I have been using 158 grain semi-wadcutters that are Hi-Tek coated and are Brinell 12 (according to Missouri Bullet Company) to make a target load that is propelled by 4.1-4.2 grains of Unique. I am running out to them and the wait to get replacements is long. I have on hand a bunch of 158 grain semi-wadcutters also Hi-Tek coated, but a harder alloy at Brinell 18.

Can I keep my same load 4.1-4.2 Unique and WSP primers? Or will the lower velocity cause leading with the harder bullet? I am hoping that the coating itself will prevent leading even is the velocity is not quite sufficient to get the harder bullets to seal.

Mzuri,

From my perspective, I don't see leading as the problem. The BHN 18 bullet will be harder, and as a result not deform to the bore and groove diameter as quickly, resulting in higher case pressures. If I were you, I'd drop my starting load a few tenths and work my way up on the powder charge. Always watch for signs of high pressure.

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Judge control not gun control!

The coating will protect against leading.

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Freedom is never free!!
SWCA #3437

No firm rules on any of this. You'll have to experiment. If the load is not maximum, you can go up and down on charge weights. Shoot groups from a benchrest at 25 yards, checking for bore leading with each different charge. Go with what's most accurate and doesn't lead the bore. Velocity is secondary.

To simplify things a bit and also avoid all that "signs if high pressure" controversy I would suggest that you view your hard cast bullets as the same as a jacketed bullet. This will have you loading to data that assumes a higher degree of friction between bullet and barrel and hte attendant change in the pressure curve.

BTW, I am one of those who believes that if you can actually see indications of higher pressure in a fired case that you have already exceeded the safe maximum pressure. If you want an example just look to 357 Magnum versus 38 special. Loaded to maximum recommended charge levels the fired cases won't show any indication of "high pressure". So guess what happens when you see a "high pressure indicator" on a 38 special. Yeah, you have just fired a 38 special that was loaded well beyond the safe pressure for a 357 MAGNUM.

If you want to load by pressure then do what the big boys do, purchase pressure testing equipment to directly measure the produced pressure. If you aren't willing to spend the $$$ for the correct equipment then be sensible and load by trustworthy load manuals.

Higher BHN for coated bullets is almost "worthless". I have been coating my cast bullets for a few years and found anything from my handgun alloy (BHN 10-11) to my rifle alloy (BHN 15) makes no difference. I think of them the same as the BHN of the lead in a FMJ, the coating protects the bullets the same as a jacket. Perhaps there is a difference in terminal performance, but I'm not sure about that...

What are you shooting, a 38 or 357 ?

J frame or L frame?

I can't help unless I know a few facts.

The main consumer of this ammo is K-frame 357 (2.5 inch 66) and occasionally a 4" M10. So .38 but mostly in a gun that can or should be able to handle higher pressures. And when I say "target" I don't mean bullseye or any thing that requires real precision. These would be for IDPA minor loads. I bought the harder bullets for 357 loads, but right now they are all I have and I need to make light .38 loads for a match this weekend.

You won't hurt anything, load a practice batch, and give them a try! Otherwise, you will be without ammo for Saturday! And a little practice never hurt anyone!!!

Ivan

Bullet size is more important than alloy for leading. The alloy bhn isnt changing pressures that much, so at the below starting lad in 38sp I assume, you should be fine. Check your cyl throats, if the bullet gets sized down in the throats, decent chance with hard alloy you get a bit of early leading.

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NRA Cert. Inst. IDPA CSO

For low fps target loads you can't beat Trail Boss.
In my 686 6" 4.0 grs gives me 755 fps that hits at POA

Red Dot will also do this same fps and be at POA

I don't load much lead in my .357.
Good shooting.

I looked your load up. I wouldn't think twice about swapping those two. I doubt you will be able to discern a difference.

Cylinder throat way more important than BHN at that velocity. Other than that, try them. You have no worries.

You shouldn't be getting any leading with any coated bullets regardless of BHN...