Questions for the guys that load subsonics

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  • shocker998md

    Ultimate Member
    May 29, 2009
    1,357
    Snow Hill MD
    I have a few questions regarding 300aac subs in a bolt gun and then 9mm in a stribog a3

    Remington 700 spa 300aac, suppressed. When I start working up subsonic load development, or working down in powder charge, will you hit a node going down like you would chasing a normal supersonic load up towards max charge? I'll be shooting all over a chrono. Or do I just ladder charge down for measured accuarcy and watch the chrono. My fear with this one is getting a squib. At first I'll just be looking to develop 25-100 yard plinking subs.

    Second is the same scenario but for a semi auto stribog a3 in 9mm. I figure that will be a balance of volocity and case pressure to cycle the action before worrying about a squib like above.

    I havent messed with loading subs before so I just want to throw my ideas out there before making a dumb mistake.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    I have a few questions regarding 300aac subs in a bolt gun and then 9mm in a stribog a3

    Remington 700 spa 300aac, suppressed. When I start working up subsonic load development, or working down in powder charge, will you hit a node going down like you would chasing a normal supersonic load up towards max charge? I'll be shooting all over a chrono. Or do I just ladder charge down for measured accuarcy and watch the chrono. My fear with this one is getting a squib. At first I'll just be looking to develop 25-100 yard plinking subs.

    Second is the same scenario but for a semi auto stribog a3 in 9mm. I figure that will be a balance of volocity and case pressure to cycle the action before worrying about a squib like above.

    I havent messed with loading subs before so I just want to throw my ideas out there before making a dumb mistake.

    Last first;standard loadings of 9mm 147gr FMRNs and up are by nature, subsonic. That's what I load and shoot for subs in my AR9 pistol. Squibs are usually reloader error. Uncharged rounds.

    For 300AAC, you'll be working down(always work down when developing subs). There are plenty of 'formulas' on reloading sites to get you started. You're chrono will tell you what your particular gun will 'like'. I always try and usually succeed keeping my loads close to the supersonic/subsonic breaking line. That's where I've found best consistencies. I have only come across one squib out of a couple thousand round in my 300AAC SBR and yes, there was no powder in the case. My fault. The primer pushed the bullet just slightly into the lands, where it stopped. I load several different bullets and charges from 208gr to 225gr, both poly coated and jacketed, depending on my needs.

    Be careful. Take your time and have fun.

    ETA: Pay attention to your gun as well as your backstop. If a shot felt 'funny', stop and inspect. The one think about shooting subs, you will normally hear your round hit the backstop with a thud, even with hearing pro on. No thud? Stop and inspect.
     

    shocker998md

    Ultimate Member
    May 29, 2009
    1,357
    Snow Hill MD
    After reviewing data for 147s again I see what your saying. My thought process mushed the two together. I'll just work a load up that will group and cycle reliably.

    For the 300 I basically just wanted to throw my ideas out and make sure I wasn't way off in left field with it.
     
    At least with a bolt gun you don't have to worry about enough pressure to cycle the action in your 300 blackout. My 10.2 inch 300 blackout pistol likes 10.1 grains of h110 over a 220 grain pill. Anything less than that the action isn't reliable anything more than that you're on the verge of breaking the sound barrier. I get right at 1050 FPS.
     

    mtlcafan79

    Ultimate Member
    Sep 11, 2008
    1,279
    PG
    For a bolt gun you can chase a quiet load that's still stable. Besides clearing the barrel you need to make sure it won't keyhole. For single shot subs I use N320 at around 920-950fps. There's no reason to run the usual gas gun powders in a bolt gun. It's just more noise. If you can get things stable around 900fps there will be substantially less noise than something that's transonic at the usual 1050-1080fps that's needed to cycle a semiauto. Some bullets just won't work at those velocities so don't be surprised if that's the case. I find round nose styles to work better than ELD styles at lower speeds.

    9mm 147 has a ton of data out there to start with. You'll most likely run into feed and stovepipe issues long before squib territory. Look at brianenos.com and the minor power factor guys. There's a treasure trove of load data there. 3.5gr of Titegroup or N320 is pretty popular if you have either of those.
     

    alucard0822

    For great Justice
    Oct 29, 2007
    17,643
    PA
    9mm subs are easy, but with a longer PCC barrel you might have the usual 147gr@1K FPS go supersonic with some powders. 9MM blowbacks will function down to a pretty light load. I load 124gr plated RN over 4.7gr or CFE pistol for a nice light load that runs just over 1K FPS out of a 5" handgun, but still subsonic from my 7" and barely subsonic from my 16" AR9s. 4.5gr runs great in all, and keeps 1K or less, only reason I use more is to make minor PF for handgun competition. I load 147s with 4gr for just over 850FPS from handguns, and 1K from carbines, quieter, still makes PF, similar recoil, but bullets cost more expensive. 300 subs are all about the powder, like 9mm the small case capacity helps keep reliable ignition and decent accuracy with light charges. Where you may need more powder and a charge at 1K FPS or more to cycle a semi, you can use faster powders and lighter charges without an issue, and end up with really quiet loads. Best to shoot a few at paper to make sure the bullet stabilizes before adding a can though. I load for semis and can usually take 220gr subs down to about 10gr of CFE BLK(published is 12gr @1050), 900FPS from my 9" and pretty quiet, and still cycles.
     

