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    • #27183
      az-jim
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      Guys, I’m about to take a dive into the 300 BO world. Tell me what I need to know about taming the beast. From what I have read, this caliber seem to be a pretty good muti purpose round. I would use it both super and sub sonic, cast and jacketed.
      I want a 16″ barrel but dont know which length gas system to get. Do you guys have a preference on buffer weight or carrier weight?
      Anything I should know before commiting?
      Thanks guys
      az-jim

    • #27186
      Harter
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      I’ve heard. ….um….read that it is run with a carbine length gas and an adjust gas block . Those run standard buffers and springs . It will take a little bit of fidgeting to get the exact balance to run ,say a 125 gr supper and a 250 sub .
      If you intend to run it with a supressor it is my understanding that the gas requirements are different.

      If you expect to run unsupressed and more loads to super say 125 to 150 gr a mid length may be better .

      This is reading vagaries from the net not based on experience. I bought a 6.8 SPCII and throw brass in a 5 gallon bucket 5 ft from the port at 1:00 . With all stock kit parts from the lowest bidder. I should get an adjustable gas block but will instead wait for the deal on the 18″ rifle length and be happy. .

      It sounds like you have your parts picked out but yo can cruise Blackthorneproducts.com and look at the kits and what GI parts they have in them to get a better idea of what to look for.

    • #27189
      Smoke4320
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      If you intend on Suppressed Subsonic MAKE SURE to get a pistol length gas system ..

      if you want to run 230-247 gr projectiles get a 1:7 twist and it should still shoot 150’s just fine ..

      Also get a name brand .. many of the lesser brands are coming with the wrong gas hole size for subsonic use ..
      Adj gas block is a nice feature and can make life simpler ..

      powders will be 4198, Lil gun, H110, RL7

      Std spring and buffer usually .. If you have issues full cycle on suppressed you can try a H3 Buffer

    • #27197
      Artful
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      My experience is that it’s pretty easy to load for – You can use cheap PC coated to plink with – I don’t use many supersonic myself.
      You can use an AAC 45 Ti-rant for subsonic loads – sounds pretty good
      – my powders of choice are 5744 or 1680/680
      – mine is a carbine position gas port
      – I agree a pistol position gas port would help me sometimes.

      I have yet to do it but like this idea

      This gives you Carbine and Pistol with a turn of a screw and the carbine position is adjustable.

    • #27198
      Goodsteel
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      It’s a great round. Treat it like a pistol shooting heavy bullets (what’s not to like about that?).
      Best advice I can give is do what works regardless of speed FIRST. Then hone in on SS if you want to.
      Second, never underestimate the power of a long, slow moving bullet to PENETRATE THINGS. It will surprise you.

    • #27205
      Smoke4320
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      I shot a approx. 120 lb deer at about 75 yds with ablackout and can using a NOE 247 HP 50/50 Pced ..traveling at a little over 1450 FPS .. It sounded like I hit a tin building with a baseball bat ..
      fell right over .. left a blood spuirt about 5 ft on backside ..
      Wish I had taken a pic of the blood .. unbelievable

    • #27215
      Fishman
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      It is pretty easy to get a 150-160 grainer running about 1800 fps and cycling the action with AA1680 or H110. Read my cautionary tale regarding tight chambers in a previous thread. For this reason, I would avoid getting a barrel that is chromed or otherwise coated which would prevent opening up the chamber. Grumpa sells great brass that is ready to load if you want to go that route.

    • #27290
      az-jim
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      Thanks for the replys, I was out camping all weekend, had a good time, weather was great.

    • #27681
      az-jim
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      So I finished the build this week, havent been out to shoot it yet…..uuuggghhhhh, another week of that dirty 4 letter word before I can go try it out 🙁
      I went with an Anderson upper, lower, and 16″ pistol gas 1-8 barrel. I was happy with the Bushnell AR series scope I put on my 22 build, so I picked up the centerfire version in 3-12x for this one. Now I have brass, powder ( W680, H110, 1680, 5744 ) and some 155g SMK palma bullets, 150g Hornady SSTs, and might be able to scrounge up some 110-125s.
      My next question is COAL: Obviously function/ cycling being priority, what do you all do for load length with various bullets? Do you go for mag length as much as possible or do you focus more on contact with the rib in the mag to keep alignment for feeding reliable? I have read some guys seating to where the ogive measures .250, making contact with the mag rib, any merit to this?

    • #27684
      popper
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      110, 4227, RL7 for the midweights. Mag problem isn’t exactly OAL. Ribs can jam the mag up when many rnds in it. You can file/sand the ribs down a ways. You probably will want an adjustable port for pistol if you go super, 1400-2000. 125 is probably the lightest you want to go, long jump to the lands. & a 10 rnd mag for the bench. Hope the 4 letter word doesn’t get in the way of having fun.

    • #28016
      az-jim
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      Finally got out to shoot the new toy today. Its fun to shoot as I expected it would be. I ended up with 3 loads that look to have some potential, all at 100 yards.
      147g FMJ over 16.0g of W680
      135g SMK over 17.0g of H110
      155g Sierra Palma Match over 15.0g of H110
      I had some 168 SMKs over W680 also but they all shot patterns instead of groups so back to the loading bench on those. So I’ll fine tune the 3 I have so far then come back and do 168 and a 208-210 load. I dont see myself shooting anything heavier than that and those will do fine for subs. I didnt chrono any of them today, didnt have time to mess with it. I’ll do that when I fine tune. And finally after all of that, and deciding on a mould will come work with cast.

    • #30342
      sundog
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      A friend asked me to do some load development for him with a carbine length gas tube and a ‘no-name’ upper. Short of it was that after a little web research I came up with three very good loads very quickly.

      125 Nosler BT/17.0/W296
      RCBS 308-165-SIL/14.6/N110
      SAECO #301(200gr)/11.8/H116

      Methinks the 300BO is an impressive round within the constraints of what it can be used for, which is quite a bit.

    • #30352
      Goodsteel
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      Well said.
      The cartridge seems beset with people who think either more or less of it than it deserves.

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