Hardness on a Checked Bullet

studman5578 · August 24, 2011, 12:43 AM

So I am planning on loading 45/70 in the near future, and am going to put a GC on it. From my understanding, the gas check's job is to simulate that of a copper jacket and allow the use of cast at higher pressure loads.

Would the alloy used need to be very hard if a GC was used? Obviously hardening the bullet to what it would be without a gas check isn't required, as that would defeat the purpose of the check, but logic would dictate (mine atleast, and it has proven to be lacking on more than one occasion

), that the sides of the bullet would shear off from the stress of the rifling. Any thoughts? Anybody worked with the hardness in a checked bullet at high vel. rifle loads?

For that matter, if the check is doing a good job of keeping the bullet from leading in higher velocity loads, couldn't I just check pure lead bullets for use in my 9mm loads rather than alloy my lead up to the proper hardness (at a cost to me of about $10 per 500 rounds of 124 gr). Any help is greatly appreciated as always!

Ideal Tool · August 24, 2011, 01:10 AM

Hello, studman..Your giving that little copper cup way more credit than it deserves. The gas check could be thought of as a wrench..giving additional purchase on the rifling than just the soft surface skin of a lead bullet. And while it does protect the vulnerable lead base from hot powder gasses, the sides of the bullet are still very much in contact with the bore & using a too soft alloy..even with a check will give you a bore full of lead. The best you can expect is a bit over 2000fps. with lino & gas checks plus a very good lube. If you want high velocity with pure or nearly so lead..you'll have to paper-patch. This acts just like a jacketed bullet..a barrier to friction between lead & bore.

GP100man · August 24, 2011, 05:50 AM

To add to Ideal Tools comment , the bullet still has to be hard enuff to grab the rifling & start spinning ,the check helps this to happen but only after it enters the throat far enuff. The checks main job is to protect the base from deformation from pressure distortion.

Here`s a pic of a typical chamber throat ,barrel .

The free bore is the area we have to work with , some seat to it some seat off of it . Typically we tend to think we need to seat to it ,but not always !!

reloader28 · August 24, 2011, 08:25 AM

I've noticed that if I use straight WW alloy with a plain base boolit, I can go to about 15000-16000psi before leading the barrel and losing accuracy.
If I use a gas check boolit with the same alloy and hardness, I can run it around 29000-30000psi.
Everything may vary a little, but this is pretty close. I have a hardness tester, but I dont have a pressure tester, but it takes a certain pressure to make a certain speed, so with a chrono you can tell pretty close.

This might not have anything to do with anything at all, but I've come to keep tabs on psi the last couple years and load this way, and it works pretty good for me. Some people that have been doing cast alot longer may find something completely different. I've still alot to learn.

BTW, we've been running max loads in 9mm with air cooled WW and Bullseye powder. We use a plain base gas check on the boolit, and it works great. No leading and great accuracy. Before, it didnt matter what we tried, it leaded the barrel.

studman5578 · August 24, 2011, 02:43 PM

Ideal Tool - Paper patching huh? I hadn't considered that. I'll have to do some research and see if it suits my needs. Do you paper patch? If so, can you give a bit of an explanation how it affects your casting process? Thanks!

thanks for the pic GP100man.

reloader28 - I've been having leading problems in my 9mm with my first batch of cast boolits. I'm currently trying to work myself one of the freechex devices (making your own GC out of aluminum for a materials cost of about 5% of factory price) and plan on putting GC on my 9mm loads. you said plain base gas check, that would mean you're talking boolits from a mold that doesn't have a GC shank cut into it and crimping them on? What sizing & crimping method do you use? Thanks!

hornetguy · August 25, 2011, 08:03 AM

First off, I'm not a ballistician.. (and I don't play one on TV

)

I DO read a lot, though, and I've read some enlightening things lately on shooting cast lead bullets (boolits, if you prefer).
I will share them as I read them.. don't mean to start any shovin matches.

A gas-check is just what the name implies... it is a "check", or a stop, for the hot gases created when firing the cartridge. It keeps the gases from blowing past the base of the bullet, melting the lead as it goes. It creates a flat, consistent surface, with a good seal to the bore to accomplish that.

Leading is NOT caused by the base of the bullet melting. People have used "gas-checks" cut out of thin wax, then recovered the bullets with wax still intact, unmelted, on the base. If the gases don't melt the wax, it certainly won't melt the lead base.

