Cast tumbling.

Standard Member

hunterspistol posted this 29 July 2009

How do you charge the cases with powder? I use a micrometer powder measure but, weigh every charge. I trickle them all to exactly the same grainage. Are you coming straight off a powder measure? If so, it could be throwing some +or- charges that's messing you up. How about the bullet base? Is it good and square without a bad sprue? When you seat bullets, are you shaving off lead from one side? And, are you pushing them too fast or too slow? Too fast and hot comes to mind.

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CBA Member

Duane Mellenbruch posted this 29 July 2009

I hope that you will check those items already mentioned and then also slug the barrel to see what minimum diameter you really need to fill the grooves. The throat might need something larger still. And you should measure the bullet to be sure it is large enough that it is sized and not just passed through the die. It would also be beneficial to know what charge range you have tried so we can refer to our own manuals and see if it is too hot or not sufficient to stabilize the bullet. Is the bullet alloy sufficiently hard? Thanks for any additional information you care to provide. Duane

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Standard Member

CB posted this 30 July 2009

Jim

Try casting 90 grn bullets from another mold. It's not the powder or the charge, not the bullet sizing, not barrel throating, not most of the other stuff.

Your barrel twist is too slow for a 120 grn bullet. Some 9mm will handle the 120 grn and the 90 grn, not yours. Be willing to bet it will shoot 90 grn Cast all day without any problem. The 95 grn jacketed is the standard ammo for a 9mm.

Stephen Perry

Angeles BR:fire

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CBA Member

Ed Harris posted this 30 July 2009

JimH wrote: I am casting several pistol rounds and I am having a problem with only one round. The 9mm 120 gr round nose i cast tumbles, changed loads, powders and pistols. 3-4 out of 15 rounds show tumble on the paper. I sized them at .355 and .356 . I really cant figure this out. Any ideas on whats happening? I have loaded them with Bullseye, Red and Green dot. I have some W231 in the way.

Try sizing the bullets to .357 or shooting them as-cast and unsized, if they will chamber freely. Correct bullet diameter is NOT the barrel groove diameter, but should be the ball seat or throat size immediately forward of the chamber. You can determine this from a chamber cast or upset a soft lead slug into the throat.

Euro, CIP and NATO chambers may require bullets as large as .358, most SAAMI chambers do well with .357. Your .355-.356 is too small and bullets will be gas-cut. Keep the loads light, about 3.5 grs. of Bullseye or 4.2 grs. of 231, or the lightest charge which will cycle the gun.

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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canalupo posted this 30 July 2009

Jim

Are they really tumbling or does it just seem that way? My experience with a TC contender in 30 30 (.308 after slugging barrel found it was .309) shooting undersized bullets caused groups all over the paper in excess of 12 inches at 25 yards and severe tumbling. Went to a .311 tumble lube bullet and the group closed up and now is about 4 inches (I have bad peepers and open sights) good for me. In my Berreta 92 shooting bullets from the mold, 125 gr truncated cone (.357), and getting decent groups( for me).

Are the tumblers, flyers and have you tried longer distance to see if all of them start to tumble at longer ranges. I suspect an undersized bullet or shaved bullet as others have mentioned.

Thanks Bob D

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JimH posted this 30 July 2009

Ok guys, were gonna see. I have 60 reloaded that have been sized to .357. With 4 grains of Bulllseye. I have a few of the older ones sized at .355 that i will try out at a greater distance. Just to see if it show more tumbling at a greater distance. I will get back here when i get to try them out. Today i hope but not sure. Thanks for all the responses.

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JimH posted this 31 July 2009

OK, sizing made no difference. I fired 60 rounds in sets of 15 at different paper targets. Each set had 3-5 tumblers. The ones i fired at longer distance were also about the same. Tonight im loading some lighter loads and see what happens.

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hunterspistol posted this 31 July 2009

Try that with 3.2 grains of Bullseye, that's the closest my Contender gets without switching to N340.

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CBA Member

billw_willy posted this 20 August 2009

Your bullets are too soft, not a sizing diameter, twist or weight problem. You could try water dropping from the hot mould, age 30-72 hrs and try again. Heat treating at 450F in your kitchen oven for 45 min and quickly quench in tap water will get them much harder than water drop from the mould. Age as above. WW alloy or WW + scrap alloy is best for heat treat or water drop. I use a coffee percolator aluminum filter to hold the bullets and the holes in the bottom allow water to quickly enter. Do not drop hot bullets into water as the bullets are too soft and could bend them. I have used a steel can from tuna or vegetables. Punched holes in the bottom works to allow water to enter but punch the holes from the bottom side to avoid cutting your hand.

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deltaenterprizes posted this 11 September 2009

Is this a USA made barrel? If not the problem is with the twist rate being too fast and the bullet skips over the rifling and does not get enough spin to stabilize it. This info came from Irv Stone of Bar-Sto barrels in the late 80s when I was doing commercial casting. The problems first became evident with Taurus barrels. Barrels designed for semiautomatic pistols are designed for jacketed bullets so the rifling is shallow and looks shot out compared to a revolver barrel, and this is part of the problem. The import barrels have twist rates as fast as 1 in 9", Us Barrels use the same twist rate as a 38 aprox 1 in 16". I have had luck with light charges of Bullseye (3.5 gr). Slow burning powders like Herco or AA#5 with moderate charges can help. The best solution is a more surface on the driving bands to engage more rifling and this can be acomplished with a heavier bullet like a 147 gr.

