300Blk subsonic

[osprey]

It's easier to build enough gas pressure to cycle the action on an AR when playing in the subsonic velocities with the heavier bullets. That's it. If you run a bolt gun I would think the lighter bullets could be made to work.

 

[B5Ben]

Thanks. That makes sense to me.

 

[v0lcom13sn0w]

to cycle our ARs while still staying subsonic

 

[DizzyJ]

I just got into 300BLK so please bear with me as I figure this one out. I am starting some load development and am curious why all the subsonic loads I see are using 200+ grain bullets. I was looking at hodgdons online data and see some loads for lighter (110-150) bullets and running in the 1000 fps range using trail boss. I have never used TB for anything else but have some 147fmjs and 125 HPs that I think should work. I'm just curious why the bigger bullets get all the subsonic love when it appears that these might be ok as well.

More "thump" when it hits?

 

[Caveman Jim]

I'm subscribed guys, I haven't even built my pistol yet and already wanting tostart building some super test loads since I don't have a can...

 

[v0lcom13sn0w]

I'm subscribed guys, I haven't even built my pistol yet and already wanting tostart building some super test loads since I don't have a can...

i really like the speer 125gr TNT bullets over 17-18gr h110.



IIRC the powder charge is just off the top of my head i would have to look at my manual to be sure.

 

[B5Ben]

I dont have a can but my buddy is only a couple months (hopefully) away so I will only be running the supers for now. Waiting on my handguard/barrel nut to show up and I will be ready to go. Only load dev is left to do. I will be starting with some 110-125gr HP's that i have around to see how they go. I read that the H110 is good for the supers but I have a lb of 300 blk CFE as well and will look into using that for the supers as well.

 

[v0lcom13sn0w]

did more 300blk testing with chrono.

turns out my avg is 1034fps. only a 5 shot group. last time it was 1047ish.
it was raining pretty good this time. idk if that was a factor or not

 

[v0lcom13sn0w]

also, i recovered a few projectiles. not expanding as expected

 

[DizzyJ]

did more 300blk testing with chrono.

turns out my avg is 1034fps. only a 5 shot group. last time it was 1047ish.
it was raining pretty good this time. idk if that was a factor or not
View attachment 352531

Where were you shooting at?
I was at DRRC on Sunday for a couple hours.

 

[v0lcom13sn0w]

Where were you shooting at?
I was at DRRC on Sunday for a couple hours.

in keizer, on private land close to the willamette river

 

[DizzyJ]

in keizer, on private land close to the willamette river

Ahhh... That's nice to have!

 

[v0lcom13sn0w]

FYI the original load i posted at the start of this thread has been working great. the downside is, for 100 pills its $36.

FAST FORWARD 2 YEARS i was at cabelas this past saturday and found that berry's is now making plated 220gr "300 blackout" bullets. 200 of them cost me $55.

i loaded up 30 tonight.hopefully gonna chrono them this weekend.

10.9 -11gr A1680
220gr berrys 300blk.
cci sm rifle primer
2.100"
ive shot 5. they are subsonic. i will post chrono results hopefully this weekend

 

[saxon]

FYI guys, i just got my suppressor and have been reloading subsonic 300blk with excellent results... except for one thing... i dont have a chronograph. now before yall go sideways on me, i am no n00b to reloding and have done tons of research on 300blk subs... i decided i would work up my load from below starting charge(no brainer). i know its subsonic because there is NO sonic crack. maybe im being ignorant/wreckless/irresponsible for not having a chrono but i promise, i am going to get one.

Here's what i came up with:
Weapon: 10" Pistol Gas AR Pistol.
Primer: Winchester SR
Powder: 10.7-10.8gr Accurate 1680
Pill: Hornady .308 208gr BTHP Match
COL: 2.120"
Velocity less than 1100fps maybe 1050-1075fps?? it is subsonic for sure.

upon firing: super quiet thru thr SiCO hybrid, cycles 100% reliably, bolt holds open on empty mag.

**use my recipie at your own risk. always start with published data and work up your own load**

View attachment 349046

100 Rounds of Blackout Fits perfect in the Hornady box

View attachment 349047



View attachment 349041

^^ idk this photo wont delete. it keeps showin up every time i delete it.

remember that when working with subs you should start at just over super and work down to sub,
if you start low you may well have a squib at some point.

"most" don't use TB for light subs unless it is in a bolt for semi you may have to compress and velocity goes all over the place with TB.

some powder like lil gun are weather dependent, lil gun in cold weather can cause malfunctions and pressure issues.


1680 is a good all around for supers and more often then not you can get better FPS out of it then H110

 

[v0lcom13sn0w]

remember that when working with subs you should start at just over super and work down to sub,
if you start low you may well have a squib at some point.

"most" don't use TB for light subs unless it is in a bolt for semi you may have to compress and velocity goes all over the place with TB.

some powder like lil gun are weather dependent, lil gun in cold weather can cause malfunctions and pressure issues.


1680 is a good all around for supers and more often then not you can get better FPS out of it then H110

ive used h110 when i couldnt find 1680. it works well with my 125gr speer tnt. now, i use 1680 for both supers and subs. it has worked well for me for the last couple years!

i was just updating this thread i started a couple years ago with some more load data since i have changed projectiles recently. yes, use my load data at your own risk!

i use TB for my 308 win subsonic rounds

 

[Member 5605]

Wonderful!

 

[flashpan]

Good info gents ...thanks. I'm trying to find an inexpensive subsonic supressed loads as we speak. 7 1/2" suppressed barrel seems picky about accuracy but cycles and locks back with a variety of loads. So far using only IMR 4227. I have been trying coated bullets ... Leatherhead 220grn and Eggleston 200 so far. These coated bullets are less than 15 cents each. Unfortunately my rifle does not like my receipes so far with 3" groups at 50yrd. I'm ready to try other bullets and prob AA1680 so if anyone wants to trade some plated or jacketed subsonic bullets for these coated just give a shout. Good luck with new builds and loads.

 

[v0lcom13sn0w]

shot 30 rounds of the new load today. 100% reliable from my 10" ar pistol with a suppressor on it.

avg velocity: 975fps

i may bump it up 0.2gr or just leave it.

 

[v0lcom13sn0w]

ended up bumpin it up to 11.1gr-11.2gr just to get a few more fps. runnin about 1000 now. loaded 200 of them!

 

[Cannonsville69]

I just got into 300BLK so please bear with me as I figure this one out. I am starting some load development and am curious why all the subsonic loads I see are using 200+ grain bullets. I was looking at hodgdons online data and see some loads for lighter (110-150) bullets and running in the 1000 fps range using trail boss. I have never used TB for anything else but have some 147fmjs and 125 HPs that I think should work. I'm just curious why the bigger bullets get all the subsonic love when it appears that these might be ok as well.

Not sure if you ever found answers but I asked myself the same question. After alot of searching and ALOT of testing, I found a few that work for 100, 110, 130 and 150 grain projectiles. After alot of Trail Boss ladders, I decided to try some Red Dot. I found Red Dot to be more consistent, lower SD, less sensitive to half full case volume and I started to find some rounds that were tack drivers...at 925-1020 Fps (RA 300AAC 16" bolt)

ballpark for 16" bolt , these were the winners for consistent tight groups

110 gr 3.9gr Red Dot 976Fps
130 gr 4.1gr Red Dot 925Fps
150gr 4.8gr Red Dot 940Fps
150gr 5.1gr Trail Boss 1020Fps
150gr 5.1gr Unique 975Fps (but louder)