sluged my Ruger New Blackhawk 45 colt

[josper]

I'm having an issue with leading In my NBH so today I slugged the barrel trying to sort it out. I cast a few bullets from pure lead and tapped one [oiled] through. Started tight , went easy ,then was tight again where the barrel enters the frame. The slug measured [with a mic.] .451 The cylinder throats are .452. So what should I do next? If I lap the barrel won't this get every thing out of wack again?

[C. Latch]

what did the rest of the barrel measure?

[olereb]

I shoot .452 cast in my Ruger new Blackhawk with no leading issues

[kenyerian]

http://www.castbullet.com/misc/accrsa.htm Read this link very carefully. It really helped me.

[pal82]

Sounds like you have a slight barrel constriction, but I wouldn't start there. That may not solve the leading problem. Your cylinder throats are close. .4525 is ideal for .452 sized boolits. Reaming the forcing cone to 11 degrees may be helpful. Matching bullet hardness to chamber pressure is the key to accurate and foul free loads. There is an excellent article on this topic on rugerforum.net. The article is located in their library. To access the library, you have to register and post a few times. It's worth the trouble. There is a wealth of knowledge on revolver accuracy with lead boolits.

[MtGun44]

How does it shoot with cast?

Are we crystal balling or is there an actual problem?

Bill

[contender1]

The OP stated he's having leading issues.
Lots of excellent advice above.
Fermin Garza penned an excellent article about firelapping. (He goes by 2 dogs here.)
As noted, leading can be from one of several different issues.
I've never heard of any gun being worse after lapping. Most have shown an improvement.
I would look at things I can change easily, from the cheapest, graduating to the most expensive.
Start with the boolits. Hardness? Lube? Velocity? These are things you can change w/o changing the gun at all. THEN look at the gun & start slow. Do one thing at a time & test, test, test.

[frank505]

sound like the usual thread constriction at the frame, so fire lap it out.

[Larry Gibson]

Are we crystal balling or is there an actual problem?

Outstanding observation by Mtgun44;

"leading issues" are most often from other "issues" than the dreaded "barrel restriction". Actually if the alloy, lube are correct there is no reason for leading because of a barrel restriction. I've owned a lot of Rugers and other revolvers over the years and have yet to get leading from a restriction. I have yet to lap a revolver barrel as the cure for leading. Look to the alloy and lube 1st.

Larry Gibson

[josper]

Thanks for all the input. The bullet I'm using is from accurate molds,45-270saa sized to .452 on top of 9.0gr. power pistol . My alloy is 1# of lino. to 4# range lead which is about 8BHN. The bullet tested 10BHN. My lube was BAC, I changed to NRA 50/50 but haven't had a chance to try it yet. All I shoot is cast. Off a rest I'm getting 3" groups @25yds. With my trifocals I think that's not to bad for me. I think maybe I'm trying to read more into this than I need to.[crystal ball] I will keep the fire lapping as an option but I will use Larry's and Bill's suggestion first. Again thanks for the ideas.

[Char-Gar]

Are we crystal balling or is there an actual problem?

Outstanding observation by Mtgun44;

"leading issues" are most often from other "issues" than the dreaded "barrel restriction". Actually if the alloy, lube are correct there is no reason for leading because of a barrel restriction. I've owned a lot of Rugers and other revolvers over the years and have yet to get leading from a restriction. I have yet to lap a revolver barrel as the cure for leading. Look to the alloy and lube 1st.

Larry Gibson

Yep...my experience as well.

I would only add it is fairly common to have some lead wash in the barrel. If you can take a new bronze brush with solvent and a dozen fore and aft strokes takes it out, you don't have a leading issue. The barrel will smooth out in time with enough rounds.

[Larry Gibson]

My alloy is 1# of lino. to 4# range lead which is about 8BHN.

My guess would be that mix is very rich in antimony and very poor in tin. Your "leading" may in fact be antimonal wash. I suggest you add 2% tin to the range lead alone. That will probably push the BHN upwards to 10-12 on 10 day old AC'd bullets. Or, you can WQ them and the BHn should run 17 - 20 after 48 hours. Save the linotype for other cast bullets or alloy mixes. I use a lot of BAC for magnum level bullets also and it is a good lube. But then so is the 50/50 lube. Neither should be the problem.

