Anyone come up with a action Cycling Subsonic Load yet

[Nukes]

Fragmentation is a bet against one's own marksmanship. If one selects and hits the correct target, there is no need for fragmentation. In fact, fragmentation lessens penetration—a net negative. Fragmenting a subsonic projectile guarantees a superficial wound (think of the Glaser Safety Slug), ugly but relatively ineffectual. Peppering a superficial area with metal dust is far less effective than a yawing and tumbling projectile penetrating into the vital zone that the shooter selected. Small arms projectiles are not "area weapons." [laughing]

[txgunner00]

I'm not talking about frangible projectiles like shot filled jackets (Glaser) or sintered copper. Controlled fracturing is very different. RE: http://lehighbullets.com/products.asp?cat=26

[joker31]

the lehigh works well in 300 AAC. I know its not a Grendel but I think if you could get the bullet to come out at about 1080 and maintain the numbers for a good distance then the round would be very effective against a given target, and even more than the 300. I'm relatively new to the Grendel and have only used subsonic rounds against two legged targets but I think it would be nice for hunting if we could get a heavier bullet and it maintains velocity. Expansion is overrated at subsonic speeds btw.... subsonics that are used with cans are effective because you can fire multiple rounds quickly without recoil or excessive flash and the heavier bullet with more frontal area displace a lot of tissue very rapidly. Headshots with high amounts of hydraulic pressure do the job very well. occular displacement is very good indication of this, (not to be too graphic)...pressure in with no place to go, takes the path of least displacement. it either results in occular blowout or extreme rapid expansion (Think Gallager in a watermelon patch.) Its not pretty an def not PETA safe but then again we are more HUMANe to animals than people.

[txgunner00]

The upside however is that by changing mags you can shoot supersonic to 1,000M which is something the SMG cannot do..

This is exactly my reason for doing this.

I think the key will be a bullet that destabilizes and tumbles in a short distance. In the water jug and ballistic gel tests I have done the bullets that yawed created very large wound channels. Problem was they didn't turn over until the were 12" or more into the gel. I have an idea of a bullet similar to the Lehighs but with petals cut only on one side. Anyone have a CNC lathe that can crank out a few hundred?

[joker31]

I'm not seeing any application for Civies, even LEO's. Might be a novelty but novelties hardly make money or have the customer base to make it commercially. I guess a custom setup for hog hunting would be a stretch because there are already viable options out there. 300 for close in subsonic then swap upper to grendel for long distance. I have carried 2 uppers in the past in my pack. Its not that bad if one is a very short barrel and if the ammo count is low (Less than 100 each) I carried 2 rifles and a pistol downrange and I'll tell you that sucks when one is an M14 platform and the other is a mk18 uppered M4A1. I did end up swapping the M14 for a M16A4 upper later and it was nicer because you can do cave work with the 10.5" then swap out for A 20" in Mountains.

[txgunner00]

All valid points. Trail boss didn't work at all for me. Even a compressed load gave only 700 to 800 fps with very high extreme spreads. If I remember correctly my 8208 load density is somewhere around 70% and velocity ES#s are consistently very low. I feel comfortable saying SEE has a low probability of occurring with this load.

My reasons for doing this-

I wanted to carry 1 rifle and change loads only by changing magazines.

I wanted to have 400+ yard lethal range. Blackout doesn't cut it in this area.

I wanted the ability to dispatch critters (racoons, hogs, etc.) without blasting everything out of the area.


It's definitely not the end all/be all load but it works for me.

[txgunner00]

Time to bring this thread back from the archives.

Just got my new 12.5" upper together and running. Initial test look good. With my old load of 13.7 grains of 8208 behind a 160 Hornady I get full cycling (3 rapid shots) but not reliable lock back on an empty mag. 14 grains locks the mag back but might be too hot. Hopefully tomorrow I can put some over a chrono.

More to come...

[Variable]

Sounds great man.

An idea what your gas port diameter is on the new barrel?

[txgunner00]

Not sure exactly. I'll have to ask Mark.

[Sgt45]

I'm shooting a 20" barrel but interested in sub-sonic. Has anyone tried 140 gr bullets and IMR 4198? I've found 4198 works very well in my short 300 BLK, just wondering about the Grendel? I haven't found a source yet for the 160 gr bullets and was curious about the 140.

[Mountain Man]

I'm shooting a 20" barrel but interested in sub-sonic. Has anyone tried 140 gr bullets and IMR 4198? I've found 4198 works very well in my short 300 BLK, just wondering about the Grendel? I haven't found a source yet for the 160 gr bullets and was curious about the 140.

I'm interested in 140gr data as well. I made some 140s the other day with 7.5gr of Unique that were definitely subsonic, but I'm not sure the 140s build enough pressure to run the action at subsonic speeds. Going to try loading a few backwards tomorrow. Helped a lot in .223 loading M855s backwards......

[txgunner00]

I have not tried 140's. You could get the 140's to work but you would have to enlarge the gas port, lighten the bolt/buffer, etc. to the point where it would be unsafe to fire full power loads. A switchable gas block would help but even with that my 160s are right on the edge and not 100 reliable on fully cycling the action. After much trial and error I get maybe 95% on picking up rounds out of the magazine but only about 50% or so on locking back on an empty mag. For my application this is plenty good as I'm not counting my life on it.

It's a fun and sometimes frustrating project. Just be careful to not over charge with a pistol powder (catastrophic failure!) or under charge and get a bullet stuck.

[55Kingpin]

Any new updates to post?

I plan to start with the known 8208 load and see what happens.

I'll have my 11.5" rifle built within the next 30 days (waiting on ADCO to do their magic on the barrel and send it back to me).

My purposes are the same as txgunner.

I'll also be using a Silencerco Omega can.

[55Kingpin]

Just wanted to bump this thread for any new developments.

I have some 8208 on hand now and I plan to get some rounds loaded up within the next week or so.

[IMG][/IMG]

[burnsome]

we'll be anxiously awaiting results sir!