Help with subsonic load.

[J-bird]

Hi,
I've been lurking and reading all I can find on this site, very informative!

I'm from South Texas and we have big hogs here! I have been enjoying the 450 hornady rounds and have been reloading my own for a wile now, but need some help on a starting point for some subsonic rounds.

I have some 405Gr and 550gr .458's that I re-sized to .452. I also have a few pounds of lilgun, h4831, and some Retumbo powder.

I'm looking for a good starting point for a load to shoot suppressed around 100 yrds.

I also have a lee side crimp die that I'm working cutting down to work, I understand that a heavy crimp and slow burning powder are staples of subsonic rounds but can some one figure out for me what charge of any of the above powders I should be using.

I plan to eventual make my own suppressor on a form 1(the legal way) but would like to get an idea of what the rounds would consist of, and what kind of accuracy I can expect before I get started on the paper work for the can.

I really doubt that the 550 grain bullets will stabilize, but I'm hoping the 405 will!

Thanks,

Jeremy

[Siringo]

Maybe someone who has quick load can shed some light on this subject. While the 458S folks do this, there really is not a reason why we can't. Of the few posts that I have read on subsonic 458S, pressure is a problem (high). Whatever the 458S people are using for powders in subsonic loads would also work for the 450B. Charges would be different though. I have no clue what the gas port diameter is or its location in relation to the chamber. I would assume that it is the same at the 450B -- but making assumptions is dangerous when it comes to loading.

I have experimented with 405's (lead and jacketed) that I wanted to be 45-70 velocities (1300 fps) or so. I had used 5744 powder and had velocities as low as 900 fps, but lots of unburned power (this stuff is dirty anyway) that left enough powder granules in the chamber to prevent chambering of the next round. Load Data lists 4198 powder being used for the 500 gr bullet at 1070 fps.

ALSO -- which was very important -- I had significant Rim bending on the case. This means the action was trying to open before the pressure had dropped to a save level. Has to do with velocity AND powder/pressure burn characteristics. I am using a carbine stock and at that time I had a 2.8 oz buffer. I have since changed to a 5 oz buffer and added a carrier weight system (Tubb's). This serves to slow the opening of the action and make chambering a little gentler.

Regarding twist rate -- the 45-70 was/is 1:22. This was for 405's and 500's. We would be on the edge. I have shot 405's at about 1500 fps and they work great.

[J-bird]

I went ahead and ordered the quickload software, so maybe this will help work up a safe load! I also have a heavy buffer and the tubbs carrier weight system, and I do believe that this will help keep her locked up longer. I was trying to look up load data for the .458socom, but the 458socom forums are down.

Thanks,

Jeremy

[J-bird]

Does anyone think the following loads would be unsafe?

405gr with 25gr lil'gun 2.19OAL
550gr with 27gr lil'gun 2.19OAL Compressed powder charge

I loaded up one of each that I want to try this weekend just to see what it does, but if anyone thinks this is unsafe I will forgo this test.

Thanks,

Jeremy

[BD1]

Assuming that these are cast boolits, Quickload tells me that the 405 grainers over 25 grains of LilGun would give 1394 fps out of a 16" barrel at 23,491 psi.
However, Quickload says you're not going to get 27 grains of LilGun under the 550 grainer at that COAL, and if you did you'd be pulling the trigger on a bomb, something over 150,000 psi. DON'T SHOOT THAT ONE.

The 550 grainer wants to be seated longer, (2.250) and loaded over 20 grains of LilGun for something like 1,200 fps at 35,000 psi.

If these are jacketed bullets, you'll need to cut back the charge under the 550 grainer to 19 grains.
BD

[J-bird]

thank you

that is what I was looking for!! I'll start at 19 gr for the 550, they are jacketed. what load would you use behind the 405 jacketed to get to around 1000 Fps?

Thanks

[BD1]

Somewhere in the 16 to 17 grain range of LilGun should yield 1,000 fps +/- with the 405 grain jacketed bullet seated to 2.190
You'll need a chrony to work to a precise subsonic load as you're getting pretty far off the data that thye quickload model is based on. Whether or not it will cycle the action is another thing. QL shows 90% of the charge burnt, so if the pressure stays high enough it may work. I loaded up a variety of subsonic loads last summer using Unique. They shot well but didn't cycle the action.

The answer to this question may be more in the range of Blue Dot, AA #9 2400 or one of the WC820s. It's a question of having enough pressure available when the bullet passes the gas port to cylce the action, without so much un-burned crud left in the system that it quits after a shot or two. I;m waiting on a "taller" gas check die. When it comes in I'll go back to plying with cast boolits, including the subsonic heavyweights.
BD

[Siringo]

Go to the knowledge base of this thread. I had used 27.0 grs. of LG under the 400 gr. Speer. Got 1550 fps. So, the 25 should be OK.

On the 458 threads (becareful of these -- in fact do not open them, they are full of viruses. Had to have my home computer and work computer fixed after visiting their site.

Anyway, in reading using the 500's pressures can spike quickly -- as BD1 said.

[BD1]

We need to remember that in addition to increasing pressure due to the heavier bullet with a longer bearing surface, we are also decreasing case volume when we go to heavier bullets as we are limited in over all length due to the need to function out of a magazine with a 2.260 max OAL. When you push these two factors against one another, pressures go up fast.
BD

[J-bird]

I only had enough brass to load up one of each:

405 gr pushed bu 25gr of lil'gun = 1434fps no problems cycling the action
550gr pushed by 19gr of lil'gun = ??fps(chronograph gave errors was getting late and too dark) but I'm confident that it was close be being sub sonic and cycled the action no problem.

this is all with a 20" barrel.

BD, is 16 to 17 grains of lil'gun behind the 405gr bullet going to need cream of wheat or something to take up the extra space, or do you think it would work with out it?

One more thing, I did not thing the 550grain wold stabilize in our barrel, but I did get a nice clean hole( not key hole) at 30 yards. I think more testing is in order, but I was quite pleased that my zero it the 550'sat 30 yard is the same as my zero with 250 grain flex tips and 100 yards. I am also impressed with the penetration of this round. I dug it out of the berm were I shoot and it went in to loose dirt 14 to 16 inches!!

Thanks,

Jeremy