Leading is usually caused by (1) gas blow-by (2) incorrect, insufficient bullet lube

Hardness of bullet alloy is not quite as important as most people think. Harder is NOT always better. Bullet alloy that is soft enough to allow bullet obturation (swelling to fit the bore) is highly desirable. If the bullet can't obturate, you get gas blow-by. Not good. Too hard an alloy is also usually too brittle to hold together for penetration, and will "shatter" or break up when hitting bone.

Like I said, these are just a few of the things I've run across that punctured a LOT of the "fact balloons" I'd been told as I got into shooting cast bullets.
Open for discussion...

dahermit · August 25, 2011, 09:23 AM

Quote:

...The gas check could be thought of as a wrench..giving additional purchase on the rifling than just the soft surface skin of a lead bullet...

I disagree. In regard to the old Ideal/Lyman type gas checks, they did not crimp onto the bullets like the more modern Hornady/RCBS gas checks. The Ideal/Lymans were not securely attached to the bullets enough to "act as a wench". If the check was turned by the rifling it was too loose to put any rotational forces on the bullet as a result. The checks were so loose (prior to crimp-ons), it was common for them to fall off during normal handling.

dahermit · August 25, 2011, 09:29 AM

Quote:

...So I am planning on loading 45/70 in the near future...

I do not know which 45-70 you have, what you are intending to do with it. But, for hunting, I would use a plain base soft bullet at modest velocity. For target, I would join the Cast Lead Bullet Association thereby getting access to the "Fouling Shot", and their data and developments for target shooting loads for the 45-70. On this forum, you will get mostly opinions...from the CBA resources you can get tested data.

dahermit · August 25, 2011, 09:37 AM

Quote:

...Hardness of bullet alloy is not quite as important as most people think. Harder is NOT always better. Bullet alloy that is soft enough to allow bullet obturation (swelling to fit the bore) is highly desirable...

That has been my experiance also. For instance, I had a Winchester "Legondary Frountiersman", that was chambered in 38-55 with the original specification of .379 bore. My bullet mold would not cast anything larger than .376 diameter bullets, despite being intended for the 38-55. I found that the accuracy was poor even if the bullets were shot unsized, only lubed. I switched to a very soft alloy, and found that the bullets would obturate and fill the bore despite being cast undersize and my group size shrank to the size which would be considered acceptable for hunting with a '94 lever-action.

reloader28 · August 26, 2011, 08:25 AM

Studman, my mold is a plain base design. The gas checks are from aluminum pop cans.

Size and lube the boolit exactly like normal. Then put a check on it and run it thru one more pass and your done.
Piece of cake.

August 24, 2011, 12:43 AM	#1
studman5578 Senior Member Join Date: March 4, 2009 Location: Varying between 1 and 3 hours from Chicago Posts: 152	Hardness on a Checked Bullet So I am planning on loading 45/70 in the near future, and am going to put a GC on it. From my understanding, the gas check's job is to simulate that of a copper jacket and allow the use of cast at higher pressure loads. Would the alloy used need to be very hard if a GC was used? Obviously hardening the bullet to what it would be without a gas check isn't required, as that would defeat the purpose of the check, but logic would dictate (mine atleast, and it has proven to be lacking on more than one occasion ), that the sides of the bullet would shear off from the stress of the rifling. Any thoughts? Anybody worked with the hardness in a checked bullet at high vel. rifle loads? For that matter, if the check is doing a good job of keeping the bullet from leading in higher velocity loads, couldn't I just check pure lead bullets for use in my 9mm loads rather than alloy my lead up to the proper hardness (at a cost to me of about $10 per 500 rounds of 124 gr). Any help is greatly appreciated as always! __________________ Rev 5:13 "To him who sits on the throne and the Lamb be praise honor and glory and power, for ever and ever" Last edited by Shane Tuttle; August 24, 2011 at 07:22 AM. Reason: BULLET, not boolit

August 24, 2011, 05:50 AM	#3
GP100man Senior Member Join Date: August 1, 2007 Location: Tabor City , NC. Posts: 1,969	To add to Ideal Tools comment , the bullet still has to be hard enuff to grab the rifling & start spinning ,the check helps this to happen but only after it enters the throat far enuff. The checks main job is to protect the base from deformation from pressure distortion. Here`s a pic of a typical chamber throat ,barrel . The free bore is the area we have to work with , some seat to it some seat off of it . Typically we tend to think we need to seat to it ,but not always !! __________________ GP100man

