help with quickload barrel time

[jimbires]

I recently worked with my 260rem , so I thought we could play with it , while it's still fresh in my memory . I'm getting a bbl time of 1.194 . so where do I go from here ? I found one OBT chart , but it was marked for a 6mm dasher . are there different charts ? thanks for the help . Jim

the specs are ;
260 rem
25 inch bbl
54.33 water capacity
125 grain Partition
44.5 grain RL17 powder
2.767 COAL off the tip , 0.020 jump yes it's short in the throat
1.194 bbl time

this is the load I'm asking about . it shot great , but I think it falls between bbl time on the chart I have . I have 1.1461 next is 1.2788

 

[Ridgerunner665]

Tweak the velocity a little in both directions and see which one is more accurate.

Caliber doesn't matter on OBT charts...

If you can safely reach the 1.14 node (or get within 2%)... Try it and see.

If not.... Try the 1.27 node, again within +/- 2%.

 

[SJB358]

I'm watching how this works for you Jim. I've done a little with the barrel time charts as well.

Still not sure it isn't some kinda voodoo witchcraft :mrgreen:

 

[Ridgerunner665]

Here's the thing.... OBT can and will help you find the smallest group... But not all by itself.

The load has to be consistent... Low SD and ES, every time, all the time.

Find a load combo that is very consistent AND on a node.... and its a beautiful thing.

 

[Wyo7200]

What kind of barrel? Sporter, heavy?

 

[Wyo7200]

Two more questions, is that 3002 fps chronographed? Magnetospeed attached?

 

[cloverleaf]

:shock: So much to learn......CL

 

[jimbires]

it's a shilen #4 magnum sporter barrel . it measures about .615 at the muzzle . the velocity wrote on the target is a quickload estimate . quickload actually says 3001 fps , I mistakenly wrote 3002 fps . I have not chronied this load . I have a shooting chrony that is temperamental at best . someday I might spring for a lab radar .

I question the short throat my chamber has . how is this made up for , or does it matter ? my thinking is to quickload it would look like a long jump .

 

[Wyo7200]

Cool- I wouldn't trust QL's velocity estimates without calibrating it for chronographed velocity.

As for the short throat, I don't think it matters unless you are into the lands.

Do you know how much neck tension your rounds have? If you use a mandrel, and are close to .001 tension, I'd swag your at the lower node. If you run a expander ball, .003 or so, I'd swag your at the faster node. Getting a chrono reading will allow us to change the burn rate for your round and get a more accurate model of your barrel time pressure and velocity.

 

[jimbires]

right now I've been using a die with the expander ball . I just bought bushings for my bushing die .

I sure wouldn't want to swear to my velocity readings from the chrony I use . I use it to get a ballpark idea for jbm ballistics , then I shoot my rifle to prove my drops at distance . I need a perfect overcast day to really trust my chrony .

OBT , does intrest me , but I'm not sold on it . I guess I've made to many rifles shoot decent just by the seat of my pants . it's the old dog new trick thing . thanks for your time fellas . Jim

 

[Wyo7200]

Well, if the load was worked up to the point where you started seeing pressure signs, this estimate may be closer what you are seeing, and closer to the 1.147 node. Only way to tell is a good chrony reading. This is using my powder profile for .002-.003 neck tension, so it's a little faster.

Cartridge          : .260 Remington
Bullet             : .264, 125, Nosler PART SP 16320
Useable Case Capaci: 48.152 grain H2O = 3.126 cm³
Cartridge O.A.L. L6: 2.767 inch = 70.28 mm
Barrel Length      : 25.0 inch = 635.0 mm
Powder             : A_Alliant Reloder-17 .260

