Throating for Berger Hybrids vs Sierra SMK vs Warner Flatline in .308 Winchester

MidRangeCrisis

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  • Aug 22, 2020
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    I'm having a chamber cut with a Bisely 150 reamer but I plan to adjust the throat as needs must for some long-for-caliber and heavy for cartridge bullets. The barrel is a 24" Proof carbon 1:10" .308 Sendero. I have a PTG reamer that I like and a 1.5 degree throating reamer to make adjustments with.

    Looking at running Berger 175 OTM for ELR, 185 Juggernaut and 215 Hybrid for long range supersonic, Sierra 210 (9240) and 220 (2240) Match Kings for long range, and perhaps the 180 grain Warner Flatlines if I can get them to stabilize in the 1:10 for real.

    Are there any chambering recommendations for these projectiles? Looking for insight on freebore length and leade in particular.
     

    b6graham

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    i believe we settled on a 208 freebore for 208s and 215s for 308. Kiff could confirm and get you the smith who has the reamers
     
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    MidRangeCrisis

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  • Aug 22, 2020
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    Awesome, I'll ring them up in the morning. I'd like to keep the same exterior dimension on my brass that I'm prepping for Palma. Perhaps I'll luck out and they already have one that combines proper throat dimensions and my case dimensions.

    Any insight on bore land and groove true dimensions for the Proof barrels? I specified a .299/.308 1:12 5R from Bartlein for my Palma/UMR and the reamer drawing PTG supplied for specs a .2996 mandrel. I'll have to see if it's a removable pilot but I don't recall it that way.
     

    jbailey

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    Correction. Looks like I can't start a conversation with him. Probably my too new status.

    Hope he sees this thread.
    I copied him on this thread via email and he wrote back:

    Anything from 070-135 has been used very successfully.

    I dont know about longer than that in a 308 as most guys shooting up to the 200.20x are using about 95-110
     
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    avidflyer

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    95-110 would be very short for the 200x. everyone in the ftr world that shoots the 200x uses a 170-180 freebore. Not saying the above wont work but how much bullet is below the shoulder junction. Warner needs a lot extra. hard to shoot all those in one barrel. If not single feeding almost impossible with many.
     

    MidRangeCrisis

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  • Aug 22, 2020
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    No chance there is a resource out there that someone could point to for projectile base to ogive and/or bearing surface measurements on the common long range bullets? It need not be free, so long as it us not more expensive than buying whole boxes or sampler packs of the bullet in question.

    I assume conventional wisdom still dictates a significant amount of purchase on the bullet shank at the case neck as it departs and aligns in the freebore as it engages into the rifling. Say full caliber length or full neck length on the bearing surface as the ogive engraves the rifling? Or is that too much?

    Such as that is the case, I'd like to optimize the chamber for the bullet that strikes the best balance for magazine length with minimum case intrusion. I can fudge the magazine length some as the rifle is a Tikka T3 and adapted to both long action and short action bolt throw.
     

    MidRangeCrisis

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  • Aug 22, 2020
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    95-110 would be very short for the 200x. everyone in the ftr world that shoots the 200x uses a 170-180 freebore. Not saying the above wont work but how much bullet is below the shoulder junction. Warner needs a lot extra. hard to shoot all those in one barrel. If not single feeding almost impossible with many.
    Absolutely understood. The Warners would certainly be the outlier and single loaded if for no other reason than economy's sake.

    Quickload is showing me a few options on the Bergers that cover 185-215 grain Hybrids at mag length with acceptable case capacity. There are some compromises but I am hopeful to find a sweet spot once I can take some measurements on the various bullets.

    Same with the Sierras though there is a huge difference in bullet profile between the 200 210 and 220 SMKs that I would need accurate measurements to fully understand. Those 210s are loooong and pointy.
     

    b6graham

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    95-110 would be very short for the 200x. everyone in the ftr world that shoots the 200x uses a 170-180 freebore. Not saying the above wont work but how much bullet is below the shoulder junction. Warner needs a lot extra. hard to shoot all those in one barrel. If not single feeding almost impossible with many.
    I'm with you on that

    and even longer when shooting the 208s and 215s
     
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    MidRangeCrisis

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  • Aug 22, 2020
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    I'm with you on that

    and even longer when shooting the 208s and 215s

    Randy over at Manson Reamers seconds the sentiment that a .170 freebore seems to be good in the 200.20x and most of the folks running 215s are at .200-.240 (yikes!). I can only imagine what the Warner Flatline 180 would take. Apparently there is a similar bearing surface on the 208 and 200.20x suggesting a compromise between .170-.200 might serve my needs best.

    Gratefully I can bump the throat forward with a 1.5 degree reamer fairly easily for adjustments.
     
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    6MT

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    I'm having a chamber cut with a Bisely 150 reamer but I plan to adjust the throat as needs must for some long-for-caliber and heavy for cartridge bullets. The barrel is a 24" Proof carbon 1:10" .308 Sendero. I have a PTG reamer that I like and a 1.5 degree throating reamer to make adjustments with.

    Looking at running Berger 175 OTM for ELR, 185 Juggernaut and 215 Hybrid for long range supersonic, Sierra 210 (9240) and 220 (2240) Match Kings for long range, and perhaps the 180 grain Warner Flatlines if I can get them to stabilize in the 1:10 for real.

    Are there any chambering recommendations for these projectiles? Looking for insight on freebore length and leade in particular.

    I throated my new barrel +.170" for the Juggernaught. At .010" off the lands, it seems the faster I push it, the more accurate it is. I'm up to 2740fps with the 185gr Berger's. And I'll push them a bit further until I just reach the bottom of the bullet in the case with powder. My barrel is finished at 28" with 1:9" twist.

    BTW, there's no way these feed from a magazine and I don't mind single feeding them. My CBTO is 2.360" @ .010" jump.
     
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    MidRangeCrisis

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  • Aug 22, 2020
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    I throated my new barrel +.170" for the Juggernaught. At .010" off the lands, it seems the faster I push it, the more accurate it is. I'm up to 2740fps with the 185gr Berger's. And I'll push them a bit further until I just reach the bottom of the bullet in the case with powder. My barrel is finished at 28" with 1:9" twist.

    BTW, there's no way these feed from a magazine. I don't mind single feeding them.
    That's cooking for the Juggernaut...very encouraging.

    I'm at 24" with 1:10" on mine so my speeds should reflect a bit lower. I'm running IMR-4166 so I tend to run out of pressure about the same time I run out of case capacity. Rough modeling shows a touch north of 2650 at 2.950" COAL. We'll see what actually happens when I get some in hand.
     
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    avidflyer

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    I throated my new barrel +.170" for the Juggernaught. At .010" off the lands, it seems the faster I push it, the more accurate it is. I'm up to 2740fps with the 185gr Berger's. And I'll push them a bit further until I just reach the bottom of the bullet in the case with powder. My barrel is finished at 28" with 1:9" twist.

    BTW, there's no way these feed from a magazine and I don't mind single feeding them. My CBTO is 2.360" @ .010" jump.
    known node for the jugs is 2740-2760 28-30 inch barrel