Subsonic 223 help needed

i8asquirrel · Oct 30, 2012

I know that Hogeden list data for 55gr FMJ with Trailboss. Clays & Tightgroup . I'm looking for data for bullets in the 60 to 90 grain range. Does anyone have some loads you're wiling to share!

AMProducts · Oct 31, 2012

The problem is, these big bullets simply do not stabilize at these velocities, you would need a rifling rate that is nearly a 1:2" to come close.

I highly recommend sticking with the 55gr FMJ loads if you have any pretense of accuracy.

i8asquirrel · Oct 31, 2012

AMProducts said:
The problem is, these big bullets simply do not stabilize at these velocities, you would need a rifling rate that is nearly a 1:2" to come close.

I highly recommend sticking with the 55gr FMJ loads if you have any pretense of accuracy.

I have a5.7x28 that shoots 60gr V-max Subs very well it 1x8" my 300 black out is 1x8" also and will do <1moa with 190 & 220 grain. I do feel its possible

AMProducts · Oct 31, 2012

I've tried it, was a waste of components... but hey, what do I know?

55 GR. HDY FMJ Hodgdon Titegroup .224" 2.200" 3.1 1064 4,000 CUP

That's the hodgdon data. If you look, it's only generating 4000CUP (Copper units of Pressure), with a pressure that low, you could probably fill the barrel with lead and not be over Pmax.

IIRC I think I was pushing 4.0grs of Titegroup behind a 69gr SMK bullet. The reason for the increase was to make sure the bullet was actually doing near the speed of sound. Most of the bullets at 100 yards landed in a 10' circle, many that actually hit the target keyholed. I would not recommend shooting these through a suppressor.

Also, if it wasn't obvious, none of these cycled.

AMProducts · Oct 31, 2012

Behold... The greenhill formula!

Greenhill Formula
The formula to determine the correct rate of rifling pitch for bullets of usual construction (lead alloy or jacketed) is known as the "Greenhill Formula".
Step One: Determine the length of the bullet in calibers. (Bullets length in inches divided by the bullets nominal caliber).
Step Two: Divide 150 (a constant) by the bullets length in calibers.
Step Three: Multiply the result of step two by the bullets "nominal" caliber. This will give the desired rifling twist rate.
Example: To find the correct twist for a .30 caliber 220 grain bullet 1.35 inches long.

1.35
150 33.33 x .30 = 9.999

.30
= 4.5 calibers 4.5

= 33.33
(or 1 in 10 inch twist)

i8asquirrel · Nov 1, 2012

Thank for the heads up.... I'm trying to come up with a load youse with the can on. Look like 5 gr might be the max then

AMProducts · Nov 3, 2012

Baffle strikes ahoy!

There are a lot of issues that make the AR-15 loud with a can. If you want it quieter, start by installing an adjustable gas tube/block and either turning off the gas system first.

If you want to start playing with the ammo... load up some rounds with a minimum charge, and then start backing the charge off... keep backing off the charge until you get to the point that the gun will just barely cycle (without the can). This will probably be about 2300FPS or so.

While you're still shooting a fairly fast round, most of the noise coming out the end of that gun is still from gas. Dropping the load will greatly reduce the amount of gas, and will allow your suppressor to work better. Also, the suppressor will act as a booster for your gas system.

Starting slow, and then trying to move faster is a much more difficult problem for a lot of reasons, as you may stick bullets in the barrel, experience baffle strikes, etc, and all of these problems can become very expensive fixes.

i8asquirrel · Nov 4, 2012

Just home from range... Loads from Hogden a failure from my weapon! All had full keyhole strikes at 50yds. I am giving up on 5.56 subs and sticking with the 300blackout for quite work. Thanks for the help, I ell pull down remaining rounds.

AMProducts · Nov 5, 2012

Hopefully you found this out without damaging anything... loading ammo like anything technical requires experience. Now that you've had some you know what I mean!

Like I said in my last post... you might try just backing off a regular load and minimizing the signature that way.

i8asquirrel · Nov 5, 2012

No dammage used safe procedure.. simply taking a standard load and working down is a great way to get hurt. it increases chance of a detination rather than ignition and is generaly a poor idea. ( I have worked out loads for my .308 win and 5.7x28 and have many working loads for 300Blackout....) just starting to think that with the case to bore diffirence of 5.56 the powder lays in the case and ignites differently depending on case position..

deadshot2 · Nov 6, 2012

i8asquirrel said:
and sticking with the 300blackout for quite work.

For quiet work use a cross-bow. If you want to hit something beyond 75 yards reliable screw the noise and use a full power .223/5.56 round.

Burt Gummer · Nov 6, 2012

Forget 5.56 for quiet work, although a suppressor is nice for noise at the shooter. 300blk subsonic 220g, 9mm 147g AR, .22lr 60g, etc, etc - lots of really quiet options. 223/5.56 not so much.

i8asquirrel · Nov 6, 2012

Burt Gummer said:
Forget 5.56 for quiet work, although a suppressor is nice for noise at the shooter. 300blk subsonic 220g, 9mm 147g AR, .22lr 60g, etc, etc - lots of really quiet options. 223/5.56 not so much.

have a nice blackout carbine built by Kevin at Ole's gunshop....was just trying to and another tool....

nrc · Nov 7, 2012

52 and 53 gr softpoints will stabilize at 1000 fps in a 1:7 twist. Look at data with Unique, or (better) Trailboss.

Test fire your rounds for accuracy - if they aren't tumbling at 100 yards you've made it - and don't have to worry about baffle strikes.

edited to add: they won't cycle any semi auto... but they'll stabilize ok.