Chosing the right .243/6mm

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by wvcountryboy, Dec 2, 2010.

  1. wvcountryboy

    wvcountryboy Well-Known Member

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    I am sure this question has been asked a lot, which 243/6mm do you guys prefer. I plan on shooting 55 70 and 80 grain bullets so i will get a short throated reamer. Never intend on shooting 100s but maybe i would in the future. I want to build this gun for coyotes and deer in the 8lb range. I plan to have my wife shoot it (make her think its for her) so it cant recoil a whole lot.

    I have been looking at, tell me if i missed a good one, 6 ppc 6br 243 win 243 improved 6mm rem, 6mm improved 6-284 243wssm and 240 weatherby. The ppc and br are the most accurate i know, but i'd like bigger. I want something cheap to shoot that brass is easy to come by so that kills the weatherby. I read some really bad reviews on the wssm. I dont want to lose an inch of barrel to a rechamber every 500 rounds.

    That leaves the 243 win, 243 improved, 6mm, 6 mm improved and 6-284. They say the 6-284 doesnt shine until you get big bullets, i dont plan to shoot big bullets so how would it do with small bullets? I am wanting to shoot the 55 at 4-4200 if i can. I dont mind sizing the 284 brass but i'd PREFER to not have to fire form unless there is a big gain. What do you guys think? Also what twist would you go with? Would a 12 stabilize the 80s or should i go 10?
     
  2. MTBULLET

    MTBULLET Well-Known Member

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    I use a .243 AI in a 1-10 twist varmint contour bbl. for 75 gr. bullets. When I build another, I will use the 6mm as the parent case, just for the slightly onger neck, altho the .243 has worked well for me.
     

  3. MTBULLET

    MTBULLET Well-Known Member

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    I use the .243 AI in a 1-10 twist varmint contour bbl. with 75 gr. bullets, when I build the next one I will use the 6mm as the parent case jsut because of the slightly longer case neck, altho the .243 has worked well for me.
     
  4. Trickymissfit

    Trickymissfit Well-Known Member

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    been thru a few 6mm's in one form or another over the years, and have made a few opinions as well.
    * if all you shooting is under 400 yards for coyotes and things like that; then a 6BR is the perfect round for you. An extremely accurate design that just seems to shoot everything well. The 6BRX is it's big brother, and does things a tad better

    * might want to give some thought to the 6XC. Pretty much nothing but a 22-250 necked up to 6mm. Very accurate, and has some more range than the 6BR. I shoot the 6/250AI, which is nothing but a 22-250AI necked up to 6mm. In a fast twist barrel it's good for an honest 650 yards on coyotes, and will punch paper out to 1000 yards on a good day. Neck is a little short, and my next barrel will use a 2" overall length (made out of .243 cases). The nice thing about these rounds as well as the 6BR is that they shoot very well in heavy short barrels (23")

    * 243 Winchester has been playing catch up with the 6mm Remington for 50 years now. Barrel life is about 2/3rds as long as the 6mm at best. Does not handle short bullets all that well due to it's too short of a neck length. Also dosn't do long VLD's and such all that well because you have to sing the bullet into the shoulder area with a standard length chamber. The 6mm handles the full range of bullets well if it has the correct twist rate (the same would apply to the .243 as well)

    * the 6mm HLS maybe the perfect 6mm round! It's pretty much a .243 with a 6mm neck and shoulder. Chambers can be reamed with a standard 6mm remington reamer, or better yet a 6mm Ackley reamer. Very accurate with a good barrel life. Best version yet is the one reamed to the same shoulder length as the 250 Ackley. This round does everything right

    * 6/.284 shoots fast, and eats barrels fast. Is no better than a 6mm Ackley, and has about half the barrel life (way overbore). But there are a couple 6/.284 versions out ther that seem to work much better. One is a 6/284-.100" short (at the shoulders), and the other is .150" short. The latter seems to be about 150 fps slower than the full bore .284 case, but the barrels seem to last over twice as long (if not longer yet)

    * 6 Vias is just one bad Jose! It shoots 70 grain bullets faster than a max loaded 220 Swift shooting 50 grain bullets! Pretty much nothing but a 6.5x55 Ackley necked down to 6mm. It's a better round than the 6mm-06 and the .240 Weatherby. There's also the 6x47 and 6x44, but have not been around them much if any. Cases can be hard to come by and somewhat expensive.

    So it's kinda pick your poison! I like the HLS reamed off an Ackley case with the 250AI shoulder length. Yet if you just gotta go realy fast the 6mmAckley is probably the best of everything
    gary
     
  5. Trickymissfit

    Trickymissfit Well-Known Member

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    that would be known as a 6mm HLS.
    gary
     
  6. B23

    B23 Well-Known Member

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    Will you be using a short or long action?
     
  7. Long Time Long Ranger

    Long Time Long Ranger Well-Known Member

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    I have several of the big 6mm's that push 55 grain bullets in that 4000-4300 fps range you want. I like the 243 AI best of the ones I have shot. It is slower by just a bit than my 240 wby, 6mm-06 imp, 240 gibbs, etc but it seems to be a bit easier on barrels. Accuracy is amazing with the 243 AI. Mine consistently shoots under 3/4" groups at 300 yards.
     
