Gas check vs powder coating

[TexNAss]

#Hopefully I'm not hijacking the thread#
Just a couple of questions for you blokes who have played with hard cast bullets if I may.

1. At what point are gas checks needed?

Looking at the .454 Loads (Max loads).
1,762 fps 42,100 CUP -260Grn/33grns Ar2205
1,269 fps 48,300 CUP -395Grn/21grns Ar2205
Is it a pressure requirement, or more of a velocity/acceleration issue? Or just a 'suck it and see' approach?

2. I've stumbled across a factory made cast&coated projectiles "......with a rated hardness of #7 Saeco/ #16 Brinell Hardness Scale...." (Probably the 250grain version of these http://shop.hrbc.com.au/45cal-200gn-rou ... pperhawke/ )

Now these aren't gas checked bullets- but the Copperhawks have a HY TEK coating and are "rated to 2200fps+".

Would it be best to run them through a .452 resizer/lubricator anyway and gas check them or is this not needed due to the superduper coating and supposed hardness?

3. If a .454 was loaded to within "45 Colt" speeds- can we use plain .452 jacketed low speed projectiles?

I keep seeing references to XXXXfps limit on projectiles- and yet "Not suitable for 454 Casull- See .452+MAG" in the published guides.

Only two things I could see for this warning:
A) thinner jackets/bases for pistol bullets=reduced velocity rating due to core separation concerns above its' rated speed, or
B) the higher CUP pressures (at release from the case) causing base flaring/distortion therefore barrel damage making it a "not suitable as a 454" projectile.
..Or??

4. (Referring to the cast bullet powder loads) Every published load I see is for pistols- a rifle will achieve another 150fps or so. If we look at running a 250grain hardcast with/without gas checks- how do we work out where to start from (with regard to load data)?

Can I use the load data from a pistol with a jacketed 250grain (minimum load of course) and work up for a 250grain cast bullet?
Or drop 10% below that minimum and work up?

5. (Finally but a bit off topic) While trying to find answers to the previous questions- I stumbled across a few guys running extreme loads in 45Colts. And of particular interest that I've seen published a few times is, "Straight walled cartridges do not exhibit normal 'over-pressure' signs like bottle necked cartridges do".

Cratered primers, sticky extraction, case head marks are not normally seen- to the point; that they blew up a cylinder and the cases still looked fine.

So- how so we know we are getting close to the limit? Just go off the chrony readings?

Looking forwards to any insight you can provide,

Tex.

[donhuff]

MoonTree,

I fully intended when I got this rifle, to go through all my cast bullets and find "THE ONE". that did it all. That aint happened yet! I surely thought that my old favorite Lyman 170 SWC would be "IT" because it has been so good to me for so many years. Well, at full tilt level, it does pretty good. Lots of power and decent accuracy. But slow it down a little to plinking levels, and it totally sux. You cant hardly hit the paper @50, but while sighting in at 25, I thought that is was great. At 100, it'll make you check the barrel to be sure the bullets are getting out! It's really that bad! And it made the Lee 158 look bad! I could not get that one to do anything good. I have read that other folks say it does a good job for them, so I tend to think that maybe I still have not found that just right combination that it likes.

The very best slug for plinking seems to be the Lee 125RF. At low powder levels and 1000fps, it is very acc at 100. And it holds onto that accuracy as you speed it up. At 2000fps it did not do so well, but that's to be expected. That's pushing pretty hard on a little bullet and it has no real value in that area. The big surprise was the lyman 358156, which out shot the 429 every time. The Lee 158 swc looks real similar.

BUT, since you already get the SNS bullets. I would get a box of the 125fp or the 130rnfp for plinking> That 130 looks like a dead ringer for the Lee bullet. Also I really like the looks of the 158fp. Wide enough meplat and wide driving bands. Also, it has a rounded base which should be easy to load. I like the truncated cone designs as they keep more weight aft, compared to SWCs of the same weight, and they usually feed like greased butter. Melt that blue crayon stuff off and put some real lube on them (or PC) and I bet they would be good shooters.

I'll have to look and see if I have 40 of those left. I think I do. But if a slug does not work for me, I tend to throw em into the next melting pot to get em out of the way. I have too many 357 designs as it is.

I think your idea of a bullet trade is pretty good. Might be kinda slow as we do not have a lot of casters on this site yet.

[Ranch Dog]

Just a couple of questions for you blokes who have played with hard cast bullets if I may.
1. At what point are gas checks needed?

I think it is a multi-dimensional issue of; alloy, pressure, and velocity. You must always reference the alloy you are talking about as it controls what happens to the next two. I would also add another at the front of these three but no one ever whats to talk about it; the bullet caster. The fellow that is really in control of the what is happening to alloy and mold; temperature consistency, fluxing the alloy, consistent pour and time in the mold, etc. This fellow can make or break what the alloy and mold drops.

