Hard Cast & Glock Algorithm

[duncanjk]

Good Morning All, I am a new member to this forum but not new to hand-gunning. This year, I have taken 3 pigs 80-300 lbs with my 10mm, Glock20 G4. What I have really struggled to understand is specifically, Hard Cast and how it interacts with Glocks.

There is lots of information on the web, much of it conflicting. so here is the question.. Please respond with Evidence Based Information not just opinions.

What is the algorithm for shooting cast from a Glock20?
ie.
Buffalo Bore 220- need aftermarket barrel(ie. KKM), need heavy recoil spring (<22lb recoil spring)
Underwood...
Double tap...

The idea is how to effectively use hard cast through a Glock with no or minimal modification, maintain safety and ensure proper function of the firearm. I would be using Hard cast specifically for defense against Hogs/ Coyotes/ Black Bears

Thank you

[sqlbullet]

Welcome aboard, and a solid question.  The answer is actually really straighforward, though often Glock fanboys don't like it.  (And for the record, my EDC is a Glock 20 or 29, and I also have a Glock 19 and 27 as well as 2 Glock 19/23 frames and a Glock 17/22 frame in build...So I am a fan).

The algorithm is very simple.  Cast bullets must measure groove diameter of the barrel of YOUR gun (not nominal for cartridge) + .0005"-.002" with the most accepted sweet spot being .001" over.

Nominal size for 40/10mm is .400, so most commercial cast bullets are sized .401".  But, go measure you Glock...I can wait.  It will measure between .401 and .402".  Both of my 10mm Glocks measure a healthy .402" groove to groove.  This means any lead bullet that measures .402" or less will almost certainly have accuracy destroying, and potentially dangerous, amounts of leading.  And...harder bullets won't help at all.  In fact, they will make it worse.

The reason under-sized bullets lead a barrel is due to plasma cutting.  Super heated and pressurized combustion gases escape the chamber/bore around an undersized bullet.  When those gases are contained, they can only carry so much heat to the base of the bullet before the vast mass of the bullet base compared to the tiny mass of the gas molecules next to the bullet base is normalized by entropy.  But once that pressurized gas finds a way to move past the sides, the fixed mass of the bullet is exposed to a constantly renewed stream of hot gas. 

The lead melts off the sides of the bullets and is left behind to cool in the bore.

The irony here is when people experience this that don't know the reasons leading occurs, they move to harder bullets.  This is wrong twice.

First, a soft bullet can "obturate" or deform by swelling to seal the bore if the amount it is undersized is small.  In fact, we kinda depend on this since barrels are not perfectly the same size from breech to muzzle.  The amount of pressure needed to obturate a bullet without permanently deforming it is a function of hardness, and harder bullets require more pressure to obturate.  As a result the solution to leading is often either MORE pressure or softer bullets, which is counter intuitive. 

An observed and repeatable experiment of this is to shoot hard cast bullets sized .401" in my EAA Witness full size with "practice loads".  175 grain LEE SWC bullets will lead with Blue Dot loads in the 1150 fps range, but switching to Unique fixes the issue.  Unique, as a faster powder, generates a higher peak pressure in these lighter loads, which obturates the bullets, sealing the bore and preventing leading.  Blue Dot, with it's slower burn rate, maintains a higher average pressure to make velocity, but does not see as high a peak pressure.  As a result the bullets don't obturate, gas blow-by occcurs and leading results.  Increasing to full power (and peak pressure) Blue Dot loads with these bullets also eliminates leading.

Second, pure lead, which is very soft, has the highest melting point of any of the commonly used lead alloys.  Pure lead melts at 621.5°F where some lead alloys like linotype melt nearly 160° cooler at 462°F.  Compared to the enormous heat carrying capacity of a plasma stream, this difference is minor, but is not to be ignored totally.

Getting away from the explanation of what the issue is and back to the solution for your Glock:

You need an aftermarket barrel that has a groove diameter of .400 or less.  Several of my 10mm handguns actually "slug" out at .399" and this will be common in some of the better barrels.  Most aftermarket barrels will be less than .401" and therefore should work fine with most commercial "hard cast" loads.

But...

You also need to pull a bullet or two from those loads and measure them.  Seating and, more often, crimping can reduce the as selected bullet diameter.  It doesn't matter how big it was going into the case, it matters how big it is when it hits the lands of your barrel.  If heavy loads are being over-crimped, then can actually be .400 or even .398-.399" when they hit the lands.

Revolver hunters have to worry about cylinder throats for the same reason.  Tight cylinder throats can reduce the diameter of the bullet before it reaches the rifling, resulting in poor performance.  Colt had some real issues with inconsistency in the throats of various SAA guns throughout the years.

