Thoughts on IMR 4198....

jagermeister

Beginner
Jun 1, 2012
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I have been loading it in my Triple deuce and this powder has produced very good groups, both with 50 and 55 grain bullets.

Very fast powder, much faster than Norma 200.

I was wondering though and that's the reason I am posting here to get your opinions....

...I have got the impression this powder doesn't like high humidity too much...

Sayng so because, more than once, my super-tested BT55 load groups have "opened up" substantially in high humidity conditions, unlike the other two powders I am using in the same caliber (Norma 200 and Vihtavuori N133) which seem to hold their performance.

And I am talking...same rifle setup, same primers, brass, loading procedure and so on...the only variable being the Humidity factor....

What are your experience on this matter ?

Thanks
(y)
 
I have shot IMR-4198 in several calibers at the range and in hunting situations and have never noticed any change due to humidity. Rick.
 
I doubt that it is the powder. I would think it is more likely a generalised phenomenon observed with a wide variety of powders, much as barometric pressure, elevation, etc. affect accuracy of loads, making good rifles appear to have gone bad.
 
I would suggest that single based powders, like 4198, use graphite as a retardant to control burning rate. Graphite also serves the purpose of coating and waterproofing powders against attack by moisture. I makes sense that 4198 would be more susceptible to humidity than a slower powder with a much thicker graphite, retardant coating?
 
But the 4198s ate singles based, Charlie. I don't see how humidity could affect powder burn anyway. Powders contain their own oxygen for combustion.
 
RiverRider":2ufkdp95 said:
.....I don't see how humidity could affect powder burn anyway.......

Mmmmh...I'd say it does.... :mrgreen:

My impression was that 4198 was affected more than other powders I have used....
 
I stand corrected IMR 4198 is a single base. Anyhow is says in the MSDS that it will not polymerize, so how does it get sticky?

I think that I have having a senior moment? I guess almost all Dupont (IMR) powders are single based (nitrocellulose)? It is the double base that have Nitro added (Reloader powders). Yikes, I am losing my mind!
 
LOL! I can relate to that Charlie. I think I've moved from senior moments all the way through senior days and right into senior life!
 
Is it a wood stock? If it is maybe the wood is swelling with the higher humidity and causing things to move?
 
shoots_5":30zyqfh9 said:
Is it a wood stock? If it is maybe the wood is swelling with the higher humidity and causing things to move?

Yes and no..... :wink:

Yes. it is a wooden stock, but....

...no, it can't be because of that, since it's a break-open rifle and the small and tiny forend does not touch the barrel and, for sure, does not put any kind of pressure whatsoever... :wink:

(y)
 
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