115 Dtac's in the Rbros/Surgeon 6mm Creedmoor

longrangehunter · Apr 3, 2018

So I decided to switch the barrel job I wanted to do from 6.5mm to the 6mm Creedmoor since a lot of the top shooters are using a 6mm cartridge of some kind. I decided not to do a 6x47 Lapua since I have a 6.5x47 L, so I would never make the mistake of chambering the wrong case in the wrong gun, and this makes it simple for that reason.

Travis over at R Bros Rifles did the work for me which was great since I've watched him, and his brother shoot for the last four years at RPS Events I've been too. Super nice guy, a top shooter, and one of the best rifle builders in the USA.

Pretty simple job: A 26" M24 Broughton 5C barrel w/a 1:7.3 twist (these are pulled button-rifled barrels), I can't say what he spec'd the reamer to or who it's from, but with the 115 Dtac bullet which uses a rebated boat tail that sits right below the neck/shoulder junction in the case which I always prefer. These are bare, non-coated bullets also.

Travis test fired the gun prior to shipping it to me, and I think he does a barrel break-in job? I did a light break-in job myself with a single box of Factory Hornady 108 ELD-Match ammo. So those were F/L sized, 0.002" shoulder set back, and I used a .269 bushing. Nothing fancy other than a light VLD chamfer job, and remove the carbon from the primer pockets with a Sinclair uniforming cutter.

I found the time today to test these out, and I must say it's always nice working with well made guns by people that are so good it makes this look easy! :mrgreen: Even better is the New Nightforce ATACR 7-35x56 scope my old rifle now wears! :grin:

115 Dtac (uncoated), for those that don't know about these they're made by Sierra for David Tubb.
H4350, F210M primers, 1x Hornady 6mm Creedmoor brass @ 2.0950" CBTO = 2.800" COAL.

Dwh7271 · Apr 3, 2018

Very nice rifle.
I'll be interested in your opinion on the ATACR.
Load workup doesn't look like it's going to be too hard. :lol:

SJB358 · Apr 3, 2018

Darn Kevin, that sucker looks on point! Very danged nice.

longrangehunter · Apr 3, 2018

Thanks Scotty..... it's rough when these rifle builders make them so well!

Dwh7271":201u1wxg said:
Very nice rifle.
I'll be interested in your opinion on the ATACR.
Load workup doesn't look like it's going to be too hard. :lol:

It's very clear glass, tracks well so far, this one has the Mil-C reticle which is simple, yet effective. I wanted a Horus reticle, but not for the extra money to have it. Haven't had much time behind it, but I did take it out to 620 yards w/the factory Hornady Match ammo last week.

Oh, and having a high magnification scope makes picking out which part of the target to hit more predicable! I grew up using 10x, then 12x, 15x, and 25x..... now at my age 35x makes sense!

Dwh7271 · Apr 4, 2018

Thanks!

Code:

now at my age 35x makes sense!

Yeah, I have the same issue.

longrangehunter · May 8, 2018

Yah,

Here's a interesting point....... I shot a match this past weekend, and for almost the entire time I had it set at 10x-12x! Yep, even while shooting. I had been dialing up and back down, and finally just left it for better time management on the 2 minute clock for each stage, two stages the RO's made the mistake of thinking 120 seconds was a minute twenty (80 seconds) which is not a lot of time, but since they started that way from the beginning they had to keep that for the two day match.

On day two something went terribly wrong with my POI they were all high after running perfectly all day the day before. Cost me a lot of points only to start back to working correctly. I thought it might have been from dialing up in magnification and causing the POI go high? Not sure at the time so I started to take out .2 Mils with each hold and work further down until I could make hits. After 4-5 stages the gun came back to life and I just left the scope at 12x, but after the day was done on the last stage I cleaned but timed out on the last two shots I asked the RO if I could test the POI at High Magnification 25x...... Held dead center and hit dead center, 2nd shot just slightly left....... so much for that theory, but I still have no clue to what happened for the first 5 stages on day two?

Guy Miner · May 8, 2018

Cole - I can't help you on what was up with the rifle/scope/ammo for those first five stages on day two.

