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Gunsmithing Looking for Subsonic .30 Cal Advice

168BTHPM

168BTHPM

Werepig
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Full Member
Minuteman
    • Mar 1, 2008
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    259,262
    Nevada
    I would like to build a subsonic .30 caliber rifle and was wondering if anyone has any advice or information about the calibers available and which is the best choice. Build advice would be appreciated, like which calibers feed and function the best or what mods to the action are needed to get them to function.

    I am using a Rem 700 short action, it currently has a standard bolt face but I wouldn't need much motivation to buy a PT&G bolt with a small face.

    The only calibers I am familiar wth are .300 Whisper and .308X1.5", I am leaning towards the .308X1.5" because brass would be easier to find and make.
     
    Re: Looking for Subsonic .30 Cal Advice

    I took EE360 Acoustics at the U of W and hand load 62 different cartridges.

    Still someone else had to figure out for me that sub sonic gas escapement sets the threshold of pellet gun quiet.

    Someone else had to calculate the gas pressure threshold of sub sonic gas escapement.

    Someone else had to calculate the noise level at cavitation.

    I can see the optimization for quiet is small case volume driven to high pressures.

    32 S&W cut back to half it's length would be a good cartridge.
    A case full of the fastest- densest gunpowder might not get the pressure high enough.

    Make sure the riflings go all the way back to the bullet.
    Be sure to use lead bullets, for efficiency.
     
    Re: Looking for Subsonic .30 Cal Advice

    300 whisper, brass are really easy to make from 223, and subsonic is easy out of this case.
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: rlane08</div><div class="ubbcode-body">Why not leave it in 308 and just load it down. </div></div>

    in comparison to the whisper to case is inefficient and gives erratic velocities at subsonic loadings due to its volume.
     
    Re: Looking for Subsonic .30 Cal Advice

    The velocities variances of the .308 are not as extreme as one may think. I'm using Winchester brass, Sierra 175 SMK, Federal 210M, and 10.7gr. of Trail boss and my velocities do vary but not enough to make any accuracy differences. I don't have the actual numbers in front of me but IIRC it was in the area of +-15fps. I'm not denying that some of these custom made cartridges will perform better for subsonic loadings but if you already have a .308 the money spent on converting it to something else would be better spent on ammuntion or other things.
     
    Re: Looking for Subsonic .30 Cal Advice

    300-.221. Use a reamer from PTG that cuts a .336-.337 neck so you don't need to neck turn .223 brass and don't have to worry about using .221 Fireball brass. 1 in 8 or 1 in 7.5 twist barrel,
    shoot everything from 125's all the way to 240's. Unless you're going to go big Whisper, the 300 is the way to go.
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Luke</div><div class="ubbcode-body">The velocities variances of the .308 are not as extreme as one may think. I'm using Winchester brass, Sierra 175 SMK, Federal 210M, and 10.7gr. of Trail boss and my velocities do vary but not enough to make any accuracy differences. I don't have the actual numbers in front of me but IIRC it was in the area of +-15fps. I'm not denying that some of these custom made cartridges will perform better for subsonic loadings but if you already have a .308 the money spent on converting it to something else would be better spent on ammuntion or other things. </div></div>

    The problem being that to get any kind of terminal performance at distance you need at least 220 grains going 1050 fps or there abouts....Requires an 8 twist unless you are waaay above sea level... Difficult to find that rate of twist in a factory barrel.
     
    Re: Looking for Subsonic .30 Cal Advice

    I just started a 308 subsonic load today in preparation for getting my suppressor in. Started out with 9.6gr behind 168 Amax and was getting 880fps. 10.0gr gave me 950fps. I ended up at 11.0gr of IMR Trail Boss, 168 AMAX, LC Match Brass, GM210M primer and they were flying 1020-1040fps quite consistenly.

    If its nice tomorrow Ill get out to 100yds and see what the groups look like. The 168 AMAX is the only bullet I have right now so if it doesnt stabilize I may have to switch to a roundnose.

    This is a Savage 12FV, 26" 1-10 BBL.
     
    Re: Looking for Subsonic .30 Cal Advice

    Lots of 308 Win. subsonic loads:
    http://www.snipershide.com/forum/ubbthreads.php?ubb=showflat&Number=468230

    I get better results with TiteGroup than with Trailboss, plus it meters well.

