14 September 2011, 22:52
Antelope SniperGreybrid, different folks have different methods. The general rule of thumb is to back of 10%. With quick load, you can set a "burn rate variation". Some guys will set this to 10%, and use this as their starting point. I typically set the burn rate variation to the minimum (3%), and back off what ever looks reasonable.
In the example you gave:
Cartridge : .243 Win.
Bullet : .243, 80, Barnes 'TTSX' BT 24338
Useable Case Capaci: 50.298 grain H2O = 3.266 cm³
Cartridge O.A.L. L6: 2.710 inch = 68.83 mm
Barrel Length : 24.0 inch = 609.6 mm
Predicted Data for Indicated Charges of the Following Powders.
Matching Maximum Pressure: 59400 psi, or 409 MPa
or a maximum loading ratio or filling of 115 %
These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window.
C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested
loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand
that all of the listed powders can be unsuitable for the given combination of cartridge, bullet
and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations.
USE ONLY FOR COMPARISON !
12 loads produced a Loading Ratio below user-defined minimum of 50%. These powders have been skipped.
Powder type Filling/Loading Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time
% Grains Gramm fps % psi psi ms
--------------------------------- -----------------------------------------------------------------
Norma MRP 104.2 50.4 3.27 3407 98.6 59400 11906 1.072 ! Near Maximum !
Alliant Reloder-25 112.1 51.7 3.35 3404 99.8 59400 11562 1.066 ! Near Maximum !
Vihtavuori N570 115.0 56.2 3.64 3403 91.2 59396 12691 1.071 ! Near Maximum !
Norma MRP 2 114.7 53.2 3.45 3392 96.7 59400 12003 1.076 ! Near Maximum !
Vihtavuori N560 105.8 50.1 3.25 3386 95.4 59400 11957 1.069 ! Near Maximum !
Raufoss RA15 106.1 49.7 3.22 3370 97.4 59400 11628 1.073 ! Near Maximum !
Bofors RP5/NP ~approximation 106.1 49.7 3.22 3370 97.4 59400 11628 1.073 ! Near Maximum !
Alliant Reloder-22 106.1 49.7 3.22 3370 97.4 59400 11628 1.073 ! Near Maximum !
IMR 7828 110.2 49.6 3.22 3368 95.8 59400 11597 1.061 ! Near Maximum !
IMR 7828 SSC 104.2 49.6 3.22 3368 95.8 59400 11597 1.061 ! Near Maximum !
Winchester WXR 108.9 50.0 3.24 3367 97.3 59400 11623 1.074 ! Near Maximum !
Ramshot Magnum (Big Boy) 107.9 53.6 3.47 3365 96.4 59400 11700 1.066 ! Near Maximum !
SNPE Vectan SP 12 108.1 53.5 3.47 3364 96.5 59400 11678 1.066 ! Near Maximum !
Accurate MAGPRO 106.0 52.3 3.39 3364 93.9 59400 11886 1.077 ! Near Maximum !
PB Clermont PCL 517 108.3 53.6 3.47 3364 96.4 59400 11689 1.066 ! Near Maximum !
ADI AR 2213 105.1 49.3 3.19 3351 95.6 59400 11462 1.060 ! Near Maximum !
Somchem S365 100.2 46.2 2.99 3346 100.0 59400 10288 1.081 ! Near Maximum !
Alliant Reloder-17 90.6 44.1 2.86 3345 100.0 59400 10487 1.060 ! Near Maximum !
Winchester 760 92.8 45.5 2.95 3332 98.5 59400 10966 1.077 ! Near Maximum !
Hodgdon H414 92.8 45.5 2.95 3332 98.5 59400 10966 1.077 ! Near Maximum !
Ramshot Hunter 98.2 47.0 3.05 3332 99.1 59400 10925 1.076 ! Near Maximum !
I would probaby start with RL22:
Cartridge : .243 Win.
Bullet : .243, 80, Barnes 'TTSX' BT 24338
Useable Case Capaci: 50.298 grain H2O = 3.266 cm³
Cartridge O.A.L. L6: 2.710 inch = 68.83 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Alliant Reloder-22
Predicted data by increasing and decreasing the given charge,
incremented in steps of 1.042% 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
-10.4 92 43.00 2878 1472 36800 9950 89.4 1.317
-09.4 93 43.50 2914 1509 38100 10100 90.2 1.299
-08.3 94 44.00 2950 1546 39450 10246 90.9 1.282
-07.3 95 44.50 2987 1585 40853 10390 91.6 1.265
-06.3 96 45.00 3023 1624 42308 10529 92.3 1.248
-05.2 97 45.50 3060 1663 43827 10665 92.9 1.231
-04.2 98 46.00 3096 1703 45403 10796 93.5 1.213
-03.1 99 46.50 3133 1743 47042 10923 94.1 1.192
-02.1 100 47.00 3169 1784 48749 11046 94.7 1.173
-01.0 101 47.50 3206 1826 50524 11164 95.3 1.154
+00.0 102 48.00 3243 1868 52373 11277 95.8 1.136 ! Near Maximum !
+01.0 103 48.50 3280 1911 54298 11385 96.3 1.117 ! Near Maximum !
+02.1 105 49.00 3316 1954 56304 11488 96.8 1.099 ! Near Maximum !
+03.1 106 49.50 3353 1997 58395 11585 97.2 1.082 ! Near Maximum !
+04.2 107 50.00 3390 2041 60573 11677 97.6 1.064 !DANGEROUS LOAD-DO NOT USE!
+05.2 108 50.50 3426 2085 62846 11762 98.0 1.047 !DANGEROUS LOAD-DO NOT USE!
In this case, backing off the powder charge 10% would put you around 44 grains, and looks like a reasonable starting point. I'd still check it against any manuals I had avaliable. If a major loading manual was telling me this would be unsafe with a standard cup and core bullet, I'd start lower. A little powder and a few bullets is a small price to pay for an extra magin of safety.
15 September 2011, 04:20
graybirdAntelope Sniper,
Thanks for the comments.
I've been looking at using a faster burning powder versus a slower powder like RL-22 because of the light weight of the 80 grain bullet. I'm looking at a powder in the RL-15, Big Game or IMR 4064 range; or possibly even faster in the varget and IMR4895 range. So, here are some numbers I was crunching look at some starting loads.
Taking a look at Hornady's newest manual #8 with their 80 grain GMX bullet they recommend using the 85-87 grain data. Therefore, using RL-15 their maximum load is 37.5 gr. When you look at QuickLoad using this 37.5 gr load, it computes only 45.6K psi; therefore, it leads me to believe this is on the lower end of the spectrum (rate range) versus the upper. If you appraoch 60K psi, then your max load should be in the 41.5 gr range according to QuickLoad. Thereby, subtracting the 10% for a starting load, puts you at 37.35 gr, which is the max load in the Hornady manual.
I took a look at Alliant's website and wouldn't you know it, they don't have RL-15 listed in their recommendations for the 243 and a Speer 80 gr SP bullet. They have RL-10x and RL-17, but not the middle of the road between these two powders. They list the max load for RL-17 to be 44.0 gr and RL-10x to be 35 gr, so based upon these data I'm tending to lean towards what QuickLoad is telling me regarding a max load of around 41.5 gr for RL-15.
The other manuals I have(Speer, Nosler, etc.) don't have a load recommendation for the 80 gr bullets and RL-15; therefore, the Hornady manual is the only one I can really lean on; however, there is quite a difference between what the manual says and what QuickLoad is telling me.
Hence, my final thoughts on RL-15 should be a starting load of 37.4 gr and max of 41.5 gr.
Thoughts?
Thanks again!