Shoot enough, and weird things happen.

Jesse, the other half of R-Bros, is a friend of mine, and we're on the board at the NCW Gun Club. I think the world of Jesse and his wife, and barely know Travis. His reputation as a rifle-builder is extreme!

I'm glad you've got one of the best built rifles in America! And yes, I feel that strongly about the quality of R Bros rifles. Wish I had one! Maybe someday I'll con Travis into rebuilding my ol' "Green Machine" with PRS in mind, now that I'm no longer a SWAT cop. It's a good rifle, but being refreshed by one of the best rifle builders anywhere would be good.

I've always liked the 6mm bore, starting back in 1974!

Congrats on a good-shooting rifle. Guy

longrangehunter · May 8, 2018

I know Jesse, and his wife Kate. I'm more friends with her then Jesse to be honest.... he can get a little tense and turned off chatting during a Match. I've shot a lot of match's right behind him, and Travis. I watch how he runs the stage and repeat it like he did, but I'm not as consistent of a shot as he is. Jesse rarely misses, and Kate is almost as good...... she's just nicer to talk to! So I talk to her throughout the day just to wish her well, and how she's doing.

I did chat with them both this past weekend, right after they both finished the last stage of the match...... He ran it perfectly with a score of 6 on stage 24-The Colors game. Although this past weekend they were behind me the whole time so I never got to watch how they ran their stages! I was the Guinea Pig this weekend for my squad for the entire first day........ I like to just run and gun and not sit around losing my concentration and stay on a roll as fast as possible.

Dwh7271 · May 12, 2018

Had to wait on new software Kevin, sorry!
Here's where I think you are.
Let me know if you need others.

Code:

Cartridge          : 6mm Creedmoor
Bullet             : .243, 115, Berger VLD  #24430
Useable Case Capaci: 44.608 grain H2O = 2.896 cm³
Cartridge O.A.L. L6: 2.760 inch = 70.10 mm
Barrel Length      : 26.0 inch = 660.4 mm
Powder             : Hodgdon H4350 ?

Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   77    31.04   2395    1464   34568   7432     96.2    1.628
-18.0   79    31.82   2447    1529   36733   7613     97.0    1.590
-16.0   81    32.59   2498    1594   39021   7785     97.6    1.546
-14.0   83    33.37   2550    1660   41441   7946     98.2    1.503
-12.0   85    34.14   2601    1727   43998   8097     98.7    1.462
-10.0   87    34.92   2651    1795   46701   8237     99.2    1.423
-08.0   89    35.70   2702    1864   49559   8364     99.5    1.386
-06.0   91    36.47   2751    1933   52582   8479     99.7    1.349
-04.0   93    37.25   2800    2003   55779   8582     99.9    1.314  ! Near Maximum !
-02.0   95    38.02   2849    2073   59161   8671    100.0    1.281  ! Near Maximum !
+00.0   96    38.80   2897    2143   62742   8749    100.0    1.248  ! Near Maximum !
+02.0   98    39.58   2944    2214   66534   8824    100.0    1.217  !DANGEROUS LOAD-DO NOT USE!
+04.0  100    40.35   2991    2285   70553   8896    100.0    1.187  !DANGEROUS LOAD-DO NOT USE!
+06.0  102    41.13   3038    2357   74814   8966    100.0    1.158  !DANGEROUS LOAD-DO NOT USE!
+08.0  104    41.90   3084    2429   79336   9033    100.0    1.130  !DANGEROUS LOAD-DO NOT USE!
+10.0  106    42.68   3130    2501   84139   9098    100.0    1.103  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba     96    38.80   2983    2272   72954   8442    100.0    1.174  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba     96    38.80   2769    1957   52558   8938     98.2    1.347

longrangehunter · May 12, 2018

Thanks Dewey!

That pretty much confirms what I thought........ A lot of guys run that at 3,000 fps which is node 4, but I went down to something more reasonable that shot well which is 38.8 in new cases, and 38.9 in 1x and 2x cases .040" off the lands, it shot well.

Thanks again buddy!