latest lead order tumbling

[theaccountant]

To update this thread...

- I shot 100 bullets at the longer OAL (1.145",) crimp area at .382-ish, with slower powder (W231)...50 were run through the factory crimp die, 50 weren't - all tumbled out of the CZ 85 combat
- I then shot the rest of the evening with cartridges that I knew were CZ tumblers out of the Glock 34 - not one of them tumbled...perfect round holes in the cardboard. 

So it doesn't seem like the slower powder mattered.  Tomorrow I'm going to go to a sporting goods store (that sells fishing and gun stuff) and buy some soft lead sinkers and slug the barrel in this CZ.  If I had to form a conclusion right now about what is going on, based on all you guys have told me in this thread and my experiences so far, it would be that .356 is borderline too small for my CZ barrel...the crimps are all measuring in the .380" range, but differences in the wall thickness of the range brass I'm using is causing this softer lead to get resized to different degrees (based on how thick the walls of the particular piece of brass is) - the ones getting sized down too much are the tumblers...the round nose flat point design of the 147 gr bullet is more prone to tumbling if everything isn't perfect...the .356 size is plenty big enough for the Glock barrel, so that's why there are no issues with these bullets despite using the FCD, loading shorter, and using the fast S1000 powder...and basically, if I want to shoot 147's that are the same softness of these 147's, I'm going to have to order them at a size greater than .356.

One question I have is - is there any negative effect of using a cast bullet that is too large?  For example, if I order .357's for the CZ and then shoot them out of the Glock (which probably has a smaller bore size,) what (if anything) will be the negative effect?  I have to imagine there is some reason that folks wouldn't want an oversized cast bullet, otherwise I'd imagine .357 and .358 would be what most casters were making/selling...

I'll update this thread after I slug the barrels of the CZ and Glock.

[1SOW]

One question I have is - is there any negative effect of using a cast bullet that is too large?  For example, if I order .357's for the CZ and then shoot them out of the Glock (which probably has a smaller bore size,) what (if anything) will be the negative effect?

I don't load lead.  The books say the risks are higher pressures, expanded case may not feed and  leading the bbl.

I ran into the case thickness variations some time back  I shoot plated bullets that also can't be resized by the dies.  I don't like damaged jacketted bullets either.  My solution was to sort by headstamp, and that helped a lot; but even sorted headstamps can show some thickness variations.
Longer cases are also going to taper crimp tighter than short cases.   I set the taper crimp for fairly long cases.  They all run fine.

[jameslovesjammie]

I'll update this thread after I slug the barrels of the CZ and Glock.

Before you do anything else, DO THIS!

[john16443]

One question I have is - is there any negative effect of using a cast bullet that is too large?  For example, if I order .357's for the CZ and then shoot them out of the Glock (which probably has a smaller bore size,) what (if anything) will be the negative effect?  I have to imagine there is some reason that folks wouldn't want an oversized cast bullet, otherwise I'd imagine .357 and .358 would be what most casters were making/selling...

I'll update this thread after I slug the barrels of the CZ and Glock.

You've found that the barrel differences in these 2 guns is most likely the cause of the tumbling.  Here's some information directly from the Penn Bullets 9mm product page regarding bullet sizing.  I think this should answer your question about sized bullets greater than .001 over the actual barrel bore.

A word about 9mm sizing... Most 9mm pistols were never known for being a "bullseye type" firearm. Original specs for the 9mm cartridge gives + - specs that are quite "loose" The most common problem that I hear from most customers is they encounter a lot of bullets that tumble or very poor accuracy when they hit the target. This usually indicates that the bullets are loose and one is not achieving a good fit of the bullet to the barrel. Certain pistols were more prone to these problems. Ruger and Beretta pistols were the most notorious in having oversized barrels but it could be found on other brands as well. Sig Sauers and Browning Highpowers were the "tightest". It was not uncommon to see barrels with dimensions of .357 or .358. Slugging the barrel to determine the right size is the first step to eliminating the problem. I have sold many 9mm bullets sized to .357 and .358 to get the guns to shoot well. Yes, the cases do bulge but they still feed and function in the guns so the problem is cosmetic. Reloading Tip..... Even if you are using carbide dies to resize your 9mm cases, lubricate them with a spray on lube ( RCBS Case Slick is the best.) The carbide insert in 9mm die sets is a full case length carbide insert due to the fact that the 9mm case is tapered unlike most other calibers which utilize a short carbide ring for resizing on straight wall cases. This will minimize stretching of the cases and excessively distorting them during reloading. You will also find that the effort to resize the cases will be cut by 50%.

