Bench-Talk

As usual, for the recent IA State Championships (IBS Registered Group event), I opted to try something a little different - for the HV 100/200/Grand: I screwed a Broughton 1:8"(5C) 6MM barrel ( actual twist is closer to 1:8.5") onto the [Borden TURED] Time Precision HV rig and worked up decent loads using the 121 Gr. and 116 Gr. 6MM FB bullets, propelled by hefty charge weights of the "new" IMR 4007 - oh, the 6MM DASHER chamber was cut by pal, Mike Bigelow. After little tinkering, both bullets showed substantial potential. To minimize recoil and pressures, I opted to shoot the 116 Gr. FB (G1 BC of about .53) at a chronographed MV 2830 FPS - at this velocity, the calculated 100 Yd. wind-drift is right at 0.060" per mile per hour of perpendicular cross-wind; at 200 Yd., this figure jumps to about 0.25" per MPH of wind velocity. For comparison, in the same wind condition, my beloved 118 Gr., 10 ogive thirty caliber bullet, at a MV of 3050 FPS, will drift, respectively, 0.08" and 0.380" ! The math drives me nutz . . . the other 17 shooters were shootin' either 6PPCs, .22 Waldogs, or, 6MM Beggs - one of the Beggs shooters, Terry Meyer, despite grumbling about "tight cases" all day (during the LV stage), managed to win the 200 and the Lv GRAND AGG - his is a turned neck version . . .

But, back to the DASHER combo . . . despite seating the bullet bases almost to the shoulder/body junction, and the fast twist, and bullets with, "too much bearing surface", and HEAVILY COMPRESSED powder charge,  the rig managed to post one of the only two aggs, "in the twos" at 100, placing second. The 100 Yd. performance was followed by another first loser trophy at 200 Yd, where every group was trying to be a sub 1/2" deal  - garn ! This, on a THOUGH day (sustained winds in excess of 25MPH and up to much higher), the HV/DASHER/Heavy Bullet combo was one of only two rifles which kept all five [200 Yd.] groups under 1.0" . . so, is there anything to it? Oh, I shot "moly coated" bullets throughout the HV without cleaning the barrel - this Broughton is a KEEPER! ;)

Oh, there were ZERO bullet failures (moving backers, don't ya know) and ZERO signs of bullet failure (over 100 rounds without cleaning and every bullet-hole was nice and round, with NO lead spray) - the reasons: 1) the 24" barrel, which, compared to the typical 28-30" barrels, reduces FRICTION (HEAT) to , respectively, 85% & 80%, while sacrificing only about 8FPS per inch of barrel; 2) even more friction reduction due to the molybdenum-disulfide coating; 3) the "odd" (unopposed) land/groove configuration of the 5-groove barrel.

I think there is promise - the winner is a very good shooter - Jim Carstensen - who would be expected to finish ahead of me 99% of the time: Jim shot extremely well ! However, I believe that had he been shooting my combination (equally as well as he managed his 6PPC), he would have knocked roughly .3" off each of his [200 Yd.] groups - yes, I believe the BC was "giving me" that much on my BEST groups and, as compared to my neighbors, saving me at least 0.5" on my mistakes ! As David Letterman asks . . . " Is this anything? ;) RG

RG,

Yes to me it all makes good sense. If we are having to hold off for the wind much at all then why wouldn't a higher BC(which means less wind drift as well as flat shooting) bullet be a good choice. I was just talking to a fellow shooter last night about trying some 135-145gr 10cal ogive or even 12 cal FB bullets for my HBR gun(of course they still have to be made). Seems to me that a lot of us get bit by wind changes that a higher BC bullet might not see. Especially at longer yardages, but at 100 as well. I'll do some Math. and see what advantages there really are. A small amount can save the X count. What BC are your 136gr 10cal bullets?

Great info Randy, it's the what if guys like you that keep us all thinking and moving forward.

Rory D

Fine shooting and a great write up Randy .