    180 Hornady RN
    8.0 gr. TiteGroup
    Magtech Brass
    WLR primer (important, WLR give best results)
    2.650" COAL

    To stabilize the velocity: run an oil patch through the bore prior to the 1st shot. Rub a bit of oil on each bullet. I needed to do this with Trailboss as well.
     
    Re: Looking for Subsonic .30 Cal Advice

    While we are talking sub sonic,
    anyone got any input for me, we've just stuck a 9.3 bullet in a .308win case, and also in a 6mmBR case.
    looking at developing these 2 this year..

    i suppose this belongs in the reloading section eh,.,.

    Pete
     
    Re: Looking for Subsonic .30 Cal Advice

    Pete , currently working on a 338 X 39 and a 510 whisper copy. The 308 case has always run erratic velocities for me with heavy bullets....unsure why other than capacity?

    The work Ive done off a 30 cal x 6mmBR case went fine until I figured out it was doing what a whisper did.....with real expensive brass?

    The 9.3 X 6BR sounds very much like a 338 whisper, which absolutely rocks....out to 600 yds. I'd bet with equal bullet weights the load data will interchange.
     
    Re: Looking for Subsonic .30 Cal Advice

    Trying to load your sporting rifle to shoot subsonic but it is a waste of time. The subsonic game about heavy bullets as your velocity is the fixed part of the energy equation. I only use 240 grain SMK's they are heavy, available and relatively cheap.

    It just so happens that JD Jones 300 Whisper or closely copied 300/221 appear to be optimal for this application. Amazingly this little cartridge also performs well with 125, 135 and 150 grainers in the supersonic range.

    Just remember unless you want to wipe the baffles out of your supressor you need a 1:8 twist or faster barrel to stabilize the 240 grain SMK's.

    In my opinon playing with subsonic 308 and other big cartridges in the 30 caliber class is a waste of time, effort, powder and bullets.

     
    Re: Looking for Subsonic .30 Cal Advice

    AKA Spook. the 9.3x6BR started life as a 9.3x39, after discussions with Redding and Dave Kiff and due to the availability of the lapua 6BR brass we switched parent cases.

    Ive got a hard on for 9.3 bullets.
    We have employed the 9.3 RSM ( 9.3x.300WSM) very effectively. very accurate and very effective on game.

    we've a 9.3 in a .338LM,
    then the 9.3x.308win version, i see that as a driven boar cartridge for ladies and youth. or an effectve subsonic.

    the BR version is just because we can..

    M21black . ive had good resulty with .308 win subsonic in my 1 in 10" twist barrels,

    I haven't realy got the time for this tinkering, but it interests me, and i have a guy doing most of the ammo tinkering for me,
    Pete
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: m21black</div><div class="ubbcode-body">Trying to load your sporting rifle to shoot subsonic but it is a waste of time. The subsonic game about heavy bullets as your velocity is the fixed part of the energy equation. I only use 240 grain SMK's they are heavy, available and relatively cheap.

    It just so happens that JD Jones 300 Whisper or closely copied 300/221 appear to be optimal for this application. Amazingly this little cartridge also performs well with 125, 135 and 150 grainers in the supersonic range.

    Just remember unless you want to wipe the baffles out of your supressor you need a 1:8 twist or faster barrel to stabilize the 240 grain SMK's.

    In my opinon playing with subsonic 308 and other big cartridges in the 30 caliber class is a waste of time, effort, powder and bullets.

    </div></div>


    Do you think it is a waste of time because it is "impossible" to get consistent velocities? Because if you get consistent velocities with say a 308 then what really is the difference between the two? Velocity is a constant, so your barrel is the deciding factor, and if you have a fast enough barrel to stabilize the bullet...then why couldnt a 308 be just as effective as the wildcat subsonics?
     
    Re: Looking for Subsonic .30 Cal Advice

    Got out today to test this subsonic load. Conditions not what I wouldve liked, 20*F and 10mph FV wind. Set up at 100yds and dialed 12moa up elevation (total guess). First shot through the chrono measured 947fps and hit 2" low and right. Second shot was 1049 and dead elevation still right. Walked out to target to see where I was hitting at this point. Next shot cold bore again was 835fps. Heres the rest of the group one after another.