Larry Gibson.

[376Steyr]

If it was my gun, I'd try experimenting with a couple of powders of different burn rates, such as a Bullseye load and a Unique load with the current bullet alloy. Then I'd try casting with straight range lead and repeat the process. I suspect that Power Pistol isn't giving you good obturation.

[josper]

My alloy is 1# of lino. to 4# range lead which is about 8BHN.

My guess would be that mix is very rich in antimony and very poor in tin. Your "leading" may in fact be antimonal wash. I suggest you add 2% tin to the range lead alone. That will probably push the BHN upwards to 10-12 on 10 day old AC'd bullets. Or, you can WQ them and the BHn should run 17 - 20 after 48 hours. Save the linotype for other cast bullets or alloy mixes. I use a lot of BAC for magnum level bullets also and it is a good lube. But then so is the 50/50 lube. Neither should be the problem.

Larry Gibson. Larry :I thought that Lino had 4% tin and would be enough. I'm not casting for anything else that would require lino so I intended on just using it for my .45 bullets.I do have a bunch of 50-50 solder in 1/2 # ingots . How much to add per 5#?

[josper]

If it was my gun, I'd try experimenting with a couple of powders of different burn rates, such as a Bullseye load and a Unique load with the current bullet alloy. Then I'd try casting with straight range lead and repeat the process. I suspect that Power Pistol isn't giving you good obturation. That would be grate if I could. The only gun shop I get to hasn't had popular powders in quite a while. I have to make do with what I can find. I had ACC5 , found some blue dot. Used up the last of my Bullseye and unique. I do have some 2400.

[Larry Gibson]

Larry :I thought that Lino had 4% tin and would be enough. I'm not casting for anything else that would require lino so I intended on just using it for my .45 bullets.I do have a bunch of 50-50 solder in 1/2 # ingots . How much to add per 5#?

Problem is linotype also has 11% +/- antimony. COWWs has 3-4 % antimony and negligible tin. That means that even with the 4% tin the linotype had the alloy you ended up with had way to much antimony and not enough tin.

Add 1.6 oz of tin to 5 lbs alloy for 2%. Divide the 50/50 solder bar into 8 parts with a magic marker. Each of those sections is close to 1 oz. You want 3.2 oz of 50-50 solder(50% of that is 1.6 oz) for the 5 lbs of range lead so eye ball at 3.2 sections, cut that much off and use it.

Larry Gibson

[North_of_60]

I will be interested in hearing what you do with your Blackhawk.

I have two 45 Colt Vaqueros that are the same way. Once I get the slug 3/4" inside the muzzle I can push it by hand all the way to where the barrel threads into the frame. At one point it almost free falls. On one of them I can force the slug through the frame constriction with hand pressure on the punch and on the other I have to tap it through the rest of the way with a hammer. Both slugs measure .450 + or - with a mic. I also stopped short of the frame and pushed the slug back out the muzzle and measured it. They were nearly identical to the ones I pushed all the way through. With a constriction on both ends of the barrel there is no way of knowing what the rest of the barrel measures.

I started to fire lap the one with the tightest throat but I only have 220 grit compound so I stopped after I could push the slug through by hand. The fire lapping only affected the throat and not the muzzle because the slug still measured the same as before. As soon as I get some medium and fine compounds I'll finish the job.

Al

[josper]

Thank you Larry.

[h8dirt]

1# of linotype and 3# of pure lead will give you 4# of 1% Sn, 3% Sb & 96% Pb for a Bhn of about 12. It shoots good in my 44 Special BHFT now that I removed the thread crush by hand lapping and fire lapping. I had to put a lot of energy and $$$ into my new BHFT to make it shoot reliably and well.

[MtGun44]

I was figuring that the leading may be fixable if the gun is shooting
good groups, change alloy, size, lube, design, etc.

Certainly serious leading is an issue to be dealt with, but it is hard to
assess from here. May need to unscrew the bbl, take a hair off of
the shoulder and reset with red Loctite. This eliminates the frame
constriction.

So far no group info.

Bill