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CB posted this 12 September 2009

In my experiences, the most common problems with autoloaders have been caused by too much case crimp swaging the bullets down below groove diameter. Pull a bullet from a loaded round (very carefully) & measure to see if you've made your bullets smaller by over crimping. I also size 9mm to .358 & check to make sure it chambers properly, if it does, that's where I start. It's not a good idea to get your sizing dimensions from a book, your firearm will tell you everything you want to know, but you have to ask it by slugging the barrel & taking a chamber cast. It won't volunteer this information, and the book you're reading has never examined your gun. I've cast for several 9mms, and none of them were happy with any bullet from .354 to .357, they all needed .358 & even larger.

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Texasflyboy posted this 17 September 2009

As I've been down this road before with a FN mfg High Power, my cause was wrong size.

The clue that I needed to solve the mystery was to fire a few loaded rounds into a water trap (a barrel filled with water) and retrieve the fired projectiles and closely examine for rifling marks.

For projectiles sized .356” - Zero Rifling For projectiles sized .357” - trace indication of rifling (groove measured .3565") For projectiles sized .358” - strong indication of rifling.

I settled on sizing those cast bullets at .358". I changed no other component (powder, primer, case) just fixed it with sizing.

The alloy used was Lyman #2 water dropped. The bullet was the Hensley & Gibbs #115 120 grain. Lead Round Nose Bevel Base.

With bullets sized at .356 and .357, more than 20% of rounds fired keyholed on a paper target. With .358", 100% of rounds fired cut nice round holes.

The only barrels I have ever measured that were right on at .355” were Ruger Autoloading Pistols in 9x19mm. All of the others I measured (Colt Commander 9mm, Star 9mm, S&W 9mm Autoloader, S&W M547, varied between .3555” and all the way up to .360".

YMMV.

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Standard Member

Texasflyboy posted this 17 September 2009

double post

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CBA Member

JetMech posted this 17 September 2009

I might as well throw in my .002. It seems you have minimum stabilization, as most are in the group, 25% tumbling. As someone pointed out, 1:16 twist is standard for US 9mm barrels, it should handle up to 147gn bullets. So, it would seem that you have either 1) minimal rifling engagement (bullet too small), 2) too low a velocity to stabilize, 3) too soft an alloy (if you're pushing them fast enough and the bullet is stripping the rifling or being sized smaller as they are seated in the case).

I'm certainly not the smartest guy here, but I would start by water dropping the bullets. If they are slightly deformed, accuracy will suffer, but you're trying to solve a different problem and this gives you the quickest answer. Lube unsized, push them around 1000fps with a middle of the road powder (W2312, AA #5) and see what you get. If you can, shoot a couple into a water trap. That will tell you if rifling is stripping, gas cutting, etc.

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docmagnum357 posted this 04 March 2010

I have never experienced tumbling, but I do believe the twist in my Cz75b to be too fast at 1 turn in 9 1/4 inches. It also shot very well with some 357 jacketed bullets. I would try the following. 1) get a batch of 147 grain lead bullets, and try them. 2) try anything with more bearing surface, even wadcutters. they may not feed , but if they stop the tumbling problem, you know to try to find a bullet with more bearing surface. 3) hardest alloy you can get, biggest bullet. This may solve the problem.

I have put load development on hold until i can get a i in 16 turn barrel. I haven't much use for a 9mm, but if i am goint to shoot one, it will be the Cz. Twist is too fast, bore too big for most molds

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CBA Member

giorgio de galleani posted this 05 March 2010

I am not a fan of the 9mm,in Italy we are forbidden the th9 luger,we can have all the other nines except that.

I have a browning 35 HP in 9x21 and a 911 in 38 Superauto,that shoots the 9Steyer and the 9x21 brass if passed in a 38special sizing die.

I had keyholes only once in1982 using linotype bullets 356402 sized to 356,following fallacious indications from the Lyman Handbook.

I remember an article on Gun World magazine,nov 1972,Machine gunning with cast Bullets by byCharles E. Hudak,and he had keyholing with truncated cone bullets in full loads with fast powders.

He used with success a round nose 358242 bullet cast in quenched wheel weights.

In a Unique load at 1212 fps,in a Browning HP.

I follow Ed Harris advice and shoot 357 bullets in any scrap lead alloy( a little harder than plumber's lead) at 100 fps,as I am required a power factor of 120 for the steel plates.

High velocity loads and cast bullets do not go well together.Keep your pressure LOW if you do not want leading and keyholes in the 9.

If the targets are the wily bowling pins I roll them with my 45.

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CBA Member

giorgio de galleani posted this 05 March 2010

Alzheimer kicked me again, my 125 grs bullets must fly at 1000 feet,not 100.

I have ordered a HIVIZ fiber optic front sight for my HP 35.

It glows in the sunlight and can see it well with my short sighted eyes.

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Cast tumbling.

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