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   86    40.05   2812    2195   45412   9000    100.0    1.311
-09.0   87    40.50   2840    2238   46922   9048    100.0    1.292
-08.0   88    40.94   2867    2282   48483   9096    100.0    1.273
-07.0   89    41.39   2895    2326   50097   9143    100.0    1.255
-06.0   90    41.83   2922    2370   51769   9189    100.0    1.237  ! Near Maximum !
-05.0   91    42.28   2949    2414   53497   9235    100.0    1.219  ! Near Maximum !
-04.0   92    42.72   2976    2459   55286   9280    100.0    1.202  ! Near Maximum !
-03.0   93    43.17   3003    2503   57140   9324    100.0    1.185  ! Near Maximum !
-02.0   94    43.61   3030    2548   59058   9368    100.0    1.168  ! Near Maximum !
-01.0   95    44.06   3056    2593   61043   9411    100.0    1.152  !DANGEROUS LOAD-DO NOT USE!
+00.0   96    44.50   3083    2638   63101   9453    100.0    1.135  !DANGEROUS LOAD-DO NOT USE!
+01.0   97    44.95   3109    2683   65233   9495    100.0    1.120  !DANGEROUS LOAD-DO NOT USE!
+02.0   98    45.39   3135    2729   67442   9536    100.0    1.104  !DANGEROUS LOAD-DO NOT USE!
+03.0   98    45.84   3162    2774   69731   9576    100.0    1.089  !DANGEROUS LOAD-DO NOT USE!
+04.0   99    46.28   3188    2820   72096   9615    100.0    1.074  !DANGEROUS LOAD-DO NOT USE!
+05.0  100    46.73   3214    2867   74538   9654    100.0    1.059  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     96    44.50   3134    2727   69866   9271    100.0    1.094  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     96    44.50   3019    2530   56674   9675    100.0    1.183  ! Near Maximum !

 

[jimbires]

no heck that was the first time out with the partitions . it was just a load I put together . I went one grain under quickload max with a .020 jump .

 

[jimbires]

ok , I thought of another question . I've never loaded bergers in this rifle . I'd like to shoot a 140 berger vld hunting , using RL17 powder . I'm touching the lands with a COAL of 2.888 measured off the tip . it's the same rifle and brass mentioned above , so use those specs . where do I want to be as far as powder charge and COAL ? or doesn't OBT work this way ? this is what I'm wanting to learn about OBT . thanks Jim


edit to add ............
in case the 140 bergers don't match up . I also have ;

berger 130 VLD hunting touching the lands is 2.889 COAL off the tip

accubonds 130 grain touching the lands is 2.793 COAL off the tip

 

[Wyo7200]

the specs are ;
260 rem
25 inch bbl
54.33 water capacity
125 grain Partition
44.5 grain RL17 powder
2.767 COAL off the tip , 0.020 jump yes it's short in the throat
1.194 bbl time


You sure nailed it with that one load. I had to ask about the magnetospeed because my 22-250 shot an amazing group with it attached, but spread to 4-5” without it attached.

There are a ton of powder charge, seating depth, and neck tension combinations that can get you on a node. This is pretty evident when playing in QL by adjusting the seating depth and powder charge. QL really needs to get calibrated with velocity to narrow down on the OBT. Touching the lands QL says to increase the starting pressure to 7200- which these estimates are using:

I’d say 37.5 or 40-41gr on the 140 berger to start.

Cartridge          : .260 Remington
Bullet             : .264, 140, Berger Hunt VLD #26504
Useable Case Capaci: 46.998 grain H2O = 3.052 cm³
Cartridge O.A.L. L6: 2.888 inch = 73.36 mm
Barrel Length      : 25.0 inch = 635.0 mm
Powder             : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   82    37.35   2586    2078   43520   8551     99.9    1.370
-09.0   83    37.77   2610    2118   44753   8608    100.0    1.355
-08.0   84    38.18   2634    2158   46025   8662    100.0    1.341
-07.0   85    38.60   2659    2198   47335   8713    100.0    1.327
-06.0   86    39.01   2683    2238   48686   8763    100.0    1.314
-05.0   87    39.43   2707    2278   50081   8812    100.0    1.300
-04.0   88    39.84   2731    2319   51521   8861    100.0    1.287  ! Near Maximum !
-03.0   89    40.26   2755    2360   53006   8909    100.0    1.273  ! Near Maximum !
-02.0   89    40.67   2779    2400   54537   8957    100.0    1.260  ! Near Maximum !
-01.0   90    41.09   2802    2442   56119   9004    100.0    1.247  ! Near Maximum !
+00.0   91    41.50   2826    2483   57752   9050    100.0    1.234  ! Near Maximum !
+01.0   92    41.92   2850    2524   59437   9096    100.0    1.222  ! Near Maximum !
+02.0   93    42.33   2873    2566   61181   9141    100.0    1.209  !DANGEROUS LOAD-DO NOT USE!
+03.0   94    42.75   2896    2608   62979   9186    100.0    1.197  !DANGEROUS LOAD-DO NOT USE!
+04.0   95    43.16   2920    2650   64838   9230    100.0    1.184  !DANGEROUS LOAD-DO NOT USE!
+05.0   96    43.58   2943    2692   66759   9273    100.0    1.172  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     91    41.50   2876    2571   63505   8871    100.0    1.200  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     91    41.50   2764    2375   52417   9269    100.0    1.274  ! Near Maximum !

