Gentlemen,
   I love my 10mm and have a "hankerin" to shoot some 200 grain projectiles. I also want to experiment with hard cast lead bullets.
What do I need to know venturing forward?

Barrel leading... Is it taken care of with regular maintenance? After shooting, clean the bore as usual?

Prob very important is the bore size.... usu lead bullets need to be .001 or so larger to prevent blow-by ( possible melting of lead which can cause lead buildup )
Also you can powder coat lead these days at home.


Cleaning for me after lead is a simple copper scrubby ( chore boy ) run thru the barrel a few times to remove any possible buildup

Afternoon slayer,
If these will be Shot from a Glock, you will want to look into an aftermarket barrel, KKM, or other. If it is not a Glock, just be certain you are removing any leading

Ken

slayer61, as tommac919 has mentioned bullet size plays an important part for lead alloy and lubed bullets.  I size my 10/40 cal at 0.4015" and lube with White Label's Carnauba Red with no issues in my G-20 or G-29 factory or any of the aftermarket barrels or any of my other 10mm firearms.  I have considered the powder coating process but haven' seen the need as of yet, but it is a great option.
I have several different molds for 10mm...

I have been casting bullets now for a good many years, and shoot cast bullets in guns ranging from mild 38 special loads to 300 Win Mag.  Here is my list if things to consider for success with cast bullets.

Fit is King

More important than hardness or velocity is fit.  The bullets must be as large or larger than the groove diameter of your gun.  Not the nominal diameter the gun should, the actual measured diameter.

If the bullet base doesn't seal the bore of the gun, then super heated expanding gas can pass around the bullet. As the gas passes the bullet it will liquefy and/or vaporize some of the lead which is then easily deposited on the bore of the gun. This is the worst kind of leading, as the lead was effectively soldered onto the bore, and is very difficult to remove.

Step one then, is to measure the actual groove diameter of your gun, and ensure that commercially cast bullets sized .401" are actually .001" over that size.  There are numerous videos on youtube on "slugging the bore", but the short version is get a soft lead fishing weight that is over .405" diameter, and section of 3/8" dowel and a rubber mallet, and beat the soft lead weight through the barrel.  Then measure it.

Too Hard?

If you are buying bullets, probably.  Hard cast bullets sell, and the harder the better.  But the truth is too much of a good thing isn't a good thing.

Size alone is not enough to seal the bore completely for the entire trip from one end to the other.  Your gun barrel will have minor imperfections and variances in tolerance.  A bullet that seals the bore at the breech and muzzle may not quite seal it in the middle.

We need a bullet that is soft enough that it flexes a bit at the base due to pressure, but not so soft that the base permanently changes shape.  The technical term is elastic deformation, but not plastic deformation.  If the bullet base isn't a little elastic, then it can't swell and keep the bore sealed as the groove diameter varies a bit.  But if the pressure is too high and bullet base deforms accuracy will go out the window, and you might "blow the seal" allowing hot gas by anyway.

Elmer Keith is well known for favoring hard cast bullets in his heavy six-gun loads.  He shot a 16:1 mix of lead and tin, which has a brinell hardness number of about 11, and to him this was very much a "hardcast" alloy.  And this is downright soft compared to most commercially hard-cast bullets you see today which tend to run between 18 and 22 bhn.

There are lots of internet arguments about how to calculate the right hardness to use and bullet casters get really invested in their personal system.  The Lee manual goes into some depths about using pressure/1422 to get good results, though for 10mm that would indicate a 26 BHN bullet.

You are going to be buying bullets, so you don't have nearly the control over BHN that a bullet caster does, but in general I would suggest you try to buy bullets more in the 16-18 bhn range.  I personally use air-cooled isotope lead that I have tested to be in the 14-16 range and have great results with this in a wide variety of gun, including my 10mm's.

Similarly with lube, your bullets will be pre-lubed.  Personally I prefer a medium soft lube like Felix Lube or Carnauba Red for a hard lube.

If all you can get is BHN 20-22, it will work, and I have such hard bullets with fine success.  But heavier loads work better with such bullets.

Which brings us to....

Velocity

Another old wives tale is that velocity has to be kept low.  I shoot cast bullets in my M1 Garand running 2000 fps and have shot cast bullets from my 300 win mag at higher velocities without leading issues.

The old wives tales are that leading was encountered, velocity was lowered and the leading issues disappeared.  Must have been the velocity right?

Probably not.  Velocity is a secondary measure.  It is determined by the average pressure on the bullet base during travel down the barrel.  When observe a reduced velocity from the same bullet, same gun then you have a lower average pressure.  Reducing pressure (and therefore velocity, temperature, amount of blow by, etc) can correct a bunch of issues.  But some of them can be correct other ways, including increasing pressure.

A common example of this in 10mm with hard cast bullets is mid-range loads that lead a gun where both lighter and heavier loads with the same bullet do not.  I encountered this early on in load development when I found that max loads with unique were fine, but light loads with blue dot that produced the same velocity leaded the barrel. Both were producing the same average pressure since the velocity was the same...So what's up?  I tried some lighter loads of Unique, velocity went down and leading went up.

