Anyone come up with a action Cycling Subsonic Load yet

[Variable]

What twist rate are you guys using with the 160 grainers and are they stabilizing them?

I have a 1:7.5" twist in my 10.5" barrel. It stabilizes fine with the Hornady 160 grain bullet. I just couldn't find any load that would cycle in my upper at subsonic velocity. I'm pretty sure my problem is lack of dwell time. If I could do it over again I would wish that someone would make a 10.5" chromed bore with a pistol length gas system (instead of the carbine length on the AA Tactical upper.

My dream upper would probably be a 10.5"-12.5" chromed barrel with either a pistol length gas system or (preferably) a Noveske style switched gas block sitting over a larger gas port. If it was feasible then the switchable gas block would have a folding front site and three orifice sizes. One regular sized for conventional ammunition, one oversize to cycle subs with a can, and one "off" setting for maximum sound suppression while cycled manually. I can dream...

[txgunner00]

I have a 1:7.5" twist in my 10.5" barrel. It stabilizes fine with the Hornady 160 grain bullet. I just couldn't find any load that would cycle in my upper at subsonic velocity. I'm pretty sure my problem is lack of dwell time. If I could do it over again I would wish that someone would make a 10.5" chromed bore with a pistol length gas system (instead of the carbine length on the AA Tactical upper.

My dream upper would probably be a 10.5"-12.5" chromed barrel with either a pistol length gas system or (preferably) a Noveske style switched gas block sitting over a larger gas port. If it was feasible then the switchable gas block would have a folding front site and three orifice sizes. One regular sized for conventional ammunition, one oversize to cycle subs with a can, and one "off" setting for maximum sound suppression while cycled manually. I can dream...

You dream has come true- almost. Paladin Machine will make a switchable gas block to your specs. I'm not sure about the front site though.

[Variable]

My barrel is 1:8.75.

I was surprised to read that "Trail Boss" didn't get you enough velocity. It worked great (except for cycling) in my 10.5" upper. I guess those long 160 gr. telephone poles have too much friction for that powder in barrels as long as yours.

I haven't had time to tinker with mine for a while, but I might give it another whirl this year when the weather gets better. I should probably just give up and start over with my 14.5" upper instead, but I'd much rather get the shorty running.

[txgunner00]

Kind of surprised me too. My first attempt with TB actually got the bullet stuck about 2" from the end. Even with compressed loads I couldn't get much velocity. I even tried the other end of the spectrum with US869. It actually cycled but not all the powder burned even with Federal LR magnum primers. I would have unburnt grains of powder stuck to the neck of the ejected case. I wish I had a picture of it.

I also tried Unique at 7.4 grains. 1050 avg, 57 es, good groups but no cycle.

[Retooferab]

Keep in mind I know nothing about subsonics in a Grendel. I have had a lot of experience with subs in a 300 Whisper. I have had excellent results using N110 and AA9 with subs in my Whisper. 1680 worked well also but took more powder and was loud! Has anyone tried any of these?

[txgunner00]

I'm just thinking out loud here a bit. But has anyone tried using a lighter buffer and a loser spring?

I believe Rapier did. I have not as of yet because I don't want to switch any parts to shoot one or the other. One option is a switchable gas block with an oversize port for subs. It does come with some risk because shooting full power loads on an oversize port could cause damage.

[Smoke]

Just a heads up .. I loaded 3 rds 6.5 160 grn (.267) 13.5 grns H335 Seated at 1.850 (touching the rifling of my barrel ) WITHOUT a Suppressor Attached
2 in mag.. all 3 cycled the action no problem ..and Stripped the next round.. Thats on a 18" mid length AA barrel .. next I will load another 5 and chrono

again just a heads up looks promising on this gun anyway

Thanks
Smoke

[txgunner00]

Good deal. Looks like we have several known loads for a mid length. Rifle length is proving to be more of a challenge.

[Variable]

You dream has come true- almost. Paladin Machine will make a switchable gas block to your specs. I'm not sure about the front site though.

