Subsonic Ammo Not Cycling Action

[Morrey]

I have a Ruger SR 762 and tried to shoot 3 different subsonic factory loads this week...they would not cycle with a can attached despite gas piston adjustments for under-powered ammo.

In a previous thread, someone suggested different calibers may cycle more effectively. Is the 300 Blackout one of those? I would like to stick with a 30 caliber round or at least close...but not .223. I am not bound to semi-auto, so a decent bolt gun could be an alternative for my needs leading me to an equally important topic:

Can a sub sonic load offer effective killing power on medium sized game like feral hogs? I realize shot placement is critical and some hunters boast hogs can be killed with a .22 rifle....but I am a bit more realistic than that. Knowing my effective killing range is quite short and limited, can subsonic loads be effective at all for medium game at short ranges no greater than 100 yards?

 

[hq]

Switching calibers because some rounds won't cycle is like buying new shoes because laces are too tight. The easiest solution is to install a suppressor, which will increase the gas pressure and impulse duration to the gas piston, and this is how the majority of subsonic ammo has been designed to work. Few .308 SS rounds cycle my R-25 without a can but I haven't come across one that doesn't with one, even though the rifle has no gas port adjustments and has never been designed with suppressed use in mind.

You might want to try different combinations of recoil spring, recoil buffer and gas port adjustments first. I have yet to come across a semiautomatic firearm that wouldn't work with subsonic ammo after slight tweaks.

In hunting applications you lose the vast majority of hydrodynamic shock so you might want to look into compensating that by increasing bullet weight, diameter and consequently penetration; the combined, bleeding surface area of the wound channel to induce as rapid loss of blood pressure as possible. Permanent wound channel is pretty much all you have to work with so you'll have to make it count by a careful shot placement. I'd limit the shots to 70-80 yards in most situations, bullet drop will be considerable but nevertheless, effective game shots are a perfectly doable proposition at subsonic velocities.

My personal subsonic favorites are the heaviest .45ACP bullets from a rifle and ultra-heavy handloaded shotgun slugs. They've proven very effective for a variety of medium game over the years.

 

[SamT1]

The blackout cycles perfectly. I switch back and fourth with no issues or modifications. (Pistol length gas system)

I cast a 192 grain lead bullet. It’s works nicely on pigs out to 100 yards. Lead is the king when you don’t really have enough power. If I were buying a new mold I’d go even heavier, but I already had a nice Lyman mold I was using for 308 win supersonic hunting.

To get the 7.62 to cycle and kill game reliably your going to have to start casting and reloading. If your willing to modify it for subs only then you may as well buy a blackout so you have a rifle that’s going to work for sure every time.

 

[someguy2800]

I suspect you may need to have a lightened buffer spring and buffer to make a normal length gas system ar10 work subsonic but I have no experience in that. My 300 blackout works great. Its a neat caliber if your in the market for an ar15.