Back to the first point of your question. I cast with water quenched Lyman #2 alloy with one ounce of #8 shot added per 10# of alloy. My expectation, based on pressure and velocity testing, is that a non-gas checked bullet will fail at 1800 ~ 1900 FPS - 25.0 ~ 30.0 KPSI, whichever is crossed first. The reason for the range I've given is that, in my experience, it seems to depend on the powder's response at combustion. Common pistol powders at the lower end and rifle powders at the upper end.

Add a gas check and you bump the pressure quite a bit with my same alloy to about 48.0 KPSI. I'm not real sure about the velocity as I've shot various caliber of bullets over 2500 FPS without issue.

Looking at the .454 Loads (Max loads).
1,762 fps 42,100 CUP -260Grn/33grns Ar2205
1,269 fps 48,300 CUP -395Grn/21grns Ar2205
Is it a pressure requirement, or more of a velocity/acceleration issue? Or just a 'suck it and see' approach?

Gas checked water quenched Lyman #2, they would be okay. I take it these are suggested loads from a data source. If so and if you are using this data in a R92, I would add an: "it depends" to the second load. Any published data I've looked at for the 454 Casull is for revolvers. My experience is that the pressure is going to be a bit higher when it is pushed out of tight chamber (no gap into a forcing cone) and long barrel.

This year, I've started shooting my R92 454 Casull at max pressure with a 50/50 wheel weight/linotype alloy that is water quenched. The bullet is gas checked.

2. I've stumbled across a factory made cast&coated projectiles "......with a rated hardness of #7 Saeco/ #16 Brinell Hardness Scale...." (Probably the 250grain version of these http://shop.hrbc.com.au/45cal-200gn-rou ... pperhawke/ )

Now these aren't gas checked bullets- but the Copperhawks have a HY TEK coating and are "rated to 2200fps+".

Would it be best to run them through a .452 resizer/lubricator anyway and gas check them or is this not needed due to the superduper coating and supposed hardness?

All you can do is try them. I'm not a fan of checks on a plain base bullet. I was sent some to test and found them an awful idea at the sizer and out the barrel.

I cast my 7.62x39 bullet a couple of days ago and as soon as I got in from hunting, I took my BHN samples for the records that I keep. This is the typical BHN I see four days after the cast.



For grins I included a 50/50 bullet because I see many that start in about bullet failure when linotype is mentioned. This is a 444 Marlin bullet that was shot at 45.0 KPSI and near 2500 FPS. It was shot into a nilgai, through both shoulders, and hung up in the hide at exit. It killed the critter, a bull of 700 lbs.

I will be shooting those 7.62x39 bullets, gas checked at near 50.0 KPSI without issue.

3. If a .454 was loaded to within "45 Colt" speeds- can we use plain .452 jacketed low speed projectiles?

I keep seeing references to XXXXfps limit on projectiles- and yet "Not suitable for 454 Casull- See .452+MAG" in the published guides.

Only two things I could see for this warning:
A) thinner jackets/bases for pistol bullets=reduced velocity rating due to core separation concerns above its' rated speed, or
B) the higher CUP pressures (at release from the case) causing base flaring/distortion therefore barrel damage making it a "not suitable as a 454" projectile.
..Or??

You summed this up I think. The bullet was just not designed to operate at 60.0 KPSI.

4. (Referring to the cast bullet powder loads) Every published load I see is for pistols- a rifle will achieve another 150fps or so. If we look at running a 250grain hardcast with/without gas checks- how do we work out where to start from (with regard to load data)?

Can I use the load data from a pistol with a jacketed 250grain (minimum load of course) and work up for a 250grain cast bullet?
Or drop 10% below that minimum and work up?

The pressure at the shot will be the same. In a revolver it is relieved rather quickly. You need a chronograph to know what the velocity will be, I don't think there is a reasonable "factor" to use. Just figuring out the loss from a cylinder gap is pretty much impossible.

Just use the data with the appropriate work up and a chronograph to record your results for the ballistic tables.

5. (Finally but a bit off topic) While trying to find answers to the previous questions- I stumbled across a few guys running extreme loads in 45Colts. And of particular interest that I've seen published a few times is, "Straight walled cartridges do not exhibit normal 'over-pressure' signs like bottle necked cartridges do".

Cratered primers, sticky extraction, case head marks are not normally seen- to the point; that they blew up a cylinder and the cases still looked fine.

So- how so we know we are getting close to the limit? Just go off the chrony readings?

Looking forwards to any insight you can provide,

Tex.

I don't think that you can know for sure unless your have pressure trace equipment. A chronograph cannot give you any indication of what the pressure is doing, this is a from a guy that uses both at the same time.

Finally, the only other thing that has not been covered is lube. I use Alox in all my applications so it is part of what works for me as documented above.

[donhuff]

Tex,

I'll give you a little info as best I can.

1... I varies as you might have guessed. It seems to depend a lot on the gun/finish of the bore, but in general when dealing with a 454 your gonna have the pressure way up there (and yes it's more pressure than velocity). RD can tell you better than I can, but around 35-38000psi seems to be the point where they are needed.