Somehow I missed this post last time. I'm a goober. Anywhoo-- I looked at what pics I could find of his blocks, and they are interesting. They kind of look like they are milled out of that soft free machining stuff we used to use in machine shop class. They also kind of look homemade? I guess if they work well that's all that matters though. I'm going to try to keep my eye out to see what everybody else comes up with.

The dual switch blocks looked pretty neat in this thread on Arfcom: http://www.ar15.com/forums/t_3_121/474337_.html

[txgunner00]

I have had a set-up like that in my head since that was originally posted but the thing that has kept me from pursuing it is the fear I would forget to close the first port and fire a full powered load. I'm sure the gas system, extractor and brass would not like it at all.

Very cool solution though.

What someone needs to invent is a self regulating gas system for a rifle like whats on a shotgun.

[Rapier]

Just to let you guys know, I picked up my can yesterday. So this weekend with a little cooperation from Ma nature I should get up to the farm to run a few rounds. The proof is in the pudding and we shall see if the calculations prove true. I have 50 rounds loaded that function the gun with a 3 oz buffer and a carbine spring and should be sub sonic. I can shoot them without the can and hear the impact on every shot at 100 yards, which should be sub sonic.
Ed

PS: The can was made by Liberty and is their QC Torch can. They did the 5.56 to 6.5 mod for no additional fee although they quoted me an additional $100 to start with. It was $580 plus $20 shipping. Order to delivery yesterday on Corp paper was 42 weeks.

[txgunner00]

Sweet! Looking forward to your AAR.

[QuadCam]

Wouldn't using a light weight bolt carrier help out in this situation?

[txgunner00]

Yes, but I'm trying to find a load that doesn't require modifications to the rifle. I'm already using a standard carbine buffer and AR-15 carrier because that's what works the best for full power loads in my rifle.

[Rapier]

It was wet and windy this weekend, but I did get out with the new 6.5 can and the Grendel. Good news and bad news. The bad news is I got my reloads off a tad for some odd reason and had chamber feed problems due to the OAL being just off a tad. The bullets were seated out to far and were being jammed into the lands, on over half the bullets, to the point that the bolt was out of battery, which should be an easy fix.

Now the good news: Previously I had full function from 12 and 12.5 gr of AA-2015 using Hornady .267 bullets seated deep and using a carbine spring plus a 3 oz buffer from the carbine, in a full rifle stock. My estimated subsonic threshold was 1116 fps the 12.5 gr load was 1100 and the 12 gr load was 1024 so I decided to take 12.2 gr loads to my range at the farm. There was no failure to function with the 12.2 gr load using the 3 oz buffer and the carbine spring but the chamber problem was obviously exasperated by the light spring, so after 15 rounds I changed to the rifle stock's full length spring. The load with that longer spring functioned flawlessly as well, with the 3 oz buffer. The additional power helped feed the rounds better. But, this feeding issue was my fault to start with and had nothing to do with the load or its function. However I suspect it probably had to do with the velocity's extreme spread.

I have some work to do on the load, as the highs and lows were very wide for my taste, 974 fps for a low and 1098 fps for a high with two 5 shot averages between 1074 and 1076. But even at 974 fps the load still functioned the action with the rifle spring! I just want to snug up the extreme spread and I hope revising the bullet seating to a depth without contact with the lands will do the trick nicely. This load remained sub sonic at its highs through 40 rounds and the load still shot under 1 inch at 50 yards for 5 rounds in a high wind, over 25 mph.

I am running a Rock River lower with a White trigger, a rubber wedge, and a Model 1, 6.5 Sporter, upper with a 16 inch ER Shaw 1-9 twist Carbine barrel with a mid length tube, the bolt is a Model 1 matching bolt, lubed with white lithium grease. I removed the carbine stock and replaced it with a full rifle stock which I am used to. Scope is a 3x12x50 tactical with a lit red dot, topped by a laser. The can is a Liberty Torch QC 6.5mm, which is 8 inches long.

Full Function= Strips 5 rounds from 10 round mag without failure to cycle and locks the bolt back on last shot, every time. I made no effort to place the powder in the case before each shot, like raising the muzzle, etc.
Ed