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Joined: Jul 2001
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Like all of the Extreme line of Hodgdon powders, Benchmark is very temp-resistant.


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John Steinbeck
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Definitely would prefer to have everything just as it would be hunting. True cold bore shot. In the end, as long as it hits in the same place I'm happy.

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MD - I see a similar powder book to accompany your bullet book.

You have access to real pressure equipment and a wide range of temperatures. "The Definitive Study of Powder Characteristics" should hit shelves in early 2013......... wink

Seriously, this book needs done and can be updated every few years as powders change. Heck Winchester powders would keep you in material forever at the rate they introduce/discontinue powders. I would work for free in any capacity necessary to put it together.


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As John said Tac and Big Game are very temp consistant because they are ball powders made first for military use in 7,62x51Nato and other rifle cartriges like 5,56x45Nato with heavy bullet (Tac). They are made in Belgium in Poudrerie de Clermont a plant who belong to the French SNPE and they use a modified Olin brevet. The plant was put at work during the cold war. They even make one very slow ball, slower than Magnum for use in 338Lap and .50Bmg.

The only differences between cilivian and military powders is a conservation product that allows 50years stocking in military wharehouses. May be today this thing is no more real because of the quantities of ammo burn in wars for ten years....
RL15 is from Swedish Bofors company (have good ties with SNPE and Vitahvuori and works together in powders and explosives business).Some batches are used for US military ammo in 5,56x45, not same name but same powders. It seem to be a bit less temp variation resistant, but nothing to brag about.
All the best
Dom



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Results are preliminary and, to me at least, a bit of a surprise. I have produced only one 3 round group, on a trip to the range this last Monday (temperature 18.7 degrees C). 63.5 grains Big Game, COAL 3.315, 250 NAB, WLR primers, new Lapua brass, 100 meters, avg velocity 2402 fps, 0.857 inches centre to centre.

I'm now stimulated to try and reproduce this pleasing result, which is one of the better groups this rifle has produced. After much fooling I am getting right around an inch plus or minus with 58.5 grains of Varget and ~2400 fps. Best ever group, but again preliminary, is 57 grains of RL 15 behind a 250 grain TSX loaded to 3.291 COAL at ~2150 fps according to the chrono, which measured 0.58 inches centre to centre (3 rounds).

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Genehunter,

To tell the truth, that sounds like a typical 9.3x62! I've loaded for several, and they've all shot very well.

Those loads match traditional velocities with the round, and will definitely work well in the field.

They can also be pumped up a little, if you don't mind the extra recoil, at safe pressures.



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The rifle does seem forgiving!

I found some of your suggested loads on-line. I will play with these, exercising appropriate caution. Thanks for these...very helpful. I am getting to the point where the case is rather full, so would imagine I am nearing the top end...

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I see most of the conversation is directed toward cold weather sensitivity. How about hot weather? The prairie dog towns get pretty warm in the summer. I switched to H-322 from H-335 for that reason in .223, and have moved to Big Game from H-414 in .22-250 loads with good results.


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The powders that show less sensitivity to cold also are less sensitive to heat. It's different, though. I have tested a number of powders that didn't lose any velocity from 70 F. down to zero, but above 70 they ALL gain some velocity--which means that pressure also increases. The temp-resistant powders just don't gain as much.

I have seen some real wonky things happen with tradition ball powders on prairie dog towns in July. Those tend to be the most heat-sensitive powders of all, and I have actually seen a few rounds "cook off" when the shooter ran a cartridge into the chamber of a hot barrel and then paused to looked for a dg to shoot.

Haven't seen that happen with any of the newer temp-resistant powders.


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Well, I didn't have one cook off, but I did get some sticky bolts after some .223 rounds with H-335 rounds got hot! I have not had the problem with H-322, TAC or Big Game. I have also gotten the best accuracy ever out of my Kimber Varmint .22-250 with Big Game under 50 and 55 gr Ballistic Tips - many 3 shot groups under or at 3/8 inch.


�That rifle on the wall of the labourer's cottage or working class flat is the symbol of democracy. It is our job to see that it stays there.� George Orwell
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Big Game is a GREAT powder in the .22-250--and the .220 Swift.


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I have done a fair amount of 'testing' geared towards temp sensitivity in a cool to hot environment. I don't get much opportunity to shoot at sub-zero temps but I can shoot at temps over 100 degrees all summer long.

I would load and test in 40-60 degrees and then retest in 100+ temps. Some powders are pretty poor in this regard ie. H870, H450 and IMR 4064.

I found the Ramshot powders to fair very well in this environment. I have used them quite a bit and nearly always 'try' them to see if they work well. I use TAC more than anything else in that burning range. I use it in .222 through 30-30 and many things in between. I use Big game in 22-250 and 220 Swift. It is the only thing I like better than 4064 in 220 Swift!

I don't think Hunter is as good as the others and certainly not as good as Magnum as far as getting good velocities compared to similar burn rate powders.



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I haven't tried it yet, but Hunter looks like it would be good (velocity-wise) for the 85 gr TSX in a .243. When I get time, I intend to play with that combo a little.


�That rifle on the wall of the labourer's cottage or working class flat is the symbol of democracy. It is our job to see that it stays there.� George Orwell
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