Question on gas checked boolits

[44man]

I have a strange thing with my .475 in that using 2 boolits of the same diameter and alloy but one with a gas check and one without ( the gas checked boolit is 10 grs. heavier.) I can load 2 or more grs. of powder with the plain base without sticky cases but will max out sooner with the gas checked one. I have not had a chance to chronograph them together yet because it is just too hot outside and it makes the gas checked boolits stick more. I only have 3 of them left, having shot them in cool weather when they were OK. Using 296. Backing off 1/2 gr lets the brass fall out of the gun.
I have gone to 29 grs with a plain base 414 gr boolit without pressure signs, but at 26.5 the gas checked one will stick a few out of a cylinder full.
Only thing I can figure is it is sealing better.
Both boolits are a very close fit to the throats.
The amount of leading is the same for both too but it just pushes out with a tight patch, not sticking in the bore. Once I push it out, I can not find a trace of lead left in the bore and no way of cleaning will reveal the slightest speck. Shooting the gas checked boolit after the plain base will not remove the lead either so I don't worry about it. Accuracy doesn't suffer any from the small amount left in the bore.
Going down to the .45 and .44, I don't get any of these problems or leading even with heavy loads. Seems to be just the .475.

[Bass Ackward]

I have a strange thing with my .475 in that using 2 boolits of the same diameter and alloy but one with a gas check and one without ( the gas checked boolit is 10 grs. heavier.) I can load 2 or more grs. of powder with the plain base without sticky cases but will max out sooner with the gas checked one.


44,

Two bullets of the "same design and length", the PB should be the heavier. So if the GC bullet is heavier, it would be longer. If it is seated to the same OAL, then the GC bullet occupies more space in the case. But even if it isn't, the extra inertia from more weight, will naturally throw more pressure. No rocket science there.

The leading has to be pressure / friction / gun related as opposed to caliber. And you know how to deal with that. This is why sticky cases aren't always a good pressure barometer. Different case designs and brass hardness can give greatly different indications. I would trust you lead mix (if it is consistent) along with primer flattening and case extraction indicators.

Just obey what it is telling ya.

[felix]

Basically, the same pressure curve, the same velocity will result. Better seals with checked boolits. I have found this is generally true with all calibers. It is very easy to damage the base of a naked boolit, for whatever reason you can think of. That case full of 296 is acting like a sand blasting machine, making checks a necessity for long range scoped shooting. ... felix

[44man]

Thanks Felix, thats what I was thinking.
Bass, both boolits are hard cast and have the same length in the case. The PB has a shorter WFN and the gas check is a WLN. That is where the little extra weight comes from.
I have another WLN boolit just like the gas checked one but PB and I can load much more powder with it. It is only the gas check that is raising the pressure. The strange thing is that every boolit I have from 400 to 420 grs., shoots extremely tight groups with the exact same powder charge. With both the gas checked boolit and the plain base WLN, I have groups much smaller then 1" at 50 yd's with the 26.5 gr load and I even put 5 of the gas check boolits in 1/4". When it is cool outside I will get maybe one sticky case out of five and it could be the Hornady brass. I have, however backed down to 25.5 grs. This will still hold a little over 1". The WFN does not group as tight at around 1-1/2 to 2" but will be my deer boolit this coming season.
I don't load to max but will work up to it looking for the most accurate load. I usually find that in this gun I will be 2 to 2.5 grs. under max. Just strange the gas check would shoot so good with the same charge and also be at a lower max powder charge.
Another strange thing about the WFN is that it shoots the exact same size groups fron 24.5 to 27 grs. There is no opening or closing of groups like all of my other boolits and guns. Darndest thing I ever seen!

[44man]

Felix, one more thing. I shoot the Lee 400gr with a plain base, same powder charge, and can hit pop cans all day at 100 yd's and have kept them on a small steel swinger at 400 yd's. I did fair at 500 meters with it too. I do this from Creedmore at long range and from bags at 100 yd's.
It doesn't appear I am getting any base damage. Of course I cast hard boolits too.
The next question you are going to ask is why do I keep making boolit molds for this gun if the Lee shoots so good? !!!!!!!! I guess because I can!

[Bass Ackward]

44 Man,

Well, if you guys got it figured out, prove it.

If you are correct that the GC is causing a better seal raising pressure, then take off the check. So then you should be able to shoot both bullets with the same powder charge. Don't worry about accuracy, just pressure.

See what happens?

