.22 Hornet subsonic!!

[BABore]

The faster the powder, the less you need, and the less noise it will make in a rifle bbl. I've went as low as 0.75 grs of Bullseye with a CCI 500 primer and 48 gr PB boolit. 0.5 grains just would barely get it out the bbl. 1.2 to 1.5 grains was where the load became accurate enough in my gun for 50 yard wabbits. No filler used. The load sounded like an adault pellet gun.

[FLHTC]

The faster the powder, the less you need, and the less noise it will make in a rifle bbl. I've went as low as 0.75 grs of Bullseye with a CCI 500 primer and 48 gr PB boolit. 0.5 grains just would barely get it out the bbl. 1.2 to 1.5 grains was where the load became accurate enough in my gun for 50 yard wabbits. No filler used. The load sounded like an adault pellet gun.

I'm considering something similar with Red Dot. I used Trail Boss and it was much louder than expected.

[telebasher]

So when someone says "subsonic " what actual velocity do you have in mind? I see that telebasher offered a load producing 1160fps but is that not above the speed of sound at sea level?
I live at just over 6000 ft above sea level so under standard or average atmospheric conditions what is the speed of sound for me, what is subsonic?
I am working on a boolit order for which the customer has asked me for subsonic load data for the 22 Hornet with the #225107 at 38gn. I have never developed such a load so need some teaching in this area. I guess I need to ask him what elevation he is at.

The elevation where I live is just under 3000 ft, but the rifle range is located SE of town down in a big creek drainage. Probably another 100-150 ft lower elevation. FWIW. By the way this load was recommended and used by Paco Kelley in an indepth write up about cast boolits in the Hornet.

[Larry Gibson]

I made a correction to the subsonic load with Bullseye in a previous post. The 2.7 gr Bullseye load under the 225438 is a sonic load.....an excellent one but still sonic.

Larry Gibson

[Dewey von]

The 22 Hornet case has a very, very small volume. Most use SP primers to lessen the brisance. I don't think you'll find any "powder position sensitivity" with such a small amount of Bullseye in the 22 Hornet case. I base that on having shot several thousand such loads (225462s, 225415s and 225438s) through my own 22 Hornets including a suppressed one. Velocity does not vary outside normal ES and accuracy can be excellent.

I also used the same load as telebasher suggests. Suggest you try it before condemning it.

Larry Gibson


CORRECTION

telebasher's load of 2.7 gr Bullseye under the 225438 is an excellent one and one I use often. However, it is not subsonic. It runs about 1400+ fps. My subsonic load is actually 1.7 gr of Bullseye under that bullet. Suggest you start at 1.5 gr and work up until you get a "crack" and then back of .2 gr.

Thanks a bunch Larry! I will be sure to try it out. I work away from home, and still have about a week to go. Can't wait to get home, and try it out!

[Whiterabbit]

I wish we could ship powder easily. Say, a regulation that says we can ship powder in 1lb qty or less if we box it in a certain way, etc.

My local shop got a shipment of TB two weeks ago and it no only hasn't sold out yet, but there are probably over a dozen cans on the shelf still. Id be happy to buy one and forward it to you. But that pesky Hazmat cost makes it a pain.

I'm thinking we need to find a low cost mortar shell or something, make a cast boolit plug, and ship 8 ounces of powder at a time via UPS as live ammo. free 8 ounces of lead too.

50BMG brass has potential, but not enough case capacity.

[Bullshop]

So if I had to produce subsonic ammo that would stay subsonic under all conditions would it be safe to say that 900 fps is max?

[starmac]

White rabbit, some guys that live in fly in only villages does exactly that. They bring the biggest cases they have to town, and fill them with powder and stick a bullet on top, so they can fly back home with powder. lol

[rhbrink]

I believe that the 22 target ammo is loaded to 1080fps and is considered subsonic. So I think that I would shoot for 1050 to 1080 for myself and call it good. There might be chart somewhere to help a guy figure the speed of sound under different conditions but don't recall ever seeing one.

RB

[Whiterabbit]

White rabbit, some guys that live in fly in only villages does exactly that. They bring the biggest cases they have to town, and fill them with powder and stick a bullet on top, so they can fly back home with powder. lol

I'm telling you, those Alaskans must know something we don't, with their 50bmg's loaded with 200 grain wad cutters!

(and a spent primer)

[rhbrink]

Well I just went and looked up the speed of sound on the old puter and there is a formula! Imagine that! It actually says that Sea level doesn't mean chit, air pressure is a non factor, the only controlling factor that has any real value on the speed of sound is air temperature. With a handy plug in formula the speed of sound at 0* F is 1050.91, at 32* F it's 1086.947, and at 90* F it's 1149.27. There you go!

RB

[Whiterabbit]

more to it than that. According to books on ballistics, the transonic barrier is more than just a brick wall concerning sonic crack of bullet flight. There are accuracy issues as well. That bullets approaching the speed of sound are in transonic limbo as well, and it can be detrimental to accuracy in a big way. Thus for example, a long range shooter who wants to stay supersonic may want their bullet to be going much faster than 1150 fps when it's 90 degrees out. It's not just a brick wall from happy-fun stability to transonic breakdown.