130 Berger: 39.8gr

Cartridge          : .260 Remington
Bullet             : .264, 130, Berger Hunt VLD #26503
Useable Case Capaci: 47.288 grain H2O = 3.070 cm³
Cartridge O.A.L. L6: 2.888 inch = 73.36 mm
Barrel Length      : 25.0 inch = 635.0 mm
Powder             : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   82    37.35   2620    1982   40691   8559     99.3    1.356
-09.0   83    37.77   2646    2021   41821   8631     99.5    1.342
-08.0   84    38.18   2671    2060   42987   8699     99.6    1.328
-07.0   84    38.60   2697    2099   44190   8764     99.8    1.314
-06.0   85    39.01   2722    2139   45428   8825     99.9    1.301
-05.0   86    39.43   2748    2179   46706   8882     99.9    1.288
-04.0   87    39.84   2773    2219   48025   8935    100.0    1.274
-03.0   88    40.26   2798    2260   49384   8985    100.0    1.261
-02.0   89    40.67   2823    2300   50787   9031    100.0    1.248
-01.0   90    41.09   2848    2341   52234   9076    100.0    1.235  ! Near Maximum !
+00.0   91    41.50   2873    2382   53727   9121    100.0    1.223  ! Near Maximum !
+01.0   92    41.92   2897    2423   55271   9165    100.0    1.210  ! Near Maximum !
+02.0   93    42.33   2922    2465   56861   9209    100.0    1.198  ! Near Maximum !
+03.0   93    42.75   2947    2506   58506   9251    100.0    1.185  ! Near Maximum !
+04.0   94    43.16   2971    2548   60203   9294    100.0    1.173  !DANGEROUS LOAD-DO NOT USE!
+05.0   95    43.58   2995    2590   61958   9335    100.0    1.161  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     91    41.50   2930    2478   58965   8925    100.0    1.188  ! Near Maximum !
Data for burning rate decreased by 5% relative to nominal value:
-Ba     91    41.50   2802    2266   48860   9313     99.7    1.263

130 AccuBond, 39.5gr.

Cartridge          : .260 Remington
Bullet             : .264, 130, Nosler AccuBond 56902
Useable Case Capaci: 46.613 grain H2O = 3.027 cm³
Cartridge O.A.L. L6: 2.793 inch = 70.94 mm
Barrel Length      : 25.0 inch = 635.0 mm
Powder             : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   84    37.81   2663    2047   42873   8614     99.6    1.329
-09.0   85    38.23   2689    2087   44102   8680     99.7    1.315
-08.0   86    38.65   2715    2128   45365   8743     99.8    1.301
-07.0   87    39.07   2741    2168   46676   8802     99.9    1.288
-06.0   88    39.49   2767    2209   48026   8857    100.0    1.274
-05.0   89    39.91   2792    2251   49419   8907    100.0    1.261
-04.0   89    40.33   2818    2292   50858   8954    100.0    1.247
-03.0   90    40.75   2844    2334   52342   9000    100.0    1.234  ! Near Maximum !
-02.0   91    41.17   2869    2376   53878   9044    100.0    1.221  ! Near Maximum !
-01.0   92    41.59   2894    2418   55465   9088    100.0    1.208  ! Near Maximum !
+00.0   93    42.01   2919    2460   57104   9132    100.0    1.195  ! Near Maximum !
+01.0   94    42.43   2944    2503   58798   9175    100.0    1.183  ! Near Maximum !
+02.0   95    42.85   2969    2545   60549   9217    100.0    1.170  !DANGEROUS LOAD-DO NOT USE!
+03.0   96    43.27   2994    2588   62359   9258    100.0    1.158  !DANGEROUS LOAD-DO NOT USE!
+04.0   97    43.69   3019    2631   64233   9299    100.0    1.146  !DANGEROUS LOAD-DO NOT USE!
+05.0   98    44.11   3044    2675   66172   9339    100.0    1.133  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     93    42.01   2975    2555   62737   8938    100.0    1.162  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     93    42.01   2850    2344   51858   9348     99.9    1.234  ! Near Maximum !