Another option is to opt for powder coated bullets.  Heat transfer to the powder coat material protects the barrel from leading.  While I don't have a lot of solid information about this, I suspect when bullets are undersized, the powder coat material absorbs a bunch of energy being converted from a solid to a gas, and protects the sides of the bullet like an ablative armor during the trip down the barrel.

Finally, you can try casting, sizing and reloading your own bullets that are sized .402"+.  This presents a number of challenges to the reloader though.  First, there isn't alot of tooling out there for bullets that size.  You will end up having to enlarge a sizing die for sure, and most likely your mold won't drop bullets that big, so it will have to be enlarged by "beagling" (using aluminum tape on the mold face) or by lee-menting (creating a cherry from a cast bullet, drilling it and installing a shank, and then enlarging the mold using an abrasive like valve lapping compound, the home-made cherry and a drill). 

Even if you do get bullets that are sized .4025-.403", the next problem will be getting them loaded without reducing their size during seating or crimping.  Lyman makes tools that make this possible, but they aren't your standard reloading dies or steps. And the final issue is they resulting ammo may or may not chamber in your gun, due to the outside case dimensions at the mouth now being .002-.003" out of spec.

I would further opine...and this is definitely an opinion, that if you are hunting with a modern lead "hard cast" bullet in the BHN 22-24 range, you might as well just use an FMJ WFN.

The benefit of a "hard cast" bullet over an FMJ is it's ability to both penetrate and expand.  It doesn't open up as far or fast as a JHP, but a proper hard cast bullet in the BHN 12-16 range should both penetrate deeply and expand to about 25-50% original diameter at the nose.  And shed very little weight.  The reality of the 10mm is it just doesn't have the oomph to get a 22 BHN bullet to expand.

Of course, finding a nice WFN FMJ is quite the challenge, where as hard cast are available.  The the large flat nose and sharp transition to the ogive does hit hard and cut a nice hole in game.

If you want to shoot hardcast in your Glock with a factory barrel, get some of the new powder coated Underwood WFN hard cast.  If you don't want powder coated bullets, you might be able to roll your own (I load bullets sized .402, and they work without leading in my Glocks), but you probably should look to a Lone Wolf, KMM, barrel.  I would only replace the recoil spring IF I saw issues (excessive bulge, bolt over base FTF), though probably no real harm in stepping up to a 22 lb spring.

[The_Shadow]

duncanjk, also another welcome to the forum.    sqlbullet has done a amazing job here explaining the situation. 

Double Tap is the only one selling their cast bullets loaded with a gas check, Underwood and Buffalo Bore are not.

From my experience with my Glock factory barrels and my own cast bullets from older Wheel Weight alloy air cooled (probably 12-14 BHN), I size my bullets to 0.4015" in the STAR sizer where bullets are placed nose down entering the sizer die and pushed through on their base.  I am using White Label Lube's Carnauba Red rated at 2700+ fps as a quality lube.  The four bullet styles I cast have a beveled base which I think helps in the easier loading but also absorbs some of the heat generated and applied to the bullet's base.



Like mentioned about the seating and crimping, I am meticulous about handloading with attention to fully seating my bullets as not to squeeze them smaller in size and taper crimping is done on a separate step, to also take care not to squeeze these bullets any smaller while maintaining case neck tension.

With my bullets at this BHN and good powder choices, they tend to obturate better and even more as they are engaging the polygonal rifling of the Glock factory barrels.  It has worked well for me.

I also have various other barrels with cut rifling and they tend to be even better accuracy wise.  Many times I go to the range I'll use these aftermarket barrels Lonewolf and Storm Lake because of what they do offer for my needs. However I carry my Glocks with their factory barrels.

I am considering the polymer coating of my bullets, but haven't started that process as of yet because of the good results I get.

[MyAlias789]

I've got over 7k 200 gr. coated round nose lead bullets that chrony at 1160 FPS through my stock g40. This is my practice load.

My ideal woods load is a 200 gr WFN going 1200 FPS with current book load data. But to shoot quickly and accurately, I'm of the mindset that you gotta practice with recoil close to your performance ammo.

I back off just a bit on my practice load because my practice ammo is loaded on a progressive press.

The .401 sizing works for me but that's from a sample size of one. No leading and no signs of excessive pressure. Barrel only gets cleaned every 1k rounds now. Your mileage may vary.

I prefer the coated stuff as it doesn't throw that huge smoke screen you get with plain lead bullets.

From my experience a very large WFN meplat starts to bind in the Glock magazine if seated to an overall length >= 1.25". You can strip rounds off the mag with your thumb and actually feel the difference in spring tension. With such rounds I have to seat it deeper to get a reliable feed from the magazine which is not ideal as it decreases case capacity.


