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338-378 & Powders

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  #8  
Unread 08-17-2009, 12:25 AM
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Re: 338-378 & Powders

David, I have seven 338-378's right now. Have been shooting this round since the 70's. Great cartridge for long range anything. H-870 has always shot best for me through the years with best velocity and lowest extreme spreads. Just varies a bit batch to batch so I order quite a bit at a time same lot number. Since Retumbo came out I have been working with it and getting very good results. Have never tried vito powders. In the 28" 1-10 Hart barrel I was shooting this evening I was pushing the 300's at 3050 fps, the 250's at 3325 fps and the 200's at 3615 fps. I have quite a bit of data on this round. All of mine are 28-30" barrels and the 300's all run between 3000 and 3100 fps depending on the rifle.
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  #9  
Unread 08-17-2009, 06:06 AM
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Re: 338-378 & Powders

Quote:
Originally Posted by David Long View Post
Am using 8lb containers, but burn rate is changing from loading tom loading out of same container. Has changed while sitting in loaded cases.
If you're "burn rate" is changing from shot to shot out of the same jug, I doubt it is the powder.
Did this just start happening?
If you're intent on using VV, then don't overlook 24N41. I use it in my .30-.416 Rigby Improved with excellent results shooting the 240 gr and 250 gr SMK.
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  #10  
Unread 08-17-2009, 07:39 AM
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Re: 338-378 & Powders

The H50 BMG and the H869 are both extreme powders and should be very consistent
in the 338/378.

Like joel Your problems may be some where else. I use a lot of these two powders and
get very consistent SDs and velocities.

J E CUSTOM
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  #11  
Unread 08-17-2009, 09:13 AM
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Re: 338-378 & Powders

This post was originally started by my Father, and l'm not sure you guys are quite understanding what he is saying. When we are loading with the Hogdgon powder, we are finding consistent velocities. However, the problem we are running into is this; lf we load 20 rounds and shoot 10 of them, the velocities are consistent. When we shoot the other 10 rounds at a later date, the velocities are consistent, but have increased by as much as 100 fps overall averages. This seems to be a problem with the guys in our area that are using hg powder, which is why he inquired about different powders. And we use 2 chronos connected in series, so are confident in our numbers.

l would like to say that l have been in a few other forums, and you guys seem to at least be knowledgable and worth talking to. Thanks for the intelligent replies.

Vince
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  #12  
Unread 08-17-2009, 09:55 AM
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Re: 338-378 & Powders

Bigdawg,

The loads I was reffering to that I shot yesterday with the 200 grain noslers were loaded 10 years ago with my pet load of H-870. Ten years ago they averaged 3615 fps. Yesterday they averaged 3615 fps. So that is not a problem with the H-870.
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  #13  
Unread 08-17-2009, 10:44 AM
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Re: 338-378 & Powders

We need more information to help solve the problem. When there is a fluctuation in velocity, is it up or down? What is the ES between shots between different days? Are you using cheap digital scales or old balance beam? Are you using a lube in the neck that is causing a chemical reaction? How are you storing the "other" rounds that are varying in velocity? Are you cleaning the barrel between different shooting sessions?

Do you have any fouling at the end of the barrel? The 40" barrel is excessive for this case, and you may be experiencing "slow down".

Are you're chronographs in 100% working condition and are they at the same distance from the muzzle every time?

I doubt that the problem is with the powder, since you stated that you had the same problem with H-1000 in other guns.

My guess is that the problem lies somewhere in your scales, powder storage, chronograph or primers...
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  #14  
Unread 08-17-2009, 11:22 AM
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Re: 338-378 & Powders

Hi Joel,
Thanks to all for the input. Let me say, I'm a real nut about this stuff. Consistent velocity, 8 to 12fps in 10 shots. Chrono always set up the same distance. Using the new RCBS Chargemaster scales. I'm quite involved with these biug guns as I build stocks & do all the bedding. Every gun we are using & there are 10 of us, is shooting 1/4 moa or better. Like I said, we have good chronos & I am only having this problem with 4 guns all of which is using H50BMG or H1000. Was shooting 30-378 'til 2 yrs ago. Not only does the chrono show increase in velocity, but cases show signs of sticking & pressure. Am running 2990fps and not wanting to work with max loads as I just don't need all that energy. Once I get velocity at 2990fps, the gun is super accurate. Any ideas you may have will be appreciated. No copper fouling. Gun don't go more than 15 rds without cleanup. Have been in this game for 35 years. Just got a new 8lb cannister of H50BMG for the newest gun I built this year. Can't really try it 'til I find some 300grSMK. I know burn rate changes from lot to lot, but never had this problem 'til about 2 yrs ago with Hodgden. By the way, powder stoted in controlled conditions, as well as Fed Match Primers. Both chronos, which are hooked up in series are reading 7fps difference and always show the increase.

Last edited by David Long; 08-17-2009 at 11:27 AM.
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