Just as something to look at if you back off the lands: 39.5, 41.7

Cartridge          : .260 Remington
Bullet             : .264, 130, Nosler AccuBond 56902
Useable Case Capaci: 46.613 grain H2O = 3.027 cm³
Cartridge O.A.L. L6: 2.793 inch = 70.94 mm
Barrel Length      : 25.0 inch = 635.0 mm
Powder             : Alliant Reloder-17

Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.0% 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

-10.0   86    38.70   2660    2042   40233   8872     99.4    1.408
-09.0   87    39.13   2688    2086   41540   8941     99.5    1.387
-08.0   88    39.56   2716    2129   42890   9006     99.7    1.366
-07.0   89    39.99   2744    2173   44286   9067     99.8    1.346
-06.0   90    40.42   2772    2217   45728   9123     99.9    1.327
-05.0   91    40.85   2799    2262   47222   9173    100.0    1.307
-04.0   92    41.28   2827    2306   48767   9219    100.0    1.289
-03.0   93    41.71   2854    2351   50366   9261    100.0    1.270
-02.0   93    42.14   2881    2396   52020   9302    100.0    1.252  ! Near Maximum !
-01.0   94    42.57   2908    2442   53732   9342    100.0    1.234  ! Near Maximum !
+00.0   95    43.00   2935    2487   55505   9382    100.0    1.217  ! Near Maximum !
+01.0   96    43.43   2962    2532   57339   9421    100.0    1.199  ! Near Maximum !
+02.0   97    43.86   2989    2578   59241   9459    100.0    1.183  ! Near Maximum !
+03.0   98    44.29   3015    2624   61211   9497    100.0    1.166  !DANGEROUS LOAD-DO NOT USE!
+04.0   99    44.72   3041    2670   63253   9534    100.0    1.150  !DANGEROUS LOAD-DO NOT USE!
+05.0  100    45.15   3068    2717   65364   9570    100.0    1.134  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 5% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 5% relative to nominal value:
+Ba     95    43.00   2995    2589   61444   9173    100.0    1.170  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 5% relative to nominal value:
-Ba     95    43.00   2860    2362   49999   9609     99.8    1.271

 

[jimbires]

ok , I think I'm starting to see . so just for instance , lets say most bergers seem to shoot best with about a .050 jump . I would just take my touching 2.888 COAL and subtract my .050 jump , to get a COAL of 2.838 . I would use that 2.838 and look for powder charges that get close with the bbl times on my chart . this should give a good starting point . shoot these over my chrony to see how the velocities match up with quickload . then adjust quickload to get those velocities to match my actual velocities , and look at powder charge and bbl times again .

 

[Dwh7271]

You can, in the future, run an " all powders" list based solely on barrel time. Sometimes helps you find powders you may not be thinking of that may work. Also lets you rule some out. Depends on what you want. Running a high speed node can show you if it's even achievable.
Jim, the chrono readings are what will let you really dial it in. Once you've run 8 or 10 over the chrono you'll get a series of readings that will let you calibrate your burn rate in QuickLoad to what your batch actually is. (Also a good reason to buy 5 or 8 lbs of favorite powders) once you get your burn rate figured as you already have case capacity and barrel length you're good to go.
I'm sure you don't want to hear this but weighting and temperature settings sometimes have a lot to do with it also.
Oh. And don't let Scotty fool you. He's experimenting with the "voodoo" also. :grin:
I also learned something else after a lot of fooling with this. The burn rate of the same powder can vary between cartridges. :grin:

 

[jimbires]

DWH7271 said ... " I also learned something else after a lot of fooling with this. The burn rate of the same powder can vary between cartridges. :grin: "


Dewey , I've thought this before , about burn rate . I also think temp sensitivity changes between cartridges too .


thanks for the help fellas , I appreciate it .

 

[DrMike]

Burn rates can vary not only with cartridge, but with projectile weights.

 

[Dwh7271]

Yessir, I agree.
I just wanted to make certain readers of this thread didn't try to apply one burn to everything.

 

[RiverRider]

I read about the OBT stuff several years ago and thought it was interesting, but had no idea how to make use of it and put it all on the mental back burner. These recent discussions pointed out another capability of QL I had never utilized, so I went back and read all the stuff over again with intent to fully comprehend, and now my mind is racing...I slept poorly last night as a result!

I really want to try this stuff out, so I started looking at my M70 in .264 Win Mag and playing with QL to see what I could see. I was disappointed to see that I'd have to give up a lot of velocity shooting 140 ABs, and it began to look like the 26-inch barrel length was a real hindrance causing me to dislike the OBT theory. Why have a 26-inch .264 if I can't optimize a load for it??

It looked as though I could hit a node using lighter bullets, but then again---why bother if I can't take full advantage of the cartridge's potential? Then I looked at the 125 Partition in QL...and bingo, it appears that a node can be hit with decent velocity using Retumbo. I'll go back over all this later when I can devote my full attention to it, but I think I was doing everything correctly. I am excited by the prospect of proving OBT to myself and look forward to some experimentation!