With the 454 especially, why not gas check all of your high press loads? It's not like your gonna go out and do a few hundred rounds with it shooting tin cans. Usually more of a hunting and sighting in issue I'll bet. Then if the desire to plink comes up, I would drop down to a more sane power level that did not need a GC. OR buy a 45 colt to plink with.

2...I have shot my powder coated bullets cast from plain wheel weight ally to some pretty high velocity, and not had a problem with leading at all. Hi-Tec is real similar. I have also tried lubing the coated bullets, and it did absolutely nothing for them except make smoke and black soot.
Don't do it, the coating really is that good.

3...Yes

The reason for the magnum vs 454 projectiles is that the 454 will go faster than most all the magnums are intended to travel. When you hit an animal with the mag bullet going that fast, it tends to break apart and not penetrate. So the 454 NEEDS a tougher construction to hold up to the impact forces.

4...Surprisingly, the same bullet shot from a pistol, and showing signs of being being pushed too hard. Will usually work just fine in a rifle. Assuming that it's sized 1-2 thousands over the bore size. And I have no idea as to why! I have shot bullets fast in my revolvers, and got them to the point that they are losing accuracy. Put that same load in the rossi and it goes 300fps faster and shoots great.

Usually I have no fear using jacketed bullet starting loads as a starting load for cast. The cast bullet offers less resistance against the bore than the jacketed one does. So usually the pressure is less too. But normally the velocity will be higher with the cast.

5...I still look at the primers, it seems kinda silly cause you look at the primer in a 454 @50000psi and then the same primer in a 357 @38000 and you think you actually can see a difference????? Sticky extraction is about the same way too. Usually if you see any of the signs...you're WAY over the limit. Stick with the published data (not always internet data) and you should be ok. And yes, the chrono is a valuable tool when you start pushing a load way up the ladder.

It's like so many other skills, in that after so many tens of thousands of rounds, you can get a feel for it. If you pay attention. The way the cylinder turns, or the extraction, or the look of the case head/primer, all play a factor in it. Sticking with good data is good as long as your using typical powders for the caliber. But sometimes when trying a new to the shooting world powder. And not much to no data exist for it. Then it gets a little scary.

[jdb]

...The reason for the range I've given is that, in my experience, it seems to depend on the powder's response at combustion. Common pistol powders at the lower end and rifle powders at the upper end.

Add a gas check and you bump the pressure quite a bit with my same alloy to about 48.0 KPSI. I'm not real sure about the velocity as I've shot various caliber of bullets over 2500 FPS without issue.
...

An excellent point Ranch. It's been a while, but the best I remember, I had more failures using ball type powders than others. If I'm remembering right, I always got fowling quicker without a gas check with a ball or flat ball powder like 296 than something like Unique.

But that's IF...I'm remembering right. I ain't gettin' any younger and it's been a couple years since I was playing with this stuff. Could have actually been the other way around. In that case, never mind. LOL

ALSO, an excellent point about the alloying process. Temperature control is CRITICAL to casting. Lead melts at about the lowest of most all solid metals. So, we can use a low temp to remove contaminates from the lead before we use it. They float to the top and we skim them off.

By the same token, some of the metals used to alloy melt at a much higher temp than lead. So, in order to get a homologous alloy, it's critical to get the temp above that higher temp and HOLD it there during the casting process. Which means accounting for temp loss during the dipping process. But ya can't just crank up the heat and let 'er eat, cause that extra heat will likely destroy the molds OR incorporate some metal into the alloy that you don't want going down your barrel. Either way, not good.

So you are dead on. The skill and knowledge of the person alloying the metal and the caster can make a HUGE difference in just how constantly those bullets will perform.

[parson48]

For what it's worth; I've shot shot Lee 158-swc with gas checks in my 357 maximum, lubed with the alox/johnsons wax/mineral spirit recipe, at what should be 2000+ fps (don't have a chrony) without leading being an issue.

[TexNAss]

Thanks for the insight, experiences, and explanations from everyone. It is appreciated very much.

Now I need to search more though the old threads.

Cheers,

Tex.

[Ranch Dog]

I started casting from a new mold yesterday, a Lee .360" Round Ball mold. I noticed that the instruction sheet was newer than the last that I've seen so I went through it. They have some alloy vs. pressure suggestions that are helpful.

Alloy_01.jpg

They also have a comment concerning pressure against a plain base bullet.

Alloy_02.jpg

I personally have not seen a plain base survive this much pressure.

[jdb]

...

Alloy_02.jpg

I personally have not seen a plain base survive this much pressure.

GREAT info Ranch. And LOL...I heard that. 34,000 is right at the top for most lever gun rounds from what I've seen. That's kind of surprising to me too.

[Zippidydoodah]

RD, do you find micro grooving to provide better gas seal on all cast design bullets, and would a hybrid micro rear grooves be helpful on conventional BP bullet?