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Thread: 6x45AI or 6mm TCU

  1. #1
    randfal
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    6x45AI or 6mm TCU

    Any body shooting either 6x45AI or 6mm TCU in a bolt gun? I'm looking for some real world info on each. Not very interested in the AR shooters shooting out of mags with OAL of 2.260" or less. I am thinking about doing one in a Savage and shooting longer bullets 88gr bergers to 95grainers. Seating to "standard" 6x45 lengths would rob way too much case capacity with the heavier bullets. OAL is not a concern for me. I can't find anything on the TCU over a 14" barrel. I think the only difference between the two is the TCU is throated long. Can anyone confirm that? or what's your experiance? I would like to hear what kind of speeds you are getting from a longer barrel TCU of 6x45AI (24-28" barrel) with heavier 6mm bullets. Thanks.

  2. #2

    Re: 6x45AI or 6mm TCU

    I have a 6 TCU in a 20" Contender carbine. I'm shooting 80 gr Hornady SSP's out of mine. My load gets just over 2700 fps (2740-2750 fps IIRC) in my "short" 20" barrel.

    I have not tried any bullets heavier than 85 grs. If you're going to run heavy bullets, make sure you specify a fast twist on your barrel. I would at least go 1-8", and maybe even a 1-7". A 95 gr bullet is pretty heavy for that small of a case capacity.

    As I said mine really likes the 80 gr Hornady's.

    This is 5 shots @ 100 yards, and yes, I pulled one shot.

    [img width=600 height=450]http://i490.photobucket.com/albums/rr268/slowpokeslim/6TCU.jpg[/img]

    This is not a "max" load, but when I hit an accuracy node like that, I stop looking. A few more fps doesn't really matter if the group opens up.
    12F, McGowen 6.5x284 1-8&quot; twist, Nightforce 12-42x BR<br />BVSS, McGowen barrel, 22-250 1-9&quot; twist, Nikon 6-18x<br />16 FHLSS Weather Warrior, Sinarms 257 Roberts, Pentax 3-9<br />Stevens 200, 223 bone-factory-stock, Nikon 3-9x<br />Scratch-built BVSS, LW 243 1-8&quot; twist, Viper 6.5-20x50 mil-dot

  3. #3
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    Re: 6x45AI or 6mm TCU

    I shoot a 6x45 I built on my Savage fp10 SA, while not the AI though its close. You will get a tad faster speed in the AI.
    My bbl is a 24" varmint taper with a 1/10" twist and it will spit the 85 & 95 gr bullets out very accurately to 600yds in which I smack 12x12" steel at the range with no problem. All my loads, 65vmax/70g nosler BT/85g sierra GKHP/ 95g nosler hunting BT are usually at .333" - .800" @ 100 yds.
    The 85 is at 2800 fps, the 95 at 2653. My col is 2.285"due to the fact I want them to feed from the magazine & not single load them.
    Mine does not shoot the 80g speer hotcores (av .900"- 1.250") nearly as well as the above bullets..
    I could step up in speed, but I like the accuracy at these nodes in my gun VS speed.

  4. #4
    randfal
    Guest

    Re: 6x45AI or 6mm TCU

    Thanks for the info. That's good stuff. I'm building one from a Savage 10FP also. But from a 1:14 twist "recycled" 6br barrel. Should still finish 22" with the new chamber.

  5. #5

    Re: 6x45AI or 6mm TCU

    I have a Win 70 SA PF that was rebarreled from 223Rem to 6TCU. It's a 20" w/ 1/12". 60s go mid 3200,70s mid 3100, 80s to mid 2900 and 87s a 2900. Mine has a long throat and if loaded to work out of the magizine it has a mile and a half jump to rifleing. That 40deg. shoulder is like a speed bump if you work the action with rds. out of the mag. I tried about 10 different powders in it (12yrs ago) from 4198 to Re15 and overall H335 was best. In the last couple years I have gone over to N133 as my powder. As the case vol. is almost the same as the 6x47(6x222Mag) and 6PPc I have useded starting loads for those two as a starting point.

  6. #6

    Re: 6x45AI or 6mm TCU

    Quote Originally Posted by randfal
    Thanks for the info. That's good stuff. I'm building one from a Savage 10FP also. But from a 1:14 twist "recycled" 6br barrel. Should still finish 22" with the new chamber.
    That barrel isn't going to even come close to stabilizing those longer bullets that you want to shoot. A 1:9 is recommended for those bullets at .243 Win velocities and you will be a good bit short of those with either the TCU or 6x45.

  7. #7
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    Re: 6x45AI or 6mm TCU

    I have 2two 6-204rugers and a 6Tac (20Tac necked up) all with 14 twist and the heaviest bullet they will stabilize is the 68 gr berger. All are EXTREMELY accurate. They 6-204 is capable of 3400fps with the 68gr but hard on brass. The 6-tac can run about 3100fps with the same bullet.


    Steve
    LOVIN LIFE!

  8. #8

    Re: 6x45AI or 6mm TCU

    The 6-.204 sounds like a 6x47 improved and the 6-20Tac sounds like a 6x45 improved.

  9. #9
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    Re: 6x45AI or 6mm TCU

    6-204 is a slight improvement over the 6x47 but the 6Tac has the same case capacity as the 6x45. The shoulder is pushed back to 30deg instead of being blown forward but has less body taper than the 6x45. Only reason I went with the Tac round is I lready had the 6-204 reamer and could hold it .100 short.
    So I didnt have to buy a new reamer. For most people the 6x45 would be better becuase of avaliable dies(at a decent price).


    Steve
    LOVIN LIFE!

  10. #10
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    Re: 6x45AI or 6mm TCU

    BigRyan just sold some of his 6tcu items. he may be able to give you some data.

    Good luck. It looks like it may be tough with the 1 in 14.
    Couple rf's, couple cf's, and 1 12g.

    Everything I once held dear
    I count it all as lost

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