Anyone come up with a action Cycling Subsonic Load yet

[TxAggie94]

I'm not using a suppressor...yet. I have one on order. I'm just trying to get a jump on it.

How much do you find the suppressor affects the velocity? Or will it be in the noise, considering the spread we're getting anyway?

[BjornF16]

Honestly, I don't know how much the velocity is affected (I haven't chrono'd the subsonics). The suppressor basically prolongs the amount of time pressure is present in gas tube (and possibly increases pressure some) which helps with cycling. Theoretically, the suppressor should increase the velocity due to "free bore" while passing through the suppressor (no friction of rifling; pressure still present behind the bullet pushing it along). Maybe someone who has a good chrono who has done this comparison can chime in.

You will definitely hear the difference...I love the suppressed sound of subsonics!

[BjornF16]

Aggie,
BTW, the 1200 fps rounds will not be sub-sonic...at 100F, speed of sound is approx 1160 fps; at 20 F, it is approx 1075 fps (air pressure doesn't matter, temperature dictates with a little input from humidity).

You will suppress the detonation sound, but still get a sonic crack with 1200+ fps...but it still sounds cool!

[TxAggie94]

Yeah, i'm pretty close to the limit already. Given the spread, I need to shoot more to see if the loads will all remain subsonic. If the can increases the speed, i'll be over.

[txgunner00]

Well, I made it out the range this morning. I started with TxGunner's loads. Every round successfully ejected the empty. But it never successfully loaded the next round or locked back on an empty magazine.

First, my hardware:
16" AA barrel, mid-length gas system
1:8" twist rate
"Standard" carbine buffer, tube and spring

I do have another lower with a rifle tube, buffer and spring. I have fired the Grendel upper on both lowers, and they function interchangeably with full power loads. I did not think to try the rifle lower today. Maybe next time.

All loads were 8208 powder under the 160 grain Hornady RN (0.264).

I had some Wolf (PPU) brass with large rifle mag primers.

I also shot some out of Hornady brass using small rifle magnums. Surprisingly, the hornady brass was giving 200-300 fps faster for the same charge.

Brass / Charge / Avg Vel / StdDev / ES
Wolf / 13.9 / 1110 / 56 / 109
Wolf / 13.7 / 1086 / 19 / 27 - 2-shot group
Wolf / 13.5 / 1182 / 66 / 131
Horn / 13.9 / 1417 / 109 / 154 - 2-shot
Horn / 13.7 / 1371 / 67 / 95 - 2-shot
Horn / 13.5 / 1265 / 142 / 201 - 2-shot


Point of impact is about 3" below my full power loads at 50 yards.

My 1:8 barrel is not stabilizing the 160s. All of the sub 1200 fps rounds were keyholing.

An interesting side note: the 160 grain round nose want to fall into the hornady cases once they get a little past the cannelure. Someone on here commented they noticed that, but I can't remember who. In order to get them to hold, I put the hornady's back through the sizer just enough to increase the neck tension. I had no problems with the Wolf brass holding the bullets.

You will probably need to go with a faster powder with a 16" barrel. Check out Rapier's load data for that. This is all about timing the pressure curve with the gas port and barrel length.

I'm surprised the 1:8 is not stabilizing. You might have to stick with 140's.

I had the 160's fall in the case also. At first I was trying to seat them deep to increase load density but I found that longer COL's (2.240-2.260) actually produced more consistent velocities and better groups for me. I use a Lee factory crimp die and put a heavy crimp on them. It seems to help with consistency also.

[Lead Chucker]

The suppressor doesnt change velocities, but will change your accurcy. I need to get to work and do some testing with subs for my grendel. I will say that I do love shooting it suppressed even with supersonics. You can really tell how hard the grendel hits steel when you dont hear the boom from the gun.

[GregP42]

I was out in a gun shop about 100 miles from home last weekend, and I found two boxes of the .264 160gr round noses. I can seat these out a lot longer in my Grendel and was wondering about a starting load with these. I am using a m16 bolt carrier and A2 buffer and tube with an 18" barrel on my rifle. I will be using IMI brass with CCI #34 primers. Since I have never tried any sub-sonic loads before I thought I would ask here if the loads you worked up with the .268 bullets would be ok to start with in my rifle.

