Slugged my 41. Got .408!? Could this be right?

[Highway41]

So I got my cylinder out for Doug to ream so I thought I'd go ahead and slug the barrels on my Redhawk and Blackhawk 41s.

Did the Redhawk first and the largest reading I got was .408. Figured I screwed up somewhere so I used the other fishing weight I was going to use on the Blackhawk and did it again with the same .408 result.

Checked the bore at the muzzle with my calipers (they're HF but have been calibrated and are accurate) got .408 to .409.

Didn't have another weight to slug the Blackhawk but I put the calipers on it and the largest reading I got was .410.

Could this possibly be right?

Redhawk was made in 1987, the Blackhawk is only a couple of years old.

[skeettx]

I hope so,
While 410 is the standard, most folks us bullets sized to .410, the 408 will make a good fit and gas seal

http://buffalobore.net/HandloaderFeb2003.pdf

BUT, and I mean BUT, I do not use the 41 Mag at top end pressures.
If I want more power, I move up to 44 Mag
and if I want more power, I move up to (well you get the picture)

Mike

[DougGuy]

Sorta hard to measure accurately with calipers. You can get close but a mic that reads in .0001" is what to use.

If you have a cleaning jag, patch it real tight at the muzzle and push it down the bore. If it gets tighter where the barrel joins the frame, you might be having a little thread choke which will size down your slug too because it gets pushed through the tightest part of the bore. This could be why the slug is coming out like it is.

You can also use a wooden dowel, a couple inches shorter than the distance from the breech face to the muzzle, drop the dowel in the barrel and then push the slug in until it stops at this dowel, and use the dowel to push the slug back out the muzzle. That would give you groove/bore diameter of the barrel while not getting pushed all the way through. If this slug is noticeably bigger than the slug you drove all the way through, then something is choking the barrel down at the frame threads.

[Highway41]

Sorta hard to measure accurately with calipers. You can get close but a mic that reads in .0001" is what to use.

If you have a cleaning jag, patch it real tight at the muzzle and push it down the bore. If it gets tighter where the barrel joins the frame, you might be having a little thread choke which will size down your slug too because it gets pushed through the tightest part of the bore. This could be why the slug is coming out like it is.

You can also use a wooden dowel, a couple inches shorter than the distance from the breech face to the muzzle, drop the dowel in the barrel and then push the slug in until it stops at this dowel, and use the dowel to push the slug back out the muzzle. That would give you groove/bore diameter of the barrel while not getting pushed all the way through. If this slug is noticeably bigger than the slug you drove all the way through, then something is choking the barrel down at the frame threads.
I slugged an Enfield once that had tight spots so I was paying attention to the feel. Didn't notice a tight spot but that said I will definitely run a tight patch like you advise.

My next question. If 408 turns does turn out to be my bore diameter what would you advise that I size cast boolits to?

I will slug just the muzzle when I get the right size sinkers.

[skeettx]

410 is standard, I see no issue with that and the expander plug will work just fine

[DougGuy]

Most of the 41 magnums have a .410" groove diameter, and I have good luck sizing to .412" with cylinder throats sized to .4125" ~ .4128" they will finish between those two numbers. I can also finish them tighter than that by not using the reamer and using only the Sunnen hone itself.

With the Sunnen there is no set dimension, not like the reamer where it cuts a finite size. I can pretty much walk all the throats up to the diameter of the largest one with the Sunnen hone but even then the largest throat may gain .0002" by the time the stones touch down in there and shine it up to see if it is round or oval or thimbled.

The most important thing with the throats, is that they are all even. You can always size to fit the throats, and with magnum loads an alloy that's BHN14 or less will obturate to fit the throats anyway. I try and send them out within .0002" of each other, this causes the gun to recoil more consistently in the shooter's hands and will group much better than a cylinder with uneven throats as the tighter throats cause more pressure to build which causes the gun to recoil differently than it would with the same load and a larger throat and so the boolit strikes a different point of impact.