9mm m&p pistol leading first inch of the barrel

[scorpion]

i just started casting . I use a lee and a lyman mold 120gr sizing the bullets @.356 and using lee alox/beewax as lubrication . So i shot 25 bullets of each mold . And had leadding the first inch of the barrel . The thing i dont get is why the first inch only ??? The rest of the barrel is spotless . My load is 3.5gr vectan ba 9 .120gr cast bullet .
Alloy 50%pure lead 50%monotype . I haven got an hardness tester yet so i figured i couldnt go wrong with that ?! Who can help me out??

[Bullwolf]

i just started casting . I use a lee and a lyman mold 120gr sizing the bullets @.356 and using lee alox/beewax as lubrication . So i shot 25 bullets of each mold . And had leadding the first inch of the barrel . The thing i dont get is why the first inch only ??? The rest of the barrel is spotless . My load is 3.5gr vectan ba 9 .120gr cast bullet .
Alloy 50%pure lead 50%monotype . I haven got an hardness tester yet so i figured i couldnt go wrong with that ?! Who can help me out??

My first suggestion would be to read MtGun44's excellent sticky on setting up for boolits in a new 9mm.

http://castboolits.gunloads.com/showthread.php?121607-Setting-up-for-boolits-in-a-new-9mm

Other than looking at hardness already, I would be taking a much closer look at boolit fit. Small boolits gas cut and cause leading in barrels. None of my stable of 9mm pistols will perform well with a boolit smaller than .358

In addition to my recommendation to read the above sticky, I would also suggest going with a larger sized boolit.

You could slug your gun and see just what size you need, but so many of my 9's perform nicely at .358 that I don't bother anymore, and just start at .358 now.

Another option would be to check for a sharp throat, or a lack of a leade in your new 9mm pistol. Some barrels lack the gentle taper or have never even seen a chambering reamer applied to them. I guess its a cost thing now, but it was common practice in the old days to do this.

If sizing larger doesn't cure your leading problem, I would take a long look at the 1911 throating sticky

http://castboolits.gunloads.com/showthread.php?232061-1911-Throating

It explains the sharp throat problem that is common with newer manufactured guns in detail, and also explains how to go about fixing the problem.


- Bullwolf

[scorpion]

Ok thing is that i used lead bullets before . Frontier 125 gr .356 . 2000 +And had no problems with leading . Thats why i didnt slug the barrel an assumed .356 is a good fit . Also if there is gascutting why its the first inch only and not the whole barrel ? Btw a m&p barrel is throated . No sharp edges at all .

[Bullwolf]

Ok thing is that i used lead bullets before . Frontier 125 gr .356 . 2000 +And had no problems with leading . Thats why i didnt slug the barrel an assumed .356 is a good fit . Also if there is gascutting why its the first inch only and not the whole barrel ?

Many different variables involved.

Did you mic, or can you mic some of the previously working Frontier 125 grain boolits? Are they the same size as what you are casting or is that just the advertised size. Many times commercial boolits are not the same size as advertised.

Did they use the same lube or a different lube?

Were your cast boolits aged first, and allowed to harden or just cast, then loaded and fired. Were they sized at all, or just shot "as cast"?

A harder boolit resists case deformation much more than a softer boolit and can be a bandaid in your loading process for not enough case expansion with 9mm boolits. Small tough 9mm cases can swage down the bases of your cast boolits making them smaller and more prone to undersize barrel leading.

Were the boolits that worked the same shape, and were they loaded to different cartridge OAL's?

Same loading process? What dies and loads were used? Did you try pulling a loaded cartridge to see if the boolit was damaged during the loading process (over crimped) or sized down during the loading process. (not correctly expanded brass or used a Lee CFCD)

A barrel with a rough or sharp throat can tear a fired boolit some, causing barrel leading in the first inch or so of the barrel.

If you seat and crimp in the same step, and shave a ring of lead while seating... Well that ring of lead has to go someplace as well. It will often end up in the first inch or so of your barrel.

If it was me, I would try to change one thing at a time from what works to what doesn't while trying to narrow it down. I would also take a close look at the barrels leade vs the boolit design you are using, and likely dissect (pull) one of my loaded rounds that is currently leading to measure it, and closely examine it for damage during the load process.

Since 9 times out of 10 too small boolits are the cause of leading, that's often a good place to start. If you are dead set on using small (.356) lead boolits I would suggest slugging your barrel with a dead soft lead slug or sinker and see if that plan will work for you, or not. Hard lead is not a good choice to slug with as it can spring back giving erroneous measurements. Measure using a micrometer, and not calipers.

