Brinell calculation

[tke861]

I would like to figure out the exact (or as close as possible) brinell I need for my XD with the velocities I'm using. I had found a calculation on the web a while back that you could enter your velocity and some other variables and come up with the exact brinell you needed for your particular setup.

Problem is leading in my XD9SC. The short throat of my particular XD means I have to load (for what seems to me) a little on the short side, between 1.070"-1.080". I'm getting a little leading and am thinking I need this calculation to get the exact brenell I should make to keep my pressures/heat down so I don't have this problem.

Anyone know the calculation. I seem to be google search illiterate when it comes to finding the calculation I need!

[tke861]

Ok, my illiteracy has ended. I found the calculation. I was smart enough to save it as a favorite on my iPhone many months ago!

Ideal hardness in BHN = Pressure/1,920
Maximum BHN = Pressure/1,422

Now I can find what I need!

My current load has been 4gr bullseye with a cast 115gr RN with OAL 1.080. I think my pressure may be a bit high and need to back down a few tenths of a grain and try again with a different hardness on my casting.

Anyone else have an idea? Am I on the right track?

[alamogunr]

You don't mention whether the boolet fits the barrel. A too small boolet will cause more problems than hardness.

[tke861]

alamogunr, my apologies, I did forget that important piece of information.

XD9SC barrel is .355 and my casting is sized to .356. The case is crimped to .358, which for me historically, has worked in my m&p and SR9 with only very little leading after 150-200 rounds.

I'm wondering if I need to step up to .357 on my sizing and .359 on my crimping?

[yovinny]

Ideal hardness in BHN = Pressure/1,920
Maximum BHN = Pressure/1,422


Thats good info to know, but I'm having a question.
Is that pressure in PSI, CUP, or something else ?

TIA
Cheers, YV

[tke861]

Ideal hardness in BHN = Pressure/1,920
Maximum BHN = Pressure/1,422


Thats good info to know, but I'm having a question.
Is that pressure in PSI, CUP, or something else ?

TIA
Cheers, YV

The author of the site says either will work as the the numbers are close enough for the calculation to work with either number. I did find a post from this site in my search just a few moments ago. It has a calculator based on the same numbers. If you look at Optimal pressure equation in cell B14 it is almost the same equation that I list above just used to find pressure instead of Maximum BHN. You can use any BHN and find the ideal pressure so you can work with any BHN you have at your disposal

http://castboolits.gunloads.com/showthread.php?t=94273

I've been loading for a long time and have just now, due to my XD problems, started to understand the science behind the lead and how to make it work for you and your accuracy. This site has brought all of this to my attention and will hopefully make me not only more accurate but safer as well.

[Larry Gibson]

Your load of 4 gr Bullseye is an excellent one and you don't need to back off. Something else is causing the leading. I've shot a lot of pretty low BHN cast bullets through numerous 9mms with no leading using that load under 115 - 125 gr bullets. I've also shot a lot of them sized at .356 back in the day when that was the thing to do. I now size at .358 and just use them that way.

You don't mention the alloy and the lube used?

Larry Gibson

[Bret4207]

Like Larry says, exact Bhn with an alloy made up of what, treated how, used with what powder at what pressure? Do you have a ballistics lab that will tell you your exact pressure? And is that your max achieved pressure or average pressure? And is that the pressure the formula says the Bhn will take or where it start turning to putty?

What I'm getting at is that there is no way to say what the ideal Bhn is. It's going to vary widely and at that, your are limited by your test equipment to determine Bhn. It's just a relative number.

[cajun shooter]

I have loaded and casted since 1969-70 and when first starting out I didn't even know about BHN.
My mentor knew what to do and guided me well. As the others have said there is no way for the average shooter to have all the lab equipment that is needed for these formulas.
If you have a bad alloy but it test at the correct numbers they will have problems. You may use a soft bullet that fits and have no leading.
Your bullet to bore fit is the most important thing you can learn.
Most guns will shoot well when the bullet is just short of the lands so your OAL is fine if your pistol functions as it should.
Slug your barrel and work on your shooting from that angle instead of getting the correct BHN.
If the fit is correct then the gun will shoot great groups with several different BHN bullets.

