Running too hot ???

Gunner46 · May 9, 2015

I just finished a round of testing my 7mm/08 using 140 gr BT's with RL-19 and Varget. A couple of loads are showing some excellent promise, but I want to make sure I'm not over the edge pressure wise.

The Nosler manual list a max charge of RL-19 at 49.0 gr, however Alliant shows 51.0 gr with a 145 gr bullet. I got my best group with 50.5 gr.

Likewise Varget. Different sources showing different max charges. I was shooting 43.5 gr.

This is out of a 22 inch barrel, R-P brass, and WLR primers. Am I OK, or do I need to drop down some?

DrMike · May 10, 2015

Here are some QL projections.

Code:

Cartridge          : 7 mm-08 Rem.
Bullet             : .284, 140, Nosler BalTip 28140
Useable Case Capaci: 47.351 grain H2O = 3.074 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : Alliant Reloder-19

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   91    39.52   2240    1560   29629   7639     81.1    1.447
-18.0   93    40.51   2300    1645   31703   7929     82.6    1.407
-16.0   95    41.50   2361    1733   33933   8217     84.1    1.367
-14.0   97    42.48   2422    1823   36331   8499     85.6    1.328
-12.0  100    43.47   2484    1917   38913   8776     87.0    1.288
-10.0  102    44.46   2546    2015   41699   9045     88.4    1.246
-08.0  104    45.45   2608    2115   44705   9307     89.7    1.206
-06.0  106    46.44   2672    2219   47959   9559     90.9    1.168
-04.0  109    47.42   2735    2326   51479   9800     92.1    1.130  ! Near Maximum !
-02.0  111    48.41   2799    2436   55298  10029     93.2    1.094  ! Near Maximum !
+00.0  113    49.40   2864    2550   59448  10246     94.3    1.060  ! Near Maximum !
+02.0  115    50.39   2929    2666   63966  10447     95.2    1.026  !DANGEROUS LOAD-DO NOT USE!
+04.0  118    51.38   2994    2787   68888  10633     96.1    0.993  !DANGEROUS LOAD-DO NOT USE!
+06.0  120    52.36   3060    2910   74290  10802     96.9    0.961  !DANGEROUS LOAD-DO NOT USE!
+08.0  122    53.35   3126    3037   80206  10952     97.6    0.930  !DANGEROUS LOAD-DO NOT USE!
+10.0  125    54.34   3192    3167   86711  11082     98.3    0.900  !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    113    49.40   3026    2846   71679  10398     98.9    0.979  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    113    49.40   2659    2199   48628   9583     85.9    1.162

Code:

Cartridge          : 7 mm-08 Rem.
Bullet             : .284, 140, Nosler BalTip 28140
Useable Case Capaci: 47.351 grain H2O = 3.074 cm³
Cartridge O.A.L. L6: 2.800 inch = 71.12 mm
Barrel Length      : 22.0 inch = 558.8 mm
Powder             : Hodgdon VARGET

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   80    33.84   2267    1597   32029   7273     91.9    1.413
-18.0   82    34.69   2319    1672   34070   7489     92.9    1.379
-16.0   84    35.53   2371    1748   36215   7699     93.9    1.346
-14.0   86    36.38   2423    1826   38474   7902     94.7    1.310
-12.0   88    37.22   2476    1905   40870   8098     95.6    1.273
-10.0   90    38.07   2527    1986   43410   8285     96.3    1.238
-08.0   92    38.92   2579    2068   46106   8464     97.0    1.204
-06.0   94    39.76   2631    2152   48966   8634     97.7    1.171
-04.0   96    40.61   2683    2237   52003   8793     98.2    1.139  ! Near Maximum !
-02.0   98    41.45   2734    2323   55228   8942     98.7    1.109  ! Near Maximum !
+00.0  100    42.30   2785    2411   58656   9080     99.1    1.080  ! Near Maximum !
+02.0  102    43.15   2836    2500   62302   9206     99.4    1.051  !DANGEROUS LOAD-DO NOT USE!
+04.0  104    43.99   2886    2590   66183   9320     99.7    1.024  !DANGEROUS LOAD-DO NOT USE!
+06.0  106    44.84   2937    2681   70316   9422     99.9    0.998  !DANGEROUS LOAD-DO NOT USE!
+08.0  108    45.68   2987    2773   74724   9510    100.0    0.972  !DANGEROUS LOAD-DO NOT USE!
+10.0  110    46.53   3036    2866   79430   9584    100.0    0.947  !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    100    42.30   2891    2598   68577   8840    100.0    1.011  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    100    42.30   2638    2164   48929   8928     94.5    1.169

More important, does your brass show indications of overcharge? That is the most important determinant since it speaks of the situation in your own firing system.

Gunner46 · May 10, 2015

I just off graveyard. I'll measure the web later this afternoon. Extraction was fine, primers good. Anything else I should check ? It looks as I'm skirting the edge either way.

JD338 · May 10, 2015

I think I would back them off a little bit. If nothing else, you will get longer case life.

JD338

Gunner46 · May 11, 2015

Using the thinnest part of the micrometer blades, I got .003 on the largest swell. (.467 - .470)

kraky · May 12, 2015

I'd highly recommend dialing in the use of chrono in your decision making. I've used quickload for years and two of the powders it seems to have trouble with happen to be re19 and varget. My re19 loads almost always turn out milder than ql predicts....and varget hotter.
The 7mm 08 case is just like the 308....different case brands and capacity give quite varied results. Rp brass usually results in slightly "warmer" results. Dial in freebore that many factory chambers have and anything could be happening.
I would seriously get some chrono results and get someone modify the actual results to match on ql and see where it comes out.

Gunner46 · Aug 27, 2015

I finally got a chance to get out to the range with the Crony. I loaded up a string of rounds, in 1 gr increments, with both the Varget and the RL-19.

Well, the Crony doesn't lie. The Varget worked out to pretty much match the QL predictions.

The RL-19 still has me scratching my head. Not Even Close !! Per grain change, from 46.0- through 50.0, my loads averaged 125 fps slower than QL predicted !! This is so far off, that I'll abandon that powder, for the 140's, simply because I won't be able to stuff any more powder into the case.

Looks like it's going to be 42.5 gr of Varget. That is putting my pressure level right at 60,000.

longrangehunter · Aug 27, 2015

Gunner, try RL-15! It worked great for my 7mm-08 w/various 140 gr. bullets (1/4''- 3/8" groups), 41.5 gr. RL-15, CCI-BR2 or F210M primers and used the 140 NBT and the 140 SGK.

The 160 NAB 45.0 H414 F210M in Winchester Brass worked very well for me also.

I think RL-19 is just too slow for that weight bullet in the 7mm-08.

Gunner46 · Aug 27, 2015

I tried RL-15 with the 140's and it just didn't stack up against the Varget and RL-19, as far as accuracy. Does fine with 120's & 150's though and works great out of my 308. I tried RL-19 because a friend gets 2900 fps, and 1/2" groups out of his 7mm/08. All I got was the accuracy part.

It's getting close enough to Lope season I'm going to load the Varget and play with OAL a little, before it gets too late.