Anyone come up with a action Cycling Subsonic Load yet

[txgunner00]

Good news

[Variable]

Excellent! Thank you for sharing your results!

[Rapier]

Ok, got the crazy stuff figured out. My initial loads were done with an Alexander Seating Die (Lee) and I switched to a Redding. It turns out that both dies, even set down all the way would not reach my correct seating dept, remember I am using .267 bullets. The Lee looked OK but was using the body, not the plug to seat the bullet. So my easy fix turned into a project. I made a new seater plug for the Redding die that was longer by .250 or 1/4 inch. I used a stainless bolt that was cut down to the smooth shank with the head rounded to fit inside the body while the shank fit the body/collet tube and moved freely, worked like a champ. So now I have the chamber/bullet jamming issue solved. I am hoping this setup will give me more stable Standard Deviation and Extreme Spread readings.

Just to let you know the easy fix got a bit more complicated. But I do have 40 more 12.2 gr rounds loaded and ready to roll, when I get back from visiting the son in Vegas at the end of the week.
Ed

[txgunner00]

Waiting to hear your results. I'm planning a range trip one day this week and I hope to get my loads ironed out.

[Variable]

Looking forward to hearing you guy's results.

[txgunner00]

Well I'm having heck trying get a SS load to cycle my rifle length rifle. The last time I chronographed them I was getting and average 1017 fps with 13 grains of AA2015 but the bolt would only throw back about 3/4 of the way. I just shot a series of loads working up to 16 grains but the bolt still didn't lock back on a empty mag. I sure I'm over the threshold at this point so it's back to the drawing board.

Other pertinent info on the rifle:

20" Satern
Carbine spring
3 oz carbine buffer

I don't know what the gas port size is but I did try an H3 buffer at one time with full power loads and I had reliability problems. It seems the port may be on the small size or I have some other restriction in the gas system but the rifle functions flawlessly with a wide range of full power loads so I don't want to mess with that.

Opinions on where I should go next? Faster or slower powder?

[txgunner00]

Just tried X-terminator. Anything below 22 grs would eject the casing but not pick up the next round.

I should also mention I'm using IMI brass, sized but not fire formed and a CCI 250 large rifle magnum primer. Load densities are above 50% even with the sub-sonic AA2015 load and cases are not too sooty. No evidence of unburnt powder.

[Gswamp]

Too bad AA#9 won't work. I have 8lbs and nothing to shoot it in.

[txgunner00]

AA#9 is actually in the ball park of the next powder I want to try. Unique was too fast, AA2015 too slow, hopefully in the middle is just right.

[txgunner00]

Too bad AA#9 won't work. I have 8lbs and nothing to shoot it in.

What length barrel and gas system to you have?

[Rambozo]

TXgunner
have you tryed H322 .. According to the hodgdon burn rate chart its next to
AA2015.. Just curious as I have alot of H322
any reason not to try it like heat sensitive or not good for reduced loads?

Thanks
Smoke

H322 is a great powder. It's my favorite, but it's fairly fast burning, and you will likely run into load density problems and port pressure problems. In my experience, the powder isn't very temp sensitive. It's a Hodgdon "extreme" powder.

Personally, I would look at slower burning powders, maybe even something that would be used in a heavy magnum cartridge. I'm sure you can find something that offers a good fill, low velocity, and slow enough burning for port pressure. at the same time though, I have heard of secondary pressure spikes due to using too slow of a powder relative to projectile weight. I don't know how much of an issue that would be with lapua 144s and the 6.5 bore volume of the grendel though.

anyway, just some thoughts.

[txgunner00]

H322 is a great powder. It's my favorite, but it's fairly fast burning, and you will likely run into load density problems and port pressure problems. In my experience, the powder isn't very temp sensitive. It's a Hodgdon "extreme" powder.

Personally, I would look at slower burning powders, maybe even something that would be used in a heavy magnum cartridge. I'm sure you can find something that offers a good fill, low velocity, and slow enough burning for port pressure. at the same time though, I have heard of secondary pressure spikes due to using too slow of a powder relative to projectile weight. I don't know how much of an issue that would be with lapua 144s and the 6.5 bore volume of the grendel though.

anyway, just some thoughts.

