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Joined: Feb 2003
Posts: 3,382
Campfire Tracker
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Campfire Tracker
Joined: Feb 2003
Posts: 3,382 |
You mean this one?? For a long time I have wondered about how barrel length affected velocity. I had always been told you need a certain length barrel for certain calibers. I have read when folks compared one gun to another with different lengths but I always thought that was not an apples to apples comparision. So I did a few test myself. All these were Shilen barrels. I used the same brass through out the whole test. All weighed to with 1 grain. Bullets were tested on the Juenke machine. Powder charges were weighed to .1 grain. The same rest, chronograph, Redding press, primers all from the same lot, bullets for the same box, same lathe, same crowning tool, same cutoff tool, and each rifle done from start to finish on the same day. Ambient temperature was the same because I shoot from inside the shop. I held the rifle the same way on the rest every time. I shot ten rounds first to break in the barrel. Then cleaned with Sweets and fired one fouling shot. Then shot five rounds and took the average. I used a midrange load fron the Nosler book, not too hot but certainly not a reduced load. Here is what I got.
22-250 Hodgdon 380 34 grains Federal GM210M Remington brass 55 grain Ballistic Tip 27 inches 3469 fps 26 3451 25 3425 24 3407 56 fps from highest to lowest
270 Winchester Hodgdon 4350 54 grains Federal GM210M Winchester brass 130 grain Sierra 27 inches 3115 fps 26 3093 25 3071 24 3054 23 3035 22 3027 21 3001 114 fps from highest to lowest
300 Winchester mag Federal GM215M Winchester brass 74 grains of Reloder 22 180 grain Partition 27 inches 3055 fps 26 3031 25 3024 24 3003 23 2984 22 2960 95 fps from highest to lowest
340 Weatherby Federal GM215M 250 grain Sierra 81 grains Reloder 22 Wby brass 27 inches 2837 fps 26 2817 25 2809 24 2791 23 2777 22 2755 21 2731 106 fps from highest to lowest
I think I will do a little more thinking before I recommend a barrel length in the future. What do you folks think ? Charlie
Here is the info about the 338 Win and the 257 Roberts. 338 Win mag Winchester brass Federal GM215M primers Reloder 19....73 grains 250 grain Partitions 27 inches.....2806 fps 26 inches.....2787 fps 25 inches.....2761 fps 24 inches.....2743 fps 23 inches.....2716 fps 22 inches.....2697 fps 21 inches.....2676 fps 20 inches.....2656 fps 150 fps from 27 inches to 21 inches
257 Roberts Federal GM210M primers Remington brass H-4350....45 grains 120 grain Partitions 27 inches.....2860 fps 26 inches.....2834 fps 26 inches.....2815 fps 25 inches.....2815 fps 24 inches.....2798 fps 23 inches.....2775 fps 22 inches.....2760 fps 21 inches.....2739 fps 20 inches.....2717 fps 143 fps from 27 inches to 20 inches I want to test this on the next 450 Marlin I build and on a 222 Remington. If I get the same results with those, in my mind the test is over. I think this will be enough data to support the findings. Are there any folks out there who have a degree in this sort of thing ? Maybe explain how many data points would be needed to be able to say this would work with the majority of calibers ? Someone with experience in statistical(spell check) quality control ? Charlie
A few weeks ago I done some testing with shortening barrels with various calibers. I just finished this test with a 300 Ultra. These loads were EXTREMELY HOT !!!!!!!!! I will not post the grains here because on the third loading the primer would fall out of the case . I never load this hot , only this time for the test. I used Remington brass, Federal GM215M primers, 220 grain round nose bullets. I used the same procedures as the last test. length.... H-4895 .....H-870 .....27 .....2740 .....3107 FPS .....26 .....2709 .....3088 .....25 .....2685 .....3062 .....24 .....2663 .....3046 .....23 .....2636 .....3018 .....22 .....2612 .....2997 H-4895 lost 128 fps H-870 lost 110 fps Charlie
Cancer Sucks
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Joined: Aug 2005
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Campfire Outfitter
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OP
Campfire Outfitter
Joined: Aug 2005
Posts: 10,759 |
Very interesting. Thanks.
A true sportsman counts his achievements in proportion to the effort involved and fairness of the sport. - S. Pope
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