Try to change only 1 thing at a time, rather than a bunch of different variables all at once so you can find out where your leading problem is coming from.


- Bullwolf

[scorpion]

Ill start with sugging the barrel first . And look at my loading proces. I load on a dillon rl550 with dillon die's . Almost no crimp . Just straiten the tromp . The bullets are more to less the same shape tapered flat nose . My casts from the lee mold have a slightly smaller oal. The lyman is a different shape they are mutch pointyer.
Ill look into it tomorrow and post what i found out .

[Bullwolf]

Ill start with sugging the barrel first . And look at my loading proces. I load on a dillon rl550 with dillon die's . Almost no crimp . Just straiten the tromp . The bullets are more to less the same shape tapered flat nose . My casts from the lee mold have a slightly smaller oal. The lyman is a different shape they are mutch pointyer.
Ill look into it tomorrow and post what i found out .

The Dillon case flare may not be expanding the brass enough for use with your cast boolits.

Many use a custom powder funnel, or an alternate one to get more flare with cast boolits for gentle seating. 9mm cases are tapered, and much tougher than most cast lead boolits. Sometimes seating boolits into the tight 9mm case can deform or swage the base of your cast boolits down smaller. Commercial cast boolits are often silly hard as it's more durable and they are less likely to get damaged in shipping. An overly hard boolit will resist this kind of case swaging down more. It's masking the problem really, the solution is a larger expander.

Try pulling the boolit from a completely loaded cartridge, and measuring it to see if it's become undersize after the loading process. A custom expander can cure this, if you find out that it's your problem.


- Bullwolf

[runfiverun]

I'd just look in the barrel and notice there ain't no throat.
then borrow a reamer and put one [a throat] in there and move along with my day.

[gloob]

Fouling = bullet too small, 99% of the time.

That first inch is the problem. It could be a variety of things. But for some reason, your bullet is too small for the bore in that area. And either the bullet is bumping up and sealing after that first inch (most likely), or your bore is getting tighter after that first inch (not very likely)

Obviously, your bullets might be too small, to begin with. You can slug your bore to make sure and/or you can try shooting larger diameter bullets. Most 9mm's will handle larger bullets without a problem.

Aside from that, there are 2 other fairly common problems I have encountered.

One problem is that the throat is too narrow for oversized cast bullets. Another common problem is your cases could be too tight and could be squeezing the bullet. This is the result of a sizing die that is too small in diameter.

Pull some bullets out of a variety of brass and see what they look like. Is there a deep crimp groove in the bullet? If there is, take that same headstamp of brass, seat a bullet, but back off the crimp. Does the round still chamber? Your chamber could be so tight that the crimp can't open back up. You would have to sort out and use only thinner brass, or you could have to open up the chamber. This is not a hugely common problem in 9mm guns, in general. You never said what you're shooting, though.

Measure the base of your pulled bullets. Check all around the circumference with calipers/micrometer. The case can swage down the bullet, making it too small. You will also see a pronounced "coke bottle" bulge in your reloads. The most expedient fix for this problem is to buy an oversized expander, of the same size as your bullet.

You might have both problems. You might have something else, altogether. But this gives a solid place to start troubleshooting.

[Greg S]

First off, was the barrel clean? Copper fowling will attract lead like a magnet till it gets worn off or cleaned. I have this problem in my 9mm 1911 with a Kart barrel with a .355 throat.

[Harter66]

After reading any 100 s of posts here I learned this about leading.

1 if there's lead at the breach end it is bullet fit ,usually to small.
2 if there's lead at the muzzle it's a lube failure ,not enough or not suitable.
3 lead all over is a bullet failure, too soft ,too hard ,too much pressure ,not enough, bbl defect.
4 9mm is a pain as is 40 S&W

I will venture that you have a slight undersize with your boolits being just enough harder that it takes that 1st inch to slug up .
Since you've used other cast I will defer on the case expansion sizing your boolits down if your seating depth is the same as with the commercial cast .

Also since the leading is confined to the 1st inch I doubt it is a copper issue but it could be a copper solvent patch will let you know if there is.

If the round will chamber the boolit will go down the bbl,so if you need a .359 to shoot lead free use it .

[runfiverun]

one more thing I know will help because I also tried using the same set-up.
change out the sizing die from a Dillon to a LEE and swap out the funnel for a 38 special funnel it's a couple of thou larger [mine is anyway] both of these changes are needed to make proper cast ammo for the 9mm.

[zomby woof]

I load .357 in my M&P pro. When I go to .358 it's a little big. No leading at all. I do use Hi-Tek.