Is the barrel crown as critical in a revolver as a rifle? I ask because I ordered a 5" 625 barrel assembly to retrofit a 4" and it looks like it was machined by a retarded monkey using an old hand drill.




Initially I was delighted to see the barrel arrive. The rifling in it is great looks but that crown is just knarly looking, but then again I got a savage rifle with train track rifling that puts 3 shot groups in a dime at 100. Return it, or just a get the smith to redo when they fit it, or leave it cause it will be ok?

IMO the barrel crown isn't that critical on a revolver, expecially in a low pressure caliber such as the 45 ACP. However, it is so easy to re-crown a loose barrel that I'd have the smith do a precision 11 degree crown on it even if it had shipped with a perfect crown. At the same time you could also have him lap the forcing cone because that will reduce leading and likely help the accuracy by a small margin.

BTW, that's an ECM rifled barrel so I would suggest that you avoid shooting lead bullets. I know some do without issues but the ECM barrel in my 620 leaded up so badly with just 50 rounds of Blazer LRN that I now only shoot jacketed ammo in any of my guns with the ECM rifling.

BTW, I have a new 625 JM that came with a cockeyed barrel and am looking into getting a frame wrench to set it straight. Since I have full access to our machine shop at work I also plan on crowning the barrel and lapping the forcing cone. Already have a custom cutter made up to do an 18 degree crown and past experience using valve lapping compound has shown me that would produce a surface finish to the new crown that would very nearly match the bead blasted finish on the gun. End result would be a gun that looks a lot like a Factory custom and not having to send my new gun off to strangers.

If you want a similar look with a more "proper" 11 degree crown ask the gunsmith if he has an 11 degree lapping stick. If so, hit an auto parts store and pick up a tube of valve lapping compound and ask him to use that for the crown. It doesn't produce a really polished finish, it's a duller look very close to the bead blasted finish. It's also a good starter compound for the forcing cone but you'll want him to finish that off with a standard fine grit lapping compound.

The very last thing the bullet touches, before leaving the barrel, is the crown. If your happy with the accuracy, at whatever range it's intended to be used, then so be it. But, a defective crown never helps.

Thanks, that's what I thought, but I have no way to determine accuracy without installing and shooting and then I'm stuck as returning is no longer an option. I just need to weigh the cost of return vs cost of recrowning. I was a little shocked this made it past QC, but every company has its bad apples.

I don't think it looks real bad in your pic, but this: 45° BRASS MUZZLE LAP - Brownells, a variable speed drill motor, and some 320 grit lapping compound will take care of it.

It's pretty off center, real deep on one side and virtually nonexistent on the other ie just breaking the edge kind of chamfer. I had a hell of a time just getting those two pictures focused enough.

Just to clarify things a bit, there are 2 purposes to a barrel crown.

One is to protect the end of the barrel from dings and the like.

The second is to assure that when the bullet releases from the barrel it does it evenly around it's full circumference. If the bullet release unevenly it will cause the formation of temporary gas jets that can cause the bullet to "wobble". Naturally as the pressure in the barrel increases so does the importance of a very well centered barrel crown. BTW, this is why I said that that crown isn't that critical in a 45ACP, pressure is low enough in relation to the mass of the bullet that the crown would have to be really off center to have a measurable effect.

So, having the barrel re-crowned really isn't that important. However, it is just so simple to do on a loose barrel that it shouldn't cost much to do and it does look cool.

I DISAGREE. THE CROWN OF THE MUZZLE IS VERY IMPORTANT FOR ACCURACY. I LENT A MDL 14 TO MY MY BUDDIE AND FINALLY AFTER SEVERAL YEARS HE RETURNED IT. WHILE PREPARING FOR THE N.P.S.C. I RANSOM REST TESTED IT AND AT 50YDS IT SHOT LIKE ****. CLOSE INSPECTION OF IT REVEALED IT HAD SEVERAL CLEANING DINGS AROUND THE MUZZLE. A COUPLE OF TURNS WITH A 45% CUTTER WITH A BORE PILOT AND IT WAS CLEANED UP. IT WENT RIGHT BACK TO BEING X RING ACCURATE. JP

If you "have full access to our machine shop at work" I have no idea why you'd be screwing around lapping the crown. Chuck the barrel in a 4 jaw in a lathe, indicate it, and cut the crown angle you think is best. Start the cutter inside the bore and come out.

The sole purpose to lapping the crown is to duplicate the bead blasted finish on the rest of the gun. I've lapped a lot of valves on various engines over the years and the grit used in typical valve lapping compounds leaves a surface finish that is darned near a dead ringer for the bead blasted finish on the 625 JM. End result is that I'd have a 625 JM that looks like it had a custom crown done at the factory prior to the barrel being bead blasted. On a minor note it would also remove any trace of a burr that might be left on one side of the lands, which can happen even on an inside out cut.

BTW, I'll be using a mill to do the work, the 4 jaw chuck we have at work weighs 110 lbs and it's a 2 man job to mount it. Have some Delrin and will make up some vise inserts to clamp it in the mill and will use a gage pin to locate the center of the bore. Then it's a simple plunge cut and about 5 or 10 minutes with a lapping stick chucked in the mill with it in neutral and lapping it by hand.

Right now the only holdup is saving up the scratch for a frame wrench, I've been having so much fun shooting the 625 that the cost for ammo has been "robbing" my tool budget. One downside to shooting with moon clips is that you can really blaze through ammo and I really need to lay off shooting for a few weeks to get that frame wrench. BTW, I've also thought about making my own frame wrench but the cost of not getting it quite right has me leaning toward purchasing a professionally made frame wrench. MGW makes one that uses delrin inserts for the various sizes and that's what I'm looking at.

MGW is the hot ticket , build the wrench and buy the insert's , got one I made years ago .