I'm reloading 180 grain Missouri Bullet Company TCFP lead for the S&W 610 revolver and am having trouble with the lead bullets preventing the rounds from fully seating in the chambers. As a result the cylinder will close with difficulty and on some occasions, will not close at all.

Brass is new Starline and measures an average of .983.

Rounds are loaded to 1.255.

The cylinder closes and has plenty of room to turn with unloaded sized brass and with factory FMJ ammo, both with and without a moon clip. It is only with loaded lead bullets that I have the problem. The problem occurs both with and without a moon clip.

Measuring the distance from the front of the cylinder to the back of chambered round shows a difference of .02" between unloaded sized brass and rounds loaded with the lead bullets. If I shorten the rounds to 1.235, they will be well under all published CAOL.

This leads me to believe the chambers need to be bored out slightly following the ledge for the cartridge rim.

Dropping rounds into the chamber of my 1006 barrel shows the same issue, I can feel the lead engage before the rim and the loaded rounds do not fall right out, rather they are a bit sticky.

Any other thoughts would be greatly recommended.

Yours is a fairly common problem with cast bullet reloads. It happens with cast .45 ACP leads too.

The fix is not to ream out the chambers but to seat your bullets deeper. The 10mm/.40 S&W cartridges headspace on the case mouth like most rimless cartridges: .380 ACP, 9mm Parabellum, .45 ACP. Any lead protruding past the case mouth can jam in the cylinder throat area. This is mostly caused by the seating or crimping operation pushing a bit of bullet lead in front of the case mouth.

Try seating the bullet deeper so that the bore bearing surface is covered by the case mouth. With the high-pressure 10mm and .40 of course, you do not want to seat excessively deep, as that would increase chamber pressures.

In order to get the complete rounds to sit fully in the chamber, I need to seat the bullets to an overall length of 1.218. I'm only running 6.2 grains of WSF, so pressure should should not be a problem, but I'm concerned as other forum members have indicated they are using the exact same bullets in a 610 with a COAL of 1.260.

I could run the rounds through a Lee Factory Crimp Die, but this would resize the lead bullets to .400, and accuracy would go out the window.

Make sure you're not applying too much crimp. Too much can make the case bow outwards and prevent chambering. Crimp groove shape/depth, and case length can exacerbate the problem.

It doesn't appear to be a crimp issue. I have a very light taper crimp applied and the chambering issue goes away when I reduce COAL to 1.218. I just feel a bit nervous going that short.

You are shooting 10mm yes?

Have you been shooting 40 SW out of the gun?

I use the same bullets in my semi auto 40"s, just wonder if it is the same situation as shooting 38 spl in a 357 and getting the crud build up.

Flare a empty 10mm case so it just fits the cylinders and tap it in each cylinder, it will act like a scraper and remove any lead/carbon build up. Then brush them out with a over size bore brush with solvent.

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Still Running Against the Wind

Nope, never shot any .40 in the gun, empty cases seat just fine on the rim.

Time to measure the O.D of the loaded round at or near the case mouth. Also measure the diameter of the expander plug. The diameter of the chamber throats needs to be determined also.

Bruce

Thanks Bruce,

I have a few questions:

What is the expander plug?

Do the chambers taper? My calipers are not long enough to reach me mouth of the chamber throat, but judging by the inability to push a lead bullet .401 in diameter through, they are somewhere between .4001 and 4.01.

I use the Leed FCD with my lead 10mm reloads and have not had any accuracy issues. Not shot them from a revolver though, a 1006 and 1076.

"What is the expander plug?"

With most pistol die sets, it's the insert in the 2nd die. After the case is resized, the I.D. is or should be substantially smaller than the diameter of the bullet. The expander is supposed to increase the case I.D. slightly so that the bullet can be seated without deformation. The expander also flares the case mouth so that the bullet can be started during the seating procedure without damaging the case mouth or bullet. The diameter of the expander should be about .003" to .005" smaller than the bullet used in order to provide adequate neck tension and prevent bullet setback. Crimping in autoloader ammo does not prevent setback and roll crimping in magnum revolver is absolutely the last line of defense, not the first, in preventing bullets from jumping the crimp and tying up the gun.

I was waiting for somebody to jump in with the LEE FCD solution. I do not have a lot of use for the FCD used in conjunction with straight walled pistol cartridges. IMO, post sizing a round after the bullet is seated is never a good idea and is only necessary to fix a problem with something else used earlier in the loading process which isn't right. This includes a sizing die which is defective and doesn't reduce the size of the case enough or an oversized expander plug which makes in I.D. ( and correspondingly the O.D) of the case too large. Mixed headstamp range pickup brass of unknown quality also comes to mind.

From what you're telling me about not being able to push a .401" diameter bullet through the cylinder throats, I'd say your best bet would be to have a qualified gunsmith examine the gun and, if necessary, hone the leading edge of the charge holes immediately adjacent to the shoulder so the bullets do not hang up there.



Bruce

Thanks Bruce. I'll swing by the gunsmith this weekend and have him take a look.

That's probably your best bet but before you head over to a professional, cover all your bases starting with measuring your loaded rounds in order to verify that they do not exceed specified maximum diameter, etc.. Measure & double check everything you can before heading out to the gunsmith.That includes brass, die components and cast bullets.



Bruce

The TCFP is why you are having the problem. It is full diameter at the base of the TC. Your throats are smaller than the bullet, hence the problem. As has been stated, same problem with 45ACP cylinders of late.

I don't have my M610 anymore but when I did, I tried to load LRNFP 38/40 bullets with the same results. I just wanted my revolver rounds to look like revolver rounds, hence the choice of bullets.

You have to get the cylinder closed. Shortening the OAL is the simplest way to get that done. You can save powder on your loads with a shorter OAL. If you reduce the OAL by .030" reduce your powder charge by .2gr (as long as you aren't at the top end of the data now).

Either that or look for a bullet that has a reduced nose diameter and seat so the driving band is flush with the case mouth.

Have you used the LFCD and pulled any bullets? If you do, see it they fall through your throats afterward. If not, you are still good to go to use the die, use it.

FWIW

Smith Crazy, thanks for your insights. I've loaded up a batch at 1.218 with 6.2 grains of WSF and with luck, will have chance to try the out this weekend.

I don't mind the reduced length, but I can help but feel the purposed of the revolver is compromised. Not that I'm doing it now, but I'm not going to be able to load up any lead bullet screamers without getting the chambers opened up.

You do know not to make the throats larger than the barrel, don't you?

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Science plus Art

Help is what we do for one another 'round here.

Not sure I understand your last comment though. OKFC is right as rain here.

I know that some pooh pooh the LFCD but they have their place. It may be here in the 10mm for you. If you want to have a longer OAL, it looks like you either have to use it or have the gun reworked. Personally, I'm gonna leave the gun alone and work on the ammo, especially if it shoots factory stuff just fine. That's me though. Do as you wish.

If it were me, I'd see if there was some way to change bullet profiles.

Something like this may work better:


Notice how the nose is smaller than the main body of the bullet. Rather than this:


This is a lighter bullet but notice the nose on it:


At any rate, see if there is a commercial caster that has different shapes. As for sample packs, 100 of each or something. Promise to order what works best from them and they will bend over backwards to help you!

Hope this helps.