Fire Lapping Results

Brief history on the subject Ruger Blackhawk Bisley 45 Colt. After obtaining this Ruger I picked up some Winchester cowboy action loads with the 255 grain boolit and did some shooting with it. Accuracy wasn't bad but it wasn't great. Next thing I tried was some RCBS 270 SAA boolits. Results were terrible. Tried boolits from 10 bhn to 22 bhn. Velocities from mild to wild. Still would get shotgun patterns for groups. Now I had already done some measuring of the throats but at the time I did not have any pin gauges. Getting frustrated the gun was put away for another day. Selling was not an option because of who I purchused the gun from. He was family and we had recently lost him to cancer. I learned alot from you people here and alot of times I read something that would remind me of that Bisley. I decided I would order some minus pin gauges. After reading fermin's article on firelapping I decided I would go that route with this gun. Pin gauges showed the throats measure .455 and the muzzle accepted a .443 gauge but it would not trave the length of the barrel without sticking. First restriction was just behind the front sight. A .442 gauge would freely pass through the full length of the barrel. I loaded up 30 rounds of lapping boolits after getting the compound from Beartooth. I used my own cast boolits. I had firelapped a RSRH years ago with Veral's compound and boolits so I had some experience going in. I ended up shooting all 30 rounds through the gun and was cleaning the gun every 12 rounds. I was amazed when I saw the lapping rounds start grouping just like Fermin said. After the 30 rounds and a very good cleaning I rechecked the bore. Much better but felt like it needed just a little more work. I loaded six more rounds and fired them and repeated the cleaning process. Now knowing I was going to do this and needed some boolits sized to fit the throats I turned to BRP and talked to Bruce about needing some boolits that could be sized at .455 for this gun and what were my options with his molds. I had an order in with him at the time for the 462-420 GC and he told me he would check and get back with me. He did so and sent me a supply of his 454424 which were cast at 50/50 and air cooled. I sized them with a .455 sizer ( Buckshot ) and used a lube recipe sent to me by another member here. I really wanted to try some HS6 but did not have any and could not find any locally so I ended up loading 9.0 grains of Unique and used a WLP primer. I did not chrono any loads as I was only concerned with the accuracy. I was simply amazed when the first six rounds were fired and I saw the group. The first 2 shots flew high but centered and the last 4 where all in a little cluster. I shot 12 more rounds at the same target and with a some shots that I pulled off the group there were 13 rounds that measured 2.862" measured from outside to outside. Distance was 20 yards fired offhand. I was so amazed that I shot everything before I realized it. I would have liked to see what it would do from longer range. But with the past performance of this gun I am really pleased with these results. Now the only thing is to order another mold and get back to shooting. I should also report there was zero leading in the bore and there was some lube on the muzzle.

Sounds great I am just starting to get ready fo loading a S&W 29 with a 10.5" barrel . I have minus pin gages .060" to .500" and my cylinder will take a .434" pin but I have not yet slugged the barrel and would not be surprised that I will have to fire lap it. I just received a MiHec copy of Lyman's 429421 at .434" and I have to grind out my .431" sizing die for this bullet.

GSaltzman, Thanks for the report. Glad it all came together for you.

Its amazing how much better one can shoot without thier sixgun or thier ammo holding them back!

The .455 throats were probably working with the mild factory loads because they are hollow
based boolits, as are many in .45 LC at the low pressure end, specifically for this issue. They
can go up and down in diameter easily as long as the base is pressurized.

Did you ever try just the .455 diam boolits? I wonder if they would have solved a large part
of the issue by themselves. I have done the boolit size increase to .454 for a .455 throated S&W
1937 (Brazilian contract 1917) and it was a large improvement, but I still needed a hot load
to bump up the last .001 to get really good accuracy. No doubt that lapping out the constriction
will help accuracy and prevent leading, but I wonder how much of the problem is assigned to
the oversized throats and how much to the barrel constriction?

I have a new MP 454423 clone mold in .455 diam with HP pins that I have not been able to
find time to cast with, and it is specifically for the S&W 1937 and a .445 throated Colt 1917
Army. I wonder if both of the companies were taking .45 LC cylinders with the holes bored
and reamed to .455 and instead of running a .45 LC chamber reamer into them, just running in
a .45 ACP reamer and calling it "close enough"? 0.455 throats weren't bad at all when the
groove diameter was .454 for .45 LC, but when the industry went to .452 groove diam bbls for
.45 LC and seemed to forget the throats, it was a real mess. Of course, my most recent
(used) Ruger in .45 LC/ACP had .450 and .449 throats in the two cylinders, so go figure.

Bill

Bill,
The cowboy loads would group about 3.5' at best. I tried them because the boolit is supposed to be .455. If not and it is hollow based that did help it to expand. I tried shooting some RCBS 270SAA boolits I cast but they leaded rather quickly. The mold produces nice looking boolets just undersized. They would work great sized to 452. I tried seating them on top of a heavy charge of 296 but I guess it was too much to try to bump up. Maybe this mold will work great for my next Bisley!

Nice job on the fire forming
I was wondering
whats to stop the boolits from enlarging your cylinder throats when you shoot
a boolit with lapping compound on it through the cylinder

Firelapping does not enlarge cylinder throats to any degree that I have been able to measure. Remember, only one of six lap bullets pass thru your throat and throats have no rifling to "grab" the lap bullet thus not quite enough friction to engage the cutting action IMO.

Additionally, in GSaltsmans case, his leading was more due to his oversize cylinder throats, not so much .001 restriction in his barrel.