With the high quality of the current jackets-bullets and barrels I believe that it's time to re-evaluate some older concepts and endevors . We also have a better understanding of bullet motion downrange -G.S. etc.  and have accurate computer programs available to the general public .

T.J.Jacksons work with the .22 Br Rem and 60-70 grain bullets was of great interest to me -a idea possibly before it's time . I have a Husquavarna 1900 with a 1-10 twist HK polygon barrel in .22 Br Rem that is close to being done now .It's been a long time  project to get this rifle finished-no comment.

Those $50 Numrich  HK hamer forged  barrels on a M70 action shot mid 2's / 5 with 70 gr JLK at 100 yards in match competition . We loaded a good batch of Nosler 52 gr sb match at the range one day and these went aproximately .2 for several 5 shot groups that day .

 Stonewall

   Thanks for the report, Herr Boolletmeister.

   If forced to build a 6mm for VfS or Group competition, I would go with a standard 6BR case with some 71-74 gr'ers. twisted 1:13. That should be a well balanced combo that may offer some tuning advantages over the traditional 6PPC/1:14/.825 long 68 gr' combo.

   Any thoughts?    -Al

Al,

Why would you be forced or who would force you to buy a 6mm? But I too think that might be a path to follow.......Well maybe next year when I think I need to build a new gun? I still haven't joined the 6mm crowd.

Al Nyhus:

   Thanks for the report, Herr Boolletmeister.

   If forced to build a 6mm for VfS or Group competition, I would go with a standard 6BR case with some 71-74 gr'ers. twisted 1:13. That should be a well balanced combo that may offer some tuning advantages over the traditional 6PPC/1:14/.825 long 68 gr' combo.

   Any thoughts?    -Al

Al, I believe that when comparing BC / Velocity / Wind-Drift, what most of us do is look at the OVER-ALL drift comparison - what we should do is look at the drift per MPH comparison. This, because it is not the WORST case which we need to consider, but rather how much our best efforts would/could have improved (a 'worst case' miss wil take us completely out of the agg). This is an area well worth re-investigating - the last hurrah for the 6MMs[in HBR] was with the typical 68 Gr. bullets, which, in combination with the minimum HBR case-capacity, are difficult to keep tuned.

One problem here is that we must have equal agging capability - but lets assume that we DO have THAT: My first record group (.25 MOA drift per MPH)  measured .587" - this equates to having 'doped' a window 2.35 MPH wide. Had I been shooting my 30BR/118-10 combination (or, a 6PPC, @ .38 MOA per MPH),  the same wind velocity spread (doping) would have produced a .893" group (though not absolute, the vector keeps the drifts relative) !! So, in the extreme conditions, the relatively HIGH BC did, in my opinion, make me a "better shooter" than most of my peers . . . but, my ability had nothing to do with it - many others doped as well as did I. The original assumption - that the rifle was SHOOTING - was obvious to all . . . it was quite obvious that the pilot was incapable of wringing out all of the goodies - I managed to "wreck" every group.

Meanwhile, Jim Carstensen beat the bejabbers out of us via his most excellent doping and execution. There is no way to beat someone who has a well tuned rig and is "dailed-in". :)

After almost two years of half-assed messing around with longer/heavier 6MM bullets, I believe that there is a place for them in HBR (and VfS) - especially in 20MPH+ wind conditions during the 200 & 300 Yd. stages. Where I'd argue with you regarding your model is that, with bullets in that weight range, there is no appreciable gain in BC; I think, for HBR, we'd be better served looking at 85-95 Gr. bullet weights and the ability to run them at about 3150 FPS . . . we'd need to take a serious look into the per MPH drift numbers . . .THAT will have to wait for winter! For VfS, I can't argue against the BR capacity . . .and maybe not even against the <80 Gr. bullet weights. ;) RG 

   Randy, what are thoughts concerning how the rifle torques/recoils in a 1:8 heavy bullet 6 Dasher vs. a conventional 30BR with the 112-125's and barrels twisted 1:17-1:18?   -Al