trouble with subsonic loads

[Boozer]

I’m trying to work up some subsonic loads for my .223. I know that most folks feel it is a waste of time, but I don’t own a .22lr, and I need to do some varmint control around the house. I live in somewhat close proximity to other houses, and need to keep things on the hush, hush. I must say, with the suppressor on, these things are super quiet, quieter than snapping your fingers. Truly giggle inducing.

What I’m experiencing is extreme variation in velocities, about 200 FPS across 5 shots. That causes a vertical spread of about 8” at 100 yds! Now, I have read enough to know that it is typical for subsonics to not be particularly accurate, and to have high ES/SD, but 200fps seems crazy! I regularly throw charges to the kernel, and they were weighed on both an electronic and beam scale, so I do not think it was the charges. One thing to note, both times I have tried this, the FPS did seem to drop off as I shot, so higher velocity at the beginning of the shot string and lower at the end. This seems too coincidental....

4.0 grains of trailboss is getting me 1075, to about 875. This is with mixed year lake city brass, 55 gr. Hornady lead tips, CCI BR-4’s, out of a 1-7, 26” barrel, and gemtek trek. This gun is capable of ~1/2” groups with conventional supersonic handloads, so the rifle is not the problem.

A few thoughts… neck tension. Does varying neck tension have a magnified effect when loading at such low pressures/velocity? If so, I could try some case lube on the bullets when seating, or crimping them in? all cases have been annealed, and prepped the same.

Thanks!

 

[isofahunter]

I full crimp all my 300BLK SS loads, how is the case fill with 4gr of TB in that case? I run 5gr of TB in my 300BLK load and the case is full. If case not filling you might be having poor ignition of the powder charge. Single load your rounds with barrel up and then slowly level to shoot, it will keep the powder at the bottom of the case, see if velocity smooths out. If so you know its it a case fill issue. My loads are 2MOA at 100 or a minute of varmint.

 

[spife7980]

What chrono are you using and what are its sensitivity settings? Have you verified the 8" vertical variation on paper or thats just what the computer says with the velocity differences?

 

[Boozer]

Yes, the case fill is less than optimal. probably only 50% or so? but i'm unaware of any other powder that is "fluffier" than trailboss. i know titewad and clays are 2 other powders typically used for subsonic loads, but i don't think they would fill the case any more, if any it would probably negligible. are there any other powders that would provide more case fill? i can also try to run a larger bullet to help take up space, but i think at subsonic velocities i'm limited to about 75gr or so at a 1;7 twist?

That is a very good thought on making sure the powder location in the case is consistent. I will test that theory out. It makes sense that as I continued to shoot, the recoil (though nearly non-existent) would have a tenancy to increasingly shift/settle the powder in the cases to produce a trending pattern in the velocities.

 

[Boozer]

no, i have verified it on paper at 100. i did have some issues with my chrono picking up the shots, but the velocities i received from the magnetospeed seemed to correlate with the impacts moving down the paper, so i tend to believe they are accurate.

 

[isofahunter]

TB is your powder, longer bullet will help fill the case. I would full crimp the load. If you can find them Speer 70 gr spitzer would give you good case fill and long bearing surface, but they are like hens teeth. I run both 90 gr and 170 grain bullets in my 300BLK and they are a hoot with a can on the rifle.

 

[spife7980]

no, i have verified it on paper at 100. i did have some issues with my chrono picking up the shots, but the velocities i received from the magnetospeed seemed to correlate with the impacts moving down the paper, so i tend to believe they are accurate.

Interesting, when I first started chronoing my blackout 220 subs I thought that I would set my msv3 sensitivity to a high 9 to better pick them up but it turns out that there is plenty mass there for it to pick up. I would get some readings up at 1050 fps or so but then some down in the 800s as well, just like you are. Setting it to normal sensitivity I saw that I was consistently in the 800s with none of the strange spikes. But thats not your problem.

So it seems you really are getting the full range. If you have ensured that your weights and sizing is all consistent I would try heavier bullets first and then crimp. I bet the fluffy tb is getting inconsistent burns pushing that small bullet, crimp or more neck tension and a heavier bullet will help add some resistance to make for a more even burn. Thats just conjecture though, Ive never tried to sub something that small.

