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Thread: Will a barrel with a .2225" groove diameter at the muzzle shoot?

  1. #1

    Will a barrel with a .2225" groove diameter at the muzzle shoot?

    Will a barrel with a .2225" groove diameter at the muzzle shoot?

    CYA friends:


    We never get too old to learn...........

    In the past, I would have never started a new build with a barrel that was .2225" diameter in the grooves....at the muzzle..

    ( By the way, Duck Hawk will be most interested in this thread, since it was because of him I fit a barrel that big in the grooves)

    _____________________


    This barrel was one of Dan Muller's Accu-Twist, 4-MI's....

    But I started to return it....since it was .2225" in the grooves, at the muzzle...

    _____________________


    But because of the ole Hawk, ( he fit one like it and was impressed), so I decided to fit it....

    I fit it to a TCA triple, with it winding up at 27 1/4 inches.......( Like Raging Inferno)


    _____________________________


    Anyway, it was tested at the Lapua test facility...

    __________________

    CYA friends, I know nothing about the metric measuring system....

    So could someone help?

    What does the measurement of an outside diameter of 6.88mm, relate to a center-to-center inches measurement?


    Your friend, BC


    ___________________

    PS:

    Duck Hawk, don't throw that oversized, Muller ACCU-TWIST barrel away.........

    I'm serious, don't you dare throw that oversized thing away..

    ________________________

    Again, I need help.....

    What does an outside diameter of 6.88 mm, translate to a center to center inches measurement?

    Am I close, does it translate to something on the order of .048" center to center measurement?

    That's right .048", or, am I out in left field?....bc
    Last edited by Bill Calfee; 10-11-2017 at 01:04 AM.

  2. #2

    Muller Accu-Twist 4-MI

    Muller Accu-Twist 4-MI

    CYA friends:


    I was lying in bed thinking, had to pee-pee....

    So I did, then turned on my machine....

    __________________

    A story:

    Dan Muller sent me one of his new Accu-Twist 4-MI's.........was a 30 inch blank as I remember...

    Anyway, I carefully cleaned the bore, inspected it, then commenced to evaluate it.....slugging.

    Oh, the bore at the breech was extremely pristine, was not washed out from the lapping...

    Anyway, I started the first slug, and man that thing felt awesome....

    I pushed that first slug to the muzzle end of the blank.....

    Then turned the barrel around and pushed the slug the other way.

    That bore had that beautiful, gradual taper from the muzzle end of that 30 inch blank, all the way back to the breech end...

    Impressive............oh yea.

    ________________________


    Then I got a big let down.....after I picked up my micrometer.

    I caught that slug at almost .2225" in the grooves.

    I slugged it again, and the same .2225" came up.....

    A note.......the micrometer I use most measures about a tenth fat.....

    But even counting for that, and using my imagination to try to lessen the reading, it was still .2225" in the grooves at the muzzle...

    Although, it was an extremely uniform .2225" in the grooves, even measuring the slug like an 8 groove barrel.....which really tells the tale about how round the bore of a 4 groove barrel is.

    ________________

    Man, you talk about heartbreak.....

    I wasn't going to use the barrel.....I just couldn't bring myself to fit a bore that big...

    _____________________


    Well, Duck Hawk got one of these Accu-Twist MI's too......and it was big in the grooves, too...

    But the ole Hawk decided to fit it, cause his slugged so beautiful, too...

    ____________________


    After the ole Hawk fit that oversized thing he called.....

    He was kinda cited, and surprised, cause he thought it shot great....

    _______________________

    So based on what the ole Hawk discovered, I decided to fit the one I had...

    So I picked out the best 27 1/4 inches of that 30 inch blank, just because that's the length of Raging Inferno's 12,050 PSL barrel.

    And I proceeded to fit it....

    Course I used a fully engraved, 2 degree leade chamber.....

    This oversized thing was just tested, with Lapua.

    Does anyone know how to convert a 6.88 mm outside measurement, to center to center inches?


    Your friend, BC

    ______________________________


    PS:

    I've never based my work off of "exceptions to the rule"..

    Therefore, I'll not be ordering any barrels with .2225" diameter grooves....

    But, 6.88 mm will sure make one scratch their head........bc
    Last edited by Bill Calfee; 10-11-2017 at 08:26 AM.

  3. #3
    Howdy Bill,
    .048 is what I came up with, too. Thaaaaaaat's pretty stout!

    And at the Lapua test center........wow!

    One of these days I'd like to see a barrel like that on a properly set up Remington 37. Curiosity kills cats.....and Gregs.

    .048 at the Lapua test center. WOW!

    I'm sorta guessing every single round of that lot was purchased right then, and right THERE!!!

    Take care,

    Greg

  4. #4
    25.4 mm/ inch so 6.88/25.4 = .2709 inches rounded without complying with significant digits. Less .224 = .0469
    Last edited by wsmallwood; 10-11-2017 at 08:15 PM.

  5. #5
    I think they test at 50 meter,not yards to. Impressive. Todd

  6. #6

    Friends 404tbang, Wally and TE

    Friends 404tbang, Wally and TE

    __________________

    Friends 404tbang, Wally and TE:


    There is so much to discuss here about this .2225" groove diameter Muller Accu-Twist MI.

    I don't know exactly where to begin.

    _____________


    If the 50 meter, 55 yard performance, was mind boggling, what they did at 110 yards, meters, was double so...

