Plain Base Gas Checks

[longbow]

What sort of velocities are you getting in rifle?

I tend to shoot mostly PB boolits in my .303's and generally am pretty happy with results but I am wondering what the velocity limit of the PB checks is. Same as regular checks or lower?

I am wondering in regards to pressure and velocity since they are so thin. There are few handguns running pressures potentially as high as rifle loads with the exception of .460 S&W, .500 S&W, .454 Casull and maybe a few others but even there I have not seen postings of results at upper end velocities and pressures.

Just curious as I am thinking of buying or making a PB check maker for my .303's to push velocity some.

Longbow

[JonB_in_Glencoe]

My 2¢,
I'm thinking that PB GC's tend too get applied best with softer alloy's, which are not conducive to rifle velocities. It's challenging, to say the least, to size and apply a PB GC, to a alloy as hard as aged COWW or harder without tearing or smearing the GC.

[reed1911]

I honestly do not use hard alloys (at least what I call hard +20) Most of my shooting is done with 10-ish in pistol and 15-ish in rifle. So with that I do not have any issues with the checks. If I am going to full load I'm generally shooting GC design anyway, but still I use soft alloys. I'm more often than not shooting single shot so I don't need the hardness for dealing with the feed ramp, and I've not had any leading yet. I'm not shooting 3K FPS either, most of my shooting takes place 2000FPS or slower.
As for the velocity limit, I don't know if there really is one to speak of, at least in terms of what you will be accurate with. What I mean is, I think you will loose a lot of accuracy before you get to the point that you are exceeding the material strength of the check itself. I've never seen a difference between Al vs Cu checks at my velocities. Copper checks seem to be the crimp on style so if the bullet is going to be below the case neck I select them. If the bullet is going to be in the neck I'll opt for an Al check unless I happen to have a bunch ready that just happen to have a Cu check on them. One thing to note, the PB-GC will fly off shortly after leaving the barrel. As to what if any effect that has on your shooting, well we could argue it here for hours on both sides of the idea. No side here, just something to note.

[JonB_in_Glencoe]

I comments are based in my personal experience, others may have had better experiences.

When I was trying to put a Patmarlins PB GC made from popcan metal on a 41 cal boolit that was cast with COWW and aged and measured about 13 or 14 BHN...the GC would smear or tear...if I applied that GC to range scrap (BHN=9), no problems at all.

Now, as to Rifle, my thinking is about the pressure, not the speed. If the load's pressure is higher than the Maximum chamber pressure for that a given alloy (chart in this link), the accuracy gained from a popcan GC would be minuscule to the accuracy loss due to slump.
http://www.lasc.us/CastBulletNotes.htm

So that is my reasoning for thinking a popcan metal PB GC on a rifle boolit would probably be a waste of time.

[reed1911]

Okay, I had to look it up so I understood what Jon was referring to:

Bullet "slump" - the change in shape of a bullet due to the acceleration and pressure forces acting on the bullet

An outstanding point really; and while I do not disagree, I've never had the problem or if I have I've dismissed it as something else.
I don't use super fast powders in my rifle loads so I suspect that my boolits are moving before a peak pressure can impact the bullet much. I've certainly had accuracy go bye-bye at certain speeds, and it certainly may have been slump that caused it.

[outdoorfan]

Maybe a little off topic but can anyone tell me how well PB checks work at rifle velocities? I am thinking .30 cal. at 2000 FPS+/- a bit.

I am seeing lots of posts about PB checks for handgun boolits but not for rifles... or at least at higher end velocities.

Thanks,
Longbow

I don't use conventional gas checked bullets anymore, not even for rifles. I only use pb bullets with a pb check on them. My results with .35 caliber rifles at 1800-2000 fps is very good.

[longbow]

I have experienced:

- "skidding" in my .303's where the grooves in the boolit are wider than the lands due to lead swaging from inertia (rotational acceleration in the rifling faster than yield strength of lead will stand) resulting in gas leakage and poor accuracy. Oven heat treating the boolits to very hard solved that at same load level.

- boolit slump in my .44 mag Marlin where the lube grooves of several Lyman 429421's collapsed due to pressure exceeding the yield strength of the lead.

Recovered boolits all tell a story!

In both cases these were PB boolits though so no telling what use of either standard GC equivalent boolit or PB check on same boolits would result in without side by side testing. Since I don't have an equivalent GC boolit in .44 and don't have PB checks for .303 I can't compare.

I may make a simple PB check maker for the .303 to try out. I made one for standard gas checks.

I am just curious if anyone else has run the PB check up in pressure and velocity in rifles with success at least equivalent to the limit of regular checks.