  8. sniperjwt

    sniperjwt Well-Known Member

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    I am a big fan of the 6BR it is extreamly accurate, i also have a 243 Super Rockchucker (aka 243-06) and a 243 winchester. My second fav would be the Rockchucker although barrel life is not the best in it but its a screamer:D
     
  9. wvcountryboy

    wvcountryboy Well-Known Member

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    Thanks for all the info guys. This site is great. As you can see by my post count i'm new. I would LIKE to go with a short action. Not 100% on it yet. I wasnt too interested in the gibbs or the 6-06. For some reason i seem to be more interested in the short action. I have plenty of big bore long actions. I have no experience with .243 cal. I'm sure the br would be great, i just have the need for speed. I know i sacrifice a lot for it but I just like it.

    I am leaning towards the 6mm remington but someone said the 243 ai shoots greaat. I like the 243 due to all the GOOD brass available. I prefer not to have to fire form cases because i plan to shoot this gun a lot in the summer months so barrel life is an issue. If either of those cases (243ai or 6mm ai) make 200-250fps difference with the 40 degree shoulder... i'll do it.

    From some of my research it looks like with the smaller bullets i would actually LOSE velocity with bigger cases such as 6-284, 6-06 and gibbs. Would I have to worry about that with improving the 243 or 6mm? Also what twist do you guys think? I know its better to spin too fast than too slow. Should i go with 10 or 12? Also, for you guys helping me with velocity numbers I plan on a 26" barrel.
     
  10. sniperjwt

    sniperjwt Well-Known Member

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    your not kidding about this being a great site you wont find one better:D
    anyway enough of that if i were you i would just stick with the 243 winchester. The AI does not (in my opinion) give you enough extra with the lighter bullets to make it worth having to fire form them and the brass is much easier to find than the 6mm stuff. You can get 4K FPS with the 55g Nosler bullet with a bc of .267 and sight it dead on at 200 and be less than an inch high at 100 and about 4-5" low at 300 so pretty much hold dead on inside of 300 and your optimal game weight is still 101 lbs at 300 but dies off very quickly after that. I would however not use a ballistic tip on deer going that fast cause you will just cause a flesh wound however for paper or groundhogs and such it will do great. As far as twist the 12 would work great for the 55g bullets but if you ever decide to go heavier you might have trouble. I would go with a 10 just in case one day down the road you want to shoot a 80 or 90g bullet for deer
    Hope some of this helps
     
  11. Trickymissfit

    Trickymissfit Well-Known Member

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    food for thought:

    not all short action rifles are created the same. They will vary a .150" in length. The Savage will handle a 6mm Remington just fine unlike a Remington 700 using 90 grain bullets seated out to the rifeling. I also seem to remember that the Winchester is longer than the Remington as well.

    Most guys I know that shoot the .243 go thru cases on a regular basis do to neck splits (Ackleys seem to be worse). I'm using 6mm remington cases that are close to 15 years old. The 6/250 goes thru a case about every six firings, but I think if I anealed them every third or fourth firing they might last a little longer. The next problem you get is that when you form the .243AI (or really any Ackley case) the overall length actually shrinks about .03" in the neck length. With the .243 already being too short for the caliber, this creates a problem. Alot of guys I know are now using 6mm, or .257 cases to form .243 Ackley brass (most chambers have the neck cut a little long anyway, so you can take full advantage of the max neck length. (.06" will do wonders)

    If you just gotta go fast, then at least look at the 6 Vias (70 grain bullet at 4000+fps). The 6/250AI will drive a 105 grain Amax bullet at close to 3100 fps, and still do 1/4" groups at 100 yards (I use H1000 powder with a 1:8 twist barrel) The twist rate needed will parallel the actual bullets you plan on using. A 1:10 will easilly do a 90 grain bullet, but still work well with the 70 grain bullets (I like the Sierra 80 grain Blitz). But if you planning on using the VLD's or low drag bullets you need to step up the twist rate. My 6BR uses a 1:14 twist, and it barely handles the 80 grain Blitz (a 1:12 would do wonders). The 6mm's I've owned had 1:9 twist, but would not handle VLD's very well; yet shot 85 grain bullets like they going outta style.
    If I were to build a rifle around a 6mm something, I think it'd be a Savage mod. 12 single shot action. Use the laminated wood stock (the older style with the flat forend). Buy a good used one and order in a Sharpshooter barrel in whatever you decide on (you may have to furnish the reamer if it's a oddball). For me it'd be another 6/250AI, but with a 6mm neck length in a 1:10 twist
    gary
     
    Last edited: Dec 2, 2010
  12. wvcountryboy

    wvcountryboy Well-Known Member

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    I think i will go with the 10 twist. Gary, what is the 6 vias? I did a quick search and couldnt find anything. The 6mm is sounding better and better due to the neck length. According to the sierra manual, the improved 6mm is getting nearly 400 fps more. I find that hard to believe. It looks like a lot of you have the 243 ai but not the 6mm ai. I appologize for all my questions. I just find it wonderful that I have found a place that i can ask questions and get answers.
     
  13. roninflag

    roninflag Well-Known Member

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    i have a .243 with a 12 twist hart barrel. it shoots great. i mainly shoot 87 and 88 grainers. routine in the .2s ; at 100. roninflag
     
  14. MTBULLET

    MTBULLET Well-Known Member

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    why not 6mm AI ?