Thread: High Pressure signs?

@janleroux I have a Howa 6.5CM 24inch heavy barrel

When running 140ELDM It really likes them at about 2770 FPS with a COAL of 2.840"

I find the standard 2.80 Factory COAL too much of a jump to the lands and builds up pressure faster with increasing charge weight.
In my Howa pressure signs start with an increasing ridge (primer cratering) around the primer strike well before I start getting ejector smear or sticky bolt lift.

H4350/2209 is certainly known for accuracy/temp insensitivity in 6.5cm

But don't discount RL16 also very temp stable and can give better MV and accuracy in my rifle

You might not be able to reach 2770 with a Coal of 2.80 before getting significant pressure signs.

Also you need to consider how many rounds have gone down your barrel if it's still new, less than 100 - 200 rounds, you may well find a speed increase as the barrel wears in.

Here's an example from QL for your bullet with H4350 in a 24" barrel note the COAL is 2.865 also note that the cartridge case capacity may not match yours if it's smaller pressures will reach higher.

Do not take any figures like these for gospel always start lower and work up.


Cartridge : 6.5 Creedmoor Hornady
Bullet : .264, 143, Hornady ELD-X 2635 G7
Useable Case Capaci: 46.313 grain H2O = 3.007 cm³
Cartridge O.A.L. L6: 2.865 inch = 72.77 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.704% 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

-07.0 94 39.32 2548 2061 48192 8838 97.3 1.347
-06.3 95 39.62 2566 2090 49240 8897 97.5 1.334
-05.6 96 39.92 2584 2120 50310 8956 97.7 1.321
-04.9 96 40.22 2602 2149 51405 9013 97.9 1.308 ! Near Maximum !
-04.2 97 40.51 2620 2179 52523 9069 98.1 1.296 ! Near Maximum !
-03.5 98 40.81 2638 2209 53665 9123 98.3 1.283 ! Near Maximum !
-02.8 98 41.11 2655 2239 54833 9176 98.5 1.271 ! Near Maximum !
-02.1 99 41.41 2673 2269 56026 9227 98.7 1.259 ! Near Maximum !
-01.4 100 41.70 2691 2299 57245 9277 98.8 1.246 ! Near Maximum !
-00.7 101 42.00 2709 2330 58492 9325 99.0 1.235 ! Near Maximum !
+00.0 101 42.30 2727 2361 59766 9372 99.1 1.223 !DANGEROUS LOAD-DO NOT USE!
+00.7 102 42.60 2744 2391 61069 9417 99.2 1.211 !DANGEROUS LOAD-DO NOT USE!
+01.4 103 42.90 2762 2422 62402 9460 99.3 1.200 !DANGEROUS LOAD-DO NOT USE!
+02.1 103 43.19 2780 2453 63764 9502 99.4 1.188 !DANGEROUS LOAD-DO NOT USE!
+02.8 104 43.49 2797 2484 65157 9543 99.5 1.177 !DANGEROUS LOAD-DO NOT USE!
+03.5 105 43.79 2815 2516 66582 9581 99.6 1.166 !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 101 42.30 2832 2547 70203 9091 100.0 1.144 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 101 42.30 2580 2114 49511 9234 94.4 1.326

Originally Posted by spada

@janleroux I have a Howa 6.5CM 24inch heavy barrel

When running 140ELDM It really likes them at about 2770 FPS with a COAL of 2.840"

I find the standard 2.80 Factory COAL too much of a jump to the lands and builds up pressure faster with increasing charge weight.
In my Howa pressure signs start with an increasing ridge (primer cratering) around the primer strike well before I start getting ejector smear or sticky bolt lift.

H4350/2209 is certainly known for accuracy/temp insensitivity in 6.5cm

But don't discount RL16 also very temp stable and can give better MV and accuracy in my rifle

You might not be able to reach 2770 with a Coal of 2.80 before getting significant pressure signs.

Also you need to consider how many rounds have gone down your barrel if it's still new, less than 100 - 200 rounds, you may well find a speed increase as the barrel wears in.

Here's an example from QL for your bullet with H4350 in a 24" barrel note the COAL is 2.865 also note that the cartridge case capacity may not match yours if it's smaller pressures will reach higher.

Do not take any figures like these for gospel always start lower and work up.


Cartridge : 6.5 Creedmoor Hornady
Bullet : .264, 143, Hornady ELD-X 2635 G7
Useable Case Capaci: 46.313 grain H2O = 3.007 cm³
Cartridge O.A.L. L6: 2.865 inch = 72.77 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.704% 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

