Best barrel length for suppressing a 300BO pistol?

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  • kidsoncoffee

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    I've built the lower. Geissele G2S FCG, will be using a SB PDW brace, Anderson lower. I want to go with a stag left handed 300BO upper but it has an 8" barrel. Would this barrel length, while utilizing a dead air sandman L, give me good range at sub and super sonic loads? I have zero experience with AR pistol platforms as well as suppressors. I'd like to be able to reach out 150 yards accurately and still be able to take down a hog. Any input is appreciated. Thanks.
     

    stage20

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    I have no personal experience but I'm in the market for the same thing All kinds of info out there. Some manufacturers only warranty to 10". It's really hard to decipher what's truth and what's internet lol
     

    FLT

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    Daezee would be a good guy to talk to about 300blk suppressed. The internet is more lies than anything else.
     

    SAWMAN

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    Yeah,Bruce owns a few 300BLK in different lengths. Most if not all are surpressed.
    He keeps detailed records of their performance with quite a few different handloads.
    He would be the source of the info you guys seek. --- SAWMAN
     

    kendive

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    Yeah,Bruce owns a few 300BLK in different lengths. Most if not all are surpressed.
    He keeps detailed records of their performance with quite a few different handloads.
    He would be the source of the info you guys seek. --- SAWMAN

    Yes I shoot alot with Daezee and he has a few 300 BO setups. His favorite hog bullet is the Barnes 110 Gr Black Tips. He also custom reloads everything.

    I have a couple that I built. One is a full 16" and the other is a 10.5" SBR.

    The 10.5" I did my own custom work on it to make it cycle subsonics without the suppressor on. The 30 Cal suppressor is the YHM Ti-QD rated to 300 WM. Don't think I need to worry about barrel lengths and pressure problems with it. Some mention about warranty and barrel lengths. This does come into play such as my Gemtech M4-02 5.56 Suppressor. They say 10.5 or longer.

    Personally I would never shoot nothing but subs on the short barreled 300 BO. So there really is no worry as to blowing up a suppressor with subs. Hell one of my 9mm Suppressors the YHM Sidwinder is rated for shooting 300 BO through it (Sub Sonic Only) It makes for a very light compact weapon system.

    Now you got to discuss hunting Hogs with Subsonics :) If that is the plan. That is whole other ball game. I don't hunt so I'm not going there...








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    Daezee

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    At 150yd, subsonic will have quite a bit of a curved trajectory, thus one would have to know the distance the target is away and have a trajectory chart/card so you can know the hold off to hit the target exactly where needed for a good kill. While I've worked up some subsonic loads that could be used for hog hunting, my hog hunting has been at night. Since it's hard for me to estimate distances at night, I decided I'd use supersonic (suppressed) hunting hogs. Looking at my supersonic hog hunting load trajectory card, I see my bullet impact of +/- 1 inch to be from 30 to 160 yards. It's normally easy to get closer than 160 yards, more like under a hundred yards. Even though there is a crack with supersonic suppressed, I had one instance in which hogs didn't know what to do, so I got off multiple shots. On one hog, Sawman, about 50 yards away, was not aware I'd shot. I've had several instances in which deer stayed in the field or area after I'd shot one. I might have a pic of that, but don't feel like digging it up (deer feeding next to a downed deer).

    I've killed several wild hogs subsonic suppressed with Sierra 220gr Match Kings, but I don't think I mentioned it on this forum because it was not "hunting", but simply killing hogs in a trap for a local rancher. Subsonic suppressed so others present didn't need hearing protection and maybe the hogs wouldn't be moving as much. All were brain shots.

    OK, so you want to kill up to 150 yards...now you have to do some research. Pick the bullets you want to use, find out from the maker the minimum velocity for good expansion and the ballistic coefficient. Determine the muzzle velocity you can get with your bbl length. Plug the muzzle velocity and ballistic coefficient into a ballistic program (I use JBM, free on the Internet) and see the distance at which the bullet velocity drops below the minimum velocity needed...you'll have an answer for that bullet. Of course an animal is not just theory, but has fat and shield and bone and meat, but at least you'll have an idea.

    Example: The Nosler 125 grain Ballistic Tip needs 1800fps per Nosler. Doing the above exercise and rounding off distances so it's easy for me to remember, an 8" bbl gives an effective range of 100yd. 9.5-10.5" bbl gives 150 yards. 16" bbl gives 200 yards. My biggest hog was shot at ~100 yards with that bullet, the theoretical limit of that 8" bbl and bullet. He was running. Bullet went through the very thick right shield, through a couple of inches of back strap, hit the spine and stopped, fully mushroomed. Closer or with a longer bbl, I feel the bullet would have went into the spine.

