the bore.

[gunnut69]

I see said the blind man.. Of course the throater wouldn't alter the tightness of the groove diameter, just the land diameter? Correct? Since all that's being cut away is the lands the grooves wouldn't change. So the tight spot wold remain as bullets will expand to fill the grooves under the pressure of the gases.. The problem with torque induced tight spots is they sqeeze the bullets down and then allow them to get bumped up. The result is almost always severe leading. 

[Nobade]

Any spot in the grooves that is undersized is going to get cut too. Unless the groove diameter is way bigger than the cutter to start with.

I don't know what size they make a Taylor cutter to in 45 cal, that would be interesting to know. If Dusty Wheeler is listening here, could you inform us as to what size the cutter made the throat in your barrel? Guage pins are the way to check that. If it is any bigger than the bullet after it exits the cylinder it's not going to work.

[blhof]

Check Veral's cast bullet section.  My son's Blackhawk leaded badly and the throats were ok.  Got his bore sizer set and lap kit, relatively inexpensive and after 40 cast rounds as per Veral's detailed instructions; no more leading and vastly improved accuracy.