I am currently using 150 grain LSWC bullets made for use in 357 magnum revolvers in my Ruger SR9.  They measure a consistent 0.358" in diameter, and truth be told, they are some of the most accurate bullets I have ever shot out of any 9mm handgun.  It should be noted that they WILL NOT chamber in my CZ75b due to the nose profile, but plunk, chamber and shoot beautifully in the SR9.  So in my SR9, shooting a bullet that's more than .001" over the barrel bore is no problem.

[jameslovesjammie]

I am currently using 150 grain LSWC bullets made for use in 357 magnum revolvers in my Ruger SR9.  They measure a consistent 0.358" in diameter, and truth be told, they are some of the most accurate bullets I have ever shot out of any 9mm handgun.  It should be noted that they WILL NOT chamber in my CZ75b due to the nose profile, but plunk, chamber and shoot beautifully in the SR9.  So in my SR9, shooting a bullet that's more than .001" over the barrel bore is no problem.

You're correct, John!  I use 0.358" in 9mm's all the time.  I have even used this bullet diameter in the .0354" barrel on my Sister's LC9 with no issues/pressure signs.  I am currently reloading for the LC9 (.354"), Para P18 (.355"), a 75B with a factory barrel (.3545") and a 75B Compact .40 with a 9mm conversion barrel (.356").  ALL are using .358" cast bullets.  No leading, no tumbling, good accuracy.

[theaccountant]

I slugged both barrels...I think I did it correctly...I lubed the barrel and pushed a lead sinker down the barrel with a brass rod and hammer - when the sinker came out, I put it in a micrometer and spun it to find the largest diameter spots (there were two or three per slug, with most of the slug being alot less than .355...the measurements below are the largest diameter spots found on the slugs.)

- Highest spot on the slugs run through the CZ = .356"
- Highest spot on the slugs run through the Glock = just a hair under .354"
(I ran two slugs through each barrel and got the same result both times.)

I'll add one more thing - I believe the 147 gr lead bullets have more of a tendency to tumble as evidenced by:
1.  The fact that non-147 gr bullets sized at .356" never tumbled out of my CZ, and
2.  I noticed that, while some casters offer different sizing in all bullets they make and some offer no different sizing, a few offer alternative sizing ONLY in the 147 gr bullet

So, I think I now understand the situation.  The CZ has a larger bore than the G34 with the KKM barrel - that's why the CZ tends to tumble with the same 147 gr bullets where the G34 doesn't tumble at all.  I need to order .357" sized bullets if I want the best results in the CZ.  Bullets sized at .356" that are NOT 147 gr will shoot out of my CZ without tumbling, but I'm probably not getting the optimal performance I'd get with the same bullet sized at .357".

Thank you all so much for the posts, suggestions, etc.  Maybe this thread can be a source for folks with CZ's struggling with 147 gr lead.

[john16443]

Dardas cast bullets is probably the best source for .357 dimensioned bullets.  He has 147 grain styles available, and pricing is normally pretty good.  Try some sample packs in your CZ and let us know.

[jameslovesjammie]

I slugged both barrels...I think I did it correctly...I lubed the barrel and pushed a lead sinker down the barrel with a brass rod and hammer - when the sinker came out, I put it in a micrometer and spun it to find the largest diameter spots (there were two or three per slug, with most of the slug being alot less than .355...That would be the rifling.  Remember that the slug is a mirror image of the barrel.

- Highest spot on the slugs run through the CZ = .356"
- Highest spot on the slugs run through the Glock = just a hair under .354"
(I ran two slugs through each barrel and got the same result both times.)

I'll add one more thing - I believe the 147 gr lead bullets have more of a tendency to tumble as evidenced by:
1.  The fact that non-147 gr bullets sized at .356" never tumbled out of my CZ, and
2.  I noticed that, while some casters offer different sizing in all bullets they make and some offer no different sizing, a few offer alternative sizing ONLY in the 147 gr bullet I think you're reading too much into this.  I would think it is because 115 and 125 grain are the most popular sellers and they have them already sized and on the shelf.  There is NO reason that a commercial caster who can size 115 and 125 grain bullets to .357 cannot do the same with 147 grain.

So, I think I now understand the situation.  The CZ has a larger bore than the G34 with the KKM barrel Awesome barrels!- that's why the CZ tends to tumble with the same 147 gr bullets where the G34 doesn't tumble at all. Right on! I need to order .357" Should work.  So should .358"sized bullets if I want the best results in the CZ.  Bullets sized at .356" that are NOT 147 gr will shoot out of my CZ without tumbling, but I'm probably not getting the optimal performance I'd get with the same bullet sized at .357". Most likely.

Thank you all so much for the posts, suggestions, etc.  Maybe this thread can be a source for folks with CZ's struggling with 147 gr lead.