commercial "subsonic" 300 blackout ammo actually subsonic?

Bump. I want to know as well.

You mention trying two brands. Did try both in the same gun?

There is a possibility that most are being designed around the idea of a shorter barrel than your bolt action and the use with the longer barrel is pushing it over the sound barrier.

I dunno about this particular ammo, but i recently did a trade deal with a freind that netted me several boxes of ammo, including a box of 'sub-sonic' 45acp. I'd always thought .45 was already sub-sonic at around 850 fps, and then I noticed the stats on the side of the box, which said the stuff moves at 840 fps ( wow, a 10 fps difference?) If they can market this as ''sub-sonic" when it's basically identical to any other .45 ammo, I'm thinking we can take any of the manufacturers velocity claims with a grain of salt (which seems to have been borne out by numerous you-tube videos, as well).

... if i were in the marketing dept i'd be doing the same thing, making boxes of "subsonic 45" and "high power 45" that had the same stuff in them haha

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Yeah but the fellow that came up with the "High power Subsonic Tactical Zombie Sniper" loads would get promoted anyway.

I have some factory PNW arms 220gr SMK's I'm planning to try out soon... if I remember, I'll post velocity numbers from my 12.5" barrel here.

From my competition experience though, I know for sure that if you want a really specific velocity window in your gun, the only option is to load it yourself. For factory ammo to stay subsonic in all barrels in all conditions, I imagine they would have to load it to stay well below the line in most barrels/conditions.

Interesting... yeah I don't know what barrel length normally peaks the velocity with 300blk, but I remember reading it is pretty short. If you could suppress and isolate the subsonic crack (or not) I'm sure that would be helpful.

taliv, are you shooting with a suppressor attached? When I was at Remington we saw as much as a 300 fps increase with suppressors attached shooting 300 Blackout ammunition. My first project there was to develop a "cheap" in-house 220gr bullet and a cheap subsonic 300 Blackout load using that bullet. I used 16" barrels with a 1:7 twist for the development (most common configuration) and kept the velocity as close to 1,050 fps as possible. During development the load produced sub 2" groups at 100 yards and velocity was consistently around 1,050 fps. However, it was much harder to make consistent ammunition on a production scale given the idiosyncrasies of the loading equipment. I tested thousands of rounds for function out of many SBR/suppressed M4s but never tested velocity from those configurations since it would be impossible to develop a load that would work in every situation. As ny32182 stated, when it comes to the 300 Blackout you really have to work up a load for each and every rifle to have both accuracy and consistent subsonic velocity. I remember taking a few boxes of the load that I developed to a friend's house and hearing a crack accompanying many of the rounds that he shot. It was a disappointing project in many ways and harsh lesson that there are few similarities between handloading and developing commercial ammunition.

I think it really takes reloading for your set up. Too many variables out there. Or, find a small maker who is making a load which has been shown to match your set up.

I like the 300BLK but went with a bolt gun. Haven't had time to get it figured out myself yet either though.

IIRC Remington put out a lot of sub loads that weren't sub in most/any things (not a dig at you, MCMXI) early on so I have shied away from them for now.

I have a 10.5" barrel and a friend (sharing a trust) has a SilencerCo Hybrid on the way. We'll try our 220s through his gun (9-3/4") and mine and we'll see if they both run subsonic.

Tagging this thread. I'm not experienced with subsonics enough to have an opinion, but I always thought that longer barrels increase muzzle velocity as a rule. Hence all the discussions about "loss of muzzle velocity for every inch of barrel removed.

Might you be operating at a higher elevation than us lowlanders with ammo that is right on the line?

Some powders seem to make different noises that others. Sounds weird but I've noticed a big difference in report from universal to HP38. I think blc2 and varget feel different.

There's a lot of 300 BLK ammo out there and they're all coming out with their own recipes to stay around 1k fps in all temps.

HB

i guess the surprising part is that my barrel is only 8.5". makes me wonder if it is actually subsonic in longer barrels. (i.e. powder burnt quickly and extra friction from 8 more inches of barrel in a 16" bbl actually slows it to be subsonic)

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Just about any powder is going to gain velocity from 8" to 16". Even with Unique, pistol cartridge rifles gain 300-400fps over revolvers.

I've used Magnetospeed to check 3 of my subsonic loads (9" barrel) The 208gr. AMAX from Hornady is solidly subsonic. The budget Remington 220gr load is a bit hotter though and can occasionally cross the line where you get a crack. I'm guessing out of a 16" barrel, it is a bit closer.

think about taking barrel length to the extreme. what if a barrel was 100 inches long? at what point does the friction (substantial, as you would know if you try to push a bullet through a bore) overcome the pressure? the pressure obviously changes inversely with volume, and the longer the barrel, the more volume.

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Case in point, I was shooting .32ACP through an adaptor in a bunch of my rifles, and this round didn't make it out of the barrel of my 1903A3. I drove it out with a rod and mic'd the round; .307" diameter. So the barrel isn't shot out yet!



Had this happen with those mouse fart .22LR Aquila Colibri rounds in a long barrel CZ as well.