    I'm much more impressed by the 110 yard performance of this .2225" MI, and that lot of Lapua.

    _____________________


    I've tested some at 100 yards over the years, and even at 110 yards, meters...

    But I haven't ever seen anything like what this .2225" MI and that Lapua did...

    Every Olympic smallbore position shooter on earth, would literally kill for a gun and ammo like this....

    ___________________

    And then there's that goofy compensation nonsense...

    This .2225" MI was fitted with a standard HH/MD...

    That MD was not changed between 55 yards and 110 yards, yet the vertical was mind blowing at both ranges...

    This nonsense about having to change the MD setting as the range changes is just that, nonsense..

    When one has the muzzle stopped, it's stopped.....

    ________________


    Oh by the way, this .048" C to C grouping, ( 6.88 mm) has a vertical dispersion of, now get this, just .022".....

    Talk about flat.....

    __________________________


    I'm cited......

    Cause we may be learning something about barrels, maybe.......and maybe this is simply a fluke...

    _________________

    CYA friends, as bad as the 55 yard accuracy is for this .2225" and Lapua, the 110 yard performance shadows it bad...

    Simply mind blowing amazing....

    Your friend, BC
    Last edited by Bill Calfee; 10-12-2017 at 01:39 AM.

  7. #7
    Hi Bill!

    10 shot group ? 6,88 mm outside to outside to 50 m is amazing.If it was made to electronic target it is more amazing.

    If you can give 2 first numbers of this lot I am grateful.

    Priming force changes & crimping changes and how they change bullet expanding are on my intrests.

    Thats why I am intrested of 2 first number of this lot which works good on 0,2250 barrel.

    BR, Timo

  8. #8

    Friend Timo

    Quote Originally Posted by Timo View Post
    Hi Bill!

    10 shot group ? 6,88 mm outside to outside to 50 m is amazing.If it was made to electronic target it is more amazing.

    If you can give 2 first numbers of this lot I am grateful.

    Priming force changes & crimping changes and how they change bullet expanding are on my intrests.

    Thats why I am intrested of 2 first number of this lot which works good on 0,2250 barrel.

    BR, Timo
    ____________________

    Friend Timo:


    To me the most impressive part of it all, is the 110 yard accuracy.....(100M)

    The gentleman bought all of that lot they had...

    Here's the first two numbers, that stand alone, then the first two of the long row of numbers:

    27 28XXXXXXXXXX

    Your friend, BC


    PS:

    It still blows my mind about this happening with a .2225" groove diameter at the muzzle......bc

  9. #9
    Bill,
    I may have simply missed it if you posted the info........what did the 100 meter groups measure?

    Take care,

    Greg

  10. #10

    Friend 404tbang

    Quote Originally Posted by 404tbang View Post
    Bill,
    I may have simply missed it if you posted the info........what did the 100 meter groups measure?

    Take care,

    Greg
    ______________________

    Friend 404tbang:


    I'll answer your question this way:

    Every RFBR shooter needs to take the time to set a target up at 110 yards....

    Use a tall target so you don't have to correct your scope setting......just aim at the highest bull and let the group form below.

    Then fire 5 foulers off to the side.

    __________________________________


    Then fire a 10 round group, either RTB or aim between rounds......either way.

    Don't sit there are keep firing 10 rounds groups, then pick out the best one....

    Now remember, this is 110 yards.

    I'd love to know the truth about how many folks who try this, kick out a group in the fours the first group...

    And I'd be even more interested to know the truth about how many folks kicked out a single 10 round group, in the fours, even if they sat there all day and tried.

    ________________________


    Greg, I've shot quite a bit at 100 yards, and some at 110 yards......

    10 round groups in the fours, at 110 yards, are mind boggling, even if one sat there all day shooting to obtain just one of them..

    And to kick it out the first pop........at 110 yards....

    _______________________


    I can imagine there might be someone reading this thinking; "Calfee, I can do that all the time".

    All I've got to say is this, "I'm from Missouri"......."I'd have to sit there and watch them do it."

    _________________________


    What an amazing performance that oversized, Muller, 27 1/4" Accu-Twist kicked out at the Lapua test facility.

    And with a fully engraved, 2 degree leade chamber.......which I've always used for Eley in the past.

    And when I say fully engraved, I mean, there's just enough left between the beginning of the leade and the case mouth, for the very minimum of CL growth.

    Your friend, BC


    _____________________

    PS:

    I've got to add one other thing here, because it's too important not to.

    CYA is dedicated to advancing rimfire accuracy, only.

    I would like for everyone to ponder something with me here.

    If this Muller Accu-Twist is .2225" in the grooves at the muzzle, and has a beautiful taper to the breech, you can imagine what the groove diameter there is...

    I used my standard, straight sided, 2 degree .2250" diameter chamber in this barrel...

    Which means, the differential between the chamber diameter and the groove diameter, provides even less CL room growth than do the traditional groove diameters I, and everyone else, normally works with.

    In other words, this whole thing is even more mind boggling as it is explored in detail..

    Not only is the chamber "fully" engraved, with the very minimum of CL room growth, but that growth room is further restricted by the lessened differential between the chamber diameter and the groove diameter of that oversized Muller....

    There is so much to ponder here, Greg......bc
    Last edited by Bill Calfee; 10-13-2017 at 04:12 PM.

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