Getting ready to lap the throats/barrel of my new Ruger 44 Special NNBH flat top Bisley with 4-5/8" barrel. I've got 100 freshly rolled, in lapping compound, 250 SWC boolits from BTB. What powder charge would you use to just get them to exit the bore?

Thanks,

Alan

If it were me, only because I already have the powder, I'd use Hodgdon's starting load of 4.9gr of Universal or 5.6gr of CFE-Pistol.

The Universal load is ~8,000 CUP for 721fps and the CFE-Pistol load is 9,800 CUP for 784fps.

Ed

Id be wary of fire lapping throats; it generally wears at the forcing cone/rifling area first in wheelguns and removes the rifling where the bullet engages the lands. NOT metal at the throat.....

If the throats are smaller than groove, have them opened up with a throating reamer or send the cylinder off to have it done.

The only reason to fire lap is to fix an undersize cone.

If a gun shoots well, Id never screw with Stanton or Veral for gunsmith advice....

Ditto what Hawk posted.

Slug your revolver first and have real numbers to show if/where a problem lies. If the cylinder throats are tight, then have a smith open them up.

Ruger's often have a tight spot in the barrel directly under the threads. I'd send the barrel off at the same time as the cylinder and have that hand lapped by a professional if yours is tight there also.

You've got a SWEET little revolver, and I cringed when reading that you've got 100 gritty bullets waiting to assault that Bisley.

I'll agree with the others in not lapping unless you have to, having done it a few times myself. Rounding over the rifling edges at the forcing cone is not beneficial, and can promote bullet skidding in the rifling. It's also easy to go too far and end up with an oversized bore. 100 bullets is way too many, I wouldn't want to use more than 1/4 of those at most and even that would be a lot.

However, if you do go ahead, the loads above are way too fast. You want BB gun speeds, and ideally will have the bullet barely exit the muzzle. Doing that part right means adjusting your load as lapping progresses, and, you will have to determine the load yourself.

Use the fastest burning powder you can get, Bullseye, Clays, etc and start with small charges, probably not more than 2-3gr. Last time I did this in a 45 Colt I ended up using a 22 Short case as a dipper.

That's not the way to ream the cylinder throats even if it's already been determined that they need reaming.

The first step is to measure them.

And if you're going to firelap, you need to cut and try, meaning measure as you go with bore slugs!

yeah definitely don't firelap to open up cylinder throats. Reaming is more precise and won't damage your bore.

Thanks. You can see how much experience I have with fire lapping.

It certainly makes sense to go slow, that's why I said to use the starting loads.

Ed

In firelapping, if you can't see the bullets travelling downrange, they're moving too fast.

Do yourself a favor and read the article in the link. If you don't know someone in your area with a pin gauge set then shoot me a PM. I see your in Alaska part of the time. I have a set and would be happy to measure your cylinder and bore for you.

The cylinder mouth and groove diameter dimension are the first critical dimensions you need to determine before you fire lap your bore. If the cylinder mouth is not one or two thousandths over groove diameter then you need to correct that first. Otherwise you're wasting lapping bullets and not doing your bore any good.

I have one of the Bisley Flat Top 44 Specials and the cylinder mouths were all .432 and the groove diameter .4295, so it won't need the mouths opened. I haven't lapped it yet but will this winter. I wouldn't be surprised if yours measured with similar dimensions but you still need to check.

Check out this article. Great information.

fire lapping

There is some good advice here. I've firelapped several revolvers with good luck. With the 2 .44 specials i did, i started out with 2.5 grs of Red Dot. I adjusted the charge DOWN every 5 rounds.