    1069
    1037
    1033
    1037
    1020
    1040
    1018
    1014
    1020
    1005
    Mean 1031
    Std.Dev 18fps of the non cold bore shots.

    This is using very old crappy LC Match brass, and a defective Lee neck sizer (still waiting for new Redding to arrive). Even shooting full power Varget loads out of this brass shows this much velocity deviation.

    Heres the target
    subsonic_target.jpg


    As you can see, and I could see through the scope, the bullets were tumbling going into the paper, but nonetheless shot surprisingly well. Almost every shot that was not cold bore was within a 2" or less elevation spread. I think the only downfall to this setup right now is the bullet, I need to research a good roundnose possibly to use to distribute the weight better, something with a better stability factor than an AMAX.
     
    Re: Looking for Subsonic .30 Cal Advice

    I've had much better experience with ss 30cal loads using 7.62x39 or smaller cartridge. This is taking all variables into equation, mainly non-modified brass (don't want to accidentally mix brass with full power loads), any bullet type I want (don't want to limit myself on lead, fuss with moly or grease etc.) and environment (I want to shoot in subzero temperatures also).
     
    Re: Looking for Subsonic .30 Cal Advice

    It's a waste of time for 2 reasons no matter what you do, you can not take advantage of the the 220 or 240 grain bullets and infact are relegated to 180 grainers lest you want to clear the baffles out of your suppressors. If you are going to change your barrel to 1:8 twist you might as well buold it around the right cartridge. The 2nd reason being the case capacity of a 308 is 3 to 4 times greater than you need, simple put your 308 just wasn't designed for this application.

    Like I said before the subsonic game is about big bullets with big ballistic coefficents travels below 1050 +/- FPS. The bigger the bullet the more energy you can deliver at greater distances.

    You can do what you want but I recommend to the rest of you guys interested in subsonic 30 calibers build yourself a 300 Whisper.

    [/quote]


    Do you think it is a waste of time because it is "impossible" to get consistent velocities? Because if you get consistent velocities with say a 308 then what really is the difference between the two? Velocity is a constant, so your barrel is the deciding factor, and if you have a fast enough barrel to stabilize the bullet...then why couldnt a 308 be just as effective as the wildcat subsonics? [/quote]
     
    Re: Looking for Subsonic .30 Cal Advice

    That's problary why J.D.Jones,SSK Industries is way a head of the game. I would duplicate his loads,barrel twist to save a lot of troubles ,time,and money. 15 years ago ,he did have a nice littl T/C Contender carbine loaded to a .308 specs with the case cut way down to resemble a pistol case, with 8-10 powder charge with a 180 gr. bullet,tops it was good only to 80 yards,so that tells a little story there. I'd check out his stuff or call him and forumla something from there. I agree about big heavy bullet going sub sonic as the best way to get the most energy tranfer.
     
    Re: Looking for Subsonic .30 Cal Advice

    Personally I like JD Jones, he is a gentleman and has alway been helpfull to me. There are alot of other guys who for some reason have a bad opinon of him to which I say we all owe Mr Jones a big thank you for his efforts in coming up with The 300 Whisper and the Whisper family of cartridges.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Harold Dale</div><div class="ubbcode-body">That's problary why J.D.Jones,SSK Industries is way a head of the game. I would duplicate his loads,barrel twist to save a lot of troubles ,time,and money. 15 years ago ,he did have a nice littl T/C Contender carbine loaded to a .308specs with the case cut way down to resemble a pistol case, with 8-10 powder charge with a 180 gr. bullet,tops it was good only to 80 yards,so that tells a little story there. I'd check out his stuff or call him and forumla something from there. I agree about big heavy bullet going sub sonic as the best way to get the most energy tranfer. </div></div>
     
