Home Forums Hunting & Shooting Single Shots The best curve...

...is a learning curve, or so they say.

Last spring I started contemplating a threaded barrel for the Contender Carbine to be used for a very specific purpose, that being hogs at fairly close range.

I pondered...and pondered...got some good advice from a few sages here on the 'Fire and some technical help from a fellow with Quick Load software. The objective was fairly simple. MOA precision at subsonic velocity in a rimmed cartridge using cast bullets. The evolution went something like this:

The bullet objective: 180 gr 30:1 alloy, plain base round nose. With the help of Steve Brooks I wound up with this one.



The parent case is the .357 Mag. Dave Manson crafted the reamer and the sketch that went along with it set the wheels in motion for the dies.



Bullberry did the barrel and I wound up with this:



More on the next post

After all the parts and pieces arrived I set about confirming specs and am pleased to report it is all spot on, down to the .0005" yardstick. My fingers are too fat to fiddle with smaller stuff.

Anyway, went to the range today and was peppered with questions ranging from the sublime to the ridiculous. After that settled a bit I set up for the 50 yard line. I had 7 loads set with the same specs other than powder type (3) and charge. My first point of interest was to verify the bullets were stable in the 12" twist before screwing on the can. Second objective was to try and ferret out some insights for load development.

First came the Bullseye. I had no particular expectations for this load other than the thought that if it blew it wouldn't be terribly painful.



Recoil was mild to say the least, my estimate of velocity in the 650 fps range. Apparently my bore sight job on the scope was adequate? I did not touch the knobs throughout the day's effort.

Next up was a run with the WW540.



The first group with 540 was only slightly larger, perhaps .1". Maybe I'm on to something. You may notice the POI has trended downward? Me too. Scratching head over that.

Onward! Group 3 w/2400



Pulled the shot on the left, but I'm seeing a wee bit of potential in this and the WW540. Again the POI dropped, and in the case of the first load it dropped quite a bit. I found the threshold of stupid in any case.

Recoil was slightly more severe than a .22 LR, noise was lost in the din of the other shooter's guns. One fella was kinda spooked that it made no more noise that it did. Oh well...

Last bit of joy for the day was cleanup. The short version:



A very few fine particles of lead after 39 shots and 3 different powders. I'm OK with that. Next round will have a chronograph on deck and probably a bit more powder. No surprises with this in any regard and I'm pretty much a happy camper with the way it is turning out.

DD

Looking good BD!

neat project

Good stuff BD.

Pretty neat!

Keep the updates coming. Cool project.

Looking good. A tad more pressure/velocity to find the sweet spot is my guess also.

Unburned powder?

How did the fired cases look?
Leakage?
Before and after dimension changes?


The crono will tell a lot.





"Gesundheit"

Some unburned powder, see patch #1. 2400 was the worst.

More pressure is indicated.

Bullseye loads had gas leakage indications around the neck, otherwise no.

That's an interesting question. The cases fired with Bullseye measured an average of .0025" neck expansion and those with the WW540 & 2400 measured only .001" on average.

Aren't pressure curves a hoot?

Yes they are.
Eliminating any other factors, I guess the Bullseye spiked higher. My guess is early in the curve. The latest burn rate charts do not list WW540. I believe it is the same as HS6. Ball is going to act a little different than the other flakes as the loads get hotter. WW231 will act more like Bullseye, but Bullseye might be more predictable in that case form. Long narrow case with higher sectional density bullet than what WW231 is normally used for. Just thinking out loud.

I tend to agree. Other powders in the background, this is going to be an interesting journey.

Master Flake

Powders seem to be coming back on the shelves around here. But with sticker shock.

Like you said before the case is similar to the .30 Carbine. There is three notable differences. The carbine loads are @ 40k psi and a light 110gr compared to your 180gr. The go to powder for the carbine is H110 (WW296). These are magnum powders that like to live in an handgun environment of high pressures, heavy bullets and strong bullet pull.

The unburned flakes of the 2400 indicates a higher load is needed. This might exceed your velocity wishes. Only testing will give insight on this. 2400 is a forgiving magnum powder. Unlike H110 (296). They are definitely not recommended for reduced loads. It is all over loading literature for H110 (296). Some people like Blue Dot. I stay away from that powder except in heavy shotgun loads. It has proven unpredictable in long powder column loads. Even Alliant says that.

I said this before, out of the box thinking would include Trail Boss, AA Nitro 100 and AA5744. Don't forget some of the "shotgun powders" also.

At any rate you are going to have fun with this project. I envy you.

Have an idiot's delight of varieties to play with and some will shine, some not so much.

Short list beyond the 1st three that have potential.

Clays
Blue Dot
Red Dot
4227
4759
RX7
Li'l Gun
4198 and more

Speed meter will be the guiding light.

I'm betting the 4759 might prove itself in that case/bullet combo.

As an aside, that Brooks bullet Dan shows is a heckuva good design. He sent me 100 of them a while back and so far I have shot away half of them in my put-together M1903A1 Springfield with a long gentle throat that matches the bullet very well. (New Criterion barrel + vintage C-stock and late nickel steel receiver, National Match rear sight.) Mild charges of 2400 and 4759 (15 grains) turned in groups off the bench that hover in the MOA neighborhood. I'm saving the rest for when I finish mounting an old Fecker target scope on it as a Marine sniper clone. If they continue their pleasant shooting trend I'll be camping on Dan's doorstep for more, or better yet applying to have a mold of my own cut.

I'm not sure exactly what velocity you're looking for, but I would think that you want it to be just shy of supersonic which puts it somewhere in the 1000 fps range.

There's lots of powders to choose from to do that, but to get consistent burn/pressure/velocity, I think you can eliminate anything slower than Blue Dot.

AA#5 might be worth a try.

Glad they are working out for you...me too apparently? It will be probably after New Years before I make any more of them, but I don't have a problem shipping some more when I get there. Let me know.

Thinking that 4759 may be the wild card that fills the straight flush with this project, will get into that soon enough.

Velocity in the 800-1000 range will work, but precision will be the determining factor in where it winds up. I suspect but do not know at present it's running in the 650 range with the WW540, maybe a bit slower with the 2400.

I bet if you put it on a chronograph at that speed with 2400, you'll find that velocities are all over the place.

I really like 2400,....it's one of my favorite propellants, but it's made to *pop*,...as is any propellant Blue Dot or slower.

I'll admit,...it's kind of a funny cartridge,.. but even so you're talking about low pressures.

I'm guessing that the most consistency you're going to find with it at the velocities you're looking for will be in the medium/fast handgun propellants.

Basically, it's a slightly skinny, heavy .38 spl.+p.

I'm still thinkin' that if you get slower than Blue Dot at the velocities/pressures you're looking for, you're going to get erratic ignition,...which is going to cause erratic pressures and velocities,...and consequently, erratic accuracy.

Propellants start getting very particular about pressure once you hit the Blue Dot burning rate.

Also,..I think you need to pick the velocity you want to work with before you try to pick the best propellant for it.

I doubt that the most consistent propellant at 700 fps is going to be the most consistent propellant at 1000 fps.