Where are the limits? How much does this apply to 100% subsonic loads? Where does the grey area start?

Dunno. Needs an egghead bigger than mine to define. I bring it up as something to look for in regards to ballistic reference researching.

[frnkeore]

The speed of sound has nothing to do with sea level, barometric pressure or humidity, ONLY temperature.

http://www.sengpielaudio.com/calculator-speedsound.htm

Also, it will vary with the nose shape of the projectile, as the air has to speed up as it flows around the nose of the bullet. Large meplats increase the velocity at the corner of the meplat, next comes round nose and then ogive are last, the longer the ogive, the slower the speed increase.

So, to keep a bullet from "cracking" when it becomes supersonic, it needs to be done by actual testing and at a recorded temperature.

Frank

[Bullshop]

That's pretty interesting stuff. Completely changes the picture for me when I hear the term "sub sonic" now. The one right answer as with many things involved with shooting is, "it depends".

[rhbrink]

We're all going to turn into rocket scientists before we are done here!

RB

[Larry Gibson]

Well I learned something today. From the source listed above ; "Statement: The static air pressure p_ and the density ρ of air (air density) are proportional at the same temperature, because the ratio p_ / ρ is always constant, on a high mountain or even on sea level altitude.
Notice: The ratio p_ / ρ (static air pressure to air density) is really always constant." Amazing!

Thus when the ambient temperature is different the speed of sound is different. When the is low pressure the temperature is lower and visa versa with high pressure. Both of those many times affect the humidity also. Which all means if the speed of sound (in the air) is simply dependent on temperature! I've learned just how simple that is. However, as I stated before and as have others (including frank) it is the distance (hence the speed) the air moves around the projectile that determines when the crack will come, not the speed of the projectile.

Bullshop

I've tested numerous calibers up through .45 and found that your suggested 900 fps would be a fairly safe bet.

Larry Gibson

[wlc]

I try to load all my subsonic stuff to hit right at 1050fps or a tad less. I do shoot when it gets close to zero* sometimes and so far no crack. I think that if you wanted to be absolutely sure then 1000fps should work in most all circumstances.

[rhead]

It depends on if you want a load at a specific velocity or a quiet, accurate load. The velocity that you quit getting the crack will vary with the nose shape. The velocity where you get the accuracy will depend on your barrel. Once you find a load you like you may can tweak it to adjust the point of impact.

Always check for stuck boolits and if you stick one before you find an accuracy node try a different powder.

Pure lead boolit!
Fast powder!
Good lube!
No gas check
Check for stuck boolits!
Lots of range time.

The check list may be incomplete

[303Guy]

I've just found this old thread on sub-sonic 22 hornet. I did a search and rather than start a new thread, I'll just resurrect this one. It already has most of the answers!

So I'm having trouble with sub-sonic 22lr being too noisy with a silencer for my conditions. The idea of sub-sonic hornet allows me to load as slow as is needed for complete silence and hopefully still get decent accuracy. I've tried some of the available ultra slow 22 ammo out there and while some really are quite, well, the idea is to actually hit something smaller than an A4 sheet.

Enter the hornet. Now my problem is to cast boolits for it. I have a 55gr FN RCBS mold that I find very difficult to cast from and besides, it's a heavy boolit. It does shoot Ok from my rifle but at the time of testing I wasn't going sub-sonic. I have shot that boolit sans gas check in my mini 14 which I no longer have. They were Ok at subsonic velocities. The hornet has a much slower twist rate though. Thing is, I am not looking forward to casting then tiny boolits in that mold. I did make a smooth side mold which I think I still have and I also made a swaging die that I don't remember the purpose of. It does swage the RCBS boolit into a nice smooth side spitzer but it's still 55gr.

I have two powders I want to try, one being Clays and the other Trail Boss. I'm assuming that 1.4 gr of either will get me near trans-sonic and hence clear of the bore.

[Larry Gibson]

As I mentioned in an earlier post some years back it is the speed of the compressed air moving around the bullet that causes the "crack" not the speed of the bullet. Ergo a FN bullet will "crack" at a lower velocity than a RN or pointed bullet.

I have just recently suppressed my Contender 22 Hornet with a 10" barrel. A 225238 out of it will run right at 1100 fps before it "cracks" or "snaps" but a 225415 with snap just over 1050 fps.
Attachment 266106

I use Bullseye with both powders. A chronograph is not needed as the velocity is irrelevant to where the bullet cracks or snaps. You can easily work up to the load you want. Simply start low and work up in .2 gr increments with 2 shots of each increment until you just hear a "snap" in front of the suppressor. The snap indicates the bullet is breaking the speed of sound but only for a few few then it slows sub-sonic and no longer snaps or cracks. Back off to the previous tested load that did not snap, load 10 shots of that to see if you get any snaps or cracks. If not you're good to go. If you get any snap or crack back off another .2 gr and test again til you get no snap or crack for 10 shots....that be the load.......

I use the chrono anyways just to satisfy my curiosity as the the velocity. However, as mentioned, the velocity is not the determining factor ...... the absence of any snap or crack determines the load for sub-sonic use.