Pushing Our Beloved Pb To The Extremes

[Danderdude]

Howdy all,

My question to you all is, just how far are you comfortable going to the extremes?
I've been working on loads for for my Swiss K31, and so far have been doing pretty much everything right, but now it's crunch time and I'm nearing a real MAX load.

I started with Lee C312-155's sized to .309 but got the hard feeding problems associated with the short throat in K31's. They shot great, from 10-15gr Unique, 16-20gr 2400, and didn't do poorly with 32gr H4895. But now, I have my NOE 180gr bore rider mold, enriched lino (added 1:3 monotype), waterdropped, and a pound of RL17 and RL19, so it's time to really push these to their limits.

I worked up to 55.5gr RL17, which gives an estimated 52k PSI (55k max) and a ballpark 2700 fps. Published data for the Swiss is hard to come by, much less for cast data, so I've been extrapolating from .30-06, which has the same capacity as a fired 7.5x55.

After successfully testing the 55.5gr RL17 load, and with 4 grains of case capacity to spare, I hit a wall with 56.5gr. Difficult extraction, which is expected in this gun from 53-55k PSI. Just today I picked up a pound of RL19 to complete the test.

The point of this story is that I've already pushed a bullet to probably 2700fps. We all know that 2500fps is the accepted cap for gas checked rifle bullets, and that ~53k PSI is already beyond many recommendations. I've gone this far without leading, without a marked decrease in accuracy and without serious issues.

Beyond that, I'm also playing around with the idea of making the softest hollow-points possible for full-power handgunning. Something along the lines of a large gas-checked 9mm or .40 with a deep HP made of Pb with just a touch of tin added, with the goal of achieving *the best* expansion possible. Has this been done before?

List off any other extremes you've always wondered about and let's get some anecdotal evidence flowing!

[runfiverun]

30-1 and a gas check usually gives outstanding hollow point results at handgun velocities.
rl-17 will give a slower rise to pressure and a longer time under peak pressure than rl-19 does.
it also drops off quicker.
all desirable traits in a cast powder for higher velocities.
don't be surprised if you have to go to rl-22 for the next step.

[Danderdude]

rl-17 will give a slower rise to pressure and a longer time under peak pressure than rl-19 does.
.

Why is that? RL19 is slower.

[runfiverun]

rl-17 is a progressive burning powder.
it creates more gas and burns quicker as it goes along and then is done.
rl-19 has a consistent burn rate.
slower but the kernels burn at the same speed the entire time.

[geargnasher]

I'd go to RX22 (single base) or Winchester Supreme 780 (progressive ball), look more toward 100% density loads. Sounds like you really need Quickload and a chronograph going off in this territory, at least I would to be comfortable. Stiff extraction in cartridges like .30-'06 means you WAY overpressured it, like 60K-75K psi, not sure how the Swiss compares.

Gear

[runfiverun]

you are up there.
i am using 51 grs of 4831sc in the norma case and 52 in the win 284 re-formed cases.
this is pushing the combined technology moly coated 150's at 2650 and 2675 out of my rifles.
no extraction problems and excellent accuracy.

[Danderdude]

Sounds like you really need Quickload and a chronograph going off in this territory

I appreciate the input geargnasher, but this is common for swiss handloads. The extraction is not actually difficult, but due to the straight-pull and camming action of the bolt it feels way worse than it is. FL sizing those cases was no different than any of the others, and no overpressure signs were observed. K31's are just quirky like that. In the 52k-55k PSI range, the action gets stiff. But, these guns are maxed at 55k PSI (3800 atm) and proofed at 75k PSI.

runfiverun,

Learn something new every day. Thanks for setting me straight.

[Larry Gibson]

We all know that 2500fps is the accepted cap for gas checked rifle bullets,

Can you tell us the "authority" on that?

without a marked decrease in accuracy

Please quantify with test sample (# of shots in group), group size and range shot at. Also "without a marked decrease in accuracy" from what accuracy "standard"?

Larry Gibson

[badgeredd]

I'd go to RX22 (single base) or Winchester Supreme 780 (progressive ball), look more toward 100% density loads. Sounds like you really need Quickload and a chronograph going off in this territory, at least I would to be comfortable.

