need help with caliber choice

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by B Jordan, Jun 5, 2006.

  1. B Jordan

    B Jordan Well-Known Member

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    i came across a pacnor 6mm 1x7twist blank about 31" long I am wanting to build another prarie dog rifle but i am having a problem coming up with a caliber . i would like barrel life to be in the 1200-1500 rnd range if possible and would also like to be able to break 1500 yds with it i was thinking about a 6mm rem imp. but would be open to anything also feeding is not a problem because it will be a single shot

    i would appreciate any input good or bad on any caliber
     
  2. sewwhat89

    sewwhat89 Well-Known Member

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    I would lean more towards either a 6-06 AI or 6-284 just to take advantage of the Lapua brass. I think most would agree that brass would outlast your barrel instead of the other way around, and it would cut down on the fire-forming. I think they would all be pretty close to ballistic twins with 115 DTACs. Good luck with whatever you choose!
     

  3. James Jones

    James Jones Well-Known Member

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    for that kind of range I would agree that the bigger cased 6-284 and 6-06Ai would great choices you have the right twist for the 115 clsss VLD bullets.

    Now I'm not saying that their arn't others , I'm sure the 243Ai would get you out their with the right bullets just a little slower , hell the 6XC probably would also and both of these would give you better barrel life.

    Personaly I'd hold onto that tube and get another in at least 6.5 or 7mm for those kind of ranges
     
  4. Buffalobob

    Buffalobob Writers Guild

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    The 240 Wby has about the same case capacity as the 6-06 and 6-284 and fits the same bolt face and will deliver the same performance. Norma brass is readily available. 6-06AI is probably a little more case capacity and some small amount more velocity with a heavy bullet and long barrel.
     
  5. uncleB

    uncleB Well-Known Member

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    Brian,
    how many lands does the barrel have ????? if it is a 3 groove it limits your choices of bullets and chambers. I have a Pac-Nor 1-8" 3groove chambered in 6-284 and the ONLY bullet I can shoot out of it with out blowing up is the 107gr SMK. on the bright side it shoots very well as I have shot rockchucks out to 1515yds with it, but 1500 rounds is not going to happen in a 6-284 mabey a 6-250 Imp.
    UB
     
  6. hvyw8t

    hvyw8t Well-Known Member

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    I would go with a 6mm-284 and have fun with 115s if you want to be practical. My next hotrod will be a 6mm-264 winchester magnum with a 1in7 heavy barrel, should move 6mm 115s out pretty damn quick. /ubbthreads/images/graemlins/grin.gif
     
  7. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Brian,

    That is a pretty extreme twist. When dealing with a 1-7 you will have to consider that high velocity will in most cases destroy the heavy 6mm bullets on the market today.

    I have a 3 groove Lilja 1-8 chambered in 6-284. It will destroy any bullet except the 107 gr SMK at velocities above 3300 fps. With the SMK it will push up to +3500 fps but only with this bullet.

    I would be suprised if any 115 gr bullet will handle this twist much over 3100 fps and stay accurate.

    You may want to consider a 6-250 or 6-250 Imp as Uncle B suggested.

    Just trying to save you some time and money, don;t think you can drive a 115 gr bullet to really high velocites in this 1-7 twist because the bullets simply will not handle it.

    I would bet that even a 6-284 would be hard on the 115 gr pills in this barrel.

    My standard barrel twist for a 6-284 designed to shoot the 105 to 107 gr match bullets is a 1-9 twist 6 groove. Just to put it into perspective.

    If you have not already bought the barrel I would not get it. Get a 1-9 twist, chamber it for a 6-284 and shoot the 107 gr SMK at +3500 fps. YOu will get all the performance you need and a much less finicky rifle. You will probably even be able to use the 105 gr A-Max at nearly this same velocity with this barrel and they will perform much better terminally then a SMK will because they are tipped and expansion will be much more dramatic.

    Just an opinion.

    Kirby Allen(50)
     
  8. Ernie

    Ernie SPONSOR

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    IF he already has the barrel would a standard 243 Win lower the MV enough with the 115's?
    Does Richard make any heavyweight 6mm's that would work well in a 1-7 twist that would allow him to jump into the 6-284 class?
    FWIW a 243 w/a 115 is enough to get you to 1500 yds on PD's.
    My 115 DTAC had good expansion, but, have not hit enough dogs at that range to see what typical would be.
     