I am also thinking that .30 cal. PB checks would be easier to apply than larger calibers like .44 or .45 even on hard alloys. Smearing or tearing might still be an issue but lube and mirror finish dies should take care of that. Actual effort to do with the smaller diameter should be less.

Longbow

[outdoorfan]

Most of my experience with pb checks has been with softish alloy (9-14 bhn). Accuracy has been quite good at 1800-2000 fps. I have experimented with up to 20-22 bhn, and I didn't have any trouble applying the pb checks through a Lee push through sizer. I always pre-size the bullets before attaching the checks.

[longbow]

What calibers are you doing this with?

[Tailhunter]

I still get some smearing and tearing while applying pb checks. Hard alloys seem to eat them up.
Mine is a .44 mag
I am using a lube on them before sizing and presizing the bullet.
Softer bullets is the key.

[hickfu]

When I first got my PM check maker, I tried pop cans and they smeared. I then tried coil and foil and they smeared... Had to step back and think for a minute, checked the hardness on my alloy (water dropped) and it was 23. Checked the Lee push through sizing die (really needs to be polished up...) so I cast up some boolits with the alloy air cooled and used my 4500 and they went on perfect. I really need to polish up the sizing die so I can put them on without lube and heat treat back to the bhn I want for rifle.

[bstone5]

I use the 92-6-2 alloy and with a little lube the PB gas checks made from POP cans go on fine.

For hard rifle bullets some Lino and recovered shot is adder so the rifle bullets will age to a harder number.

Lately all of the PB gas checks for pistol bullets are being made from the .008 thick aluminum roof flashing, this material is thicker and is crimped deeper when going thru the Lee sizing die.

The roof flashing is really tight on the cast bullets.

For the 44 and 45 plain base bullets I still use POP can material, the gas ckeck is tall and hold well when made with POP can material.

All of the gas check makers are made on my lathe.

The factory checks are short an not very deep, the taller home made checks seem to work better.

[longbow]

Getting off topic here but... what check maker plans did you use?

[outdoorfan]

What calibers are you doing this with?

At this point, only .35 caliber.

[bstone5]

The plans came from this site, I can send the plans they are in a PDF made some years back.

If I remember correctly Ed Smith from Maine put the plans together. Ed is a little older and has some health issues.

If interested send a PM with contact info.

bstone5

[longbow]

Yes, I know those plans. I downloaded then some time ago but have not gotten around to making one yet. I made a crude hammer type punch and die that work quite well. Not much to look at but the checks are very good.

I heard Ed was having health problems but have not heard how he is doing at all. It was a nice set of plans he shared and very generous of him to do it. I hope things are going well for him.

If outdoorfan is pushing .35 cal. boolits to 2000 FPS with PB checks that about answers my question. I have to think .30 cal. will get there too.

Longbow

[tygar]

I've had no good luck at all with the Sage PB GCs. 40, 44, 45, none work, all tear, none will fit.

After reading here, I'll try a softer bullet as I usually use COWWs or harder.

[Seeker]

I've had no good luck at all with the Sage PB GCs. 40, 44, 45, none work, all tear, none will fit.

After reading here, I'll try a softer bullet as I usually use COWWs or harder.

tygar, I don't load for 44 and have not tried lead in my 40, but I've used a lot for my 45s with excellent results. I had a batch of sages when I first started using PBs that tore and smeared something fierce. Then I came up with a simple fix. It's a little time consuming but hey, it's winter here and I have the time. PM me and I'll try to explain what I do. Ohh, by the way, I use nothing softer than coww and they work. I even tried them on some water dropped boolits that were a couple weeks old.

[Idz]

when using my homemade plain base gas checks
http://castboolits.gunloads.com/show...ight=gas+check
the solutions to tearing were: 1) Polish the sharp corners off the inside of the sizing die 2) Try sizing tail first or nose first to see which works best
It is so, so easy to make your own checks (and checkmaker) that I don't know why anybody buys them anymore.
good luck!

[Tailhunter]

Okay, I had to look it up so I understood what Jon was referring to:

Bullet "slump" - the change in shape of a bullet due to the acceleration and pressure forces acting on the bullet

An outstanding point really; and while I do not disagree, I've never had the problem or if I have I've dismissed it as something else.
I don't use super fast powders in my rifle loads so I suspect that my boolits are moving before a peak pressure can impact the bullet much. I've certainly had accuracy go bye-bye at certain speeds, and it certainly may have been slump that caused it.

Bullet slump ... I always thought that was what you got when you left the powder coated ones in the convection oven too long.