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351 Posts
Hey there everybody!
This past year I firelapped my stainless 44 mag Ruger SBH following Marshall's tech book to the letter and I got good results.
I decided to buy some Hodgdon's TITEGROUP powder because they advertise consistent burning, regardless of the powder position, and I figure that's a critical factor with really light loads.
I chronographed all of the 190 shots fired (Hey, it didn't cost anything extra. Besides, if the chrony number changes each time you shoot, you can be pretty sure the bullet left the barrel.)
I pretested 6 different loads ranging from 2.5 grains to 4.0 grains. The 4.0 gave 620fps and the 2.5 grains gave 385 fps. Nothing stuck.
I decided to go with 3.3 grains. None ever misfired or stuck in the barrel. Because the lapping bullets were not all precisely the same, and I didn't crimp them, there was a wide speed range. Some were as slow as 490 and others as high as 550. Mostly they were about 520 or 530.
OTHER: The proper seating depth is to seat the bullets deep enough so that none of the bullet surface with lapping compound on it is exposed to the light of day. Tnat minimizes your chance of scratching your cylinder walls when you insert the cartridge. After seating I wiped every cartridge clean with a nice soft cotton cloth.
My lapping bullets were so oversize that I had to put a tiny bell on the case mouths so they wouldn't shave off the lapping compound when seating them. After seating I put just enough crimp on so the case would fit into the cylinder holes.
Now that it is done, the cylinder throats and barrel sure are shiny. This project took a REALLY L-O-O-O-O-N-G TIME, but I'm glad I did it. Impatient people need not apply for the job of firelapper.
The only thing not shined up was the cylinder holes the cases lie in. So I took a fired brass case, got a drill bit the size of the primer pocket and drilled a hole that size. Then I bought a 1-1/2 inch stainless steel machine screw (8-32 I think) and a lock nut and bolted that screw through the primer hole with the threads and nut on the outside of the case. I put it in a cheap, slowturning battery powered drill, put some of the lapping compound on the outside of that brass 44 case, and ran it in and out of the cylinder holes, holding the drill in one hand and the cylinder in the other. I kept my eye on the second hand of a clock and ran the drill the same amount of time in each of the six cylinder holes, stopping every now and then to add a bit more lapping compound. I think I ran it about 2 minutes in each hole, but the time will vary for every drill and person.
Now those cylinder holes are so slick the cases just about fall out before I turn the cylinder upside down!
Have fun.
Greenhorn Dave
Melbourne, Fl (the Space Coast - where we shoot really large objects really long distances)
This past year I firelapped my stainless 44 mag Ruger SBH following Marshall's tech book to the letter and I got good results.
I decided to buy some Hodgdon's TITEGROUP powder because they advertise consistent burning, regardless of the powder position, and I figure that's a critical factor with really light loads.
I chronographed all of the 190 shots fired (Hey, it didn't cost anything extra. Besides, if the chrony number changes each time you shoot, you can be pretty sure the bullet left the barrel.)
I pretested 6 different loads ranging from 2.5 grains to 4.0 grains. The 4.0 gave 620fps and the 2.5 grains gave 385 fps. Nothing stuck.
I decided to go with 3.3 grains. None ever misfired or stuck in the barrel. Because the lapping bullets were not all precisely the same, and I didn't crimp them, there was a wide speed range. Some were as slow as 490 and others as high as 550. Mostly they were about 520 or 530.
OTHER: The proper seating depth is to seat the bullets deep enough so that none of the bullet surface with lapping compound on it is exposed to the light of day. Tnat minimizes your chance of scratching your cylinder walls when you insert the cartridge. After seating I wiped every cartridge clean with a nice soft cotton cloth.
My lapping bullets were so oversize that I had to put a tiny bell on the case mouths so they wouldn't shave off the lapping compound when seating them. After seating I put just enough crimp on so the case would fit into the cylinder holes.
Now that it is done, the cylinder throats and barrel sure are shiny. This project took a REALLY L-O-O-O-O-N-G TIME, but I'm glad I did it. Impatient people need not apply for the job of firelapper.
The only thing not shined up was the cylinder holes the cases lie in. So I took a fired brass case, got a drill bit the size of the primer pocket and drilled a hole that size. Then I bought a 1-1/2 inch stainless steel machine screw (8-32 I think) and a lock nut and bolted that screw through the primer hole with the threads and nut on the outside of the case. I put it in a cheap, slowturning battery powered drill, put some of the lapping compound on the outside of that brass 44 case, and ran it in and out of the cylinder holes, holding the drill in one hand and the cylinder in the other. I kept my eye on the second hand of a clock and ran the drill the same amount of time in each of the six cylinder holes, stopping every now and then to add a bit more lapping compound. I think I ran it about 2 minutes in each hole, but the time will vary for every drill and person.
Now those cylinder holes are so slick the cases just about fall out before I turn the cylinder upside down!
Have fun.
Greenhorn Dave
Melbourne, Fl (the Space Coast - where we shoot really large objects really long distances)