I have tried few slower powders and they were definitely not the way to go in this application. They would not produce enough pressure to burn all the granules and I had unburnt powder stuck to the neck and shoulders of the case. Even a Federal large rifle magnum match primer couldn't light them off quick enough.

I can't remember which powders I tried exactly but I think they were US869 and H4831

[Rapier]

Ok Guys,
I am back from Vegas. Saw some interesting things while in the metro Vegas area with a 2 mil population, seems like they have a bit of everything you could want or not want, rolled into a ball. For us, I saw a new Polymer AR lower and bought one for $100 complete. Also found a new AR 5.56 upper with 1-9 twist, 16 inch, flat top with low gas block and a four rail free float for $298. So I got myself can gun #2 for $400. My Glock nuts buddy calls it a Glock AR.

The two powders I did get to work my action were AA #9 and 2015 BR. Now when I say work, I mean the entire show, sub sonic, lock back, strip 5 rounds, etc. #9 had the widest variances so I turned to 2015. But remember, I am using .267 bullets seated all the way down in the case as I must get clear of the throat which is .264 So my pressures have to be up, at least for a very short span of time, as I am swaging the bullets to .264 and with the 16 inch barrel it may well be all that is needed. I note in reading J. D. Jones notes on the Whisper that he was working a lot with short barrels, to make up for the can's length. One thing I found quickly is that the function is a matter of timing not just pressure period. The powder must reach a peak pressure point just prior to the gas port or that is what appears to be the case.

In silhouette shooting from a single shot, the barrel length for the Unlimited class is restricted to 14 inches so to obtain peak velocity you must burn the powder in under 14 inches. 2015 and #9 will burn in 14 inches and apparently delivers some push left over for the gas system at least in the 16. If the gas port position is relative then a 20 gas port should be aprox 4 inches further out the barrel towards the muzzle. If what I think is happening, is correct, then the next slower burning powder on the scale might be the place to look with a 20, if 2015 is just a tad fast. R #7 is the next powder on my scale with 3031 after that. But #9 and 2015 are not even real close on the scale, so.....

I will try to get up to the farm this weekend while getting ready to go tripping again, this time to Tulsa. We go to the big show every year at least once.
Ed

[Rapier]

I did get out to my range yesterday with the 12.2 gr load and suprise, suprise when you seat the bullet a tad lower it increases the velocity a tad higher and at the fringe, a tad is to much, so about 90% of my loads were just over sonic. I will drop back to 12 gr of 2015 with the bullet seated to an OAL of 1.808 this should put me back to the velocity were I was with 12.2 gr at the prior OAL setting befor the change, that had all subsonic velocities. Only thing is the 12.2 gr load this time had an ES of 100 fps with the lowest at 1063 and the highest at 1163, exactly 100 fps off. You know, to do this right, you might need to adopt a bench rerst load process, press, scales and powder to the bench and shoot as you adjust.

In my post above I said #9 functioned, that is true to one extent, the first load at 8.5gr did function, however the higher charges did not function, odd that. But I went back and reread my notes. It was H-335 that functioned through its entire range of loads in my gun but had extreame spreads of numbers like 176 fps. However 13.4gr gave me a highest velocity of 1101 with a SD of 31. So 13.2 to 13.3 might well work well at the reduced OAL in my gun.

One thing is obvious, you must fiddle with the load to get the velocity, function and accuracy into one package and it helps a lot to have some experiance in reloading otherwise you can spin your wheels for a long time on this.

Well I am off to Tulsa for the show, so it will be a while before I post again. Oh, the AR upper I bought in Vegas shot 3/4 with some scrapped up loads for the Mini-14's testing I did when I rebuilt it, so with loads built for new upper, it should shoot OK. Not to bad for $298.
Ed

[Gswamp]

Originally Posted by txgunner00
AA#9 is actually in the ball park of the next powder I want to try. Unique was too fast, AA2012 too slow, hopefully in the middle is just right.

What length barrel and gas system to you have?

I have an 18in Satern with a mid length gas system and a JP Enterprises adjustable gas block.