30br seating?

Discussion in '6BR, 6BR Improved & Wildcats' started by TrxR, Aug 23, 2019.

  1. TrxR

    TrxR

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    Where is a good starting point when testing seating depth with a 30br? How far jammed or jump to start? Also where to start with neck tension? .004 or less?

    Thanks
     
  2. Shooter13

    Shooter13 Gold $$ Contributor

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    I started with .002 jammed and ended at .006, my neck tension is 4 thou. You’ll just have to experiment and see.
    Good luck!
     
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  3. RGRobinett

    RGRobinett Silver $$ Contributor

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    Start with a neck-bushing 0.004" smaller than the loaded-round measured across the bullet heel, using a micrometer, and a "jam", or, "soft-seat" - often referred to as "full jam": when you lock -up the round, the bullet will be set back . . . upon extraction, the bullet may stick in the barrel.:eek:

    Presuming 118 Gr., or lighter bullet weight! Begin low on the powder - with H-4198, about 32 Gr.- and work up in about 1/2 Gr. increments: at about 34.0 Gr., give or take a couple of 1/10ths of a grain, it should begin to show promise, and then, get better, until the case is literally FULL, and the charge slightly compressed. If you cannot get your head around "neck-tension" and mild compression of the charge, you'll likely be, "leaving $ on the table.":eek:;) At best, presuming ZERO free-bore, and "just touch", the bullet base of the short/light bullets (based upon 0.925, or, the "pointier" 1.00" long jackets) will go less than 1/2 way down the neck - and that's with a 1.75 degree (1 deg. 45 Min.) throat angle - the typical 1.5 Deg, will be considerably longer.

    Following this simple procedure, and an established "best" charge weight, you can begin shortening the COAL by whatever interval strikes your fancy. I always keep five 0.010" (0.050" total) shims, on the Wilson seater-stems, and peal them off one at a time, which via my set-up, get me to about 0.020" off of the "just touch" length. I have yet to have a (thirty Cal.) barrel shoot better removing a single shim . . . but, I keep trying.:eek::D Having said that, some very competent individuals advise that they usually find paradise between 0.007" & 0.010" off of "just touch".

    Via these criteria, a thirty Cal. barrel which does not prove competitive, is either a "stinker" (finicky), or, the proverbial tomato stake.;) RG

    P.S. That last sentence, of course presumes a good, properly bedded action and a good/proven scope.
    Several other powders may work well: RL-7; Lt-30; N-130; H-322; and a few others: Lot after Lot, it's just tough to beat H-4198.
     
    Last edited: Aug 25, 2019
  4. TrxR

    TrxR

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    So you have found your rifles to shoot better with a slight jump over a jamb?

    So if I started with the bullet just touching the lands and worked back I should find my load and seating depth or should I try so jammed harder as well?

    My throat angle is a 1.75 based on your original reamer . I opened the neck to .331 and the .200 datum to .4715
     
  5. Dusty Stevens

    Dusty Stevens COVFEFE- Thread Derail Crew Gold $$ Contributor

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    ^^^ gospel
     
  6. Field & Cave

    Field & Cave Site $$ Sponsor

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    I think you read him incorrectly. Of course it could be me, but the way I read it, he's about .03" LONGER than touch. If he removed .05" worth of shim from under his seating stem he would be about .02" shorter than "just touching"...
     
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  7. RGRobinett

    RGRobinett Silver $$ Contributor

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    No - as usual, I'm difficult to follow: some few people find a "sweet spot" off the lands - with thirty Cals., I have yet to experienced that.:DRG
     
  8. RGRobinett

    RGRobinett Silver $$ Contributor

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    This is a correct understanding - and a math major to boot!:eek:;) For a new barrel, using a "barrel-stub" (chamber reamer) H.S. gauge, I set my Wilson to a length, which, if upon lock-up, the bullet grip was sufficient to prevent any bullet set-back, the "jam" would be 0.030" . . . of course, that is not the case: the bullets contact the lands, ideally, engaging & setting-back uniformly for a LONG time, thus eliminating the need to "chase" the
    lands/seating-depth.:eek:;) For a 30BR, this is truly a LONG time and a LOT of rounds.:DRG
     
    Last edited: Aug 29, 2019
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  9. TrxR

    TrxR

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    Ok i get it now. Thanks.