[felix]

That WFN itself is mated to your barrel quite well in terms of the barrel's vibration pattern. This is why you can shoot with a fairly wide pressure curve and not screw things up. Somewhat rare indeed with softer loads, especially. However, this does not mean this same boolit will be the most accurate one in your arsenal, because the most accurate one will exhibit the narrowest pressure curve, meaning the closest fitting curve to the barrel using the boolit's optimum powder and ignition. ... felix

[44man]

Felix, you are right that the WFN is not as accurate. I also found that to be true in my other calibers. For the top accuracy I have always found the WLN much better. But can you imagine the impact on deer with the WFN? Or for that matter any game. Since ranges are close I don't need the super accuracy when hunting.
However, I am never happy just making clusters on paper unless they are very small. I also love to shoot ranges that blow people away. It's just too much fun!
Bass, removing the check is bad as it disrupts the way the pressure is applied and can leak it around the boolit too much. This would change the pressure curve too much to prove anything, especially at the cylinder gap. It is much better to have two boolits the same but one with and one without a check. I have already done that and the PB can go to 29 grs. but the GC has to stop at 26.5 grs. One thing I wonder about is added friction from the check compared to just lead. I know a lead boolit can take a heavier load then a condom bullet but what effect does the small check have? More food for thought!
When it cools off, I am going to make a mold for the .44 with no gas check to match my GC boolit so I can see if the same thing happens with that caliber. This is getting interesting.

[StarMetal]

Man of the 44, more commonly known as 44 man......Try a test where some checks are annealed and some aren't and see what you come up with.

Joe

[felix]

Jim, the gas check on a heavy boolit with a slow powder should offer no resistance (in totum) to speak of. However, if and when the curve changes shape because of the check, you can expect something of a change at a far away target. ... felix

[Bass Ackward]

Bass, removing the check is bad as it disrupts the way the pressure is applied and can leak it around the boolit too much. This would change the pressure curve too much to prove anything, especially at the cylinder gap. It is much better to have two boolits the same but one with and one without a check.

44 Man,

I agree. It was just a way to know. If the leakage did occurr, then theoretically, you should be able to go higher than the PB. But if you are satisfied ......

I believe that it really has to do with how you shoot (what style) them. And how well that the bullets fit the gun. Ol Elmer hated GCs on bullets because they wouldn't expand and seal as fast as his PB. Also believed that they contributed to flame cutting of the top strap. He formulated that opinion from pressure testing his loads sent to labs of the day. I think that his average pressure reduction from the GC bullet was 2000 psi. Remember he was shooting a 10 BHN mix. All of this changes the dynamic. Clearly the softer base is going to seal or obturate faster than the GC. What I didn't understand is that even with hardened bullets, the GC is STILL harder.

I haven't tried it in handguns myself, thus the proding. But in rifles, I have. And my results are the exact opposite. The GC produces less pressure both times I have tried it when loads were kept below capabilities of the PB.

And as to that awful sand blasting of the base, I have actually left lube on the base in both rifles and handguns, that wasn't disturbed when the bullets were recovered. So much for heat huh? Minus the rifling marks on the sides, that base looked like you just cracked the sprue. That is from both rifle and handgun. If the bullet fits, it seals right off. And no abuse at all happened to the bullets I tested. Now if I fired undersized bullets, more so with hard bullets, then some abuse could be expected. To me that was logical if you didn't seal.

So I guess that I am bass akward again.

[44man]

Star, good idea, I will anneal some and test side by side. I have to cast some more boolits though so it will be a while.
I noticed the other day that I was hitting a little low on the target. I thought about it and when I cleaned the gun I grabbed the scope and found the base was loose. This is the third time I have had to remove the scope because the base screws came loose. I always clean the holes and screws, spray Loctite primer on them and use red Loctite. It doesn't hold with this recoil!
I cleaned everything again and used Accra Glass to glue the base to the top strap and glue the screws in. NOT coming loose again!
I was just short of shearing the screws this time. I shot some nice groups that way which I can't understand.
Bass, I have used checks in a TC 30-30 with none of the high pressure signs. I have a hunch it is just this caliber (.475) because I use heavy loads with gas checks in the .44 and .45 too, without pressure signs.
My friend bought some 335 gr. LBT WLNGC boolits for his .45 Vaquerro. They told him to work up from 19 grs. of 296 until he got sticky cases, then back off to the most accurate load. DANGER, DON'T TRY THIS GUYS! He came over and told me he went to 30 grs. without sticky cases. I turned white when I heard that! Thats more pressure then a hot .454!

[StarMetal]

44man

At least the annealed and not annealed checks will help some of the friction that the gascheck does or doesn't apply going down the bore. Be one step closer to solving the puzzle.

Joe