Polygonal barrels and cast

[fecmech]

Gentelmen--Have any of you had experience with shooting cast in polygonal barrels, I've heard of problems with Glocks and blow ups but I've also heard it can be done safely. My reason for asking is that I sure do like the little Kahr 9mm and I sure don't want to shoot "J" bullets. Nick

 

[stans]

There are a few reasons why Glocks blow up. First, the chamber, especially the 40 S&W, offers very little support to the cartridge case head. Second, since there is so little support, cases tend to bulge a bit upon firing. Then the reloader resizes them and removes the bulge. Everytime this happens, the brass work hardens a little more, this creates a weak spot in the case head. Third, the polygonal barrels do seem to lead a little more than conventionally rifled barrels. If this lead is not cleaned out regularly, pressures can get out of hand, especially if the shooter decides to clean out all of that lead by firing a full powered jacketed round.

You can shoot lead in polygonal barrels, just brush out (not shoot out) the lead frequently.

 

[Joe D]

I decided to try and validate the lead bullet/Glock issue recently. My wife and I shoot several hundred rounds a week through her G34 and my G35. I purchased a Federal 9mm barrel for my G35 so I could use lead 9mm bullets for practice.
I used lead 9mm bullets from Magnus and Valiant. Weight was 122-125 gr. Velocity ran a little over 1000 fps.
The conventional rifling of the Federal required some effort to remove the lead build up. The Glock 34 barrel had little to no leading after 400 rds. One pass with a brass brush and a couple of Hoppes #9 soaked patches cleaned the G34 barrel to a spotless condition.
The Federal barrel will probably get better as it smooths up. I just fill the bore with 50/50 peroxide and vinegar for 15 mins and the lead comes out cleanly now.

 

[M2 Carbine]

I've got a couple H&K P9S pistols that have the polygonal barrels.

9mm and 45ACP

I've been shooting cast bullets for years with no problems
and getting excellent accuracy.

I agree in theory "shooting out the lead" with a jacketed bullet sounds like a bad idea.
But since I've been running a magazine of hardball through my pistols at the end of the day, for 40+ years, I'll probably keep on doing it.
Especially since I don't own any Glocks

 

[Sean Smith]

http://www.thefiringline.com/forums/showthread.php?threadid=82

http://markco.gunsnet.net/glockKB.html

 

[Joe D]

I have asked Markco several times on another forum to show me actual data on his findings. I also asked what test barrels and transducers he was using to record his data with. So far I have never received this information.
The kaboom hysteria surrounding Glocks has hopefully been put to rest by now. Everything I have been able to read and personally observe indicate that case ruptures occur just as frequently in other makes. There are just a lot more Glocks in use. As I recall there was also an issue with some Speer factory ammo with weak brass that caused lots of kabooms in Glocks and other makes. I have seen 1911s, Sigs and HKs blow up. 99% of the time it is shooter reloading problems.
Perhaps there could be leading issues in Glocks if very soft lead bullets were used.

 

[1911Tuner]

Cast Bullets

The main issue with traditional cast lead bullets in a polygonal barrel is
that the lube can't get into the barrel to forestall leading. The lube groove
requires conventional rifling to cut into them and pick up the lube.

Cast bullets that are tumble lubed in liquid alox are messier to handle, but will get the lube where it needs to go. I'd also suggest swaged lead bullets with a light film of liquid alox. Contrary to popular belief, the
rock-hard bullets can actually promote leading because the bullet doesn't
upset and seal the gasses off. Flame and gas cutting along the side of
the bullet will deposit lead as efficiently as a soldering iron, while friction
leading leaves a coating of lead "wash" that is easily removed.
Super hard bullets don't negate leading. The main reason for hardness is to insure that the bullet takes the rifling without skidding across it.

The other factor in leading comes from the melted lead at the bullet base
being deposited in the bore. Solder again...and the higher the tin content
of the alloy, the tighter the bond between bullet metal and barrel steel.

If you really want to shoot cast bullets in a polygonal barrel, the best route to take is probably a gas-check on the base of a tumble-lubed bullet. The
lead wash that results wouldn't be a major factor in driving pressure off
the scale. I cast .30 caliber rifle bullets for use in a .308 caliber bolt-rifle,
and have been driving the 180-grain gas-checked bullets to top velocity for the weight...about 2500 fps...with no leading beyond a light wash that
can be removed with 4 or 5 passes with a wet brush and a dry patch.

Gas checks require a bullet that's designed for them, and they are a little more trouble because of the extra step involved in seating them onto the
bullet, but you can get jacketed bullet performance for about 3-4 cents
per bullet, depending on how much you pay for your scrap lead.


Where there's a will, there's a way...

Tuner

 

[Joe D]

You are correct concerning bullets that are too hard. I recovered several fired bullets from the G34 that had clear cut rifling marks in them. I think conventional lube is also deposited buy the rotational forces exerted on the lube as the bullet passes through the barrel.