The problem with heavy bullets is that they arent made in small frangible jackets like the light varmint bullets are, and if youre concerned about houses in the area I would want something that would fragment instead of skip along like a rock. The 60gr nosler ballistic tip is the heaviest thin jacket I can think of but I doubt its much of an improvement over the 55gr youre using now.

Maybe @Gunfighter14e2 will chime in, he has done these before I think.

 

[Boozer]

Interesting, when I first started chronoing my blackout 220 subs I thought that I would set my msv3 sensitivity to a high 9 to better pick them up but it turns out that there is plenty mass there for it to pick up. I would get some readings up at 1050 fps or so but then some down in the 800s as well, just like you are. Setting it to normal sensitivity I saw that I was consistently in the 800s with none of the strange spikes. But thats not your problem.

So it seems you really are getting the full range. If you have ensured that your weights and sizing is all consistent I would try heavier bullets first and then crimp. I bet the fluffy tb is getting inconsistent burns pushing that small bullet, crimp or more neck tension and a heavier bullet will help add some resistance to make for a more even burn. Thats just conjecture though, Ive never tried to sub something that small.

The problem with heavy bullets is that they arent made in small frangible jackets like the light varmint bullets are, and if youre concerned about houses in the area I would want something that would fragment instead of skip along like a rock. The 60gr nosler ballistic tip is the heaviest thin jacket I can think of but I doubt its much of an improvement over the 55gr youre using now.

Maybe @Gunfighter14e2 will chime in, he has done these before I think.

Will try some heavier bullets. i have 75 and 80 eldx's, maybe the 80's will stablize. we'll see. i have always been interested in casting my own lead bullets, but the heaviest molds I can find are for a blunt nosed 60 gr. was hoping for a 70 gr round nose/wadcutter mold. Most of the real heavyweight molds are geared toward you blackout guys. 200+ grain round nosed. not really any offerings for heavy .223

 

[isofahunter]

If using a can always shoot a couple of shots without the can on to make sure bullet is not tumbling.

 

[Boozer]

If using a can always shoot a couple of shots without the can on to make sure bullet is not tumbling.

Good idea. I literally just got my can a few weeks ago so a baffle strike would be no bueno.

 

[Gunfighter14e2]

I’m trying to work up some subsonic loads for my .223. I know that most folks feel it is a waste of time, but I don’t own a .22lr, and I need to do some varmint control around the house. I live in somewhat close proximity to other houses, and need to keep things on the hush, hush. I must say, with the suppressor on, these things are super quiet, quieter than snapping your fingers. Truly giggle inducing.

What I’m experiencing is extreme variation in velocities, about 200 FPS across 5 shots. That causes a vertical spread of about 8” at 100 yds! Now, I have read enough to know that it is typical for subsonics to not be particularly accurate, and to have high ES/SD, but 200fps seems crazy! I regularly throw charges to the kernel, and they were weighed on both an electronic and beam scale, so I do not think it was the charges. One thing to note, both times I have tried this, the FPS did seem to drop off as I shot, so higher velocity at the beginning of the shot string and lower at the end. This seems too coincidental....

4.0 grains of trailboss is getting me 1075, to about 875. This is with mixed year lake city brass, 55 gr. Hornady lead tips, CCI BR-4’s, out of a 1-7, 26” barrel, and gemtek trek. This gun is capable of ~1/2” groups with conventional supersonic handloads, so the rifle is not the problem.

A few thoughts… neck tension. Does varying neck tension have a magnified effect when loading at such low pressures/velocity? If so, I could try some case lube on the bullets when seating, or crimping them in? all cases have been annealed, and prepped the same.

Thanks!

Your issue is jacketed bullets in the 223. If you check them across the bearing surface to the 4th decimal place you will see a huge variance between them. The cure if you want to use jacketed is a custom swagging die, or start casting your own. I run 60.1gr cast bullets in my 223 an will head shoot a deer out to 150yds w/o issue. The 223 is very hard to load for when using subs, up to 3X harder than match for the same gun. My best load runs 1/2-3/4 moa. My playing around loads is a 50.1 gr an run about 1.5-2 moa but they are very easy to load for, over the former. I know of no one that sells cast .225 projos.

