Did my 9mm homework... or so I thought

[adam_mac84]

oooh, the 9mm cast loading... the finicky beast that it is.

Got my 9mm loads dialed last year for the G34. Perfection.... sold that gun

Struggling with the new M&P 2.0

Leading is following the grooves, which according to Chapter 7 of the 'bible'

Streaks, following the rifling. If the leading is seen to "follow the rifling" (i.e. streaks that twist down the barrel in close association with the rifling grooves), then this is a tell-tale sign that the bullet is cast too hard and failing to obturate. Obturation is usually thought of as a plastic deformation that swells the bullet's diameter, but it also leads to a back-filling of engraving defects along the trailing edge of the land. If the bullet is cast too hard to obturate, these defects will not be back-filled and gas-cutting will take place through these voids, following the trailing edge of that particular land. This effect can be mitigated somewhat through judicious choice of lube, but lube by itself can only do so much. The real solution here is to go with a softer bullet and a better lube.

I think at times, it has been a bit more toward the chamber than the muzzle, but can't say that is consistent... We will say 60/40 chamber to muzzle leading.

It cleans up with a bit of scrubbing after a 200 rd range trip without too much problem. I would not consider it HEAVY leading.

My considerations thus far:
38 expander
Slug 0.3555
Boolit .357 (largest that will chamber in the throat). 124gr TC, and 130gr 2rRN (lee, cast heavy)
Maintains diameter after pulling boolit
Smokes DTPC - 400 x 10 min after liquefaction of coat. Dropped in water for quicker handling. Pass smash test
Powders. TiteGroup. W231. WSF
Velocities tested :
WSF. 1041 (fair accuracy), 1110 (poor accuracy)
TG. 1087 (3.8gr best accuracy), 1113
231. 1083 (3.9 gr best accuracy), 981 (poor accuracy)

WSF tested with 5050 at 1110fps and RS (WCRS) at 1041
TG was all WCRS
231 tested 1083 with AC 50/50 1083, and same load with WCRS (also accurate). ACRS accuracy was garbage (50 rds, leaded)

Basically, all had similar leading interestingly. Poorest accuracy were with ACRS, no significant change in leading.
Previous tests with WCWW had leading as well, no velocity recordings. were at same loads as above, but stopped pursuing as WCRS had previously worked for me

Alloys:
Range scrap - (tested 2B pencil test (suggests just over 10BHN)
Range scrap - water dropped (tested H pencil, skeptical... that'd be ~22)
50/50 RS/WW - did not pencil test, assume hard
ACWW - Tested B. Just harder than RS. Seems legit, question the actual hardness numbers I received
WCWW - Have not tested with pencil,

My gut was to go harder, and investigate more with WCWW, but I think that is the wrong way to go. If I have to get it throated, I guess I can... or keep scrubbing with chore boy

Did I miss a step in here? I felt like I did my homework pretty well.
My good loads will shoot a 100 on a B8 at 15 yards off hand, which is about as good as I shoot on a good day, and good enough for gaming (for my skill).

[kbstenberg]

Your experience kind of changes my mind as to my buying M&P 2.0. I will be watching this thread.

[adam_mac84]

Your experience kind of changes my mind as to my buying M&P 2.0. I will be watching this thread.

I have had the same issues with my 1.0 4" and my mp9c. They all slug and chamber essentially the same (good for their QC i guess haha). In my 1.0 and 9c it never really mattered, just shot plated (loaded to match my SD load). the 2.0 is for games

It does shoot very well with 3.8/3.9gr 231 tho

[sigep1764]

I wonder if some JB Bore Paste might help smooth the barrel out. Might be some imperceivable imperfections. If used it successfully on a Kahr with a nice tight fitting jag and a patch covered in the bore paste. Did 10 or 15 passes. Noticeably smoother the more you did it. Don't go too far tho.

[Dusty Bannister]

You refer to the information on cast bullets with bullet lube and are shooting powder coated bullets......
Have you been able to smooth the barrel with any jacketed rounds or just going directly to PC bullets?
Is this the cut rifling or something else that does need to be polished a bit? Was it S&W that has gone to a different method of forming the rifling in the barrel?

[chutesnreloads]

Got same type leading in a CZ75.It all went away after switching to powder coat and started getting decent groups too.Suspect if you're getting lead strings after the PC there's something else going on.

[GARD72977]

You should try softer bullets. They will fill the bore better and work at your velocity.

Im not sure I understand about chambering a larger bullet. Can you seat it deeper and have it chamber? If the chamber is to tight to accept a .358 then throating will not help.

I shoot CZs and they have large bores. I shoot .358 with excellent accurracy. I have used a throat reamer in the barrel.

[jcren]

I think you have something cutting or damaging the pc. Over crimp? Sharp lead? Oven temp verified with a thermometer?

[GARD72977]

I think you have something cutting or damaging the pc. Over crimp? Sharp lead? Oven temp verified with a thermometer?

All 9mm have to have a throat. If they didnt you could not chamber a factory round. It may just look like a long chamber with the lands being beveled

[popper]

COWW PC, hitek or BLL cause no problems in my XDs9 4gr 231, 1305gr. I H.T.

[adam_mac84]

There is a throat. I can seat .357 to just covering the grease groove and no problem. .358 have to basically swage their way into the throat unless seated 1.040 (all of the contact portion of boolit in case). If I load a .358 and tap it with a mallet it will go in. But boolit comes out marked. I can try to get a photo this afternoon. No marks from lands. So it’s more the throat diameter (taking 357 not 358) than distance to the lands if that makes sense.

1.040 for the .358 made me nervous for some reason (120 TC DESIGN). I could retry that and see if the slightly larger helps. I can get them to chamber with light taper (to eliminate bulge that 38 expander causes). Pulled a couple and they maintained diameter fairly well.

I never thought about smoothing w jacketed. I bet I have 50 of each jacketed and played through. Probably 7-800 cast.


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[adam_mac84]

Thanks everyone. Got some good PMs too. Going to get some more books and start a new work up. Will keep everyone posted as to the results. Needed my brain jogged a bit on next steps. I appreciate the collective constructive wisdom here


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[GARD72977]

Even If the lands are tapered but the groove diameter is not enlarged slightly at the entrance and you shove a lead bullet larger than groove diameter through the barrel, lead will be shaved off and probably deposited in the barrel..

Im just saying your guns have a throat or you could not chamber a round.

[Lloyd Smale]

one thing to try is every new gun I get I run a 100 cheap ball jacket bullets through and then clean thoroughly. It seems to smoothen out small imperfections in the barrel. They I will add that just about any of my black guns shoot more accurately with harder bullets. Harder the bullet the better they shoot right up to water dropping. It isn't across the board but id say 80 percent of the time anyway. So going harder is sure not going to hurt. that and with harder bullets you don't get any damage running from the mag into the gun.

[Tom W.]

My CZ doesn't like .358 boolits. It will shoot .357 sized and lubed w/ CR just fine. The Ruger I have and the Glocks that I had would eat anything. Not so with my new pistol......

[Petrol & Powder]

I can't offer anymore than what has already been stated. I will agree that the bore may just be a tad rough.

One of my frustrations with 9mm and cast bullets is the incredible individual nature of the pistols. It seems that you must cast & load for a specific pistol when dealing with the 9mm. You can make a bullet/load combination that works great in 1 pistol but it's very difficult to get a cast 9mm load that works well in more than one pistol.

[blue32]

Try that 120 TC at 1.030"

[igolfat8]

Have you tried boolits that are air cooled and NOT water quenched? I had similar issues with water quenched range scrap boolits