Boolit pics to ponder

[fecmech]

I decided to do some playing this winter and shoot some bullets into the snow. The bullets shot were the Lyman "Keith" 358429 sized .358, lightly taper crimped on the front drive band to an OAL of 1.638 (to fit my GP 100 cyl). Load was 14.9/wc820/CCI SR primer and clocks about 1260 FPS out of my 6" GP. The top row of bullets was pure lead, the next was ACWW and the bottom row is a 50/50 WW/lino mix air cooled.
As you can see the acceleration forces on the pure lead Keiths turned them into FPTC's BUT they did not lead the barrel at all and as you can see did not skid on the rifling. Bases were badly distorted I think by either muzzle pressure or at the cyl gap. They left a slight bit of molten lead at the edge of the forcing cone. When shot at a 25 yd target 2 or 3 would hit together in about an inch with others 2 or 3" away. I'm guessing the flyers were ones with blown bases as they don't strip on the rifling.
Acceleration forces also show up on the ACWW in that the nose sets back slightly closing up the crimp and lube grooves along with bases showing some slight distortion but not bad. From previous accuracy testing ACWW's will average 2.7" at 50 yds for five 5 shot groups. Water dropped WW do no better.
The 50/50 bullets show no setback and have the most square bases of all the bullets. Again from previous accuracy testing with more than five 5 shot groups at 50 yds they average 1.9" groups. My wc820 tracks exactly WW296 so I'm guessing this load is slightly north of 30K PSI. Just thought I'd share with the board.

[thegreatdane]

nice pictures. Did those pure lead ones lead the bore like crazy?

[fecmech]

As I mentioned in the post I got zero leading with the pure lead bullets.

[thegreatdane]

copy. Must have missed that part.

This is puzzling to me, as I've slugged, cast good ~15bhn projectiles and still get leading around 1250.

[RobS]

thegreatdane: What load were you using?

[RobS]

wc820 tracks exactly WW296 so I'm guessing this load is slightly north of 30K PSI. Just thought I'd share with the board.

Your WC820 powder is definately running closer to WW296/H110 vs AA#9. I would say your load is running closer to 40,000 CUP with 1260 fps. Good pics of what a newly designed Keith looks like when it's on the soft side. I feel this thread is going to be interesting as other members chime in with the differences in BHN. :popcorn::goodpost:

[thegreatdane]

thegreatdane: What load were you using?

13.5gn 2400 under a 158gn Lee RNFP

[RobS]

13.5gn 2400 under a 158gn Lee RNFP

2400 is a great powder however the slower ball powders generally provide an easier or gentler push into the forcing cone and lands for those plain base boolits. 2400 is considered slow for handgun on the powder burn rate charts but I've never been able to push the velocities to the upper limits of a PB with 2400. #9 and H110 yes with #9 being somewhat more flexible regarding downloading from max charge recomendations. H110 with a PB seems to always run at max to have optimal results. I also like IMR 4227 which now a days is the old H4227 and can be loaded with alot more flexibility if one is looking for less fuss and near the performance as #9 or H110.

Gas Check boolits are an entirely different story and 2400 works very well as does just about any magnum powder.

[runfiverun]

i don't think the noses were slumping on the ww ones.
i believe the metal from the driving band was displaced into the crimp groove.

[fecmech]

i don't think the noses were slumping on the ww ones.
i believe the metal from the driving band was displaced into the crimp groove.
The acww bullets average .008-.010" shorter than the 50/50 bullets, to me that would indicate slump and the lube groove to me is noticeably narrower on the acww.

[KYCaster]

13.5gn 2400 under a 158gn Lee RNFP



So tell us....."the rest of the story". Lube? Alloy? Size?(boolit, barrel and throat) Hardness and powder charge don't tell much.

Fecmech, do your 50/50 boolits show some evidence of stripping, or is that the camera angle...or just my imagination?

Jerry

[thegreatdane]

RobS, thanks for the recommendation. I'll look up some loads for that in a few minutes - casting now :)

Fiverun, it also possible that it deformed on impact.

