Any (7mm-08 / H414 [or 760] / 139SST) 1st hand experience?

[nkyshooter]

Short of it is, I don't believe you have a unicorn. I think its time for a different chrono, good luck

I think you're probably right ... I'll be much more confident with that 47-48.5 window if they show me the same consistency but at a lower/more accurate & believable velocity - seems those "should" be in the 2750-2800ish range ... good place to be and if I get the accuracy grouping I hope for in there I will be pleased as punch.

 

[Seabeeken]

Can't lend any help on the H414 and 7/08 combo. I used H414 in my Roberts when I first started loading for it but didn't see any strange velocity numbers with that powder.

A word of caution on Quickload. What you see from quick load isn't always what you get. I had a guy run some data for me and the numbers were way off by about 200fps or maybe more. This was after very detailed data input. Never could figure out why

I get a lot more speed with 5R rifling that quick load predicts. About 200 fps

 

[nkyshooter]

That's interesting @Seabeeken ... my 7mm-08 is not 5r ... but ... the 30 sherman magnum barrel I'm expecting to arrive next week IS 5r ... and I will be absolutely thrilled if I see even have that increase due to the 5r!

 

[grry10]

I wouldn't waste much time with H414, it has been discontinued.

 

[nkyshooter]

I wouldn't waste much time with H414, it has been discontinued.

Thanks @grry10 ... Regardless, I've got 6lbs ... that's roughly 850 rounds ... probably the full hunting life of this rifle ... besides, as a few others have also pointed out, Win760 is essentially a different lot of the same powder and I have not heard of it being discontinued

This post has been very valuable to me so far as a number of folks who've paired 414 (or 760) with a 139/140 bullet in a 7mm-08 or have been able to analyze with QuickLoad have been able to offer their experiences/info ...

Have you used H414 in a 7mm-08 with 139-140's? Would love to know what kind of velocities you were achieving based on your charge weight and bbl length ...

 

[KsKevin]

@308win - here is more info ...

Temp at time of firing was approximately 45F - I was fully shaded and so was the chrono ... chrono was set up with sun shades but was close enough to rifle that the muzzle blast blew off the sunshades about half way through or so ... Roughly 2-3 feet from muzzle or so? ...

You should set your chrono about 10' from the muzzle. I've never set mine 2-3' out but wondering if this may be causing inaccuracies in your readings. Could also test velocity via shooting at 600+ to field verify drop and back calculate MV

 

[nkyshooter]

Thanks @KsKevin - I'm going to have to deploy an additional chronograph and compare to see if I am off but will definitely place it out further to ensure that isn't impacting my measurements ...

Would love to verify at 600+ but that is not as easily done as said in this region ... so ... I'll have to rely on the chronograph for time being.

 

[jimbires]

set your chrony up 10 - 12 ft away from the muzzle . you could be screwing up the chrony with the blast . at 10 - 12 ft , I still blew the sky screens off my chrony . if you could find a labradar , or magneto speed that would be great . my chrony changed speed readings according to how bright the sun was . usable case capacity is how much case capacity you have after seating your bullet . I'll run you a 56 gr water capacity at 45*F . I'll be back .

 

[KsKevin]

Thanks @KsKevin - I'm going to have to deploy an additional chronograph and compare to see if I am off but will definitely place it out further to ensure that isn't impacting my measurements ...

Would love to verify at 600+ but that is not as easily done as said in this region ... so ... I'll have to rely on the chronograph for time being.

Im a member at MRPC and we have a 600yd line if you want to plan an outing

 

[nkyshooter]

Im a member at MRPC and we have a 600yd line if you want to plan an outing

I just might take you up on that - I remember you mentioning that when I picked up the 8208xbr and h335 ...

I'm going to try Jim's suggestion and setup the chrony at 10-12 feet with another one right behind it and see if what kind of data I get. As long as I am "close" and "consistent" I'll be able to finish development ... that's when I'll be looking for the 600 yard drop validation.

You wouldn't happen to have a lab radar would you?

 

[jimbires]

the default water case capacity is 55 grain , so it will change some . looks like 49.4grain at 2918 FPS is slightly over max pressure . like 308 was saying , this is a good guess . now if you could give good chrony info I could adjust weighting factor , powder burn speed , until the powder weight matches the velocity . when you get things lined up it works well . I'd feel safe working up in the 49.5 - 50.5 grain area while watching for pressure .




