Twist and freebore for FTR

Discussion in 'Big Stuff -- 6.5mm, 7mm, 30 Cal' started by coolbox, Sep 10, 2017.

  1. coolbox

    coolbox

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    For 308win, I m planning my 2nd ftr rig, that would also serve as a backup rifle.
    My current is 11t Bartlein 32" 5r, and I shoot 175smk and 185 juggernauts, saami spec.

    I have 200 and 215gr hybrids in mind for future, but would shoot the 175/185 for now. Would a 9 twist and 0.170 freebore be ok for these bullets as is (saami spec)?

    Would the 215gr hybrids fit in 0.170 freebore and still give me decent mv?

    I know, 175smk to 215gr hybrids is a wide range and not without some complication perhaps, but looking for the best compromise.

    The barrel is 1.25" dia at breach for for 5", and straight taper to 1" dia at muzzle, fluted for weight. I could order a 33" or 34" too, and still be under 18.2 lbs with a lightish scope and rings. Any benefits of going with more than 32"?
     
    Last edited: Sep 10, 2017
  2. Papa Charlie

    Papa Charlie

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    I assume you are going .308. I just ordered my first custom barrel from Benchmark. Barrel configuration is 30", 1:10 twist, 5R, 1.25" dia at breach for 5", Straight Taper to 0.950" at muzzle. I calculated the weight at 7.45lb. I also shoot the Berger 185gr Juggernauts and plan to shoot the Berger 200.20X also. Benchmark said they wouldn't go past 30" much maybe 32". My concern was weight so ended up at 30" and reduced the muzzle diameter.
    I am under weight with this config. But planning other upgrades in the future that adds more weight (scope and F-Class Bipod).
     
  3. XTR

    XTR

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    You can shoot any of the current commercial offerings up to a 215 Berger from a 1:10 with success. It has been done by many.

    Freebore is another issue.

    You may be able to shoot the 215 from a .170FB. I haven't tried it. The ideal freebore for the 215 to get it out of the case is closer to 225.

    The 200 H will probably work from a 170 but the again the ideal freebore is probably closer to 200 to 205.

    The 200-20X should shoot well from a 170. I'm shooting them in a 1:10 barrel that was chambered up for the 200H with a .200+ freebore about 45 days before Berger released the 20X. I think it's too long in the freebore, but I've gotten it working. ;)

    The KP Ballistics 200Jack needs about a 0.125 FB I think. I don't have a reamer for this bullet yet. I think my smith chambered it with a 95 Palma reamer and then cut the freebore so I don't have an exact measurement.

    Flutes are up to you, I have done it. Of the 6 to 8 or so F-TR barrels I have 2 are fluted, but I'd rather get the contour right with out it. Now that I have a smith near me that will re-contour I'll probably not have any more fluted.

    There are differing opinions, but I don't think you need more than 30". The tests I've run dont show enough of a velocity increase to justify those last 2 inches. (I was seeing about 15 FPS total gain with my F-TR loads)
     
  4. Tempest

    Tempest

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    Papa Charlie, Benchmark will go to 32", but that's the max they will do.
     
  5. Papa Charlie

    Papa Charlie

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    Sorry, I meant that they wouldn't recommend going longer than 30" for my .308 not that they were not capable.
     
  6. BP1

    BP1 Gold $$ Contributor

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    I'm having a F/tr rifle being built right now,I went with the Pierce titanium f-tr action (great folks to deal with)the McMillan X-it stock and a Kreiger 10 twist 4 groove barrel and .170 free bore and a .340 neck going to give the 200 20x a shot but a lot of folks are saying to stick to the 200 hybrids.
     
  7. coolbox

    coolbox

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    Thank you guys.
    I will opt for 10t, 5R Bartlein with 0.170fb and 0.340 neck.
    Barrel length is still undecided betqeen 30" and 32".
    The main reason for considering 32" is that last ounce of mv. Have to decide very soon now.
     
  8. gstaylorg

    gstaylorg Silver $$ Contributor

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    That "last ounce of MV" makes little difference in reality. Just because a longer barrel can generally produce higher velocity than a shorter barrel when both are loaded to equal pressure doesn't mean that a load will actually tune in at the highest possible velocity. In fact, they most often do not. People running 32" barrels in F-TR do not usually enjoy much, if any, velocity advantage over a 30" barrel because of where the loads actually tune in. The 32" barrel will allow you to reach a given velocity at slightly less pressure, but with Palma brass, that's also usually a non-issue. The 32" barrel will generate a few considerations as far as cleaning (you need to buy a long cleaning rod if you don't already have one), and will necessitate finding a longer case that will fit, neither of which is a major issue, but still something to consider. However, the longer barrel also means a thinner contour in order to make weight, most likely a Heavy or Medium Palma. If you prefer a little heavier contour such as an MTU or Heavy Varmint as I do, it will be very difficult to make weight with a 32" barrel. The reason to go with a longer barrel is because it brings a measurable and demonstrable benefit. It is questionable that the extra 2" of barrel buys you very much in F-TR.
     
