Boolit size v. bore size and ideal hardness

[Jayhem]

2 Questions fellas!



1. What is the ideal boolit diameter v. bore diameter? If my .40 cal bore is .399 when slugged, is resizing to .401 ok? This is what my sizing die sizes to.


2. What is the ideal hardness in BHN for handgun boolits that will be pushed somewhere between 700 and 1000 FPS? I'm going by Lymans boolit making guide to mix allows for hardness. I was going to aim for around 12-15 BHN unless the group feels this is too soft for my velocities? I'm not highly concerned with accuracy and the softer I can go the longer my supply of Tin and Antimony will last.

[thx997303]

1. There is no ideal size. But starting with .002" over groove diameter is a good place to start.

I shoot .358" boolits in my XD that has a bore diameter of .355" No leading, so far good accuracy.

2. 50/50 WW/Pure or equivelant alloy would probably work quite well for your purposes. Maybe a little tin added if you are having trouble with fill out.

But again, there is no ideal hardness or alloy.

It's a matter of what works in YOUR gun. What works in mine may not work in yours.

[Jayhem]

Makes sense.

I'm after a starting point then. Just to put me in the ball park. I'm thinking of going with 3% antimony, 1.5% tin and 95.5% Pb

[fredj338]

Form the LASC site:

Approximate "Maximum" Chamber Pressure For Lead Alloys (PSI)

Plumbers lead, stick on WW 13,000 - (Black Powder Only)
Wheel weights / clip-on 25,000 - Non-Magnum handgun
loads, Rifles to 1,800 fps
Lyman # 2 (alloy varies in
Lyman cast bullet books)
35,000 - Magnum handgun &
rifles to 2,000 fps
Quench-cast WW (dropped
from mould into cool water)
48,000 - Magnum handgun
& rifles to 2,200 fps
Oven heat treated WW 55,000 - Jacketed velocities in handguns
and rifles with quality bore & balanced load
-----------------------------------------------------------------------
Bullet BHN / "Minimum" Chamber Pressure For Lead Alloys (PSI)

The formula (from the pages of HandLoader Magazine) to determine at what pressure an alloy of given BHN will obturate the base of the bullet and seal the bore. If the bullet is too hard to obturate, gas cutting usually occurs on the base band on the non-driving side of the rifling and barrel leading is likely. Simply multiply the alloy BHN by 1,422.
Example: Alloy BHN of 12 multiplied by 1422 = 17,064. An alloy of 12 BHN should be used with a load that develops a "minimum" of 17,000 psi. Need more info on minimum / maximum alloy BHN? These Glen E. Fryxell articles explain alloy BHN in easy to understand language.

[Jayhem]

Wow, very helpful info! Thanks fredj!

[geargnasher]

Makes sense.

I'm after a starting point then. Just to put me in the ball park. I'm thinking of going with 3% antimony, 1.5% tin and 95.5% Pb

Sounds like you're right on the pitcher's mound with that. Ought to cast well and shoot just fine, basically you're talking WW with a pinch of tin added and that is good to over 1,000fps plain-based without hardening, assuming all else is done properly.

I agree with .001-2" over groove diameter is a good place to start.

Gear

[cbrick]

I was going to aim for around 12-15 BHN unless the group feels this is too soft for my velocities?

At .002" over groove diameter (an excellent place to start if they chamber well) 12 BHN should be plenty hard, harder is not better. Harder is simply harder. Harder can open up it's own can worms and isn't needed. I am a die hard believer in HT'ing and have a dedicated convection oven in my loading room BUT HT'ing is simply not needed for most applications. It has it's place but low pressure, low velocity, short range shooting is not it's place. You will be well served getting the term "hardcast" out of your head.

At 700+ fps with proper fitting boolits you could shoot much softer than 12 BHN without leading. I shoot 6 BHN HP's from my Springfield 45 ACP at 800 fps without leading. For general shooting purposes with the 45 I use either straight air cooled WW or a 50/50 mix of soft and clip on WW for 8-9 BHN and it doesn't seem to matter much, both work well.

Rick

[Jayhem]

One other question. Can water dropping actually give me more hardness without the need to use more of my precious Antimony supply? If so, what is the lowest % of antimony in lead that water dropping can actually help the hardness?

[Jayhem]

It has it's place but low pressure, low velocity, short range shooting is not it's place. You will be well served getting the term "hardcast" out of your head.

At 700+ fps with proper fitting boolits you could shoot much softer than 12 BHN without leading. I shoot 6 BHN HP's from my Springfield 45 ACP at 800 fps without leading. For general shooting purposes with the 45 I use either striaght air cooled WW or a 50/50 mix of soft and clip on WW for 8-9 BHN and it doesn't seem to matter much, both work well.

Rick

Things I've been reading on here recently has me wondering if chamber pressure isn't more important to issues with hardness than velocity. My .40 S&W will produce around 27,000 PSI even with light target loads of 175 gr TC's at 900 FPS while my .45 ACP will only be around 15,000 PSI at 800 FPS with 225gr RN boolits. Can both still use the same boolit alloy efficiently?

[cbrick]

Jayhem, the alloy you posted in post number 3 should work very well with your stated 700 to 1000 fps goal and any harder than this (your original question) should not be needed. Yes, water quenching a lead/antimony alloy will harden them but you shouldn't need to take this step. Bullet fit is king and your .002" should be ideal if they chamber flawlessly sized .002" over groove diameter.