    So if i started a just touching and kept seating longer i would find the sweet spot.
     
  10. Dusty Stevens

    Dusty Stevens COVFEFE- Thread Derail Crew Gold $$ Contributor

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    What he means is seat one longer than touch and let the bolt closure set it back. This is called jam and is quite a bit longer than touch where people start vld type bullets. Hard jam sets it back every time and that length is called jam that it ends up at. Its different for each neck tension and bullet shape. Forget seating them shorter than jam- you will find your sweet spot between jam and hard jam. With the stockpile of his bullets i have for my 30br thats about .030 total movement between hard jam and jam with a .004 tension bushing if i remember right
     
  11. jimmymac

    jimmymac Gold $$ Contributor

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    I’m new to the 30BR. I did as described above...seated long and let the bolt do the final seating to find jam.

    I played with seating depth and powder charge for exactly one range session and quickly realized that my bullets grouped best at jam length with 34.5 to 34.7 of H4198. Please work up your load though to verify. Safety first.

    This cartridge is like hitting the easy button for load development. It was almost criminal how little work actually went in to it.
     
  12. vahena

    vahena Bob Schultz Gold $$ Contributor

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    I put together a 6 PPC and decided to make it a switch barrel with a 30 Br. I called Randy, in which I think he is the Godfather of the 30 Br. We spoke for 2 hrs.or I should say he spoke for 2 hrs. as he is a wealth of information and very easy to talk with but usually above my paygrade, he had me shooting tiny groups right out of the gate.
    Rob
     
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  13. Shooter13

    Shooter13 Gold $$ Contributor

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    Shhh! Don't tell everyone, let 'em think we worked hard for that!
     
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  14. Shooter13

    Shooter13 Gold $$ Contributor

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    I did the same thing, such a nice guy and very helpful, I did do 99% of the listening.
     
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  15. jimmymac

    jimmymac Gold $$ Contributor

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    Shot a group match at Chippewa Rifle Club a couple weeks ago with this gun. It’s competitive. Had small group at 200.
     

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  16. Shooter13

    Shooter13 Gold $$ Contributor

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    Super Coo!! Here is my best last weekend.
     

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  17. TrxR

    TrxR

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    I was talking to a couple of locals that are running berger 115 with a .040 jump in there 30br which i thought was odd.

    Also as you jam does that increase the pressure?

    What about a compressed load does that increase the pressure?

    How hard is it to close the bolt when running a hard jam which is seating the bullet more on chambering?
     
  18. Shooter13

    Shooter13 Gold $$ Contributor

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    Not hard at all, .006-.0010 you will feel but you can cycle it pretty easy, once the bolt is closed don't try to pull it back out! The bullet will stay in the lands. Have never had any problem with pressure at all, if you notice Randy Robinett says you can load all you can get of 4198 and compress the load and shouldn't have pressure problems!
     
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  19. RGRobinett

    RGRobinett Silver $$ Contributor

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    If a barrel shoots competitively, at any jump, jam, powder charge weight, I can't/won't argue that . . . I'm a codger, and know what I can live with - I don't like having to chase the seating depth.:D

    The idea, is to begin with a "jam" and a LOW powder charge-weight and work up, watching for excessive pressure signs.:eek: I have yet to hear of a 30BR chambered rifle, shooting bullets of 118 Gr., or less, with H-4198, creating excessive pressure. That said, always, as stated by jimmymac, above, practice safety first. Except with H-4227, and N-120, I have yet to loosen a 30BR primer-pocket. - - but those are a different story.:eek::D

    I usually shoot pretty fast - with my methodology (jam), upsetting the rifle, upon lock-up, has never been an issue.;) RG
     
    Last edited: Aug 29, 2019
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  20. TrxR

    TrxR

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    Ok so it doesnt take that much pressure to close the bolt?

    I am looking at a 24" barrel but was wondering if there would be any advantage of going longer? Like 26 or 28? I dont need to make weight.
     

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