Gear

I am in agreement with Gear on this one. In our experiments with alloys and powders to achieve higher velocities, we've used both chronographs and Quickload as tools to get where we're trying to go. One thing that Quickload showed us, was that some powders have a significantly higher muzzle pressure with a similar velocity loads. What we've found was that muzzle pressure MAY adversely affect one's accuracy, and muzzle pressure is affected by powder choice and barrel length. I am not saying that this hard rule by any means, but we have noted there does seem to be a correlation with the cartridges we are working with.

What we're trying to find out is if we can use an alloy that that will withstand the internal forces at work when shooting higher velocity loads. Some other things seem to be affecting our loads, so at present we are trying to the best of our abilities to keep our experiments to one variable at a time. Obviously we are finding there are other variables we need to address in the future to determine just how much they affect accuracy at higher velocities. Of course accuracy is a relative thing, so we have to define our accuracy around the rifles and cartridges we are working with and the purpose of our accuracy tests..

Larry is alluding to another subject that has some bearing on our accuracy determination. The number of shots in a string, and the accuracy at progressively longer ranges. His experiments have given reason to pursue these areas also. Ones accuracy at 100 yards does not necessarily correlate in a progressive way with the accuracy at 200 or 300 yards. Three shot groups do not necessarily show the same thing as 5 or 10 shot groups.

For my purposes, I prefer to use 5 shot groups, mainly because I am looking for repeatable hunting accuracy and not target accuracy. That being said, I think we all can learn things from other's experiments as long as we know what the parameters are surrounding said experiments and trials.

None of these statements are meant to be argumentative, but are statements of my viewpoint. YMMV.

Edd

[Larry Gibson]

I'm not being "argumentative" either. There are some of us that do push cast bullets to the extreme. Just want to know where the 2500fps is the accepted cap for gas checked rifle bullets comes from and what it's based on is all.

As to accuracy; was Danderdude using issue sights or a scope? Was he shootiong off hand, prone, from a rest or bench? That might not seem important but we just went through a thread concerning accuracy only to find out later in the thread the OP was just shooting tin cans at 25 - 50 yards as his measure of accuracy????? If Danderdude was shooting 3 shot groups, or even 5 shot groups at 50 yards of 4" and then shot a group of 3" is that what he means? I'm simply asking what is meant by "accuracy" and what is meant by "marked improvement" or "didn't do poorly" as those comments really do not explain anything. If he's talking about plinking then it's probably not really important. However, Danderdude is talking about going to the extremes and in that case a little more explanation would be helpful. I'm simply asking for a bit of an explanation.

Yes, Gear is correct; a chronograph or the use of Quickload is probably needed.

Larry Gibson

[badgeredd]

Thanks Larry. You explained exactly what I was trying to say.

Thinking about the accuracy "definition" per anyone's standards, I would think it is fair to say, we as a group kinda need an explanation of what a poster is expecting. I want "one shot-one kill" as my primary goal. Repeatable accuracy whether for military matches, varmint hunting. silly-wet, long range target, plinking, or game hunting I believe is all of our goal.

Edd

[geargnasher]

No Larry, I said chronograph AND Quickload. One to play with theory and the other to verify the outcome, the only way one can really guessitmate chamber pressure without a strain gauge.

Danderdude, where are you in Texas? If you don't have a chronograph maybe we can meet up and I can shoot some of your loads across mine.

Gear

[Danderdude]

We all know that 2500fps is the accepted cap for gas checked rifle bullets,

Can you tell us the "authority" on that?

without a marked decrease in accuracy

Please quantify with test sample (# of shots in group), group size and range shot at. Also "without a marked decrease in accuracy" from what accuracy "standard"?

Larry Gibson

Mr. Gibson,

I've read the same "1600fps for PB, 2500fps for GC" here, there and over yonder quite a few times and it's what the Lyman CBH #3 says. No, I don't have #4 yet.

As far as my accuracy, I am not a benchrest shooter. If you are, you may wish to stop reading right here because I am not one to lose sleep over half an inch at 150 yards.
1947 K31 Open Sights, supported standing, rear leaf at 100m setting. 6 shots, 2.5" spread on 150 yard target, group centered 5 inches over POA. Yes, I need to build a taller front sight. Oh, and 55% relative humidity, 78.382676F, 450ft above sea level and the pollen count was high.

