Moly bullet fouling

[TheBrick]

During these economic hard times I am, like others, looking to reduce the cost of my reloading.

I have tried Precision Black Bullets and Black Bullet International moly coated products in my Kimber 45 Eclipse/Target II and my S&W model 15 38 special. Either product in either gun will cause a build up of the moly coating at the entrance of the rifling. The build up usually only takes 100-150 rounds and in the case of the Kimber, it will prevent the chambering of a round by changing the headspace.

I built PPC guns in the 80's and checked the throating on the 38 and it fit the gauge perfectly. The 45 was checked by a really good local Smith and I was told that the throating was as it should be. Different powders didn't change a thing. I used the BBI recommended Clays powder with loads way below power factor and still have the problem.

I have in the past used lead with the wax lube but I can't stand the smoke. Shooting fast (USPSA) even outdoors has built a cloud obscuring the target. I have tried various powders with little difference noted.

Does anyone else have this problem and, if so,, what can be done.

I guess I would rather clean lead out of the bore than have to "brass Chore Boy" brush my bore every 50 rounds when using the moly bullets.

Any ideas? Suggestions?

Shoot fast and don't miss.

Peter

[Odawgp]

any Idea of the hardness of the bullets you are shooting???

[bill87123]

I have not had that problem but I have had the Moly rounds build up lead in the barrel pretty quickly. I would find it hard to believe you could really build up enough moly in the barrel to effect the round not being able to fully load. You sure its not lead?

[Corey]

how are you seating them? if you are seating/crimping in the same process you may be pealing the moly off the bullet which can cuase leading buildup issues.

ive shot a few thousand rounds of the Precisions with not a lot of issues.

[Kevin G.]

I had the same problem when I first tried the 147gr Precision molys in my M&P. After noticing that a few of them that refused to chamber completely had bare lead exposed right in front of the case I pulled the rest and loaded the next ones much shorter and reduced the charge. Haven't had any problems since. YMMV

[TheBrick]

any Idea of the hardness of the bullets you are shooting???

No I don't know, whatever Precision and BBI send me.

Peter

[TheBrick]

I have not had that problem but I have had the Moly rounds build up lead in the barrel pretty quickly. I would find it hard to believe you could really build up enough moly in the barrel to effect the round not being able to fully load. You sure its not lead?

The build up coming out as I clean the bbl is consistent with the black moly coating and does not appear to be lead.

Peter

[TheBrick]

how are you seating them? if you are seating/crimping in the same process you may be pealing the moly off the bullet which can cuase leading buildup issues.

ive shot a few thousand rounds of the Precisions with not a lot of issues.

All loading is done on a Dillon 550 with separate seating and crimping dies. I even adjusted the expansion of the mouth to make certain the bullets do not shave when seating.

Peter

[TheBrick]

I had the same problem when I first tried the 147gr Precision molys in my M&P. After noticing that a few of them that refused to chamber completely had bare lead exposed right in front of the case I pulled the rest and loaded the next ones much shorter and reduced the charge. Haven't had any problems since. YMMV

Good point BUT, my oal is not a problem in a clean bbl. Refusing to chamber is caused by the buildup of moly after shooting 100 or so rounds.

Peter

[Kevin G.]

I had the same problem when I first tried the 147gr Precision molys in my M&P. After noticing that a few of them that refused to chamber completely had bare lead exposed right in front of the case I pulled the rest and loaded the next ones much shorter and reduced the charge. Haven't had any problems since. YMMV

Good point BUT, my oal is not a problem in a clean bbl. Refusing to chamber is caused by the buildup of moly after shooting 100 or so rounds.

Peter

In my case, there was too much bearing surface of the bullet exposed outside the case which was allowing a slight amount of the coating to be scraped off as the bullet engaged the rifling during chambering. Over 50-60 times of this happening enough of the Moly built up in the chamber and throat that it prevented the round from seating.

I'm sure that had I cleaned the barrel I too would have gotten 50-60 more rounds of trouble free firing out of these too long bullets.

One other consideration you should give mind to is if the forcing cone on the .38 might need a slight polish.

Also measure your crimp and only use enough to allow reliable feeding. The moly coating can be cut and shed from the back of the bullet during firing with too tight a crimp.

I hope you figure out your ailment with this bullet type. Since I've gotten mine to run well they have been an affordable pleasure compared to jacketed.

[bbbean]

I've had a similar issue, but it hasn't been consistent. I've gone 4-5000 rounds at a time without any buildup whatsoever, and then then switched to a different brand or weight and suddenly I'm having problems feeding after 100-200 rounds.

I hadn't really considered the possibility that my crimp was a problem, because I bell the case more than enough before seating and don't see any moly or lead around the mouth of the case after crimping. But reading this thread inspired me to pull a loaded round, and sure enough there is a slight cut in the moly coating. I'm not sure whether this is enough to be an issue, but I will try backing off on the crimping die 1/8 turn or so. The cut is hard to see, but you can feel it with your thumbnail.

This could also go a long way towards explaining why I'd have problems going back and forth between two manufacturers whose bullets are similarly but not identically shaped (i.e. Precision and BBI).

[BallisticianX]

Ive shot BBI in my revolver and yes I get alot of buildup in the cylinder throat and forcing cone. Though I haven't found a cure I did reduce it. Light taper crimp after a good mouth expansion reduced it quite a bit. Also slower powders dont hammer the bullet heel on ignition and reduced the pressure wash of the coating that deposits within the gun. In my revolvers case, I also opened up the cylinder throats a .0015 to reduce shearing of the coating.(that is obviously not an option with auto loaders)I do not use them in my 1911, I stick with the Bayou Bullets coated lead that do not contain moly and are very clean and smokeless.