Notice the "key" words in the LASC page that Fredj posted . . . "Approximate" "minimum" etc. The formula 1422 X BHN is a guide, it is not a set in concrete law, it is intended to get you into the ballpark only. It is no more than one more thing for a boolit caster to look at. The LASC site is my web page and I wrote the casting pages with info from numerous resources and my own experiences.

I suggest you start with .002" over groove diameter and your clip-on WW clone alloy and see how things go. I'm willing to bet you'll be a happy camper without worrying about harder bullets. If you step up your 40 S&W loads closer to max you may or may not need to experiment with quenching.

Rick

[Jayhem]

You guys are an amazing community. I've been a member on a lot of different types of enthusiast forums and this one, by far, has the biggest group of helpful and eager to share information people I've encountered!

[cbrick]

Jayhem, this should give you enough reading to keep you busy for awhile.

LASC article index (http://www.lasc.us/ArticleIndex.htm)

Rick

[Bass Ackward]

Very simple question. As you go along you will see that it is not so easy an answer.

I have 22s that shoot pure lead at 1150. Elmer used 11 BHN exclusively in the 44 up to 1200 fps and 34,000 psi. But I have 45s that perform best with about 20 BHN at only 20k and 800 fps.

For every bullet design sold you will hear good reports and bad. Works for some people and not for others. Why?

Guys will buy mold after mold to try to get accuracy with what they methods they are using instead of looking at what a specific design requires.

Well, the same goes for hardness. The guy who keeps an open mind and is flexible enough not to succumb to patterns and tries everything is rewarded the most often. With all the combinations he is using he lets his gun tell him what is needed.

When it comes to cast, the only expert you will ever find is Professor Gun and his assistant Professor Target. And each gun can get a different lecture.

[yondering]

Things I've been reading on here recently has me wondering if chamber pressure isn't more important to issues with hardness than velocity. My .40 S&W will produce around 27,000 PSI even with light target loads of 175 gr TC's at 900 FPS while my .45 ACP will only be around 15,000 PSI at 800 FPS with 225gr RN boolits. Can both still use the same boolit alloy efficiently?

Exactly. I feel the .40 generally requires harder boolits than the .45, because of the higher chamber pressures, even when velocities are similar. I use mostly straight clip on ww alloy in the .40 for plinking. I've found better accuracy with HT or water dropped ww with full power .40 S&W loads, but you said that's not what you're after.

The short answer is, you have to try it for yourself to know for sure. Some here will recommend you shoot only soft boolits, some will recommend hard boolits, so you have to try it all in your application.

[KYCaster]

Things I've been reading on here recently has me wondering if chamber pressure isn't more important to issues with hardness than velocity. My .40 S&W will produce around 27,000 PSI even with light target loads of 175 gr TC's at 900 FPS while my .45 ACP will only be around 15,000 PSI at 800 FPS with 225gr RN boolits. Can both still use the same boolit alloy efficiently?


That's a pretty good observation, but you also need to consider the burn rate of your powder. A load of Bullseye that generates 27 Kpsi and a load of Unique or WSF at the same pressure may have very different results.

Jerry

[Bret4207]

Very simple question. As you go along you will see that it is not so easy an answer.

I have 22s that shoot pure lead at 1150. Elmer used 11 BHN exclusively in the 44 up to 1200 fps and 34,000 psi. But I have 45s that perform best with about 20 BHN at only 20k and 800 fps.

For every bullet design sold you will hear good reports and bad. Works for some people and not for others. Why?

Guys will buy mold after mold to try to get accuracy with what they methods they are using instead of looking at what a specific design requires.

Well, the same goes for hardness. The guy who keeps an open mind and is flexible enough not to succumb to patterns and tries everything is rewarded the most often. With all the combinations he is using he lets his gun tell him what is needed.

When it comes to cast, the only expert you will ever find is Professor Gun and his assistant Professor Target. And each gun can get a different lecture.

There ya go, that's the answer. There is no "ideal" across the board. The only ideal is what the gun and load want with that particular boolit. Instead of looking for an "ideal" one fits all idea, take what you have and make it work for you. Straight WW and a little added tin work for me from 600 fps to over 2K. Fit is king, everything else follows.

[Wireman134]

One other question. Can water dropping actually give me more hardness without the need to use more of my precious Antimony supply? If so, what is the lowest % of antimony in lead that water dropping can actually help the hardness?

Hello, there I'm doing the same, using my antimony sparingly averaging about 1.6% with both Sn and Sb. These boolits water dropped result in a Bhn around 13 plenty hard for my pistols. This mix air cooled for a few hours is 8 Bhn

[Jayhem]

Hello, there I'm doing the same, using my antimony sparingly averaging about 1.6% with both Sn and Sb. These boolits water dropped result in a Bhn around 13 plenty hard for my pistols. This mix air cooled for a few hours is 8 Bhn

That's good to know. I don't really have the time or knowledge (or need) with the amount of shooting I do to find wheel weights so I bought some roto metals 30% Antimony bars and plan to use them with the Tin I have an my stash of 500 lbs of pure lead. I'll try water dropping with 2% antimony and 1% Tin and work up from there if needed.