This may insult your sensibilities but I do not personally strive for pinpoint accuracy. I am currently exploring the extremes in velocity, pressure and soon, how soft a full power HP pistol bullet can be made. I'm happy with the accuracy I've achieved so far.

geargnasher,

As I said, stiffer extraction combined with the absence of overpressure signs is an indication of reaching the 52k-55k PSI mark, aka effective max load. I certainly appreciate the offer, though, and am 150 miles or so from your coordinates. For now I'm happy extrapolating velocity from published .30-06 cast data as they share the same diameter and case volume.

[Larry Gibson]

geargnasher

No Larry, I said chronograph AND Quickload. One to play with theory and the other to verify the outcome, the only way one can really guessitmate chamber pressure without a strain gauge.

Huh? I said you were correct. I'm not sure where you think I differentiated with what you said regarding chronograph and Quickload? You said; "Sounds like you really need Quickload and a chronograph going off in this territory, at least I would to be comfortable. and I agree with that......huh?

Larry Gibson

[geargnasher]

You said "or". I said "and", that's why I put in in caps the second time. Substituting that one word, though a tiny indescretion, changes the entire meaning of my sentence, which meant to use the two tools in CONJUNCTION, not one or the other as the person may choose.

Gear

[Larry Gibson]

You said "or". I said "and", that's why I put in in caps the second time. Substituting that one word, though a tiny indescretion, changes the entire meaning of my sentence, which meant to use the two tools in CONJUNCTION, not one or the other as the person may choose.

Gear

Well excuse me:oops:.....but to paraphrase an earlier quote from you; "you've got to be kidding me!"

Larry Gibson

[geargnasher]

Hey, I mangle my grammar enough without any help from you! :kidding:

Gear

[Larry Gibson]

Danderdude

I've read the same "1600fps for PB, 2500fps for GC" here, there and over yonder quite a few times and it's what the Lyman CBH #3 says. No, I don't have #4 yet.

I believe what Lyman's #3 says is; "Of course, there are other causes of bore leading-and even combinations of causes, but these little bits of hard metal (referring to GCs)- used with hard bullets (22 BHN or better) and Alox lubricant-permit velocities up to 2,500 fps and beyond without leading. I'm not perceiving that as meaning 2500 fps is "the accepted cap for gas checked rifle bullets". Many of us noticed the "beyond" part of that and have proceeded "beyond" 2500 fps with GC'd cast bullets quite successfully. I'm not aware of a "cap" on velocity for GC'd cast bullets that has been established yet(?).

As far as my accuracy, I am not a benchrest shooter. If you are, you may wish to stop reading right here because I am not one to lose sleep over half an inch at 150 yards.
1947 K31 Open Sights, supported standing, rear leaf at 100m setting. 6 shots, 2.5" spread on 150 yard target, group centered 5 inches over POA. Yes, I need to build a taller front sight. Oh, and 55% relative humidity, 78.382676F, 450ft above sea level and the pollen count was high.

This may insult your sensibilities but I do not personally strive for pinpoint accuracy. I am currently exploring the extremes in velocity, pressure and soon, how soft a full power HP pistol bullet can be made. I'm happy with the accuracy I've achieved so far.

No need to get your "dander" up. Just if you are going to state "without a marked decrease in accuracy " it would be convenient to us if you mentioned what the "accuracy" standard was to begin with. BTW; 1.67 moa at 150 yards at 2700 fps with a cast bullet? Be ready for someone to say "show us". Reason being is that is pushing cast bullets to the extreme, to say the least. Many here who have diligently tried very hard for such and failed will be skeptical.....to say the least. Me? Well, I'm just beginning to work the high velocity angle myself with other than the standard ternary alloys most use so it remains to be seen for me.

BTW; Gear is right, you really should use a chronograph and (maybe I should say that word again and shout it just so there is no "tiny indescretion" for Gear's benifit......AND) Quickload for where you're going. If nothing else it might be a bit on the safer side. For those of us who do push to the extreme the exchange of detailed information is necessary and good, unless you want the information to remain your propriety information?

