223/5.56 Sub Sonic Loads

[Coyote Shadow Tracker]

Anyone have information on subsonic loads for 223/5.56 using H4895 or other powders with 65gr/69gr/75gr bullets for use suppressed?
I know H4895 has been the Military's main powder since WWII and heard that it works well with under charged loads and less than 1,000fps.
Trying to get something a little quieter for my 223/5.56 SBR. It's 9" 1:7 so can handle heavy bullets.
I currently use 65gr SGK in my coyote 223 20" 1:8 suppressed YHM Can and it is still loud @ 2,800+fps. Going to keep SuperSonic loads for it hunting Yotes and hogs. Want a quieter load for my SBR.
Thanks
Len

 

[del2les]

In order to stay under sonic (1,100fps or so), often, I used pistol powders in a 222/223 and similar. Unique and H2400 have been my go to powders when desiring this low velocity. Any cast bullet handbook like Lyman give a lot of potential starting loads, but you need to adjust the powder loads slightly with jacketed bullet usage.

Be careful not to go too low, as jacketed bullets tend to lodge in rifles if vels are too far down. Your 9" SBR will have less trouble with this though.

 

[asd9055]

Try this for starts

https://hodgdon.com/wp-content/uploads/2020/07/subsonic-data-final.pdf

 

[Coyote Shadow Tracker]

Try this for starts

https://hodgdon.com/wp-content/uploads/2020/07/subsonic-data-final.pdf

Thanks much!!!!!!!!!

 

[cohunt]

I'm not sure I'd use subsonic 223 for hogs

 

[Coyote Shadow Tracker]

I'm not sure I'd use subsonic 223 for hogs

Not for hogs if you read my post. Will be keeping supersonic for my coyote/hog rifle.
Want to use subsonic in my SBR (close range & quiet)
Thanks

 

[QuietTexan]

What's the plan for the 223 subs? Just quiet fun, killing rodents, something like that? I'd be really curious to hear about cycling - I have a 5.56 SBR but I've never built subs for it.

I ask because ~60gn and subsonic is legitimately a 22LR level of energy, at that point why bother with a full-size AR platform instead of a 9mm or 15-22 platform. I have several of the 10-22s and 15-22s - they're a ton of fun and a lot cheaper than centerfire subs. Not trying to dissuade, I shoot 300 BLK subs just for the heck of it also, but small rifle primers don't grow on trees like they used to so this is the shooting I dropped when components got tight.

 

[cohunt]

I doubt subs would cycle the action-- I could be wrong though

 

[asd9055]

300 AAC subs cycle mine. If 223 subs don't, can't you change the spring and buffer?

 

[QuietTexan]

Yeah but 300 BLK has significantly more bullet mass for the gas charge to move without pushing the bullet past the speed limit.

JP Enterprises makes a gamer kit - low mass BCG, buffer, and spring, but even then I would think the port would have to be huge. 0.093" port and a switchblock so it doesn't flame thrower your face with a super? I'm not one to complain about a gassy AR but with realistically an 80gn max bullet it seems like it's going to be a specialized rig once it's put together, not one to just drop the 20" upper on without changing out parts.

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[cohunt]

300bo is a whole different animal, different powders, different gas length, diffetent gas hole size, etc. My 300bo subs cycle perfect but 308w I have to hand cycle

Most 223 subs won't cycle-- there are a few that will though buy you need the right powder

 

[asd9055]

That's why I said, change spring, buffer, and I guess BCG

 

[cohunt]

That's why I said, change spring, buffer, and I guess BCG

It would be over gassed with supers by alot if you did that.
An adjustable gas block would help

 

[asd9055]

Does anyone make an adjustable gas block like they used to for older piston guns were you just turn a knob, typically three positions. My old Swiss Sig had one