Finding the right BHN

[Fireman5045]

I need a little help with making sure I have the right BNH to prevent leading of the barrel.

From what I understand there is the formula for ideal BNH and maximum BNH. PSI/CUPS divided by 1920 and PSI/CUPS divided by 1422

I have picked out a SWC with a BNH of 12

The load that I am looking at have a starting charge 4.0 gr and a maximum of 6.2. Starting pressure is 15,700 CUPS and a maximum of 33,400 CUPS. By doing some math I come with for every .1 gr I go up I am going up 804.5 CUPS

With a little further math as long as I start around the 4.5 range and don't go over the 5.5 range I should be ok.

Am I over thinking this or does this sound like a good start. This will be my first time reloading so I wanna make sure I'm right. By the way this is for my Ruger Blackhawk in 357 mag. Thanks

[ShooterAZ]

Proper boolit fit will prevent leading. You did not list your powder, but looks like mild loads? Not sure about your math, but soft alloys work fine as long as they are sized correctly.

[bhn22]

Bullet fit is king, and is always the first consideration. 1422 is close enough to get you the results you need, it's the number I use too. I was told by one of the big names that it's close enough that we don't need to worry about it. The simplest way to not worry about obturation though is to use bullets that are properly sized to begin with, along with a good lube.

[Fireman5045]

Sorry. The powder I'll be using is Hodgdon Universal. Looking for a good target load. Would like to push the 158gr at around 1000 fps

[ShooterAZ]

I just use range scrap for that kind of load, BHN 9-10. No leading at all. I size to .358 and use BAC lube.

[Fireman5045]

I plan on slugging my barrel before I order bullets but I think I'm on the right track

[osteodoc08]

You're over thinking it/analyzing it. A BHN of 12 with proper fit and lube is good enough up to Magnum pistol velocities. My ACCOWW have a BHN of 11-12 and I can run them up to around 1300 fps before leading and even then, it is minimal and the cost of doing business.

[Pilgrim]

BHN may be the LAST item you need to consider. Size is the first consideration. With a revolver you need to make sure the boolits fit the cylinder throats first and foremost and that the throats are not smaller than the groove diameter. If either of those is out of whack, it's more likely you'll get leading than success whether the boolits are dead soft or harder than h***. A second item you might keep in mind when you slug the barrel is to feel for a tight spot in the barrel. If one exists, it usually occurs at the barrel-frame junction. The good news is that the mfgr's have cleaned up their act and both of these problems are nowhere near as common as they were as few as 10 years ago, maybe less. A second piece of good news is both of these are easily fixed and not particularly expensive. In general you need to consider size, lube, and then BHN in that order. Good boolits (filled out, no wrinkles, etc.) will help with accuracy, but critical is the boolits base. It's got to be uniform all the way around. Bevel base boolits are not as common anymore and that's for a good reason as rounded bases can lead to gas cutting and leading. Absolutely square, sharp bases are also important to preventing leading. Enuf pontificating by me...read the stickies and you will find pretty much everything you need to be successful. FWIW Pilgrim

[mdi]

I just use range scrap for that kind of load, BHN 9-10. No leading at all. I size to .358 and use BAC lube.

Me too. I use "range" lead for all my handgun casting from .38 150 gr. wadcutters to .44 Magnum 265 gr. RNFP. I used wheel weights exclusively for several years until I retired (had access to bunches of truck size wheel weights) and had no idea about BHN. I shot a lot of magnum loads with my "mystery alloy" (some .357 Mag. loads of 160 gr. SWC, plain base, air cooled, went over 1300 fps) with not knowing what number they were, they just fit my gun. Today I use a lot of range lead and because the bullets fit my guns, they are accurate and don't lead...

[MtGun44]

Ok, you are getting started on the wrong foot.
"I need a little help with making sure I have the right BNH to prevent leading of the barrel."
Although it is widely said, hardness is not a primary variable in preventing leading.

BHN is a secondary or lower variable in leading, at least once you get to the standard
10-12 BHN for air cooled wheel weights, although I have had no problems with as soft
as 8 BHN, even in full power loads in magnum pistols.

Use air cooled wheel weights to start and stop worrying about BHN. Get the fit correct,
about .001 to .003 larger than groove diameter is usually good, a good design boolit
and a good lube. It is never wrong to start with NRA 50-50 lube and then try other
stuff as you have it working with that.

Bill

[geargnasher]

Leading is caused by gas cutting/gas abrasion when boolits don't fit well at some point in the system and loss of obturation (seal) occurs. It doesn't matter if your boolits are 50 bhn they will lead if they leak.

Make sure the boolits FIT at every point from cylinder to muzzle and you won't have problems unless the alloy is too weak for the velocity and is leaking because of skid/partial strip in the rifling (being slammed too hard into or pushed too hard through a fast twist with too-soft alloy will make trailing edge gas leaks).

Gear

[runfiverun]

here's how I'd do it.
I'd get some 12 bhn 358 diameter boolits and load them.
then I'd go shoot them.
when I run out of loaded brass I'd do it all over again.

IF I seen a problem I'd worry about it and investigate further.

[btroj]

here's how I'd do it.
I'd get some 12 bhn 358 diameter boolits and load them.
then I'd go shoot them.
when I run out of loaded brass I'd do it all over again.

IF I seen a problem I'd worry about it and investigate further.

Exactly.

Don't solve a Problem that might not exist. Load some up and see how they do. Bet they are fine.

[bangerjim]

Agree^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Many seem to get "lost down in the weeds" with the BHN thing, overthinking it and trying to analyze the heck out of it. Fit is king.