[fecmech]

Fecmech, do your 50/50 boolits show some evidence of stripping, or is that the camera angle...or just my imagination?

Jerry

Jerry-- I'm not sure what you're seeing but the 50/50 bullets show no signs of stripping. What really amazed me was that the pure lead did not strip or even show much widening of the front part of the rifling grooves.

[nicholst55]

Interesting. The 50/50 WW/lino boolits look like they could almost be loaded and fired again!

[runfiverun]

the lube groove is where the shortness comes in.
many prefer a square lube groove versus a rounded one for this reason.
they claim it's stronger.

[RobS]

the lube groove is where the shortness comes in.
many prefer a square lube groove versus a rounded one for this reason.
they claim it's stronger.

Think of architecture, square is not the pinnacle of strength it is the arch. I believe that round lube grooves would actually have more strength to them and not compress as easily therefore not “pumping” the lube from the grooves as easily. Only in theory, but it makes sense to me. Additionally the square lube grooves will hold more lube if that is what a person is after.

[thegreatdane]

So tell us....."the rest of the story". Lube? Alloy? Size?(boolit, barrel and throat) Hardness and powder charge don't tell much.

Fecmech, do your 50/50 boolits show some evidence of stripping, or is that the camera angle...or just my imagination?

Jerry

Well, I don't wanna hijack the thread, BUT...

It's the NRA formula with JPW to help in pan loobing. Alloy is tinned WW sized .358. The throats measure 358 and the barrel is 357 - best I can tell... 5 lands.

I'm still experimenting.

sent from my fancy phone and fancy apps

[thegreatdane]

Oh, and they're water quenched

sent from my fancy phone and fancy apps

[Bret4207]

copy. Must have missed that part.

This is puzzling to me, as I've slugged, cast good ~15bhn projectiles and still get leading around 1250.

Bhn reading alone will not stop or cause leading. It's just part of the mix of dynamic fit. And, some guns are far more cast friendly than others. And then to top it off, your 15 Bhn alloy may not be anything like my 15 Bhn alloy. We simply don't know the alloy makeup or what contributes to the "best" alloy for our particular guns and loads.

[btroj]

Yep, BHN may be the most scientifically defined, well known, piece of sometimes worthless information we have.
BHN tells the hardness, what matters more is what gave it that hardness. Is it heat treated? High Sb alone? Too many alloys can have the same BHN yet have very different properties.
Don't get hung up on BHN . It is a number. No more, no less. It is a guide but not an absolute. Looking at the hardness a lome will lead you nowhere as it means you are failing to see how it fits in with other contributing factors like pressure, velocity, fit, etc.
Shooting cast is a balancing act. When everything is in balance you get good results, when things are not in balance you have problems.

I do not own a hardness tester. I have tested the hardness of probably 10 bullets in my life. They have limited use in my opinion because they tend to lead us down the "BHN is the key" road. I did use before my bear hunt. My Hu ting bullets measured 12 air cooled and about 19 water dropped. That was what I wanted. The extra hardness of water ripping allowed me extra velocity without leading yet the bullet was actually maleable to hold together well on impact with bones. This is one area where a hardness tester has use because it let me adjust BHN to fit my specific needs.

Brad

[Bass Ackward]

Jerry-- I'm not sure what you're seeing but the 50/50 bullets show no signs of stripping. What really amazed me was that the pure lead did not strip or even show much widening of the front part of the rifling grooves.


Stripping is an excellent indicator for consideration. Stripping is often manufactured more often than real.

If the throat friction on the bullet is too great, then the rifling has to do more work than necessary to turn over the slug. So it is more prevalent with longer bearing area (heavy for caliber) slugs

Hard bullets grip the throats tighter and require more umph to size, so you can actually manufacture stripping if you are too large in diameter for the hardness.

That's why the faster I want to go, the smaller in diameter I want to be. But that can cause other problems if the guns dimensions won't support that sizing.