.378 revisited

X-Man, I think you may have mis-read that ...

It is 113% fill - 129.07grs - 2939fps - 5754ft/lbs - 59076psi

+10.0 113 129.07 2939 5754 59076 12707 96.4 1.284 ! Near Maximum !

That's a 13% compressed load.
 
It's Quickload, btw ;)

Cartridge : .378 Weath. Mag.
Bullet : .375, 300, Barnes 'TSX' 37558
Cartridge O.A.L. L6: 3.655 inch or 92.84 mm
Barrel Length : 26.0 inch or 660.4 mm
Powder : Hodgdon H4831

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 81 84.00 2267 3424 30126 8743 89.9 1.697
-18.0 83 86.10 2322 3591 31989 9029 91.2 1.657
-16.0 85 88.20 2377 3764 33974 9308 92.3 1.617
-14.0 87 90.30 2432 3941 36090 9578 93.4 1.579
-12.0 89 92.40 2488 4124 38346 9838 94.4 1.541
-10.0 91 94.50 2544 4311 40757 10087 95.4 1.504
-08.0 93 96.60 2600 4502 43330 10324 96.3 1.468
-06.0 95 98.70 2656 4698 46079 10547 97.0 1.432
-04.0 97 100.80 2712 4899 49020 10756 97.7 1.398
-02.0 99 102.90 2768 5104 52170 10950 98.3 1.363
+00.0 101 105.00 2824 5312 55542 11126 98.9 1.323 ! Near Maximum !
+02.0 103 107.10 2880 5525 59164 11285 99.3 1.286 ! Near Maximum !
+04.0 105 109.20 2936 5741 63052 11425 99.6 1.250 ! Near Maximum !
+06.0 107 111.30 2991 5961 67232 11545 99.8 1.214 !DANGEROUS LOAD-DO NOT USE!
+08.0 109 113.40 3047 6184 71736 11644 100.0 1.179 !DANGEROUS LOAD-DO NOT USE!
+10.0 111 115.50 3102 6410 76592 11722 100.0 1.146 !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 101 105.00 2952 5807 66551 10819 100.0 1.228 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 101 105.00 2648 4671 45775 10820 93.1 1.431
 
My bad.
I have never got around to using one of those programs. I guess 131grains is the number I was looking for. I assume this wont fit?
I am wrong about RL-25?


Have used H-870 to drive 300's to 3050 fps. I know you can seat a bullet over 130gr of 870. It seems as though US869 is a bit bulkier and slower than H-870?

What about Retumbo?
Too bulky for the 378?
 
Cartridge : .378 Weath. Mag.
Bullet : .375, 300, Barnes 'TSX' 37558
Cartridge O.A.L. L6: 3.655 inch or 92.84 mm
Barrel Length : 26.0 inch or 660.4 mm
Powder : Alliant Reloder-25

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 88.80 2403 3848 32503 9706 97.9 1.644
-18.0 86 91.02 2461 4034 34622 9936 98.6 1.604
-16.0 88 93.24 2518 4224 36886 10144 99.2 1.565
-14.0 90 95.46 2575 4417 39312 10329 99.6 1.527
-12.0 92 97.68 2632 4613 41909 10490 99.9 1.489
-10.0 94 99.90 2688 4813 44696 10626 100.0 1.453
-08.0 96 102.12 2744 5014 47685 10742 100.0 1.417
-06.0 98 104.34 2799 5218 50893 10852 100.0 1.382
-04.0 100 106.56 2853 5423 54342 10960 100.0 1.343 ! Near Maximum !
-02.0 102 108.78 2907 5631 58051 11064 100.0 1.304 ! Near Maximum !
+00.0 104 111.00 2961 5841 62045 11164 100.0 1.265 ! Near Maximum !
+02.0 106 113.22 3014 6053 66355 11261 100.0 1.229 !DANGEROUS LOAD-DO NOT USE!
+04.0 109 115.44 3067 6268 71007 11353 100.0 1.193 !DANGEROUS LOAD-DO NOT USE!
+06.0 111 117.66 3120 6485 76036 11441 100.0 1.159 !DANGEROUS LOAD-DO NOT USE!
+08.0 113 119.88 3173 6706 81464 11525 100.0 1.126 !DANGEROUS LOAD-DO NOT USE!
+10.0 115 122.10 3225 6930 87299 11605 100.0 1.093 !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 104 111.00 3063 6249 76100 10757 100.0 1.172 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 104 111.00 2803 5235 49747 11686 99.5 1.386




Cartridge : .378 Weath. Mag.
Bullet : .375, 300, Barnes 'TSX' 37558
Cartridge O.A.L. L6: 3.655 inch or 92.84 mm
Barrel Length : 26.0 inch or 660.4 mm
Powder : Hodgdon Retumbo