From my research on the castboolits forum a meplat of 0.30 will resolve that. A fellow that goes by the handle "Oreo" designed a bullet mold with a 0.30 meplat and it seems that quite a few folks were happy with. I haven't had the time to test this yet but maybe others here can chime in.

[4949shooter]

I have fired gas-checked Doubletap 230 grain and 200 grain hardcast bullets through my stock Glock 20 without an issue.

I like the idea of the powder coated bullets though. I might give the Underwood version a try.

[erdyalx]

The other option is to powder coat them. I fire PC bullets in 4 different 10mm Glocks with standard barrel. Velocities from my g40 are 1200+. I only replace the guide rod spring if there is to much case expansion. The Wolff spring pack is very handy. They are all sized .401 through a lee push through size. This pic is at 100 yards with my g40 an a 200 grain wfn.

Sent from my SM-G965U using Tapatalk

[climb14er]

My particular Glock 20SF initially had some problems feeding Underwood 220gr Hard Cast. I experimented with 22# recoil spring and a Tungsten guide rod, both given to me by a friend.  Continued to have issues with the 220gr H.C.

Went back to stock and have been using Double Tap 200gr Hard Cast with no problems feeding, extracting or lead fouling. I don't  shoot many rounds of lead HC at a session and typically near the end.

So... for the back country in Colorado, Wyoming and Montana, I load the DT 200gr H.C. and carry bear spray.

Good luck with your ammo choice and enjoy the 10mm.

[Rojo27]

So... for the back country in Colorado, Wyoming and Montana, I load the DT 200gr H.C. and carry bear spray.
Good luck with your ammo choice and enjoy the 10mm.

10mm 220gr & 230gr hardcast have a reputation for having issues tumbling or keyholing out of stock Glock barrel G20. 
Here is Hickok 45 documenting the issue several years ago:
https://www.youtube.com/watch?v=-m0satEkGjw
https://www.youtube.com/watch?v=dP96z_MCJHA

My Rocky Mountain back country kit contains the same key elements as climb14er's: G20,  Doubletap 200 wfngc, bear spray.
Have a 6" drop in KKM barrel for G20 that I've used for hunting and shot some 220gr hardcast through it but not enough reliability testing to make me comfortable enough to bet my life on it yet. 
Besides 200gr Double Tap WFNGC is very, good medicine even out of stock G20 barrel.   
   

[Jimbo_Poke]

So... for the back country in Colorado, Wyoming and Montana, I load the DT 200gr H.C. and carry bear spray.
Good luck with your ammo choice and enjoy the 10mm.

10mm 220gr & 230gr hardcast have a reputation for having issues tumbling or keyholing out of stock Glock barrel G20. 
Here is Hickok 45 documenting the issue several years ago:
https://www.youtube.com/watch?v=-m0satEkGjw
https://www.youtube.com/watch?v=dP96z_MCJHA

My Rocky Mountain back country kit contains the same key elements as climb14er's: G20,  Doubletap 200 wfngc, bear spray.
Have a 6" drop in KKM barrel for G20 that I've used for hunting and shot some 220gr hardcast through it but not enough reliability testing to make me comfortable enough to bet my life on it yet. 
Besides 200gr Double Tap WFNGC is very, good medicine even out of stock G20 barrel.   
   

I watched those videos as well.  While I really like Hickok 45, I have not yet experienced tumbling/keyholing like he did.  I have tested Double Tap 230gr and Underwood 220 gr and 200 gr out of a stock G20 G4.  I haven't had leading issues with either the Double Tap and the new hi-tek coating Underwood.  After shooting you will want to be sure and clean the barrel, but I do that anyway regardless of the cartridge and bullet I am shooting. 

I was just testing the DT 230 vs Underwood 200gr vs 220 gr two weekends ago against cinder blocks with 1 inch thick outer walls.  The DT 230 gr shattered the block, the Underwood 220 gr went through the front and back of the block leaving a clean hole through the front and shattering the back.  The 200 grain only penetrated the front wall of the cinder block.  For the tests I used 4 rounds of each and the results of each were very similar.  I was very impressed by the performance of the DT 230 gr, but I have had feeding issues with Double Tap in the past (though SIG FMJ rounds have been the worst strangely) while I have yet to have any feeding issues with the Underwood.  Based on these results when I am out and about in the Bighorns, I will be carrying the Underwood 220 grains, the performance difference between them and the 200 gr was significant enough in my mind.  In the end though I would just say test whatever you plan to carry and make sure it works for you.  A lot of info out on the internet now, but nothing beats doing tests and comparisons yourself.

Here is the 200 gr. Underwood



220gr Underwood




and 230 gr DT (note that the block did not just break from falling on the ground, it fell off the stand in pieces)