Larry Gibson

[303Guy]

My idea or dream is to get good accuracy and range from a cast boolit in a 303 Brit for target shooting. High performance hunting boolits are going to be paper patched and lower volume and a lot easier to make (but slower, hence the lower volume). That's going to be a tall order so your work is going to be of great benefit to me.

[badgeredd]

I wanted to revive this thread as some new information (to me) has come up. Larry PMed a quote from Townsend Whelen about an alloy that I find tremendously interesting. Whelen mentioned a Lyman boolit alloy that was 80% Pb, 10% tin, 7% antimony, and 3% copper. He said the alloy was very good in the 30-06 with a 1-10 twist barrel. Interesting stuff considering the book it came from was written in 1909! It goes to show the old boys had information we are just re-discovering.

Now the real question for me is how do we get a know amount of copper alloyed into our mix? Any thoughts?

Edd

[mpmarty]

Danderdude be very careful with that 7.5X55 as the case head is NOT fully supported in that chamber and a rupture would be bad news indeed. BTW where did you come up with the 55000 psi as a rated safe max load in a Schmidt Rubin?

[Me not you]

The Swiss K31 does fully enclose the case head, while the Swiss G11 and K11 rifles do not.
I have one of the Steyr M95 short rifles (shortened from a long rifle) that I'm using as a utility rifle on my own land. It is surprisingly accurate with H4350 and the 207gr j-bullets. I intend to start using it with cast bullets, but really want something beyond paper punching velocities. I carry it for protection from a variety of furry "bad neighbors" that can stomp, chomp claw and gore me. I'm starting with the LEE 220gr .338 bullet that I'll be sizing down to 0.335 (groove dia is 0.334 in MY rifle).
I want to get up around 2000 to 2200 fps. ;)
I have H4350, WW760 and Ramshot TAC. Without asking anyone to expose themselves to litigation with actual data, would any of the powders mentioned be preferred? I also have some IMR4198, but don't know what kind of performance I can get with it.

[Danderdude]

Danderdude be very careful with that 7.5X55 as the case head is NOT fully supported in that chamber and a rupture would be bad news indeed. BTW where did you come up with the 55000 psi as a rated safe max load in a Schmidt Rubin?

The case head is supported, actually. "Me not you" got it right.

The original manuals for the K11 and K31 listed the max chamber pressure as 3200 atmospheres (47000 PSI) but that was derived from a faulty CUP system in use at the time, and was revised up to 3800 atm (55000 PSI) in the 1950's. CIP still lists it as 55k PSI as well.

Of course, these high-power loads will beat your shoulder up, so they will be for rare use, and I certainly don't want to strain the gun too hard, but it's all safely doable.

[Larry Gibson]

Danderdude

I believe the CIP PMAX of 3200 bar based on CUP was revised in 1984 to 3800 bar using the newer (then) Piezo transducer system. That's what my data shows anyways. Doesn't much matter as the PMAX (Maximum Average Pressure) measured with piezo transducers or strain gauges is 55,100 psi, just as you mention. Only mentioning this because many confuse the older "psi" obtained with CUP measuring is different from the "psi" now standard with piezo or strain gauge measurement.

Larry Gibson

[Bret4207]

We all know that 2500fps is the accepted cap for gas checked rifle bullets,

Can you tell us the "authority" on that?

without a marked decrease in accuracy

Please quantify with test sample (# of shots in group), group size and range shot at. Also "without a marked decrease in accuracy" from what accuracy "standard"?

Larry Gibson

Heck Larry, used to be it was 1100fps with PB and 1800ish fps with GC'd!!! We're advancing! Of course there are sites you can go to even today that state you can't shoot anything cast over 1k fps no matter what...

[Larry Gibson]

Sad state of affairs as in reading the part on bullet casting for the M1903 in "Leiutenant" Townsend Whelens Suggestions To Military Riflemen published in 1909 it seems we have regressed............considerably......:(

:drinks:

Larry Gibson

[209jones]

The DEVA Weiderladen is showing the 7.5x55 GP31 at 3800bar.
They show a 165 Sierra w/aa4350 @ 823m/s as a max load
and a 168 Hornady w/ Rottweil R903 @ 786m/s @ 3070 bar

There appear to be some warnings about some pre 1911 guns? I don't read German so well.