Optimum Brinell Hardness

[DMY]

I recently purchased my first two boxes of 135 grain round nose and DEWC hi-tek coated .358 diameter bullets from Bayou Bullets. They were more accurate than the coated Missouri 125 and 158 gr coated bullets which I have loaded in the past, which were also good. My problem is that I had a lot of leading using the same powders and similar mid-range charges. The bullets do not seem as soft as swagged bullets which I have also reloaded without excessive leading. Does anyone know the Brinell hardness number for the Bayou bullets?

[Dufus]

I don't know what is happening, but the reason for coating is to prevent leading.

Regarding hardness, you might be prudent to contact Bayou and ask the horse instead of unreliable internet dribble.

[Mobuck]

"I don't know what is happening, but the reason for coating is to prevent leading."

me too

[mehavey]

From their website: "Our bullets are cast from certified 92/6/2 alloy with a Brinell hardness of 16-17" ... above Lyman #2

If the bullet is even slightly undersize (and/or if a cylinder throat is under groove diameter/base is beveled),
low-mid pressure loads will tend not to seal.

[5whiskey]

BH usually isn't a huge factor in leading as long as you are in a range acceptable for your application. Anything even moderately hard cast (say, BH of 12 or so) should not give major leading up to mid-.357 mag loads if everything else is right.

If the bullet is even slightly undersize (and/or if a cylinder throat is under groove diameter/base is beveled),
low-mid pressure loads will tend not to seal.

This. It's likely an issue of undersized projectile or in the case of some rugers (can I say I was a huge Ruger fan but their F&F that I've seen first hand, and reports of this, is causing me to lose my fandom), the chambers are undersized and will not let you fit the appropriate size cast slug.

[Unclenick]

DMY,

I suspect this is more likely to be a coating problem than a hardness problem, especially if it's a thick coating that requires them to make the bullet undersized to still be able to fit in the throat of the gun. In such an instance, gas cutting could be an issue.

[T. O'Heir]

"...the reason for coating is to prevent leading..." Nope. It's to try and keep lead out of the air of an indoor range. Painting your bullets isn't going to prevent leading your barrel if you try to drive 'em too fast. Mind you, neither will hardening 'em.

[Paul B.]

DMY. You didn't specify if you were shooting a revolver or semi but I'd guess a revolver. With that said, measure the diameter of the offending bullets. slug your bore for the groove diameter and last of all, run some of the bullets through the cylinder chambers. What we're looking for is first the groove diameter. Example: .38 Spl. .358". Bullets should be at least .358", preferably (at least in my guns) .359". Comes the tricky part, the throats of the cylinder should be at least .358" to .359" agin preferably .359" based on my guns. If the bullet is smaller than .358", say .357" or the throats are smaller than .358" the bullets will be sized down to the smaller size that will lead the barrel. I can shoot a properly size 158 gr. SWC at BHN 8 which is close to pure lead at full powder from my .357 Mag. and no leading. Cylinder throats and groove diameter are compatible so proper sizing finishes the triad.
I cast my own bullets and my normal alloy run 11 on the BHN scale. It can be water dropped to reach a hardness of 32 on the BHN scale should I need to do so. Properly sized rarely do any of the bullets deposit any lead in my barrels.
Paul B.

[DMY]

Thanks for all of your replies. I have not slugged the barrel of my revolvers, but the thing which makes me suspect the hardness may be the culprit is this. Using similar mid-range charges of W231, Bullseye and TightGroup, I had significant (not severe) leading with the Bayou. The Missouris had vritually no leading. Both were Hi-Tek coated, although I suspect the Bayou coating may be a little thicker because none of it comes off during seating. If I don't align the Missouri perfectly before seating, a little coating will scratch off, but that could also be caused by the different round nose profile. I would like to make the Bayous work because they are more accurate out of my 3" and 6" L-frames.

[mehavey]

(Assuming cylinder throat isn't major problem)
Shoot`em hotter, and with a faster powder.

(as paradoxical as that might seem)

[USSR]

I have not slugged the barrel of my revolvers

With revolvers, the first thing you do is slug your cylinder throats. Chances are, you will see the problem there and never ever have to slug your barrel. If your cylinder throats are .358" or slightly larger, and your bullets are smaller in diameter, there is your problem right there. Commercial lead bullet casters cast their bullets too hard. Reason? Antimony is a heck of lot cheaper than tin. And, they have done a great job of convincing novice reloaders that they need super hard bullets. In the photo below, the bullet on the right has a BHN of about 7 or 8, and was driven at 945fps without a lick of leading. According to the commercial casters, I would need to use their 12 BHN bullets. So, first insure that your bullets are not smaller than your cylinder throats, and then that your barrel groove diameter is not larger than your cylinder throats.

Don

[BBarn]

Not sure why the MBCs worked well and the Bayou Bullets leave some lead behind. Looks like the Bayou Bullets are BN16-17, whereas the MBCs are available in either BN12 or BN16 (not sure which you used previously). The finished diameters might be different (which you could measure). The coating thicknesses could be different, or the coating processes could be different between the brands.

At this point, rather than chasing all the stuff that may be the issue, I would probably try some of MBC's coated 148gr. wadcutters. They are BN12 which is appropriate for midrange loads.

[snakeye]

Best piece of advice I can give you is quit using Bayou bullets and keep using Missouri Bullets until you find another bullet you like.

[Chainsaw.]

Mic the bullets and get back to us.

[5whiskey]

Chainsaw said it. Mic the diameter. And about a 95% chance this isn't a hardness issue. Too much is made of BH unless you're trying to push high velocities in a rifle, but even then paper patching is really a better route (I'm gonna do that one day).

Matt Dardas had a decent explanation of the importance of bullet fitment on his web page when his company was open. He even offered slugs to slug a barrel, and iirc be would measure it for you if you mailed it to him. He didn't have options for different hardness, he had options for projectile diameter.

[DMY]

I took Dufus' advice and perused Bayou's website and Missouri's. The Missouris I used were all Cowboy action bullets (105 gn TC, 125 gn TCFP, 140 TCFP & 158 gr RN) with a listed Brinell hardness of 12. The Bayous are listed at 16-17. Checking my range results, the Bayous gave a higher feet per second with the similar charges, although the different profile, weight and seating depth explains some of the higher FPS. Bottom line is that I will try to push the bullet a little faster (around 850 fps for a 135 gr RN & DEWC) and see what happens. Still have about 1300 Bayous to load and shoot.

[black mamba]

One of the bullet makers had a formula on their website that calculated the maximum BHN for reliable obturation in barrels. For 17 BHN it comes out to 24,000 psi for obturation. For 12 BHN it is only 17,000 psi. For the harder bullets, especially if they are even slightly undersized for your cylinder throats, you need more pressure. So either be more precise with your bullet diameters, or use the softer bullets.

[USSR]

One of the bullet makers had a formula on their website that calculated the maximum BHN for reliable obturation in barrels. For 17 BHN it comes out to 24,000 psi for obturation. For 12 BHN it is only 17,000 psi.

Just another thing the commercial casters do to try to justify their super hard bullets. You surely don't need a 12 BHN bullet that is to be driven at .38 Special pressure levels. Funny how Elmer Keith was able to develop full power .44 Magnum loads with 11 BHN bullets without leading. Once you take up casting, you will begin to understand the con game that the commercial casters are up to.

Don