Tumbling tumble lube bullets

[458winshooter]

Went to the range yesterday and it was an all 45 day.The trouble is I had loaded the Lee 230 gr roundnose tumble lube bullet in both a 45 acp highpoint carbine and a Ruger Blackhawk in 45 colt.In both I had several tumble in flight and keyhole the target at 10 yards.Could I be pushing it too hard ?The 230 gr tumble lube flatpoint shot fine out of both.It has more bearing surface and drops a little heavier.Velocity was in the 1100 fps range.

[reddog81]

Honestly most shooters have eschewed the tumble lube design because they aren't that good. I tried some when I started casting but I can't remember the last time loaded any...

That's some pretty high velocity for 45 ACP, but I guess those guns can probably handle it OK.

I can think of more questions than answers for you... what size are sizing the bullets to?
What type of alloy are you using? I use pretty soft lead for .45 but I usually keep the velocity around 800FPS.
Did you have any leading? Once a barrel gets leaded, which is can easily happen with Lee Liquid Alox at 1100 FPS, can result in problems including poor accuracy and tumbling.

[Chainsaw.]

My first thought is you velocities are really high. Is that 1100 out of the carbine or out of the revolver? Thats cookin for both. 45 is a square bullet and doesn't like to go terribly fast, doesn't need to.

As stated above, any leading?

[458winshooter]

No leading I powdercoated them .As stated before the tumblelubed flat points all stabilised just fine.I had loaded about 30 each of 3 different powders Unique,Hs-6 and Blue Dot in the Blackhawk,2 different powders in the carbine power pistol and Blue Dot.The unique loads were still dirty and the brass came out sooty.

[armoredman]

Are they casting undersized for the bore? I've been using 9mm TL bullets for years, also powder coated, no tumbling issues. Do you size after powdercoat, before, or not at all?

[res45]

1100 fps is fairly easy to do out of the 45 ACP carbine with the 16.5" barrel I have one myself,950 fps is easily doable out of a 5" handgun depending on the powder /bullet combo used. I shoot for accuracy though not velocity.

The Hi Point carbines and handguns have very shallow lands and grooves and require a cast bullet that fills the bore to get a good grip otherwise they want be stable. Bullets that tumble are a sure sign of either being undersized or to hard to obturate and not bump up under pressure to fill the bore.

Some things I would check are bullet dia. vs. cylinder throat dia. of the revolver and groove dia. of the bore on the carbine. If you get to aggressive with the taper crimp it could also undersize your bullets. On the Ruger Revolver if it's like my BH in 357 it has large throats an likes a cast bullets sized to .359"

I cast both the Lee TL 230 gr. RN as well as the Lee standard grease groove 200 gr. SWC an shoot them with standard lube and powder coated in my carbine with excellent accuracy an no leading,bullets are cast from 50/50 and sized to .452" in my Lee sizer or RCBS lubesizer depending on the type lube used.

[Unclenick]

Some of my most accurate cast bullets are tumble lube. The .38 TL wadcutter, in particular, will shoot groups half as large as my K-38 gets from any commercial Match ammo I've tried in it. So I don't know where other's problems with them are coming from, but I don't have them.

The 16" twist standard in most .45 ACP chamberings is more than fast enough to stabilize anything in the size range of the Lee bullets. However, I note that you are firing just about right at the speed of sound. This is the so-called "sound barrier" and bullets experience a jump in drag coefficient due to shock wave formation at that velocity that causes potential stability issues. I've watched 168 grain .308 MatchKing bullets fired with a 10" twist fly beautifully until they drop too near the speed of sound and suddenly start to tumble (about 700 yards in .308 Win). It's caused by a dynamic instability resulting from the geometry of the bullet, and you could have a situation where the round nose sees some of that, while the truncated cone shape does not.

However, it's also possible the round nose is getting more cocked in the chamber and shaving lead at the front end of the chamber, distorting the bullet. For the pistol, try seating the bullets out as far as you can without introducing a feed and chambering problem. The more of the nose you can get into the throat, the less freedom it has to turn sideways.

In the Revolver you would probably benefit from checking all the usual suspects: Use a pure lead bullet or a sinker to slug the bore to look for a constriction where the barrel screws into the frame. Check the size of your chamber throats in the cylinder. These days a lot of 45 Colt revolvers still have throats cut for the old 0.454" bullets, but have modern 0.451" groove diameter barrels. They almost never shoot their best with lead bullets until the bullet diameter is within 0.001" of the throat diameter. It is typical of production revolvers that the throats are not all the same diameter, either. Reaming them to the same maximum size is a standard step to take in accurizing a revolver. Jacketed bullets mostly seem unaffected by these issues, but cast bullets are frequently upset badly by them.

[458winshooter]

The Blackhawk barrel slugs at .452 and the throats all measure at .452 except one is at .4515 the bullets measure .452-.453 and I have not sized them just powder coat and loaded.I have not slugged the carbine though.My other Hi-point carbine is in 9mm and it shoots anything you want to load in it.My lead mix is at a bn of 14.

[Unclenick]

It's clear the throats on your gun are not for the old bullets if they match your bore. This slugging was done with pure lead, right? Cast bullet alloys are too springy to get an accurate reading or to let you feel constrictions clearly. Did you use a micrometer for the measurements? Calipers can rather easily be off half a thousandth to a thousandth. The 0.0001" vernier scale resolution on an OD thimble micrometer proves its worth in making these measurements (just don't forget to get a zero reading for subtraction from the final reading).

If your set of measurements are accurate, you probably want, ideally, to go to .453 throats and aim your bullets at .453 (search of posts on beagling molds to increase bullet size a little) for best fit to your bore. The undersized throat will not be your friend with hard cast bullets. However, you may find a softer bullet better bumps back up to fill the grooves. Elmer Keith used 16:1 lead:tin in developing the .44 Magnum, and that's about BHN 11 IIRC.

Did you find any bore tightness at the frame?

[chris in va]

Size after powdercoating, not before. Slow down to about 950 in the carbine, bullets should stabilize.

I haven't had much luck with the Lee 230's in any flavor so I switched to the 200 SWC.