August 24, 2011, 08:25 AM	#4
reloader28 Senior Member Join Date: October 13, 2009 Location: nw wyoming Posts: 1,061	I've noticed that if I use straight WW alloy with a plain base boolit, I can go to about 15000-16000psi before leading the barrel and losing accuracy. If I use a gas check boolit with the same alloy and hardness, I can run it around 29000-30000psi. Everything may vary a little, but this is pretty close. I have a hardness tester, but I dont have a pressure tester, but it takes a certain pressure to make a certain speed, so with a chrono you can tell pretty close. This might not have anything to do with anything at all, but I've come to keep tabs on psi the last couple years and load this way, and it works pretty good for me. Some people that have been doing cast alot longer may find something completely different. I've still alot to learn. BTW, we've been running max loads in 9mm with air cooled WW and Bullseye powder. We use a plain base gas check on the boolit, and it works great. No leading and great accuracy. Before, it didnt matter what we tried, it leaded the barrel. Last edited by reloader28; August 24, 2011 at 08:31 AM.

August 24, 2011, 02:43 PM	#5
studman5578 Senior Member Join Date: March 4, 2009 Location: Varying between 1 and 3 hours from Chicago Posts: 152	Ideal Tool - Paper patching huh? I hadn't considered that. I'll have to do some research and see if it suits my needs. Do you paper patch? If so, can you give a bit of an explanation how it affects your casting process? Thanks! thanks for the pic GP100man. reloader28 - I've been having leading problems in my 9mm with my first batch of cast boolits. I'm currently trying to work myself one of the freechex devices (making your own GC out of aluminum for a materials cost of about 5% of factory price) and plan on putting GC on my 9mm loads. you said plain base gas check, that would mean you're talking boolits from a mold that doesn't have a GC shank cut into it and crimping them on? What sizing & crimping method do you use? Thanks! __________________ Rev 5:13 "To him who sits on the throne and the Lamb be praise honor and glory and power, for ever and ever"

August 24, 2011, 01:10 AM	#2
Ideal Tool Junior member Join Date: October 6, 2010 Location: Michigan Posts: 1,080	Hello, studman..Your giving that little copper cup way more credit than it deserves. The gas check could be thought of as a wrench..giving additional purchase on the rifling than just the soft surface skin of a lead bullet. And while it does protect the vulnerable lead base from hot powder gasses, the sides of the bullet are still very much in contact with the bore & using a too soft alloy..even with a check will give you a bore full of lead. The best you can expect is a bit over 2000fps. with lino & gas checks plus a very good lube. If you want high velocity with pure or nearly so lead..you'll have to paper-patch. This acts just like a jacketed bullet..a barrier to friction between lead & bore.

August 25, 2011, 08:03 AM	#6
hornetguy Senior Member Join Date: January 14, 2011 Location: on the north side of DFW Posts: 970	First off, I'm not a ballistician.. (and I don't play one on TV ) I DO read a lot, though, and I've read some enlightening things lately on shooting cast lead bullets (boolits, if you prefer). I will share them as I read them.. don't mean to start any shovin matches. A gas-check is just what the name implies... it is a "check", or a stop, for the hot gases created when firing the cartridge. It keeps the gases from blowing past the base of the bullet, melting the lead as it goes. It creates a flat, consistent surface, with a good seal to the bore to accomplish that. Leading is NOT caused by the base of the bullet melting. People have used "gas-checks" cut out of thin wax, then recovered the bullets with wax still intact, unmelted, on the base. If the gases don't melt the wax, it certainly won't melt the lead base. Leading is usually caused by (1) gas blow-by (2) incorrect, insufficient bullet lube Hardness of bullet alloy is not quite as important as most people think. Harder is NOT always better. Bullet alloy that is soft enough to allow bullet obturation (swelling to fit the bore) is highly desirable. If the bullet can't obturate, you get gas blow-by. Not good. Too hard an alloy is also usually too brittle to hold together for penetration, and will "shatter" or break up when hitting bone. Like I said, these are just a few of the things I've run across that punctured a LOT of the "fact balloons" I'd been told as I got into shooting cast bullets. Open for discussion...

August 26, 2011, 08:25 AM	#10
reloader28 Senior Member Join Date: October 13, 2009 Location: nw wyoming Posts: 1,061	Studman, my mold is a plain base design. The gas checks are from aluminum pop cans. Size and lube the boolit exactly like normal. Then put a check on it and run it thru one more pass and your done. Piece of cake.