-07.0 94 39.32 2548 2061 48192 8838 97.3 1.347
-06.3 95 39.62 2566 2090 49240 8897 97.5 1.334
-05.6 96 39.92 2584 2120 50310 8956 97.7 1.321
-04.9 96 40.22 2602 2149 51405 9013 97.9 1.308 ! Near Maximum !
-04.2 97 40.51 2620 2179 52523 9069 98.1 1.296 ! Near Maximum !
-03.5 98 40.81 2638 2209 53665 9123 98.3 1.283 ! Near Maximum !
-02.8 98 41.11 2655 2239 54833 9176 98.5 1.271 ! Near Maximum !
-02.1 99 41.41 2673 2269 56026 9227 98.7 1.259 ! Near Maximum !
-01.4 100 41.70 2691 2299 57245 9277 98.8 1.246 ! Near Maximum !
-00.7 101 42.00 2709 2330 58492 9325 99.0 1.235 ! Near Maximum !
+00.0 101 42.30 2727 2361 59766 9372 99.1 1.223 !DANGEROUS LOAD-DO NOT USE!
+00.7 102 42.60 2744 2391 61069 9417 99.2 1.211 !DANGEROUS LOAD-DO NOT USE!
+01.4 103 42.90 2762 2422 62402 9460 99.3 1.200 !DANGEROUS LOAD-DO NOT USE!
+02.1 103 43.19 2780 2453 63764 9502 99.4 1.188 !DANGEROUS LOAD-DO NOT USE!
+02.8 104 43.49 2797 2484 65157 9543 99.5 1.177 !DANGEROUS LOAD-DO NOT USE!
+03.5 105 43.79 2815 2516 66582 9581 99.6 1.166 !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 101 42.30 2832 2547 70203 9091 100.0 1.144 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 101 42.30 2580 2114 49511 9234 94.4 1.326

Wow, thanks! I will digest this a bit. Very good info and comparisons to have. Appreciate it!


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Originally Posted by spada

@janleroux I have a Howa 6.5CM 24inch heavy barrel

When running 140ELDM It really likes them at about 2770 FPS with a COAL of 2.840"

I find the standard 2.80 Factory COAL too much of a jump to the lands and builds up pressure faster with increasing charge weight.
In my Howa pressure signs start with an increasing ridge (primer cratering) around the primer strike well before I start getting ejector smear or sticky bolt lift.

H4350/2209 is certainly known for accuracy/temp insensitivity in 6.5cm

But don't discount RL16 also very temp stable and can give better MV and accuracy in my rifle

You might not be able to reach 2770 with a Coal of 2.80 before getting significant pressure signs.

Also you need to consider how many rounds have gone down your barrel if it's still new, less than 100 - 200 rounds, you may well find a speed increase as the barrel wears in.

Here's an example from QL for your bullet with H4350 in a 24" barrel note the COAL is 2.865 also note that the cartridge case capacity may not match yours if it's smaller pressures will reach higher.

Do not take any figures like these for gospel always start lower and work up.


Cartridge : 6.5 Creedmoor Hornady
Bullet : .264, 143, Hornady ELD-X 2635 G7
Useable Case Capaci: 46.313 grain H2O = 3.007 cm³
Cartridge O.A.L. L6: 2.865 inch = 72.77 mm
Barrel Length : 24.0 inch = 609.6 mm
Powder : Hodgdon H4350

Predicted data by increasing and decreasing the given charge,
incremented in steps of 0.704% 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

-07.0 94 39.32 2548 2061 48192 8838 97.3 1.347
-06.3 95 39.62 2566 2090 49240 8897 97.5 1.334
-05.6 96 39.92 2584 2120 50310 8956 97.7 1.321
-04.9 96 40.22 2602 2149 51405 9013 97.9 1.308 ! Near Maximum !
-04.2 97 40.51 2620 2179 52523 9069 98.1 1.296 ! Near Maximum !
-03.5 98 40.81 2638 2209 53665 9123 98.3 1.283 ! Near Maximum !
-02.8 98 41.11 2655 2239 54833 9176 98.5 1.271 ! Near Maximum !
-02.1 99 41.41 2673 2269 56026 9227 98.7 1.259 ! Near Maximum !
-01.4 100 41.70 2691 2299 57245 9277 98.8 1.246 ! Near Maximum !
-00.7 101 42.00 2709 2330 58492 9325 99.0 1.235 ! Near Maximum !
+00.0 101 42.30 2727 2361 59766 9372 99.1 1.223 !DANGEROUS LOAD-DO NOT USE!
+00.7 102 42.60 2744 2391 61069 9417 99.2 1.211 !DANGEROUS LOAD-DO NOT USE!
+01.4 103 42.90 2762 2422 62402 9460 99.3 1.200 !DANGEROUS LOAD-DO NOT USE!
+02.1 103 43.19 2780 2453 63764 9502 99.4 1.188 !DANGEROUS LOAD-DO NOT USE!
+02.8 104 43.49 2797 2484 65157 9543 99.5 1.177 !DANGEROUS LOAD-DO NOT USE!
+03.5 105 43.79 2815 2516 66582 9581 99.6 1.166 !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 101 42.30 2832 2547 70203 9091 100.0 1.144 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 101 42.30 2580 2114 49511 9234 94.4 1.326

I am standing at about 150 rounds through this barrel. Very interesting to compare my results with QL output:

CHARGE AVE VEL (fps) ES GRP MOA
Factory 2669 43 0.77
37.5 2460 43 0.66
38.0 2462 61 0.37
38.5 2535 51 0.75
39.0 2527 11 0.65
39.5 2566 9 0.3
40.0 2598 2 0.57
40.5 2602 36 0.69
41.0 2622 7 0.71

My plan was to only go up to 42gr max - so this is inline with my next steps. Thanks!