Range Report Are supersonic 300 Blackouts subsonic in a pistol barrel?
- Thread starter WT1
- Start date
Generally no....example, my supersonic 125 TMK 300blk round is 2100fps out of my 10.5" AR. Going to a shorter barrel wouldnt reduce velocity by 1100fps....
Subsonic 300blk is going to have a heavier bullet (200-225gr) and different powder putting it below 1100fps.
Not just slower powder. Heavier bullet as well. You can shoot light bullets at low velocities but then it gets weird with pressure and consistency etc and people generally dont to it for that reason.
The majority of velocity is picked up in the first couple inches.
In this graph its a heavy SUBsonic in quickload I plucked off the net.
In 16" of barrel its topping out at ~1250 fps.
In only 4" of barrel though its already going 950 fps, thats 76% of its total end velocity in only the first 1/4 of the barrels length.
A super sonic is only going to be more pronounced and hit higher velocities even more rapidly. A lighter bullet with less mass requires less force to accelerate to the same speed. Acceleration=Force/Mass
I will have to pick up some pistol powder to get an idea. Thing of it is, I have a boat load of .30 projectiles. Are there 168 grain subsonics or 178 grainers? I can't seem to find any loads for those two bullet weights. Can I even use them?
Yeah, you can. @orkan had a very good write up on here at some point but here is a link to his site. He found that he got his best results with those lighter bullets actually but most want more mass for a harder hitting bullet since ultimate accuracy with these velocity capped subsonic rounds so mass makes up the other half of the occasion and is the only way to create more force without altering acceleration. https://forums.gunhive.com/topic/395/new-ts-customs-300blk
it is a 16" AR. So far is cycles any subsonic, Remington, Gemtech, and SCO Harvesters very well. But those are all 200 or 220's I believe, without going and looking at the boxes. Looking for a reloading project over the winter months. I'd like to find a load that can utilize what i have already. Any suggestions on primers?
Primers a primer imo. Spend 3-4 cents on a cci or federal and it’ll be just fine.
I’m not so sure about those powders cycling an ar though. That’s generally why you want the slower powders that will create enough gas pressure for the amount of volume in the bore behind the bullet but not in too short of a time that lets the bullet leaves the barrel and breaks the seal before that pressure is created. And since you want it to be done over a longer period of time a heavier bullet will help achieve that as more mass equals less time if force remains the same. Pushing a smaller bullet might not give you enough oomph to cycle that bolt carrier.
I mean, worth a shot if you’re just looking to figure it out and have something to do. Record the results and post them back here as a data point. Make it a nice write up
I’m not so sure about those powders cycling an ar though. That’s generally why you want the slower powders that will create enough gas pressure for the amount of volume in the bore behind the bullet but not in too short of a time that lets the bullet leaves the barrel and breaks the seal before that pressure is created. And since you want it to be done over a longer period of time a heavier bullet will help achieve that as more mass equals less time if force remains the same. Pushing a smaller bullet might not give you enough oomph to cycle that bolt carrier.
I mean, worth a shot if you’re just looking to figure it out and have something to do. Record the results and post them back here as a data point. Make it a nice write up
Any idea what the best and or most economical bullet is for subsonics that expands reliably? The Lehighs look nice but are way too pricey for what I need. Thanks.
I've seen posts where guys are using cast bullets to get expansion at low velocities. Berry's I think was the brand. But they are unjacketed lead. Gets things pretty dirty.
Yeah, I think I'll have to use something like Berry's, which actually don't look all that bad to plink with and then pick up Makers for expansion.
Don't waste your time with the Nosler subsonic bullets. If you really want to try some, I've probably got some I can send you.
The Hornady 190 is available as a component now, and will expand as low as 750 fps. Although not as good as the Maker or Lehigh, it's a good, lower cost option.
The Hornady 190 is available as a component now, and will expand as low as 750 fps. Although not as good as the Maker or Lehigh, it's a good, lower cost option.
The Hornady offering looks like an excellent choice for the money at this point: https://www.hornady.com/bullets/rifle/30-cal-.308-190-gr-sub-x#!/
Nobody has them for sale, yet that I can see.
Using Ammoseek to search for the Noslers, they would be about 10 cents more each than the Hornady, which Midway says will be $34.99 when in stock. The Noslers are $22.39 per 50 whereas the Hornady's come in a box of 100.
There is a video on youtoobs showing a guy who says he was having trouble trying to get the Nosler's to seat using a Lee 300 Blackout die set because the seater had very little contact with the ogive or something to that effect.
Last edited:
Yep, that's the ones. I never could get them to stabilize in a 7 twist, even up to 1400 fps. AT 50 yds, they would still keyhole. I've spoke
with several knowledgeable folks that had the same results. The bullet will most likely hit sideways, and if it penetrates flesh, the tip and jacket will come off within the first inch or so.
Bullet travel was R to L.
Weight retention was good, but in four pieces.
Try them if you like, but there have been several people, including myself put an ass load of time into trying to sort them out, and never had any luck.
It looks like the Hornady 190 subsonics are a pretty good deal based on the few videos I've watch of them on youtoob. Not as large of a wound channel for deer hunting as the Makers or Lehigh, but at more than half the cost, not bad either. Which is probably why you can't find the projectiles anywhere right now.
Similar threads