And then PC your boolits and you will DEFINITELY NOT have any leading! I shot over 400 rounds (9-10bhn) this past weekend in 38, 40, & 45.....all PC's (sized 0.002 over) and not a bit of leading. Bores were clean and perfect.

Now that was fun! Don't overthink hardness.........just get out there and shoot those bad boys!

banger

[Charlie Two Tracks]

I understand where you are coming from Fireman. Before I got here, I was told, read, and saw in advertisements that BHN was the first and almost only thing to worry about. Well, all that was not correct information. Try doing as these guys have suggested and you may just find that you are pushing your lead 1200fps+ out of your pistol and not leading at all and hitting where you aim. Welcome to a great site full of very useful information.

[Gohon]

I thought BHN X 1422 was the formula used to give the minimum pressure at which point a bullet would start to obsturate? On the other hand if the bullet is a proper fit as everyone has correctly said, then the formula was kind of pointless as far as leading of the barrel.

[Fireman5045]

Thanks a lot for all the replies. I'm just gonna load them up and go from there. That's exactly what I needed to hear. I'm ready to get this started but I was to worried about things that might happen to start.

[462]

My Blackhawk's .357 Magnum boolits (Lee 358-158 RF) are relatively soft, being cast of an alloy consisting of 2 parts clip-on wheel weights and one part stick-on wheel weights, and allowed to air-cool. I did a one-time experiment and loaded 25 of them to a published velocity of 1300+ fps without any signs of leading. Another 25 were loaded to a published velocity of just over 1400 fps and showed slight leading about 1/4" from the 6 1/2" barrel's muzzle. I suspect the leading was due to Lee's fascination with rather shallow lube grooves.

Concentrate on fit. Don't fret about hardness.

[mdi]

Thanks a lot for all the replies. I'm just gonna load them up and go from there. That's exactly what I needed to hear. I'm ready to get this started but I was to worried about things that might happen to start.
Good plan! It's easy to overthink/look for potential problems when starting a new hobby. But with casting bullets, mistakes are easily rectified (just remelt). I'd say ferget about BHN and just make sure the bullets fit your gun (I cast for a few years before I "discovered" the "formula", then tried it, and it didn't work for me).

Re-read geargnasher's post...

[crackerjack57]

Hey all!! slightly off topic here but I too am loading for my 9mm Jericho. it has the hex barrel. not the usual rifling im use to. Im casting and sizing the lee 124 gn round nose and sizing to .358, lee tumble lubing, roughly 14 BNH getting great groups using 4.5 gn Unique but after 20 shots have enough lead in the barrel to make another boolit!! I'm wondering if I messed up when slugging the barrel. If I might need to go bigger?? I have also heard that the Hex barrels don't work well with cast.

THOUGHTS?? SUGGESTIONS?? SNIDE REMARKS?? :grin:

[bangerjim]

358 is what I size for my 38's. I use 356 for my 9 and have no leading with 9bhn and PC. But that is my gun, not yours. Slugging is the best way to know.

Have sized down some of those 38's to 356 and tried in 9mm with varied success. Chambering problems on some loads.

But maybe some that play around with 9's a lot can chime in here. 9 is one of my LEAST favorite guns to load and shoot. I have pretty much reserved my 9 to commercial FMJ's exclusively. They work........ever time........all time! And that is what is important for personal & home protection!

Good luck on you quest for that perfect no-lead boolit! :Fire:

banger :guntootsmiley:

[newmexicocrawler]

Think Boolit fit first.....I use the pincel test a couple times per casting session.

[JonB_in_Glencoe]

Hey all!! slightly off topic here but I too am loading for my 9mm Jericho. it has the hex barrel. not the usual rifling im use to. Im casting and sizing the lee 124 gn round nose and sizing to .358, lee tumble lubing, roughly 14 BNH getting great groups using 4.5 gn Unique but after 20 shots have enough lead in the barrel to make another boolit!! I'm wondering if I messed up when slugging the barrel. If I might need to go bigger?? I have also heard that the Hex barrels don't work well with cast.

THOUGHTS?? SUGGESTIONS?? SNIDE REMARKS?? :grin:
I have a couple Magnum Research Baby Eagles, same gun as the Jericko, same Polygonal rifling...But not in 9, I have a 40 and a 45.

In general, the 9 and the 40 are troublesome rounds to begin with, in regards to loading/shooting cast boolits, because they are high pressure rounds, with stronger case walls and less forgiving. I don't think the polygonal rifling creates any problems.

I haven't had luck with tumble lubing those calibers, I'd use a beeswax based Lube like Randyrat's Tak#1 or similar lube. If you still get lead fouling, then look at the case mouth expander to see if you are expanding the case mouth enough...if not, your boolit can get swaged smaller by case tension...this also can be caused if you are using Lee's Carbide FCD.
9mm is a bit challenging, there's where I'd start to solve your issue.
Jon

PS, I never had an issue with the baby eagle in 45. But my 40 has been a long process to solve the same issue...including everything I mentioned.

[MT Gianni]

I thought BHN X 1422 was the formula used to give the minimum pressure at which point a bullet would start to obsturate? On the other hand if the bullet is a proper fit as everyone has correctly said, then the formula was kind of pointless as far as leading of the barrel.

Leading is a very small part of shooting cast. We were all going to clean our guns anyway but the formula for obduration you listed is a good one for determining the pressures needed for obduration without deforming the boolit. The gas cutting that can cause leading is devastating on groups as are misshapen, out of balance boolits.

[MtGun44]

Obdurate means stubborn.

Obturate means to expand under pressure.

Bill