 

[GBMaryland]

Tell me if any of this would make sense folks:

- Magnum / Match small rifle primers
- Match brass
- bullet swaging die

Would nylon coated lead rounds workany better?

 

[Gunfighter14e2]

Also get rid of the BR-4's an go to CCI 450's.

 

[Yondering]

Tell me if any of this would make sense folks:

- Magnum / Match small rifle primers
- Match brass
- bullet swaging die

Would nylon coated lead rounds workany better?

Powder coated lead bullets are a lot easier to develop good subsonic loads for. (It's actually polyester, not nylon, minor detail though.)

You can also experiment with a pinch of cotton (from cotton balls) to hold the powder in position in the case. I do that with the less fluffy powders (like Bullseye) with good results, although haven't bothered with subsonics in the 223.

 

[cav has been]

Check N.O.E. moulds. They make .225's up to 100 gr.

 

[Boozer]

Check N.O.E. moulds. They make .225's up to 100 gr.

THANK YOU! I hadn't seen this yet. so this begs the question, how big can i stabilize with a 1:7, or 1:8? at subsonic velocities?

Powder coated lead bullets are a lot easier to develop good subsonic loads for. (It's actually polyester, not nylon, minor detail though.)

You can also experiment with a pinch of cotton (from cotton balls) to hold the powder in position in the case. I do that with the less fluffy powders (like Bullseye) with good results, although haven't bothered with subsonics in the 223.

Now that you say this, I vaguely remember reading something about this in the past. I assume the cotton just gets vaporized? Are there other materials people commonly use for this?

Your issue is jacketed bullets in the 223. If you check them across the bearing surface to the 4th decimal place you will see a huge variance between them. The cure if you want to use jacketed is a custom swagging die, or start casting your own. I run 60.1gr cast bullets in my 223 an will head shoot a deer out to 150yds w/o issue. The 223 is very hard to load for when using subs, up to 3X harder than match for the same gun. My best load runs 1/2-3/4 moa. My playing around loads is a 50.1 gr an run about 1.5-2 moa but they are very easy to load for, over the former. I know of no one that sells cast .225 projos.

Until I start casting, If I'm running conventional jacketed bullets, I assume that sorting them by bearing length would help?

Thanks everyone for the help. This subsonic stuff is a little different.

 

[JCCinOhio]

I use 4gr TB too, but through a 16", 1/8.. When I was developing the load and looking on the internet I saw where someone recommended a small pistol primer. So I tried the Federal #100s.. and that helped a lot on ES/SD. I'm also using the Maker .223 subsonic expanding bullets & a decent crimp.

 

[Gunfighter14e2]

THANK YOU! I hadn't seen this yet. so this begs the question, how big can i stabilize with a 1:7, or 1:8? at subsonic velocities?

Weight means nothing no matter high speed or subs, it's nose an tail design with nose more so. I can run a 240gr rd nose from my 12 twist to 400+ yds an it will get there nose on, but a 175 smk at the same sub mv, will start going end over end from the same gun at 130-150yds.

 

[Boozer]

Weight means nothing no matter high speed or subs, it's nose an tail design with nose more so. I can run a 240gr rd nose from my 12 twist to 400+ yds an it will get there nose on, but a 175 smk at the same sub mv, will start going end over end from the same gun at 130-150yds.

OK, I'll bite.... So help me understand what do I need to look for in a bullet design/profile that will help stabilize a higher weight bullet at subsonic velocities.

 

[spife7980]

As short and compact of a profile as you can make it. I think of it as a canon ball is perfectly stable because at no point can the center of mass be anywhere other than in the middle, it cant tumble or catch the wind unevenly. A long high bc bullet with a long pointy nose and dragged out boat tail wont roll perfectly in all directions, it will tumble and that becomes unpredictable.

Now obviously we arent using cannon or musket balls but a flat base bullet will keep that mass towards the middle and a rounder blunter nose will do so as well. Tuck the mass into the center.

 

[isofahunter]

In prior post I suggested the Speer 70 gr Spitzer (hard to find) that is the type of bullet I would use if I was building a SS 223 load and did not cast bullets. Blunt on both ends is best for SS load in my experience.