What has happening is the unique max loads were peaking in pressure above the elastic range of my lead allow.  This bump the bullet base up to seal the bore.  Loads that did not briefly reach that pressure, like light blue dot loads that kept the overall pressure at the same level but with a lower peak, or light unique loads that just had lower pressure overall did not fully seal the bore and allowed blow-by.

If you are running 16+BHN bullets, expect some mild leading with less than max loads.  As you move up closer to max, it will probably reduce the leading while increasing the velocity.

Also, be aware that a given charge will deliver high pressure and velocity with a lead bullet than a jacketed bullet due to the lead bullet sealing the bore better.  You probabably will reach max velocity and pressure with a lower powder charge.

Glocks

I shoot lead bullets in my glock guns.  But Glocks are way over spec on groove diameter and I know that and cast and size (or rather don't size) my bullets accordingly (.403").  I also inspected barrels very frequently when I developed these loads to ensure I was not developing serious lead.  And I carefully copper scrub the barrels before I shoot lead to ensure there is no copper fouling to attract lead fouling.

And, I am kinda stupid, cause replacement barrels are cheap and easy to replace, so why not just play it save and KenK says.

It Leaded, Now What!

Learning to load lead bullets and working up loads is going to lead up a barrel at some point.  When that happens you need some copper chore boy and some Ed's Red.  You can buy Chore Boy at your local store or on Amazon.  Ed's Red can be bought from Brownells or you can just mix equal parts Acetone, ATF, Kerosene and Mineral Spirits yourself (in glass or metal as acetone may dissolve plastic). Pro-tip...A quart is four cups, quart jars are pretty common and your barrel will probably fit in one for an overnight soak if needed.

I hope that helps and welcome to the cast bullet addiction.

And THAT is why this is such a great forum! Thanks fellas. It sounds like my first task is to slug my barrel.

I won't be shooting these out of a Glock. This will be for the Kimber. (We only have 2 legal 10mm pistols here in California, well 3 if you count the G29)

Sorry in advance for hijacking this thread a little. I've shot cast lead in plenty of pistols and pistol caliber carbines, but I never considered it in .300 Win Mag. Sqlbullet, was this a proof of concept endeavor, accuracy test, hunting application? Please share some details on this.

It was a "Gee, let's see what happens" more than anything.

I shoot lots of .309 200 grain gas checked bullets in my M1 Garands.  These are cast in a 311299 mold from NOE, or from a Lee 200 grain mold that is similar, but not quite the same nose.

While searching for deals years back I picked up 32 lbs of surplus WC872 powder and then one day thought, I wonder how those heavy 30 caliber cast bullets would run in my 300 win mag.

The answer is about 4 MOA at a paced off 100 yards shooting off a table I hauled out to the desert.  At least with no real load development.  Just a case full of WC872, I think 73 grains,  and a 200 grain gas checked bullet.  I never chronographed this load, but the data seemed to suggest this would be a 2700-2800 fps load.  I had very minimal leading, certainly nothing that I was concerned about impacting accuracy or pressure.  Couple of patches with Ed's Red and the bore looked pristine again.

The gun is a Remington 700 PSS with the HS precision stock, topped with a Bushnell Elite 3200 10X fixed scope.  It is very much a range gun and not a lug around the hills chasing elk gun.  And it shoots 1 MOA with a good load using the 50 shot NRA testing protocol.

In the end after loading up about 100 rounds I decided that cast bullets were viable but I don't go shoot 250 rounds of 300 win mag on a Saturday for fun, and could therefore afford to buy jacketed projectiles.  If availability of bullets every tanks, I can re-visit this.  I think if I were to actually work at it I could get this down to a 1.5-2 MOA shooter with gas checked cast bullets.  All the tricks like weighing each bullet, manually pre-seating gas checks, probably a harder lube like Carnauba Red, and then dialing in the charge weight.

So I guess it was just a basic POC.  And the desire to say I had pushed a cast bullet to real rifle velocity.

sqlbullet, have you loaded that NOE 311299 200 grain in 308 Winchester?  Looks like a great bullet for long range play...

Thanks for the explanation. I've had those "I wonder if I can get this to work" projects, too.

Quote from: The_Shadow on August 07 2019 08:51:57 PM MDT
sqlbullet, have you loaded that NOE 311299 200 grain in 308 Winchester?  Looks like a great bullet for long range play...

I loaded some 308 loads using that bullet for my CETME.  I had issues with reliable powder ignition, possibly due to the powder being contaminated with bullet lube.  I have never really gotten back to this, but I would like to.  I bought the CETME specifically to shoot cast bullets in 308.

Thank you for that response sqlbullet!  I'll order me one soon for my 30 cal guns, very nice mold.

https://www.buffalobore.com/index.php?l=product_list&c=59

hard cast won't fowl.

Hi
Shot some 200 grainers from an RCBS mold out of a Glock/KKM 4.6" barrel. Had very good results with Blue Dot and Unique.  But every gun is different so don't be afraid to experiment.  Bullet was sized at .401".  Mix is 50/50% Lino/Wheelweights.
The Lonshot load was the fastest and was nothing to sneeze at either..

It still amazes me at the accuracy that is obtainable with Blue Dot. I have seen this in 44 magnum' spl, 357 magnum, 38 spl,10mm, 40S&W, 9mm, 357Sig, even the 9x25 Dillon and it was always fantastic in 12 gauge loadings.