9mm 147gr LRN - leading the barrel

[marlin1881]

I should know the answer to this... :roll: I've purchased a couple thousand 147gr LRN cast bullets. They shoot well and are quite accurate. But, I'm getting lead smearing the entire length of the barrel.

I've tried TiteGroup, Universal Clays, LongShot, and PowerPistol powders, with seemingly the same result. Some loads are much more accurate than others. For instance, TiteGroup produces keyholes with this heavy of a bullet. LongShot and PowerPistol are very accurate. The only other powder I have for heavy 9mm bullets, is Accurate #7.

Am I pushing this bullet too hard? Any thoughts? I'm not sure of the lube (red) nor hardness of the bullet. The lube is soft, like Penn or Missouri bullet's lube. It's much softer than the hard green lube used by LaserCast.

Good accuracy seems to kick in with the slower powders (LongShot and PowerPistol), and towards the upper end of the suggested powder charge.

Thanks,

Marlin

 

[buckshotshorty]

147 gr. bullets should not exceed 950 fps. It sounds to me like you're pushing them too hard. Most of the powders you mentioned are slow burners and as you mentioned best accuracy is near the top.

 

[Mobuck]

I doubt you'll be able to get cast 147's fast enough to lead the barrel. A more likely situation is bore diameter vs/ bullet diameter. 9mm bores are a varied lot and some may be around .357 rather than expected .354/355. In this case, the bullet will skid instead of properly engaging the rifling and smear lead ferociously. No known cure for this. Using a max load to attempt to slug up to bore diameter might improve.
Try slugging your barrel. Most loading manuals will have an article on this process but it basically means driving a soft lead slug through the bore with a wooden dowel and measuring the land/grooves with a micrometer or good dial caliper. Maybe someone else knows more than I about this.

 

[marlin1881]

I'll slug the barrel, as I have some fishing weights of pure lead that work well for this. I'm shooting a Springfield XDm, and I like the gun, but I've got to get this leading thing figured out.

Thanks.

 

[Mobuck]

I've used cast 122 grain conical flat point in my Rugers with just enough powder to cycle 100% and had no problems. I do have some 147 of similar shape that I'm going to load right away so maybe I'll check those before loading some that don't work well.

 

[marlin1881]

These 147gr bullets have the soft red lube in a wide single grease groove, and a slightly concave base which I am usually a fan of. They should shoot well as I know they can be accurate. I've just got to figure out the powder burn rate, velocity, and powder grains to eliminate leading.

 

[Yosemite Sam]

You might try using some Lee Liquid Alox on the bullets as well. It's kind of messy, but I hear it can help in these situations.

Faster powders might help.

Gas checks?

-- Sam

 

[marlin1881]

Thanks, Sam.

I've not tried the Liquid Alox yet. I'll look into that. I'll investigate some slightly faster powders, but I do know that TiteGroup causes these heavy bullets to keyhole. And, this bullet has no provision for a gas check. That's a good point though, as the slower powders I'm using may be melting the base of the bullet.

Marlin

 

[WESHOOT2]

More important: Why care about the leading if the gun shoots straight?

Power Pistol is a good choice.

 

[btrumanj]

I've had good luck with AA7 and 125 gr lead bullets and seems like it should work well with the 147 gr bullet. Sometimes leading may be caused by a barrel that's just a bit rough and Yosemite Sam's suggestion of Alox might help. Personally I agree with WESHOOT2 though, if the gun shoots well, a little leading is nothing to worry about .

 

[Luckyducker]

Do you know the BHN of these commercially cast bullets? From my experience with cast bullets I have found most of them to be of too hard of alloy which makes them hard to push hard enough to fully obturate the bore. If these bullets are around 10-12 BHN you may indeed be trying to push them too hard, but if they are 18-22 BHN you well could be using kid gloves on them with your load levels. IMO store bought cast bullets are very frustrating because there are so many variables such as final diameter, and hardness compared to load application, and the style/shape of the bullets. I have been considering buying casting equipment so that I can taylor make my own for my cast bullet needs.

 

[pps]

My bet is on the diameter of the bullet being to small and/or alloy pretty hard. You mention the faster velocities give you better results, possibly because the bullet gets squished and bumps up in diameter.

The liquid alox will help too. The stuff stays on the bullets I remelt, almost to the point where the lead melts before the alox.

As a last resort (I have done it once and it worked extremely well) you can fire lap the bore....a bit of a pita, but I have no more leading in my revolver since doing this.