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 86 92.80 2411 3872 32186 9923 98.3 1.647
-18.0 88 95.12 2471 4066 34350 10148 99.0 1.606
-16.0 91 97.44 2530 4265 36675 10348 99.5 1.565
-14.0 93 99.76 2590 4467 39179 10518 99.8 1.526
-12.0 95 102.08 2649 4673 41871 10659 100.0 1.486
-10.0 97 104.40 2707 4881 44773 10773 100.0 1.448
-08.0 99 106.72 2765 5092 47901 10881 100.0 1.411
-06.0 101 109.04 2822 5305 51281 10985 100.0 1.375
-04.0 104 111.36 2879 5521 54932 11086 100.0 1.334 ! Near Maximum !
-02.0 106 113.68 2935 5739 58883 11182 100.0 1.292 ! Near Maximum !
+00.0 108 116.00 2991 5960 63171 11274 100.0 1.252 !DANGEROUS LOAD-DO NOT USE!
+02.0 110 118.32 3047 6184 67822 11361 100.0 1.214 !DANGEROUS LOAD-DO NOT USE!
+04.0 112 120.64 3102 6411 72882 11444 100.0 1.177 !DANGEROUS LOAD-DO NOT USE!
+06.0 114 122.96 3158 6642 78394 11521 100.0 1.141 !DANGEROUS LOAD-DO NOT USE!
+08.0 117 125.28 3213 6877 84408 11593 100.0 1.106 !DANGEROUS LOAD-DO NOT USE!
+10.0 119 127.60 3268 7115 90989 11660 100.0 1.072 !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 108 116.00 3097 6390 78550 10844 100.0 1.157 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 108 116.00 2826 5321 50280 11878 99.8 1.377



Cartridge : .378 Weath. Mag.
Bullet : .375, 300, Barnes 'TSX' 37558
Cartridge O.A.L. L6: 3.655 inch or 92.84 mm
Barrel Length : 26.0 inch or 660.4 mm
Powder : Hodgdon H870

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 91 100.80 2326 3604 29798 10060 86.6 1.701
-18.0 94 103.32 2392 3811 31913 10438 88.3 1.656
-16.0 96 105.84 2459 4027 34207 10804 89.9 1.612
-14.0 98 108.36 2526 4252 36701 11157 91.4 1.569
-12.0 100 110.88 2595 4485 39413 11494 92.8 1.526
-10.0 103 113.40 2664 4727 42371 11812 94.2 1.484
-08.0 105 115.92 2734 4978 45599 12109 95.3 1.442
-06.0 107 118.44 2804 5237 49130 12381 96.4 1.401
-04.0 110 120.96 2875 5505 53001 12627 97.4 1.357
-02.0 112 123.48 2946 5780 57252 12844 98.2 1.310 ! Near Maximum !
+00.0 114 126.00 3017 6064 61933 13029 98.8 1.263 ! Near Maximum !
+02.0 116 128.52 3089 6355 67104 13180 99.4 1.218 !DANGEROUS LOAD-DO NOT USE!
+04.0 119 131.04 3160 6653 72823 13295 99.7 1.174 !DANGEROUS LOAD-DO NOT USE!
+06.0 121 133.56 3232 6959 79184 13370 99.9 1.132 !DANGEROUS LOAD-DO NOT USE!
+08.0 123 136.08 3304 7272 86273 13405 100.0 1.090 !DANGEROUS LOAD-DO NOT USE!
+10.0 125 138.60 3376 7591 94175 13420 100.0 1.051 !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 114 126.00 3187 6767 78367 12532 100.0 1.151 !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba 114 126.00 2778 5140 48478 12592 91.7 1.403
 
Well, I've heard that traditional 'pressure signs' don't start appearing until 70ksi or so. I don't doubt that you've reached 3150fps without seeing any overt signs of excess pressure
 
Could be prosper is right.

Here is my max load method.

When working up loads I increase the powder charge carefully feeling for a sticky bolt, while looking for primer malformation or ejector marks on the case head. Invariably the first and only pressure sign I experience is the slightest ejector mark. I have never experienced a sticky bolt or primer malformation. I tag the ejector marked load as "over max" and drop the powder charge a grain or two (depending on how pronounced the ejector mark was and taking case capacity into account).

Using this method I saw ejector marks at just over 2950 with H-4831 and saw the same ejector marks appear at just over 3100 with H-870.
To my way of thinking brass will begin to flow at a fairly constant pressure (apparently 70Kpsi) and I believe (used wisely) it to be the ultimate poor man's pressure gauge.

I understand that brass may vary in hardness (and the poor man's pressure gauge varies with it) but there is my experience.

Shooters using blade type ejectors (Sako, Brno) need to beware of this method as there isn't enough area to allow the brass to flow and show excess pressure until it is sky high.
 
I believe there is a better way of determining a maximum load in a specific rifle, and that is to shoot across a chronograph. If we shoot a number of rounds across the chronograph, each with an "appropriate for case size" powder charge increase, maximum pressure has been reached when the velocity increase plateaus.

This works pretty well, and for an example lets look at the numbers I got when I worked up a .308 load last week. Each subsequent round was loaded with an additional 1 gr of powder. I will not share the bullet weight or powder type, because I do not believe these loads would be safe in an off the shelf rifle.