    Re: Looking for Subsonic .30 Cal Advice

    Agree,it is said that at least 25% of the people hate you right off the bat! I would't let this bother you,just think about the other 75 % of the people that like you. I think Mr.J.D. Jones is doing very well and it is good to see someone out on the frontier!
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jthyttin</div><div class="ubbcode-body">I've had much better experience with ss 30cal loads using 7.62x39 or smaller cartridge. This is taking all variables into equation, mainly non-modified brass (don't want to accidentally mix brass with full power loads), any bullet type I want (don't want to limit myself on lead, fuss with moly or grease etc.) and environment (I want to shoot in subzero temperatures also). </div></div>

    7.62 X 39 is a great cartridge to shoot 30 cal subsonics from, as is the 6.8 Rem SPC run through a 30 Herret die, as is the 30 br....but we're back to doing what a whisper does , with expensive brass. The cost of the brass will eventually cover the cost of the bolt conversion.
     
    Re: Looking for Subsonic .30 Cal Advice

    That big medicine,,, wish it was in my budget. J.D. Jones told me a while back that he thought the 375 Whisper was the best of the Whispers for hunting, relatively affordable to shoot and big holes.

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Harold Dale</div><div class="ubbcode-body">Not enough ? J.D. Jones SSK Industries..... .510 Whisper..1050 FPS,suppressed under 126 DB,MOA accurcy at 600 yards! </div></div>
     
    Re: Looking for Subsonic .30 Cal Advice

    the paper the federal reserve is printing is worthless a 1000 bucks spent on a rifle is well spent money.
     
    Re: Looking for Subsonic .30 Cal Advice

    Can't tell you what to do, just what I did.

    I've used subsonic guns for vermin control for years, from .22LR, .22Hornet, .221, .222, .223, 7.62x39, .38Special, and a bunch I can't remember. The last effort to find a good long-range gun was setting a factory Remington .308 heavy barrel back, chambering to .30BR and shortening to 18". With full-power loads it still has more steam than 30/30 and the .308 bolthead means I can switch the barrel back to .243 or .308 easily. The .308 bullet selection is unbeatable, with 110gr HPs this thing is great. With an LTR stock its a handy little gun.

    remmy_700.jpg
     
    Re: Looking for Subsonic .30 Cal Advice

    A +1 for J.D. Jones and his .300 Whisper. He did one for my son last year on a AR platform. He personally showed him the ropes and a few personal tips. It works better than I would have believed and is super quiet using Jones's suppressor.
    J.D.'s trophy room is a must see and he is a real gentleman.
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: DFOOSKING</div><div class="ubbcode-body">Had a funny thing happen, yesterday, thought it kinda fit in with this discussion. A buddy of mine with a .308 700 heavy barrrel, was making dumbed down loads for the first time. Loaded some (unknown size .30 cal)tracers without bothering to reference any load data (hoped he get close)and when he took the rifle out to chronograph the shot, the tracer kicked off in the barrel and got stuck half way down. The neck of the brass was semi melted and cracked from the obvious cause. The round sat there and cooked for a little bit.

    The kicker of it all, he just looks up at me, totally calm and says "well I always wanted to have a .260". I died laughing. I figured since nobody posted anything in regards to down loading tracers, that maybe you would like to here it. We ended up going to runnings and bought a steel rod to pound out the tracer. A benchrest shooter neighbor of mine will check to see if the barrel is a total loss. </div></div>

    Most likely it is.... If I am right, the metal in tracers is phosphorus, and that stuff gets very hot........

    He will like the 260.....
    smile.gif


    Dave
     
    Re: Looking for Subsonic .30 Cal Advice

    Has anybody build a .338 x 39 (necked up a 7.62 x 39) 1 in 8 twist for sub sonic work? So that you can use heavier bullets
     
    Re: Looking for Subsonic .30 Cal Advice

    <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Cameron1364</div><div class="ubbcode-body">Has anybody build a .338 x 39 (necked up a 7.62 x 39) 1 in 8 twist for sub sonic work? So that you can use heavier bullets </div></div>
    Yes, but I'm using a much faster twist.
     
    Re: Looking for Subsonic .30 Cal Advice

    For simplicity you could use any 222 rem rifle and a add a 30 cal barrel with 1:10 twist and just have it chambered to 30 us carbine. At subsonic loads there is no need to modify the bolt face. 150 to 220 plus cast projs work a treat. The only thing u need to spend a bit of time on is the magazine feed.
    Gunruna
     
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