Changing conditions

T

tiny68

Member
I have been working my loads for a 30BR. I found my optimum charge at 33.5 gr of H4198 with 125 TNTs and 125 Bergers. I shot this a lot in August and September when temp was running in the 80s and 90s and found a tune that shot pretty good for a Savage with a Douglas barrel (high 0.2s and low 0.3s) with a rookie behind the trigger. I had some work done on the action. I made up some loads and went and shot today. I don't have everything I need yet to load at the range, so I pre-load. My 0.2s and 0.3s turned to 0.5s - 0.7s with todays 40 degree temps. How much can the change in temp effect the group size? Can it make it double of even worse? I have shot a couple of load latters and they clearly show were the nodes were back when it was warmer. But where at they today? I wish I had shot a latter today.

Thanks for a continuing education, tiny
 
What twist? With the slower twists those long slugs are on the edge of stability.
 
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Tim brings up a good point.

On a different note, many of us believe that 'tuning' is velocity-specific. To follow this line of logic one must take the time to load for cold/hot weather conditions such that you maintain a specific velocity.

In other words, if you were shooting 3000fps @ 80-90 then you'll probably have to add a little powder to maintain this velocity in the cold weather. REMEMBER THIS!!! If you shoot all winter in cold weather and have some of these loads left over and you bring them out on a 90* day....... watch out! They may well run wildly over-pressure.

al
 
Its a 1:16 twist

I don't think its a stability issue. It is a 1:16 that will stabilize 150 SMK. I had my chony with me today but it really cloudy and my chony only likes sunny days. I will shoot again with a charge latter and the chony and see if my groups come back.

I have been a fair weather shooter and usually stay home when the weather isn't warm and sunny. However, I want to learn this game so I intentionally shot in the cold and wind today.

Also forgot to mention this was the most vertical I have ever seen with this gun. Pretty sure it is a tune issue.

Tiny
 
Tiny,
Any chance the weather brought out more clothing that could have made contact with the rifle? I have a savage 30br and it seems to be very sensitive to how I handle it in the bags (I am also a rookie shooter). I wouldn't rule out the tune thing either though. Sounds much more likely.
Mike`1
 
Better notes..... changed lots of powder

I realized a part of the problem. I just switched to a new bottle of H4198. I actually brought an 8lb bottle but I re-filled my old 1 lb bottle from the new stuff. Way different lot numbers. I should have remembered this. :(:( I am a little slow so times. That explains the heavier than normal bolt lift.

tiny
 
tiny68 said:
I realized a part of the problem. I just switched to a new bottle of H4198. I actually brought an 8lb bottle but I re-filled my old 1 lb bottle from the new stuff. Way different lot numbers. I should have remembered this. :(:( I am a little slow so times. That explains the heavier than normal bolt lift.

tiny
Click to expand...

LOL!!!

You got a liddle lucky you didn't bust a primer! :)

al
 
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