Subsonic rifle load data wanted for 303 Brit

[knappy]

Can anyone help me determine a load for cast boolits in the 303 Brit that will be just subsonic? The powders I have are H4227/AR2205, Lil'Gun, Varget/AR2208 and H4350/AR2209.

Boolit weights are 230gr and 208gr.

I would prefer a load that nearly fills the case if possible.

The 303 Brit has a case capacity similar to the Krag and 308 (when measured to base of the neck - where the boolits will be seated to).

Thanks

303guy
Try 200 Grs proj powder RE 7 26GRS. works well in my 303 in Aust.

[303Guy]

Much has happened in the interim but revisiting this old thread came timeously as I just so happen to have a more recently acquired rifle that doesn't like to align boolits/bullets with the bore. I experimented a bit with what I had lying around and it just so happens that this rifle does align the 262 grain boolit I mentioned at the beginning of this thread. This rifle had quite bit of fluffy rust toward the muzzle which may or may not mean the muzzle end has opened up a bit and it may or may not make a difference but with such a heavy cast boolit, barrel length may be moot so so I might end up chopping off an inch or two or maybe three and fitting an over-barrel suppressor (you gotta envy us Kiwi's).

I no longer care if it's subsonic or not, just as long as the muzzle blast is gone! I'll be trying a few loads suggested way back then (plus I have developed a safer loading practice to avoid double charges). So, since I have Trail Boss, the ADI equivalent of red dot/clays, H4227 and H4895, I will be trying those. One or all must surely work. I'm moving my workshop and man-cave so it will take a while. I do have motivation for subsonic though, I'll be able to fire them in my backyard/bush - clandestinely of course! (But legally - as long as I don't disturb or endanger my neighbors).

[Bigslug]

WHOA! 9 year-old Zombie Thread! Oh well, had a useful reply cooked up - might as well post it.

Not much to add except for some comments on process.

The common safety practice of finding a working charge that fills the case more than half full to prevent overcharging is a good one, but as mentioned, it ain't gonna fly here. This technique adheres to the Keep It Simple, Stupid! principle in that it takes into account that our focus might get distracted and we'll occasionally make mistakes. Ordinarily, enough to implement, because nobody designs a cartridge with the intention of leaving half the case empty; and all of the powder manufacturers tend to formulate to fill the commonly available spaces. In your case, Simple went out the window with the goal of "sub-sonicking" a military cartridge with an intended 40-ish grain capacity and 2000fps+ nominal operating speed. The classic safety practice is no longer valid, so you'll have to come up with something else.

I would suggest having your primed empty cases thrown loose into a box on the left (NOT in a nicely organized, upright-standing loading block!), your press on the right, and your charging apparatus and bullets in the middle. Pick up a case, charge it, and go directly to bullet seating without setting the case down, and have an inviolable rule that charged cases only move to the right. I would not allow a loading block anywhere near this process because they hold cases in an orientation for filling and potentially re-charging. Having them jumbled and tumbled until the moment of filling prevents this - any case standing on its head is automatically regarded as "hot".

Intriguing concept for the .303. . .I've got my 316299 @ 2000fps load worked up to reproduce the MKI-MKVI cartridges, but the idea of running Mad Minutes with gallery loads makes me grin.

[303Guy]

My technique is as you say a jumble tray of cases that first get primed then go head up in the loading block. From there they get charged and go back in the block mouth up. They do not get picked again until a light has been shome down the mouth and the powder charge inspected. Only then do they get bulleted. This applies even when I am only loading one cartridge. I used to do the powder then bullet method until I nearly blew myself up with and uncharged case. It usually takes two or more mistakes in a row to blow something up and I did just that. The second mistake was to assume that when the cartridge didn't fire, I had neglected to reload after the last shot. The third mistake was to think the case was a bit fat or something when the next one wouldn't chamber. My final safety measure saved me - that being a full powder charge that prevent the second bullet from pushing back into the case far enough to chamber behind the first bullet sitting in the throat.

[Chev. William]

WAY Late comments:
You are not stating the Conditions under which you want the Load to be subsonic, nor by how much.
I believe the Speed of Sound at Sea Level and Standard Humidity, Temperature, and Pressure is about 1124FPS.
Changes from those conditions changes the Local Speed of Sound.

It appears that in the .202 British Case you wil be using less than half volume charges, so us ea Filler above the Powder charge to confine it to the rear of the case.

To avoid Double charges you might make it a habit to insert a Bullet after charging the Case; which means single case in hand for charge and Seat of Bullet. the steps prior to Charging can be Batched, along with those steps following bullet seating.

At end of Session, weigh each Cartridge to double check for both Too light and too heavy ones (squibs and doubles).

Chev. William

[Conditor22]

there are few powders that I use a filler with. I find that pistol powers don't need fillers. 4895 is the only powder (I have) I use fillers with.

[35remington]

I will second the notion of charging a case and immediately seating a bullet. It is possible to miss a double charge of fast powder in a bottlenecked case even after shining a light down in it. Straight wall cases are somewhat less prone to this. The narrower neck prevents a comparative look at fill levels to some extent.

Hopefully the zest for more restrictions in NZ allows you to keep pursuing your interests. If your interests included semi automatics and some types of shotguns it sounds like that is in for some revision.

[303Guy]

All I can say is I've never had a powderless round since I stopped charging then seating. I was using the charge then seat method when I had that incident with a bullet in the throat. It made me wonder how many reported SEE's were the result of that exact same thing.

The conditions for subsonic would be sea level mostly. I would probably aim for 1050 fps I should think. That would keep it subsonic at higher altitudes too but I wasn't thinking about altitude effects. What works to 22lr subsonics should work for me and those run at 1050 fps.

I use a dacron positioner with most of my loads. I did a test once and I got the impression that firing the gun straight down did things to pressure with some powders. Not sure about that but it seems to make sense to hold the powder against the flash hole so that's what I do. It's a positioner, not a filler. It shouldn't have any detrimental effects although it may be necessary.

I want to try loading with Clays, H4227 and H4895. This particular boolit is the only boolit that aligns properly in the bore of this particular rifle. While I still want to suppress it, I also don't mind maximizing the velocity.