  9. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    XP,

    Yes the 243 would help alot.

    Richard has plans for some 120 gr class 6mm bullets but again is waiting on dies.

    Velocity is not all that important with a bullet like this at these ranges, its good velocity and high BC that will get you on target.

    The trick is to not overstress the bullet. This can be done by to much twist or to much velocity.

    A 6mm Dasher would be another good choice as would a standard 6-250 or AI.

    Kirby Allen(50)
     
  10. B Jordan

    B Jordan Well-Known Member

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    ok first let me say that i just got back from my second prarie dog hunt and i have got addicted to shooting at them at long range (and sometimes killing them)it seems that i very rarely shoot at a prarie dog under the farthest distance i have killed one before i took about 900 rounds of 223,22-250and 220 swift and ended up shooting about 40 rnds of 223 while my 22-243 was colling off managed to kill a dog at 655yds with the 223 though my long range gun now is a 22-243 thats shoots great and i finally killed a pd at 1045 yds with it which was the first time i broke a 1000 before but the gun is wearing out quick i read on here the other day that i would be lucky to get a 1000rnds out of it and have decided that i would just build 3 long range guns to take on my next trip i have 2 of them done and i have this barrel the barrel is not a 3-groove and i did probably jump the gun when i got this barrel but i didnt have to wait on it and damnit sometimes i get in to big of a hurry i know none of you guys do but thats just the way i am


    i have really considered the 6mm-250 ai and have a reamer available to me and probably 1000 rnds of new 22-250 brass but was concerned about it not having enough steam to get there and was wondering what advantage it would have over a 243or 6mm remington ?

    what kind of speed can i get out of the 6mm-250 imp.with a 105,107gr class bullet?

    also i already have a 6.5x284 that i just finished so i dont really think i need 6mmx284

    anyway i really appreciate this site and all of the helpful people on it thanks for your help,Brian
     
  11. bailey1474

    bailey1474 <strong>SPONSOR</strong>

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    [ QUOTE ]
    what kind of speed can i get out of the 6mm-250 imp.with a 105,107gr class bullet?


    [/ QUOTE ]

    I'm getting right @ 3000 fps w/the 105 gr Berger in a standard 6-250. I don't feel that this is much if any over pressure either. Primers are still round, no extractor mark, very little if any primer flow and effortless extraction. I'm happy!!!!

    I guess I better put in a shameless plug for my smith as well:

    THANKS KIRBY /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif!!!!!!!!!!!
     
  12. Fiftydriver

    Fiftydriver <strong>Official LRH Sponsor</strong>

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    Brian,

    The main advantage, barrel life. Sounds like you want to be able to shoot a decent amount of rounds in a weekend and the 6-250 will offer much more then a 243 or 6mm will with much lower barrel heat.

    If you compare a 243 or 6mm Rem with a 6-250 you will see around a 200 fps advantage in muzzle velocity for the larger round.

    At 1000 yards its about a 120 fps advantage between the two. At 1250 yards the velocity advantage is about 90 fps and at 1500 yards, the difference in velocity has shrunk to only a bit over 50 fps.

    Energy difference at 1500 yards is about 25 ft/lbs of energy is all.

    Yes the larger cases will shoot flatter but bullet drop is consistant and easy to figure. Wind drift will also be less for the larger rounds but not by as much as many would think. At 1500 yards the larger round will have about 16" less windage then the smaller 6-250 which is really hardly worth mentioning at this range.

    Now if you go with a 6-250 AI, you will get a solid 100 fps over the standard 6-250. In some cases 150 fps. Yes a 6-250 AI will pretty much match a standard 243 Win with all bullet weights.

    Again I would rather put up with a bit more drop and a very small amount more windage for the greatly increased barrel life and lower recoil. Espeically for a high volume shooter.

    If your going for performance only with no concern of barrel life then add on the powder but there are costs to this performance. The 6-250 and 6-250 AI will suprise you are what they will do at long range.

    Oh by the way Bill, thanks for the plug!! /ubbthreads/images/graemlins/grin.gif

    Kirby Allen(50)