 

[1911Tuner]

Rotation

Joe D said:

I think conventional lube is also deposited buy the rotational forces exerted on the lube as the bullet passes through the barrel.
--------------------------------

Probably so, but probably not enough to have much effect unless the
lube is soft. Lyman Black magic would be soft enough. The harder
lubes...not likely. It would be interesting to conduct a test to find out.
My stepson has a USP that he may be willin' to donate the use of in
the interest of science. He's shot some conventional cast bullets in it
without a problem until around the 100 mark..As the lead smearing
started to get to the halfway point in the barrel, he started getting signs of
pressure. The load was 5 grains of Alliant Red Dot and a 234 grain
bullet cast from wheelweights with a half-pound of 50/50 solder added
per ten pound pot. Fairly soft compared to Lyman #2 alloy.

Another approach that works for me is to simply shoot a jacketed bullet
through every other magazine with conventional rifling One in every magazine might work best to clear a polygonal bore.

Tuner

 

[JohnKSa]

JoeD,

Handle your used peroxide/vinegar solution with caution. Lead oxide combines with vinegar to make lead acetate which is a rather potent poison with the added unpleasant feature that it can be absorbed through the skin.

fecmech,

Your best solution is to ask Kahr for an answer. For some reason some people on the web are really dead set on shooting lead bullets in polygonal barrels in spite of what seems to be a lot of pretty well documented advice against it. The really odd thing is that they're usually not content to just shoot lead in their own guns, they tend to be really zealous about making "converts". See what the manufacturer says--after all, I doubt anyone on this forum is going to replace your gun if it blows after following their advice.

BTW, at least one manufacturer says to NEVER shoot jacketed bullets through a barrel that has had lead bullets shot in it until the barrel has been "thoroughly deleaded". It's Beretta--and they don't even sells guns with polygonal rifling. IMO, if they think it's a problem in conventional rifling, it's probably a much worse idea in polygonal rifling.

 

[P95Carry]

BTW, at least one manufacturer says to NEVER shoot jacketed bullets through a barrel that has had lead bullets shot in it until the barrel has been "thoroughly deleaded".

MY contention John .. exactly.

I ask people to consider ....... imagine ..... that there is a lead fillet sitting against the driving side of each land ... and that when you send ''Mr Jacket'' down the tube, it has perforce to try and shove this obstruction out of the way. That I consider is not easy and almost for sure will lead to higher pressures. Whether over pressure, per se is a moot point but .. I never would recommend it. I de-lead my pieces after lead shooting - thoroughly - before resuming jackets.

Many people seem very cavalier about this - always using jackets to ''de-lead'' the barrel. Not for me!!

 

[Joe D]

I never have tried to use a jacketed bullet to clean lead from a barrel. It would seem to me this would tend to make the lead harder to remove. Thanks for the tip on the 50/50 solution, but I am very careful with lead in any form. I even wear a mask when I empty my tumbler after cleaning brass.

 

[stans]

For a brief period of time I used jacketed rounds to de-lead my 45 ACP 1911's. I don't dare do this now, I realize that the pressures go up when you do this and the jacket does not scrape out the lead, it just irons it into the pores of the barrel and puts a coating of copper over the whole mess. This becomes a real problem to clean out! The cheapest and easiest way to get lead out of a barrel is to wrap a piece of copper mesh Chore Boy around an old bore brush and pass it through a dry barrel. This will usually take lead out in chuncks!

 

[fecmech]

Thanks for the info guys, I planned on contacting Kahr but I figure that Lawyer speak will be the only thing I'll hear. I shoot 10 to 15k rds a year thru my handguns and it's all cast, actually if you use well fitted and lubed bullets at handgun velocities there is no leading to speak of. In cases where you get leading due to size , hardness or lube problems shooting jacketed rounds to clean the barrel is not something I would do. Nick

 

[billw_willy]

Joe D,
Do you have a website for Valient Bullets?
Bill

 

[Shadow 7D]

If you want to shoot cast in poly barrels can you plate your own?

Plating isn't that hard, hell you could probably use some old plumbing scrap to feed you tank and a cell phone charger for a power source.

 

[fecmech]

Boy this is an old post! BTW the Khar That I had many years ago is gone but I did put about 3500 cast bullets through it before I sold it with no problems what so ever. The gun did not lead and was very accurate with them. I sold the gun simply because I was done playing with it. I did talk to the owner of Khar at the time and he did not make a big deal out of reloads or the cast bullets. He was quite interested in how well the gun shot them. I think if you are a knowledgeable cast bullet shooter and make sure you have no leading issues cast is good in any barrel. If you are just some fellow buying bullets that may be undersize for your barrel or a lube that does not do the job you may be better off shooting jacketed or plated.

 

[rcmodel]

If you want to shoot cast in poly barrels can you plate your own?

Not unless you can come up with undersize cast bullet molds to make undersize bullets you can plate.

All commercial molds cast bore or oversize bullets, and adding an electroplated jacket to them makes them even bigger.

rc