45 grs - 2484 fps
46 grs - 2528 fps
47 grs - 2566 fps
48 grs - 2603 fps
49 grs - 2644 fps
50 grs - 2662 fps.

As we can see, the velocity rise from 49 to 50 grs is about half of what we observed from charge increases below this amount, indicating that 49 grs is the maximum load. There was no sticky bolt, excessive case head expansion, or brass flow to observe, any one of which can indicate dangerous pressure. Given the right circumstances, such as a lot of brass cases that are harder than usual, there might well be none of the warning signs we have been trained to watch for prior to crossing the pressure at which the firearm fails.
 
Boomer said:
I believe there is a better way of determining a maximum load in a specific rifle, and that is to shoot across a chronograph. If we shoot a number of rounds across the chronograph, each with an "appropriate for case size" powder charge increase, maximum pressure has been reached when the velocity increase plateaus.

This works pretty well, and for an example lets look at the numbers I got when I worked up a .308 load last week. Each subsequent round was loaded with an additional 1 gr of powder. I will not share the bullet weight or powder type, because I do not believe these loads would be safe in an off the shelf rifle.

45 grs - 2484 fps
46 grs - 2528 fps
47 grs - 2566 fps
48 grs - 2603 fps
49 grs - 2644 fps
50 grs - 2662 fps.

As we can see, the velocity rise from 49 to 50 grs is about half of what we observed from charge increases below this amount, indicating that 49 grs is the maximum load. There was no sticky bolt, excessive case head expansion, or brass flow to observe, any one of which can indicate dangerous pressure. Given the right circumstances, such as a lot of brass cases that are harder than usual, there might well be none of the warning signs we have been trained to watch for prior to crossing the pressure at which the firearm fails.
Click to expand...

Good theory, but it doesn't track with the published data or the data 444 posted earlier. It all shows a linear increase in velocity as charge is increased
 
And there lies the difference between data which has been projected from a ballistics program compared to data accumulated from shooting a specific rifle across a chronograph. In recent years I have determined the maximum safe loads in all my center fire guns in this manner.

The following is from Sierra -

"Every cartridge will have an efficiency range with a given combination of components. Once that range is passed pressures will increase sharply and velocity will increase minimally."
 
Boomer,

I always shoot over the chrono when working up loads but never found consistency with this method. I most often see minute ejector marks before encountering any significant velocity plateau. Is it possible that this is case size/pressure curve/burn rate related? I have seen evidence of plateaus in my 223, 308, and 416 Rem.

What do you think?

As a side note I reviewed a copy of Quickload at a buddy's place. My buddy is a serious (anal) benchrester and record keeper so we compared his actual notes to Quickloads predicted velocity's. Suffice to say that while Quickload is surprisingly accurate it is not perfect.
We found Quickload velocities consistently to be anywhere from 20-70fps slow. When made adjustments (I think it is called a weighting function) the velocity was closer but then we ended up with optimistic velocity with certain primer changes or bullet length changes. Certainly one should not quote Quickload velocities as absolutes.

Overall I found Quickload very useful although on the conservative side (a good thing) and will probably buy the software for myself. It is a very useful computer modeling tool...No more no less.
 
A 378 prone...hmmmmmm i just might be up for that one eh Prosper!!! You have seen how my 9 pound 416 rigby recoils from the bench and how it jars me into next week,or the 460 weatherby that MTM used to own...off the bench of course.

The 378 prone would probably be in about the same category...:D

Oh looky here 458 posts with this one...so do i get a free .458 so i have a pair of them???
 
444shooter said:
Ok, I will supply the rifle..ammo and camcorder. Who wants to do the shooting? :D
Click to expand...

Sticks and stones will break my bones but 378's excite me.......I'm in! :D:wave:

We could make videos just like Accurate Reloading. Only we would show brave lads having their shoulders pounded into the dirt and nasty scope cuts instead!

Any other suckers?:evil:


icehunter121
I would wait until post 505 to ask for my token rifle!
 
I have only been hit 19 times by scopes now and have a scarred up forehead to show for it. but by far the worst was i took a buddies 378,took the brake off it and promptly took a 6x redfield steel scope to the forehead. I got a full circle from that one and was bleeding real bad but shot the whole box of ammo off after that.....hard to do with blood streaming into your eyes though...:D:D
 
icehunter121 said:
I have only been hit 19 times by scopes now and have a scarred up forehead to show for it. but by far the worst was i took a buddies 378,took the brake off it and promptly took a 6x redfield steel scope to the forehead. I got a full circle from that one and was bleeding real bad but shot the whole box of ammo off after that.....hard to do with blood streaming into your eyes though...:D:D
Click to expand...

Hehe, wanna re-enact that? Mine has no brake and a nice sturdy Zeiss 3-9x on it.

I have only been hit once by a scope. It was a Savage 110C in 7mm RM and good thing I wear glasses. Pencil thin barrel and a cheapo Bushnell Sportview scope. All I remember was a bright orange/red flash and my glasses shoved into my face :D
 
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