by wildcatter » Wed Feb 01, 2012 8:13 pm
Here's my two-cents worth. 60+ years of history in a few paragraphs, with lots of holes in it, so bear with me.
This craze came on in WW-II, when the spec-ops, of that time, needed a sub-sonic for taking out sentries at ranges of a little more than knife welding range. Their solution was a 30 carbine, BUTTT, it was found that the 110gr bullet didn't do much more than make the Mark madder than a Hatter and for functionality, they wound up making a switch for the gas block, so they could make it a single shot,and function the action not unlike a Swedish Straight-Pull. Fast forward some, spec-ops still has a need, but the same problems are true with the 9mm, as was found with the 30 carbine, BUTTT, with a 147gr bullet, they could make an MP-5 operate reliably and still be sub-sonic. The range increased to 50yds MAX, for reliably taking out the intended targets, but action noise is still a problem.
My though is, about the sub-sonic craze, is that if spec-ops (or the military in general) wants it, then the public, at large, wants it too, just because. But there is a sub-sec that has a real need for the Pig-Bomb Plague, hence Big-Bore, semi-autos, of military design (you know the .."take a licking and keeps on ticking" reliability).
Which brings us to our rig. It's true, we have enough powder capacity, that makes going sub-sonic difficult, but not impossible. If the powders are slow enough to cycle the action, they don't seal in the chamber. If they are fast enough to seal, the action won't work well. 300-500gr bullets have this malady. Get the 300's to function and the speeds are too high (I consider 1040fps to be a usable subsonic speed and you need a margin of error, in case your ammo is being used in a high temperature area, thus increasing the pressures and thus the speeds, to super sonic speeds.).
As an asides, I've always liked the pump action AR's I have built, because the action itself makes allot of noise, then hitting subsonic's with heavy bullets becomes real easy. But then again, this is not Jim-bo's criteria, he wants semi-auto functionality.
I've have used .458" 500gr lead bullets, subsonically, with ww-296 and a pistol length gas block and done quite well. The problem here is, that you've got to use a filler, inside the case (with it's accompanying problems), if the case volume goes below 3%, of total capacity and if you want to be safe from a pressure wave event. I have been wanting to do the same thing but with Trail Boss, so I can have a full case of powder, but this remains to be seen if I can make this work??..
So, herein lies the problems, many though they are, but NOT insurmountable, at all.
Think of it, a 500gr, 45cal, full wad-cutter at 1000fps MV. The Sentries, or pigs, in my example, would not be so wounded that they couldn't sound any alarm, before succumbing, because they'd already be dead, even if the range was at 200yds and not the mere 100yds and allot less, that is expected, by the current breed of semi-auto, sub-sonic weapons, now on the market.
To me the real problem is silencing the action and I have done so, fairly well, with nylon inserts, in the action, but then again, a pump AR cures all of this, and under my scenarios, allows one to take out the whole Pig-Pack, before they know what's going on, if you whittle down the pack, from the furthest away and work to the center, OH!, I guess we've done this before. Same-same, problems with a pack of humans, in a military scenarios.
Before I sign this off, if a regular sub-sonic AR is used to engage a pig pack, they always start running after the first shot, and largely because of the action noise, and or the bullet impact noise, which is why we have used the whittling technique. Spec-Ops, have the same problems.
I've mentioned some cures or so I think they might be. But you might ask why worry about the pig-bomb, consider the amount of pig hunters and their numbers, compared to the number of weapon the military will need, which ain't many. Military needs compared to the civilian market, ain't no comparison, but the Military drives the WANTS market.
Allot of disjointed rambling here, but I hope you get the drift..
..t
Safety First..t
