9mm tumble lube cast boolits.. Does anyone have tips on accuracy and preventing keyho

[BoltLover01]

Having issues with accuracy and keyholing. Using a Lee 124gr tumble lube mold. Bullets drop at 3.55 lead is 15 Brinell hardness. Would it be beneficial to powder coat these bullets. I have loaded these with 4.3gr of Bullseye and 4.7gr of Unique.... Does anyone have a system that works for them.

[Joe_Atlanta]

.355 seems a bit small, most folks have best results at .357+. Hard to say for sure without casting/slugging your barrel/throat. Generally, best accuracy comes from fitting bullet size to throat. Do you have acess to any .357-.358 sized bullets?

Joe

[BoltLover01]

My barrel slugs at. 354 any bullet larger than. 356 will not fully seat into the chamber

[Joe_Atlanta]

Tight barrel and chamber is outside my experience, maybe some help in the 9mm sticky: http://castboolits.gunloads.com/show...s-in-a-new-9mm

[BoltLover01]

Thanks I'll try it

[tazman]

Unfortunately many people have trouble with the tumble lube designs either tumbling or leading in 9mm for some reason. If possible, try the standard lube version of the 120 TC bullet. It works for almost everyone.

[hunter49]

I was having those same issues using Lee's 356-120-TC mold. My barrel slugged at 354.5 and I was also using Lee's .356 sizing kit and just could'nt get the desired results.

After just about giving up on casting 9mm I started researching threads here and discovered pc from member smoke4320. My curiousity was now peaked and I took the plunge and ordered sample packs from smoke and I could not be more happier.

I use the asbb shake and bake method, 3.7gr Titegroup and c.o.l. 1.110. All good now and great groupings.

[lotech]

If a case loaded with a .356" bullet is the largest that will chamber, sounds as if you need a .356" rather than a .355" bullet. However, assuming your going to stay with your present bullet, and at a 15 hardness, you might experiment by reducing powder charges slightly until you get bullet hardness, pressure, and velocity in balance. This may eliminate the negative points you've mentioned. Fire at least 15-20 rounds with each change and do it at 25 yards using a good rest.

I use conventional bullet moulds and lube with a lube / sizer, but it would seem similar guidelines would apply with tumble lube designs and the tumble lube process.

[upnorthwis]

You should also give some thought to using a larger expander. The tumble lube design boolit is easily crushed by too small brass ID. Some people use the one for the 38/.357. I made my own to replace the Dillon powder funnel/expander of .353 with one at .356.

[Shiloh]

The TL 9mm boolits from LEE, drop to small. Had three at one time. Sold 'em. I need .358. This means I shoot boolits for the 38/.357 to get any accuracy at all.
I have one 9mm mold that drops at .357. A LEE 125 gr. RN.

Shiloh

[MtGun44]

Lee 356 120 TC, conventional lube, air cooled wheelweights, NRA 50-50 or LBT soft blue lube,
size to .357 or .358, loaded over a slower end powder like HS6, AA7, Unique, 800X, Herco.

Make certain that you can pull a loaded boolit and it is still .357 diam.

That is all there is to it.

[kryogen]

You need to measure with a quality micrometer. Properly zeroed. Your numbers seem small. I question them. Your 356 mold drops at 355? They usually drop 356-358. Your bore is 354, they are usually 355-357.
you need at least 1 thou over groove dia.
you need to expand the cases with a 38 spl expander or you will swage the bullet down when seating
you need a mold that reliably drops 2 thou larger than your bore so you can size at least 1 thou over groove dia.
then you need to crimp with a separate die, just enough to plunk test.

keyholing means bullet too small. Either they are too small as cast, or you size too small, or you crimp too much, or you use the lee fcd that post sizes it, or you are not expanding case enough so its swaged down when seating. After you fix all that they will not keyhole anymore.
i know, i had all those issues and now they dont keyhole anymore.

[Joe_Atlanta]

keyholing means bullet too small. Either they are too small as cast, or you size too small, or you crimp too much, or you use the lee fcd that post sizes it, or you are not expanding case enough so its swaged down when seating. After you fix all that they will not keyhole anymore.

Great summation, I'm bookmarking it. I will add that the micro bands of the TL design are particularly susceptible to case swaging (been working with the 158 TL SWC).

A trick I've used (not having a larger sized expander) is to back the case sizing die out a 1/4 inch. Because of the tapered case and sizer, this gives me a little less compression on the bullet. It could leave me open to the occasional over sized or bulged base round, but so far so good. Probably not a good idea if you've got a tight chamber.

[gloob]

^That is a creative solution!

OP, there's a whole sticky on expanders for 9mm. That's how important it is for the caliber. Many of the cases are quite thick where the base of the bullet seats, and a standard 9mm expander might not even touch this area.

A Lee 9mm flare die, for instance, expands a case to only .353", and only to a depth of a couple tenths below the case mouth. I prefer to use an expander that goes at least as deep as the base of the bullet, and which is less than 1 thousandth of an inch smaller than bullet diameter.

There are folks that go their whole lives not being able to shoot 9mm cast bullets. But if you browse the stickys and listen to the advice on the forum and this thread, you will sort it out fairly fast. Kryogen summarizes it well; there's just one caveat I would like to add. Your barrel, itself, can also be the source of undersized bullets. This could be due to a stricture in the bore. Or it could be due to having such a tight chamber that you can't use a bullet big enough to fill the bore and/or you need to use an excessive crimp to get it to fit (a crimp which has no room to release, thus swagging down the bullet as it's fired.) If you have a tight chamber, you might get enough clearance by selecting/sorting for your thinner cases. For a significant stricture, you are resigned to lapping out the bore, if you want to shoot cast. But barring that, the rest is pretty easy to sort through.

[rsrocket1]

I replaced the 9mm PTX stem with the 38 S&W stem and it acts nicely like the Lyman M die for only $3 (+ S/H). It expands the cases so the bullet is not swaged down, but there is still enough tension to hold the 0.356" sized bullet in.

[Larry Gibson]

What is the alloy?

Larry Gibson

[BoltLover01]

90/5/5 lead, tin, antimony

[MtGun44]

Another vote for the ever reliable solution: Lee 356 120 TC CONVENTIONAL LUBE.

Tumble lube very often fails for the 9mm when it works for other cartridges.

[tazman]

Another vote for the ever reliable solution: Lee 356 120 TC CONVENTIONAL LUBE.

Tumble lube very often fails for the 9mm when it works for other cartridges.

I think that boolit design will feed and shoot through anything. I as well as others use that design in nearly all the calibers it is made for.

[fredj338]

As noted, the problem is the 0.355" size. Most 9mm lead slingers will prefer a 0.356" min, 0.357" or even 0.358" is not unheard of. If your measurements are accurate, the bullet may be getting sized during & seating. Pull a seated/crimped bullet & measure that.