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  9. Highpower-FClass

    Highpower-FClass Gold $$ Contributor

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    I would too recommend doing 30". With a 30" and 0.170 fb you will be able to shoot the 185 Juggernauts, 200 Hybrids (and 20X) and also the 'low-node' of the 215 Hybrids (~2500 - 2520 fps). I shoot all of these in my 0.170 freebore 10 twist 5R Bartlein barrel with good results.
     
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  10. Papa Charlie

    Papa Charlie

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    I am having a barrel made also for .308, 30" length, 1:10 twist, 5gr. Benchmark was planning on using a SAAMI Match reamer with a .110 Freebore. I shoot the Berger 185gr Juggernauts now and want the option to shoot the Berger 200.20X also. I contacted Berger to see what they said and they recommended that I create a dummy load for Benchmark to set the throat size by. Here is what they wrote:

    ~~~~~~~~~~~
    Techsupport@bergerbullets.com
    Sep 12 (2 days ago)
    [​IMG]
    Patrick,
    That may be a little short (.110) for both the .30 caliber 185 JUG and the 200.20x bullets. At best the throat length would be a compromise if you plan on using both bullets . Upside is that they are both very jump tolerant. I would suggest reaming the throat for the 200.20x bullet since it is the longest. Make a “dummy round” with a 200.20x bullet seated into the cartridge case until the junction where the bearing surface starts to drop into the tail is even with or just above the neck/shoulder junction of the cartridge case for BECHMARK to use as a gauge to figure the throat length you need. For your bullet seating depth testing . I suggest that you start at .015 off the lands . Then work back towards the cartridge case in .005 increments using the lowest powder charge listed for the bullet/powder/cartridge combination you are testing for the 200.20x HYBRID TARGET bullet. With the JUGGERNAUT start on the lands and work back towards the cartridge case in .005 . If you cannot get the JUG to the lands. Start your seating depth testing with ½ to 1 caliber ( 0.154 to.308) of the bearing surface of the bullet ( NOT INCLUDING THE TAIL SECTION) seated into the cartridge case neck and work back towards the cartridge case in .002-.005 increments. Hope this helps Patrick. If you have any other questions please feel free to contact us at any time. Thanks for using our bullets!
    Take care,

    Phil Hoham
    Technical Specialist
    ~~~~~~~~~

    Hope this helps.

    Don't know if this helps. I see a lot of members are recommending .170, is this a sort of standard for F-TR?
     
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  11. XTR

    XTR

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    Yes, .170 has become the standard for FTR.

    In 2013 Dave Kiff came up with the 2013FTR reamer for the 185LRBT as it was known then (called the Juggernaut now), I have one of those reamers, it has a .168FB. Later that yr Kiff made one for the USFTR team with a .170FB that became the 2013USFTR reamer. It is ideal for the 185 Jugg that most were shooting then. There are a whole lot of those reamers out there. I think the only difference in the two is the freebore. (not positive on that, I've never compared the drawings)

    I personally think that .170 is on the short side for the 200H and very much so for the 215, but it will work with them. It's pretty close to ideal for the 200-20X bullet.

    So, yea, .168 or .170 is kind of the standard because it will work with most anything you want to shoot.
     
  12. coolbox

    coolbox

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    Thank you guys. I too contacted Berger Bullets. They suggested to throat for longest bullet, and recommended 10 twist with 0.170 freebore for 185 juggernauts and the 200gr hybrids.
    Ideally, 0.150 for 185s, but they are very tolerant to jump.
    And 30" barrel length over 32", mainly to reduce chances of vertical spread due to shooter errors.

    So, its 30", 10t and 0.170 freebore.
     
  13. 308BAR

    308BAR

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    The Team FTR by Kiff actually has two configuration one with a base to case mouth length of 2.025" and 2.045" both with a .170FB. So if you're to do a jump of for example 10thou of the lands, the the 2.045" BTO length will be 20thou giving you the equivalent of a 2.025" (Standard) base to case mouth length with a .190FB. A lot of the time this is over looked but a very interesting relation on how a bullet is seated and shoots.
     
    Last edited: Sep 28, 2017
  14. Dshooter

    Dshooter Silver $$ Contributor

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    I think you pretty much have your answer but the 30" is the norm. And of course .170 FB
     

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