9mm Leading

[ZombieHunter]

I have a S&W M&P Fullsize 9mm (4.25" bbl), all factory parts. A bit of history first:

I have been trying to use Missouri Bullet Company's 9mm SWC bullet with this gun... so far with no success. I first tried the .356 .. long story short, bullets tumbled and all over the place. So I slugged the bore (twice) with a groove diameter of 0.357. I ordered a batch of 0.357 and 0.358 diameter bullets (custom order) and that solved the tumbling and other issues; in fact they are VERY accurate. I've tried both N320 and WSF powders, beginning with starting load data and working up all the way to beyond published load data, trying to get this bullet to not lead, with no success. Both sizes lead in the exact same manner, which is "patchy", but pretty much along the entire bore.

I'm completely out of ideas: it's not a size issue, without a doubt. I've also pushed pressures to the brink trying to further obdurate if needed, since this is an 18 BHN bullet.

Additionally, I backed it off way to minimum load just in case it had something to do with pushing it to hard. And, I've also aloxed a group of bullets for added lubrication, with the same results.

I've tried about 30 dozen loads with various combinations with those powders, with pretty much all the same results. Doesn't seem to get better.. or worse for that matter (unless I keep shooting). The only time it was worse, was when I used the .356 diameter bullet, which obviously leaded severely after only a few rounds.

Any one have other ideas? I might have missed including something I've tried, but any suggestions are appreciated.

[ProGunGuy]

burn them up and go moly. thats what i did. No more straight lead for me

[HoMiE]

With lead the faster you push them the more they will lead up the barrel and they are going to lead up anyways. If the leading doesn't get worse, then keep shooting till accurracy goes away then clean or shoot some jacketed rounds out of barrel.

Edited August 23, 2012 by HoMiE

[FightFireJay]

Unique solved the leading issue in my .40 S&W. I tried slower and faster powders with no luck. Don't know why, but maybe you just need to find the right powder.

[TonyT]

The only time I was able to use lead bullets without inordinate leading was a 147 gr. Lead bullet at less than 900 fps - I beklieve I used 3.3 gr. W-231 which was below the W-W max of 3.5 grains. With the lower weight bullets I opt for jacketed.

[noylj]

Since lead cast bullets have been used successfully for decades, I don't think that things are so much better with moly-kote to just automatically scrap what you have for the perceived superiority of moly-kote.

Was the lead slug SIGNIFICANTLY over 0.357" (like, at least 0.362") before entering the barrel? 9x19 barrels can range up to 0.362" in groove diameter. I have a BHP that is between 0.3585" and 0.359" and Browning told me it was "in spec." If not, you may not be measuring the actual groove diameter.

In general, leading along the barrel indicates the bullet is too soft, too small, or velocities are too high.

Since all you need for 9x19 is a 12BHN, I am sure that being too soft in NOT your problem.

Since I get lead-free shooting out of all my 9x19s, I would look at the barrel.

1) Be sure that ALL lead and copper is out of the barrel. Either one, left in a barrel, will simply be a spot for lead to build up.

2) A rough barrel will cause leading. Is the barrel mirror-smooth and shiny?

Get a COPPER Chore-Boy (not the cheap copper-plated steel Chinese import), cut it up into two inch lengths or so, wrap around a 9mm cleaning brush, dip in Hoppes #9 or other cleaner, and scrub that barrel clean.

I like the Outer's Foul-Out III for removing all the lead and copper electrolytically.

Finally, I have found that when I have commercial lead bullets that cause leading (because they are too small, but sometimes due to crap lube), a single very light tumble lube in Lee Liquid Alox solves the problem.

I started jacketed bullets in 9mm and .38 from Precision Delta and Montana Gold by the case about a year ago. The price isn't that much more than most of the top-end cast bullets and they are ACCURATE.

For any larger caliber, cast lead still beats the cost of jacketed and plated bullets by a LOT.

PS: shooting jacketed bullets in a leaded barrel will not clean out the lead (all it could possibly do is iron out the lead and make it even harder to remove), will lead to copper being deposited (that will then attract more leading), and could cause a serious over-pressure issue. Common sense, folks.

Edited August 26, 2012 by noylj

[gm iprod]

Get that cleaned out and inspected. This is suspiciously similar to a problem we had with three S&W M&P I sold a ferw years back. Barrel was rough. Not just a little rough, but pothole rough. Look for radial machining marks that Evil Knievil was have trouble getting across.

[redial]

Hit the bore a few times with JB/RemClean or one of the similar compounds if it's a new barrel. It'll polish the surface a bit and ensure that all other types of fouling are gone.

I like to swab a clean bore with some Alox on a patch so the first bullet isn't pushed down a dry, totally unlubed bore. That seems to prevent it from starting in the first place. Slower powders tend to work better than fast ones, in my experience.

My two cents,

Mark

[rhyrlik]

While your bullet diameter may be the right size for the bore, it is prolly too small for the throat. You have to use throat diameter as a guide, just as you do with revolvers. I use .359" bullets in my 9, with Bullseye and 231. I like Lasercast the best as they make the most consistent cast bullet, but I also use Missouri. My favorite is their Cowboy #2 TC on top of 3.2grs of Bullseye at 1.040" OAL using CCI or FC primers. No leading, even after hundreds of rounds. My chamber throat measures .359" but these are soft enough to obturate.

[Henny]

I was having the same problem (except the tumbling part). I solved my problems by over expanding my cases. This expands the case further down in the case. If your case is too tight, no matter what size bullets you use, they will to some extent be swaged down. This could possibly be part of your problem.

I wish Dillon would come out with an expander that would go a little deeper in the case with out over flaring the case.

[rhyrlik]

They get swaged down by something like .0002" which is insignificant in terms of bullet to bore fit and leading.

[ZombieHunter]

I was having the same problem (except the tumbling part). I solved my problems by over expanding my cases. This expands the case further down in the case. If your case is too tight, no matter what size bullets you use, they will to some extent be swaged down. This could possibly be part of your problem.

I wish Dillon would come out with an expander that would go a little deeper in the case with out over flaring the case.

Haven't had any swagging - I've pulled many bullets and they measure perfectly what they should. I've conceded at this point, there is something up with the barrel itself. I've switched to FMJ only since they aren't much more expensive IMO for 9mm ($130 for 2000 lead vs. $170 for 2000 FMJ). From what I've been able to tell from some other forums, this is a common issue with M&P stock barrels and usually requires them to be fire lapped to solve the issue. I've also since looked a lot closer to the bore and do notice quite a bit of machining marks in the grooves. Since this barrel's groove diameter is .357, I seriously doubt any FMJ .355 bullet is going to effectively touch all the way down to the groove diameter to assist with smoothing/wearing those areas out; hence the need to lap the bore.

Oh well..

[rhyrlik]

If the machining marks run parallel with the bore line, then they will not influence leading. If your groove diameter is .357", then your bullet diameter needs to be at least .357" and possibly .358"+.