Thanks,
Greg

[txgunner00]

I was out in a gun shop about 100 miles from home last weekend, and I found two boxes of the .264 160gr round noses. I can seat these out a lot longer in my Grendel and was wondering about a starting load with these. I am using a m16 bolt carrier and A2 buffer and tube with an 18" barrel on my rifle. I will be using IMI brass with CCI #34 primers. Since I have never tried any sub-sonic loads before I thought I would ask here if the loads you worked up with the .268 bullets would be ok to start with in my rifle.

Thanks,
Greg

My loads were with the .264 bullets. With subs you need to work down. If you try to start low you risk getting a bullet stuck and trust me, you don't want that to happen. What powder are you thinking about using? I'm assuming your barrel is a mid length gas system so you may benefit from a slightly faster powder than what I'm using (8208). I believe Rapier was using a 18" so his data may be a good starting point.

[GregP42]

My loads were with the .264 bullets. With subs you need to start high and work down. If you try to start low you risk getting a bullet stuck and trust me, you don't want that to happen. What powder are you thinking about using? I'm assuming your barrel is a mid length gas system so you may benefit from a slightly faster powder than what I'm using (8208). I believe Rapier was using a 18" so his data may be a good starting point.

Sorry I forgot that, but yes I have a mid length gas system on mine. After playing around I can seat my bullets to an overall length of 2.285, as for powder, I was looking to use 8208 if I could since I have so much of it But I have several other powders to choose from as well. I was rereading the posts and I have about 100 unfireformed IMI right now that I could use also. If I PM you my email could you send me your data you have so far?

Thanks,
Greg

[txgunner00]

All of my load data is in this thread. Check out post #109 for the final load. I don't mind emailing to you either.

8208 may work. You just have to try it. These type of loads are on a fine line between functioning and not and will pretty much be different in every rifle.

[txgunner00]

Tested these loads in some ballistic gel recently...

http://www.65grendel.com/forum/showthread.php?4446-Subsonic-load-ballistic-gel-test&p=44021#post44021

[GregP42]

All of my load data is in this thread. Check out post #109 for the final load. I don't mind emailing to you either.

8208 may work. You just have to try it. These type of loads are on a fine line between functioning and not and will pretty much be different in every rifle.

Cool, have a hard time reading them on here due to needing new bifocals, tried to send you a PM, but it says your full up.

Greg

[txgunner00]

Made some room & sent you my email.

[txgunner00]

Some subsonic discussions came up over here (http://www.65grendel.com/forum/showt...ed=1#post44415). Since it fits better I'll continue them here...

I talked to Hawk Precision Bullets and they have some experience making bullets designed for subsonic expansion. They use double annealed (soft) pure copper jackets and can set the lip of the jacket back further to encourage expansion at lower velocities. They know they can get a 160 grain bullet, possibly even up to a 175 but I would have concerns of stability.

The cost is just under $40 for a box of 50 with a minimum of 3 boxes for a custom bullet run. Anyone interested in going in on this with me?

[Variable]

Some subsonic discussions came up over here (http://www.65grendel.com/forum/showt...ed=1#post44415). Since it fits better I'll continue them here...

I talked to Hawk Precision Bullets and they have some experience making bullets designed for subsonic expansion. They use double annealed (soft) pure copper jackets and can set the lip of the jacket back further to encourage expansion at lower velocities. They know they can get a 160 grain bullet, possibly even up to a 175 but I would have concerns of stability.

The cost is just under $40 for a box of 50 with a minimum of 3 boxes for a custom bullet run. Anyone interested in going in on this with me?

I'm in.

If they can possibly do a 175, then how about this?

I'll pony up for a minimum of three boxes---

How about we do three boxes of 160gr., and three boxes of 175gr. (or as heavy as they can go...)?

Maybe:

You-- two boxes of 160gr. and one box of their heaviest.

And

Me-- one one box of their 160gr. and two boxes of their heaviest?

If others wanted more we could adjust.

If the heavies don't stabalize in yours (but do in mine) I could buy your box?

That way we'd both get to try both. Mine might not even stabilize the heavies, but I'd guess I have the best chance with a 1 in 7 twist.