 

[Boozer]

In prior post I suggested the Speer 70 gr Spitzer (hard to find) that is the type of bullet I would use if I was building a SS 223 load and did not cast bullets. Blunt on both ends is best for SS load in my experience.

OK, that all makes sense, I have always understood the "long & pointys" to need more twist. so a "short & fatty" could do with less.... jokes abound.

I understand that a round nosed flat base bullet would put the center of mass slightly back of center, Would it be beneficial (in an ideal world) to cast something with a hollow or cavity-back, to keep it closer to center, maybe even forward of center?

 

[Gunfighter14e2]

OK, that all makes sense, I have always understood the "long & pointys" to need more twist. so a "short & fatty" could do with less...

Yes this is why most rifles of old had very slow twist rates. They did not need it with the bullets they were throwing. The farther back the bullet is balanced away from the nose, the more twist you need.

 

[mdmp5]

I’ve used 4.5g of trailboss and 77 noslers and they seem to work well. I haven’t tried much higher of a charge but maybe try 5 and see if they stay subsonic

 

[Boozer]

You can also experiment with a pinch of cotton (from cotton balls) to hold the powder in position in the case. I do that with the less fluffy powders (like Bullseye) with good results, although haven't bothered with subsonics in the 223.

So I tried this on Saturday. Same load as before 4 gr trail-boss behind a 55 gr Hornady lead tip, except I stuffed the remainder of the case with 1 grain of poly fill. I ended up with a squib load . I think my dyslexia got the best of me, I thought I had read 1 grain of poly fill, but after the squib, I re-read the post with that info, and it actually said 0.1 gr, so that is probably the reason. I didn't have a cleaning rod with me, so that ended the range trip, but when I got home I squirted a little WD-40 down the barrel, and it popped right out, easy peasy.

Has anyone else experimented with poly fill or cotton balls, and can attest to a specific amount that they used? Also, what charge weights are folks using for something in the 70-77 grain weight range? There's not much published load data out there, but I did see somewhere that a fella used 5.5 gr. for a 77 TMK, so mijp5, you may be able to push that a little faster and still be subsonic.

Thanks

 

[mdmp5]

Yeah I never chrony'd it, but I probably do have some room

 

[Yondering]

So I tried this on Saturday. Same load as before 4 gr trail-boss behind a 55 gr Hornady lead tip, except I stuffed the remainder of the case with 1 grain of poly fill. I ended up with a squib load . I think my dyslexia got the best of me, I thought I had read 1 grain of poly fill, but after the squib, I re-read the post with that info, and it actually said 0.1 gr, so that is probably the reason. I didn't have a cleaning rod with me, so that ended the range trip, but when I got home I squirted a little WD-40 down the barrel, and it popped right out, easy peasy.

Has anyone else experimented with poly fill or cotton balls, and can attest to a specific amount that they used? Also, what charge weights are folks using for something in the 70-77 grain weight range? There's not much published load data out there, but I did see somewhere that a fella used 5.5 gr. for a 77 TMK, so mijp5, you may be able to push that a little faster and still be subsonic.

Thanks

Ok, so this one is a good example of the lesson to always work light loads down, not up. If you start low and try to work up to a decent subsonic load, you're gonna stick bullets in the barrel. You aren't worried about pressure limits with this kind of load, so start a bit high and work the powder charge down to get where you want to be. 4gr of Trailboss sounds like it's just asking for a stuck bullet, regardless what you do for filler.

Again, you'll have much better results using cast bullets for this too. I don't know a good source for .225" cast bullets though if you don't cast your own.

I mentioned using a pinch of cotton ball to hold the powder in position - that is literally just a pinch, that is pressed down against the powder to hold it against the back of the case. It is not intended to fill the case, and is a different thing than something like poly fill. The pinch of cotton burns up completely in the bore; I'm not sure what filling the case with poly fill would do inside a suppressor, and not sure I'd want to find out.

 

[cav has been]

The Bull Shop advertises .225 cast from 38gr. to 70 gr. Not optimum profile on the 70's but.......
I see a 72 gr. NOE mould in my future.