[geargnasher]

I don't have an XD in 9mm, but several guys with .40s complain bitterly about a razor-sharp chamber-throat transition, or lack of throat entirely, that won't accept an oversized cast boolit without shaving some lead. Shaved lead at the beginning of the barrel can get smeared on the bore by subsequent shots, which is different from typical lead deposits due to gas leaks around a poorly fit boolit. You might check the chamber with a casting or make a chamber/throat slug and see what you're up against. If there's no taper or throat to help the cast boolit transition from the case to the rifling and swage down for a nice tight seal, the barrel will act like a cookie-cutter and just slice the boolit down to exact size, which can still leak if it isn't a slight force-fit. You might be getting leading from the smearing of shaved lead and from gas cutting. The boolit needs to travel through a tapered throat so it is swaged, rather than cut, so it will be tight the whole way through the barrel. The best way to achieve this is to use springy, antimonial alloys (like you're using) and make sure they're at least a thousandth larger than groove diameter (more with some guns) so it will fit like a champagne cork in the barrel and NOT LEAK as it's being fired.

As far as the BHN/psi theory goes, it's ok to drink the red Richard Lee Kool-aid, his formula works pretty well for standard tooling and loading techniques provided your boolit fits the gun when loaded and during the entire firing event. However, loading to this forumula is not, by any means, the whole story nor is it the Gospel Truth, so don't let it forge itself into an irreversible "law" in your head, because if you keep experiementing and start including rifles in your casting regimen you will experience things that don't hold up to Lee's formula occasionally.

Gear

[MikeS]

As the others have already. the FIT of the boolit is more important than the hardness of the boolit. Sure, how hard or soft can have it's effect, but trying to use some formula or other, and thinking because the formula says it's the best, that it will be the best is just wrong! Also, what works in my gun might not work the same in your gun!

The link you posted to an old thread here was started by a person that came to this forum, and posted his spreadsheet, discussed it in a few posts in the same message thread, then left, never to be heard of again. If his calculator was so good, and actually worked, I would think that there would be a whole lot more discussion of it. Listen to the folks that have been around here for a while, such as Bret, or Cajun, or Gear, and others (sorry if I didn't list everyone)! As was also said, BHN alone doesn't tell the whole story. A boolit that's 22BHN because it's been heat treated, or water dropped will act totally different than a boolit cast from linotype that's also 22BHN. A boolit even harder, cast from monotype might fit the bill perfectly according to a calculator, but might break in half while you're loading it because it's so brittle! In reloading in general, and even more so with cast boolits, there's no rule that if you do A+B you will ALWAYS come up with C. It's more like you might get C or D or even E or F. If you try and approach boolit casting from a view of scientific absolutes you will be very disappointed. It's much more lots of trial & error. Don't forget, what was once thought of as the most important thing (boolit hardness) is now way down on the list, with things like FIT, and using the proper type of powder (fast, slow, high pressure, low pressure, etc.) being more important.

[tke861]

I thank you all for the input. My XD is the only pistol I have this trouble with, even my PF9 can stand a longer OAL than the XD. There is NO, repeat NO, throat to this firearm. I sized 8 dummy rounds trying to find the sweet spot last night and settle on 1.097-1.098" COAL with a 115gr RN casting. I "painted" the ogive on each bullet with a marker to see where it touched the lands and until I sized down to 1.097 each round came out missing "paint". I can barrel drop the round and hear a thunk at 1.097. At 1.098 the round starts to contact the lands and won't seat in the chamber by itself. I think Gear is on the nose with the shearing.

I slugged the bore, I'm at .355". Sizing of the bullet is .356". I don't think I should go much larger than that as I'm worried I would get more shearing than I have now.

My thought is that I should go with a different casting, maybe a 124/125gr or 147gr with either a FP or longer ogive so that I don't contact the lands as quickly. Does that sound logical? Any recommendations?

All of my other 9mm pistols, including the PF9, do not have this problem as they have a decent throat on them.

I'm here to learn so let me know your thoughts.

[geargnasher]

Break the sharp edge on the barrel with a lap made from a truncated cone bullet, either copper or lead, drilled in the base and threaded onto a short section of cleaning rod. Use valve grinding compound and do it like you were lapping a valve. I've done this to a few of the new, plastic automatics having the same problem with excellent results, and suggested this to another member having "XD-itis" and he reports good results as well. It doesn't take much, mainly break the edge of the lands down until you can get a slight cut on the grooves too, this makes a funnel that will swage the boolit down to fit rather than slice it like a cheese grater.

Gear