    85MikeTPI

    Ultimate Member
    Jul 19, 2014
    2,699
    Ceciltucky
    A friend has a collection of 9mm PCCs and just found Clays normal loads that run subsonic in 115/124/147gr and cycle the actions just fine for him..
     

    Bountied

    Ultimate Member
    Apr 6, 2012
    6,893
    Pasadena
    A friend has a collection of 9mm PCCs and just found Clays normal loads that run subsonic in 115/124/147gr and cycle the actions just fine for him..

    115s subsonic that cycle? OK... Go with 147s at the lowest load in the books that they sell on reloading? 220gr .300 BLK have similar charges to the super loads but the bullet is 40% heavier in 220gr. IANAE
     

    shocker998md

    Ultimate Member
    May 29, 2009
    1,357
    Snow Hill MD
    9mm subs are easy, but with a longer PCC barrel you might have the usual 147gr@1K FPS go supersonic with some powders. 9MM blowbacks will function down to a pretty light load. I load 124gr plated RN over 4.7gr or CFE pistol for a nice light load that runs just over 1K FPS out of a 5" handgun, but still subsonic from my 7" and barely subsonic from my 16" AR9s. 4.5gr runs great in all, and keeps 1K or less, only reason I use more is to make minor PF for handgun competition. I load 147s with 4gr for just over 850FPS from handguns, and 1K from carbines, quieter, still makes PF, similar recoil, but bullets cost more expensive. 300 subs are all about the powder, like 9mm the small case capacity helps keep reliable ignition and decent accuracy with light charges. Where you may need more powder and a charge at 1K FPS or more to cycle a semi, you can use faster powders and lighter charges without an issue, and end up with really quiet loads. Best to shoot a few at paper to make sure the bullet stabilizes before adding a can though. I load for semis and can usually take 220gr subs down to about 10gr of CFE BLK(published is 12gr @1050), 900FPS from my 9" and pretty quiet, and still cycles.

    I have a bunch of cfeblk vs just a pound of lil gun so im glad to hear that. With the 9mm stuff I can defintly see how barrel length will play a part in it, I'm hoping because of the a3 upgrading to delayed roller vs the a1 being just blow back it will cycle easier.
     

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    CFE BLK is fantastic for 300AAC subs. Lil Gun is much better for supers. Just start at the bottom of the book loads for the CFE BLK, I promise you won't get squibs with them in a bolt gun.

    As for 9mm, the simplest solution is to just load up 147s to some middle of the range powder load.
     

    lazarus

    Ultimate Member
    Jun 23, 2015
    13,678
    Also do your testing without your can on. It would really suck to find out for some reason a kid doesn’t stabilize well and you clip a baffle or your end cap.

    Generally a suppressor will add some velocity, but it isn’t going to stack on like 50-100fps.

    I mean, test with the can, but get around where it looks good, make sure you are subsonic, make sure a few rounds are hitting paper at closer range and making nice neat holes and then put your can on and make sure it is staying subsonic.
     

    outrider58

    Eats Bacon Raw
    MDS Supporter
    Jul 29, 2014
    49,818
    Also do your testing without your can on. It would really suck to find out for some reason a kid doesn’t stabilize well and you clip a baffle or your end cap.

    Generally a suppressor will add some velocity, but it isn’t going to stack on like 50-100fps.

    I mean, test with the can, but get around where it looks good, make sure you are subsonic, make sure a few rounds are hitting paper at closer range and making nice neat holes and then put your can on and make sure it is staying subsonic.

    This is the point I knew I was waiting for(that I neglected to mention). Good catch lazarus!

    Always always always test your subs, whether factory loads or home brews, without the can on FIRST. :thumbsup:
     
    Last edited:

    erwos

    The Hebrew Hammer
    MDS Supporter
    Mar 25, 2009
    13,866
    Rockville, MD
    Yeah, and don't trust twist rate to tell you if something's going to stabilize. I have an 8.5" 1:7 300AAC barrel, and it didn't stabilize 240s at all.
     

    shocker998md

    Ultimate Member
    May 29, 2009
    1,357
    Snow Hill MD
    Well I messed with the stribog first. 5.9 and 5.7 grains of blue dot, shot into cardboard to see how the 147 grain projectiles from xtreme printed and they looked good.

    Screwed on the octane 45 and let it rip. They grouped about the same, 10 rounds of each cycled fine. I'm going to break out the chronograph on my next go at it and see what 5.7 grains are doing. I just want it a touch quiter, so I need some fps data to see whats going on.
     

    TrappedinMD

    Active Member
    Dec 15, 2011
    856
    Western MD
    Fwiw I developed a subsonic 220gr .300 blk out load using berrys plated pulleys and blue dot. I run a 8.5” pistol with a lightweight bcg and reduced rate recoil spring. It’s the quietest suppressed semi I’ve heard :)
     

    Bountied

    Ultimate Member
    Apr 6, 2012
    6,893
    Pasadena
    Fwiw I developed a subsonic 220gr .300 blk out load using berrys plated pulleys and blue dot. I run a 8.5” pistol with a lightweight bcg and reduced rate recoil spring. It’s the quietest suppressed semi I’ve heard :)

    Not quieter than my 10/22 running Gemtech subs.
     

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