    Other bullets will give more or less hunting range. I now use the Barnes 110gr black tip bullets if the gun likes them (not all of mine do). They give deeper penetration and require less impact velocity to expand (but since they are lighter, you will get higher velocity than 125 grain bullets). So, given your parameters, I'd see if your setup shoots the Barnes accurately. If hunting is a significant goal, I'd go with a 9.5-10.5" bbl to give more velocity and thus range. Your rifle/pistol would still be short and handy.

    Here's a boar being shot supersonic suppressed 38 yards away, that Sawman, about 50 yards from me did not hear the shot. Sawman had put sow-in-heat spray right behind me, with the wind blowing from me to the hog. The blur at first is me grabbing my rifle and turning on the thermal, as I was not prepared for a hog to come from that direction and just happened to look that way through a hand held thermal. I shudder to think about the ensuing chaos if I had not happened to scan in that direction and the boar walked right into my lap! I was expecting hogs from other, not down wind, directions, and decided to do a 360 degree sweep with the thermal. The sow-in-heat spray worked very well...you can see him hesitate and turn right towards me.

    Check to see if the suppressor maker has any restrictions on the Blackout with that short bbl...I would guess there isn't any, compared to other higher pressure cartridges. Please ask further if my reply was not sufficient. I have 2 30 cal suppressors, so I try both on any give firearm to see which works the best (gives the best accuracy). I have a Crux Ark30 (screw on) and Gemtech Quicksand (quick attach). The majority of the time, the screw on gives smaller groups.
     
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    kidsoncoffee

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    Awesome write up and information Daezee. That's definitely more than enough information for me to make a decision. I do believe the 10.5" is the way I'm going to go. Once it's built and I start making some loads, I hope you don't mind me hitting you up with a few questions. Sounds like you've done some extensive testing with yours. Which buffer and spring are you using to get consistent cycling with your subs? I've got a spikes carbine spring as well as a T1 and T2 buffer, but I would like to have other options on hand that might work better if I run into issues while dialing in the gun. I don't mind buying a few as I have a few more lowers to build.
     

    Daezee

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    I've tried standard carbine buffers, H, H1, H2, Spikes T2 and have not found any difference in function. I did try a Tubbs flat wire buffer spring (25% extra oomph Tubbs said; suppose to be good in both carbine and rifle length stocks), but found failures to allow the buffer go fully rearward in the Blackout and lock the bolt back on the last shot, so I put in in a .223 rifle buttstock and only use it there. I use standard carbine $5 buffer springs. I did replace one after 16,000 rounds, as it's length was now below the *minimum. Did buy a fancy ($10) last forever carbine buffer spring, but found no difference in function over the $5 springs. Main thing on the buffer spring is to measure it every few years to make sure it's within spec for length.

    * = Was having some failures to extract...BCG was going back faster before the chamber pressure was reduced enough to allow the empty to be extracted in one of the .223 uppers; was still working fine in Blackout.

    Go to Lowes in the plumbing department. Get a box of #60 O-rings. Put one around the extractor spring to add tension to the extractor if there is not already one in place. They last a couple of thousand rounds and are only about 10 cents each.

    Regarding subs (my opinion), use the appropriate powder to produce enough gas to function the firearm and a heavy enough bullet to increase the pressure and burning of the powder and there should be no problems. I use AA1680 and WC680 (surplus equivalent of AA1680). Sometimes folks use faster burning powders or lighter bullets, trying to "get by" with what they have on hand and have functioning problems. Of course if using a bolt action or single shot Blackout, since semi-auto functioning is not an issue, one can do all sorts of experimenting. For example, I use 3.3gr Bullseye with 108 grain M160 frangible bullets (1034fps) suppressed for armadillo control, chasing coyotes off the goat pasture and plinking. Accurate and so very quiet, it would never semi-auto function an AR. I also use it in a side charger AR like a bolt action gun.

    I agree on the 10.x" upper as a better all around length. If shooting subs only or not hunting, shorter would be fine, but you included hunting. I've taken 2 deer with short barrels (don't remember which uppers I used), but the distance was only 25-40 yards, and I knew the distance would be short on my neighbor's property (had the goat herd with me to watch for deer and distract them). When I've hunted my brother's property, since the distance can be up to 200 yards, I take a 16" Blackout. Shop around for bargains and get more than one upper!
     

    m4a1sof

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    I went with 8.5", works great suppressed and unsuppressed. YHM-4300 is rated down to I believe 8".
     

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