Help with subsonic load.

[BD1]

Any safe load of LilGun that will cycle the action should not need fillers. In any event, I'm not sure that fillers are a good idea in a gas operated firearm as they are a source of crud in the gas system.
BD

[J-bird]

I had a chance to play with my semi subsonic loads this weekend and had some interesting results.

The 550gr is a waste of time, things dropped so far I could not find a box big enough to get on paper for grouping.

the 405gr Remington flat points actually shot much better! only a few inches down from my 100yd zero with factory loads.

here is some data:

using lil'gun set OAL at 2.20" side crimped

load #1 #2 #3 #4 #5
15.5gr 1295 1282 1287 1282 1279
16.0gr 1267 1267 1270 1244 1247
16.5gr 1240 1226 1220 na 1200
17.0gr na 1200 1190 1193 1199

it seams that the more powder i used the slower the rounds moved. Quickload calculates that the fill % was 43% on the 15.5gr and 47% on the 17gr loads, so I'm thinking I was loading them too light to begin with. I am going to try some a little hotter this weekend. If I can get them down to around 1000 fps I'll be in business! These should work great with a suppressor and my d-740 night vision!

Thanks,

Jeremy

[Siringo]

Did you get anything with the 550's though? Velocties and such. I realize they drop a lot, but I could use that bullet to penetrate beaver huts to drive the little rodents out for the kill!

[J-bird]

With the 550's I was getting around 790FPS with 14.5 gr of lil'gun and about 1180FSP with 16gr of lil'gun. I was having problems with the chronograph with these loads, I think it may have been too close to the muzzle. oh yea those babies would penetrate like mad, but its like shooting a mortar round!

[BD1]

Did the LilGun loads with the 405 grainers cycle the action?
BD

[J-bird]

yes the 405 and 550 cycle the action no problems, I am also using the tubb cws and saw no sighs of over pressure on any of them. One of the 550's got stuck in the barrel about 2" form the muzzle, and even that round cycled the action?
I'm starting to wonder how much powder I will be adding before the velocity starts coming back up. I hope there is a sweet spot that can get me down to around 1000-1050 fps.

[wildcatter]

An Extreme cautionary note here. Any load that is below 80% of capacity is in danger of a Pressure Wave Event, better known as Detonation. To be sure, sacrifice a case by drilling the primer pocket out, with say a 1/4"-5/16" drill. Seat the bullet as normal, then fill with the desired powder, making sure you compact the powder, there are many methods. When you can't fill the case any more after compacting, weigh that charge. Now, Do-Not, repeat, Do-Not, go under 80% of that and I like 90% even better. So pick the powders that give the desired results, but heed this Warning and go for the 90%. As one who has experienced the Pressure Wave, on many occasions, believe me, you don't want to Calculate the % fill, you want an actual, real world, number..t

[J-bird]

Wildcatter,
Thank you for your help, this is the kind of information I needed. I'm still kind of new to reloading and have been reading every book I can get my hands on, but your suggestion was something I would have not thought of on my own.
I drilled out a case like you suggested and full capacity with a COL of 2.20 i can fit 39.1gr of lil'gun and I tried the h4831 and get 35.1gr.

I think that the h4831may be a better powder for this as quick load says that 35gr will give me 1063 fps!

Anyone have any other helpful info, I'm all ears!!

[BD1]

I do not want to portray myself as some kind of interior ballistics "expert", and I do not want to take exception to WC's warning as there have been instances of blown guns from "detonation", (SEE? Pressure wave event?). This is a real issue.

I have no personal experience in downloading jacketed bullets. There are however multitudes of cast boolit loads which occupy less than 50% of the case capacity using smokeless flake powders which have been shot for many years with no issues. Almost all of the cartridges designed originally for black powder have been loaded this way since the advent of smokeless powder. The .38 special, .45 colt and 45/70 are examples. So it is not as simple as the % of case volume occupied by powder. The composition of the powder, kernel shape, deterrent coating used and pressure range appear to play a role as well.

That said, the .450 B is a new cartridge, LilGun is a relatively new powder, (and slow for a flake powder), and you are talking about jacketed bullets, not cast.

Hogdon does not recommend downloading LilGun, claiming that it may fail to ignite, leaving a bullet stuck in the barrel. Certainly a load which will stick a bullet, yet still cycle the action of an autoloader, has the potential to be very hazardous. the Hogdon rep I spoke with recommended Trail Boss for low velocity loads.

I think we need to take great care here, and this is probably not the area for experimentation by someone fairly new to reloading. The erratic velocity readings obtained with the initial testing are also an indication that something is not going according to expectations. Pressure dropping with increasing charge weights is a very unusual result.

Does anyone know of work done with subsonic loads in similar cartridges?
BD

[wildcatter]

BD, you did very well and my caution was of a generalization, you became very much to the point and is much clearer. I didn't think you were stepping on anything, as a matter of fact you're right on, my friend.

Many of the black powder, change over loads, are using powders that don't have Pressure Wave (pw) problems. There shouldn't be a problem with H4831 either, other than it may not function the weapon, not having enough port pressures, or maybe too much port pressure, but hey, try it. If the cartridges are being thrown into the next county, well, thats too much.

Some of the powders that have had pw problems, are some of the ones we want to use. H110-ww296-lil gun, etc. And 14.5gr of lil gun under that 550gr bullet with a capacity of 39.1, is a 37% reduction, or about 63% of capacity, Danger Will Robinson!! Let's stay with 90% case capacity and everybody will be happy.

Now Trail Boss being recommended, is one I have no experience with, so I'm wondering what QL will say will be the starting load and what % full under the bullet? Listen J-Bird, try the 4831, because you've got it, but this trail boss might be an answer, but it is a very fast powder, just a little slower than green dot, but it might be as bulky as IMR SR-4756 is, which nearly fills any case and has a somewhat slower in burn rate..t