Cartridge : 7 mm-08 Rem.
Bullet : .284, 139, Hornady SST InterLock 28202
Useable Case Capaci: 48.816 grain H2O = 3.170 cm³
Cartridge O.A.L. L6: 2.795 inch = 70.99 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Hodgdon H414 ?, Temperature: 45 °F

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 83 39.52 2297 1628 30207 8050 84.1 1.433
-18.0 85 40.51 2358 1715 32315 8339 85.6 1.393
-16.0 87 41.50 2419 1805 34581 8622 87.0 1.355
-14.0 89 42.48 2480 1898 37011 8899 88.4 1.317
-12.0 91 43.47 2542 1994 39633 9167 89.7 1.276
-10.0 93 44.46 2604 2093 42449 9427 91.0 1.235
-08.0 95 45.45 2666 2194 45486 9676 92.1 1.196
-06.0 98 46.44 2729 2299 48763 9914 93.3 1.159
-04.0 100 47.42 2792 2406 52302 10139 94.3 1.122 ! Near Maximum !
-02.0 102 48.41 2855 2516 56129 10350 95.2 1.087 ! Near Maximum !
+00.0 104 49.40 2918 2628 60273 10546 96.1 1.053 !DANGEROUS LOAD-DO NOT USE!
+02.0 106 50.39 2982 2744 64775 10727 96.9 1.020 !DANGEROUS LOAD-DO NOT USE!
+04.0 108 51.38 3045 2862 69665 10890 97.6 0.989 !DANGEROUS LOAD-DO NOT USE!
+06.0 110 52.36 3109 2982 74990 11034 98.2 0.958 !DANGEROUS LOAD-DO NOT USE!
+08.0 112 53.35 3172 3106 80766 11158 98.8 0.928 !DANGEROUS LOAD-DO NOT USE!
+10.0 114 54.34 3236 3232 87059 11261 99.2 0.899 !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 104 49.40 3073 2915 73293 10521 99.7 0.972 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 104 49.40 2716 2277 48627 10020 88.5 1.157

 

[jimbires]

one of the best things I did was gift my chrony to a guy , and buy a labradar .

 

[jimbires]

same as above except at 70* F .


Cartridge : 7 mm-08 Rem.
Bullet : .284, 139, Hornady SST InterLock 28202
Useable Case Capaci: 48.816 grain H2O = 3.170 cm³
Cartridge O.A.L. L6: 2.795 inch = 70.99 mm
Barrel Length : 22.0 inch = 558.8 mm
Powder : Hodgdon H414 ?, Temperature: 70 °F

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 83 39.52 2339 1688 31598 8224 86.3 1.407
-18.0 85 40.51 2400 1778 33823 8506 87.7 1.368
-16.0 87 41.50 2461 1870 36215 8782 89.1 1.330
-14.0 89 42.48 2523 1965 38785 9048 90.4 1.290
-12.0 91 43.47 2585 2062 41550 9306 91.6 1.249
-10.0 93 44.46 2647 2163 44527 9553 92.8 1.209
-08.0 95 45.45 2709 2266 47735 9788 93.8 1.171
-06.0 98 46.44 2772 2372 51199 10010 94.9 1.134 ! Near Maximum !
-04.0 100 47.42 2835 2480 54940 10219 95.8 1.099 ! Near Maximum !
-02.0 102 48.41 2897 2591 58989 10412 96.6 1.065 ! Near Maximum !
+00.0 104 49.40 2960 2704 63372 10589 97.4 1.032 !DANGEROUS LOAD-DO NOT USE!
+02.0 106 50.39 3023 2820 68128 10748 98.0 1.000 !DANGEROUS LOAD-DO NOT USE!
+04.0 108 51.38 3086 2939 73257 10889 98.6 0.969 !DANGEROUS LOAD-DO NOT USE!
+06.0 110 52.36 3148 3059 78822 11010 99.1 0.939 !DANGEROUS LOAD-DO NOT USE!
+08.0 112 53.35 3211 3182 84876 11110 99.4 0.910 !DANGEROUS LOAD-DO NOT USE!
+10.0 114 54.34 3274 3308 91478 11188 99.7 0.882 !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 104 49.40 3107 2979 76823 10430 100.0 0.954 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 104 49.40 2764 2358 51011 10184 90.5 1.133

 

[Kerryt38]

I've been loading 47gr of Win 760 in my wife's Rem 700 with a 24" barrel. It's Running 2887 FPS average with my magnetospeed. She shoots 1/4 MOA groups with it. I'm m not going to try shoot a group with it because I'm sure it's not going to be that good!