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Velocity differences between powder lots

Texas

Silver $$ Contributor
I've been shooting an 8 pound jug of H4350 for years now. Just finished it and bought a new jug. I was hoping I could simply replace the old load but am getting substantial difference in velocities. Over 100 fps with same charge. Anyone else find this to be true? Also, have you ever switched to a new lot and had to completely change the load? This is a bit frustrating, I had 2 guns that shot extremely well and had drop charts that were exactly on. Seems like I'm starting over.
 
Just had the same happen to me... New batch of RL25 for 7WSM and Mv climbed just over 100fps on a load that I have used for at least the last four years.
 
I have ran into this with multiple powders, and I consider it par for course to work up loads for different lots of powders.
 
I have three 1# bottles of H4350. All different lot numbers. There is over 100fps difference between all three. I ended up just mixing them together and work up a new load from there. It pays to buy the large bottles.
 
Darn.

Just now getting more Varget and H4350. I know the trouble with Varget. I mix an 8# jug with any 1# bottles I happened to get. Did NOT know that was an issue with H4350.

Interesting.
 
I had 2 #8 jugs of H4350 and worked up loads for a new rifle with the first jug. I found I could get up to 43.0 grs in my .260 without any pressure signs but to keep from having any problems during a match I dropped down to 42.5 grs however after I got down to the bottom of the jug I started getting pressure signs and had to back down to 42.2 grs so I wouldn't trash my Lapua brass. I finally finished that jug and started on my second jug same lot and lost 50 fps. It SEEMED like I changed pressure during the use of the first 8 lb jug but for sure lost speed after starting the second. I've got less than a 1000 rounds on this barrel so I doubt that it took a 50 fps dump all of a sudden. I'm thinking about loading larger batches at one time and running them over a chrono to get a better MV to use during a match.
 
I had 4 -8# 2 of the same lot and 2 were different lots . Between the three lots had 12 FPS difference. With a clean 5 gallon pail and some hard shaking & mixing. Now I have 32# all shooting the same speed.

Varget had 55FPS difference.
Sounds like you may of had a pressure ring. Larry
 
savagedasher said:
I had 4 -8# 2 of the same lot and 2 were different lots . Between the three lots had 12 FPS difference. With a clean 5 gallon pail and some hard shaking & mixing. Now I have 32# all shooting the same speed.

Varget had 55FPS difference.
Sounds like you may of had a pressure ring. Larry
Primer lot's can Vary 5 FPS also
 
Its pretty normal for competition shooters to test this stuff when changing batches of components. Load back to your existing velocity and accuracy will be back to normal. It shouldnt affect seating depth or primer choice but you will have to confirm it.
 
IIRC, the powder companies spec about a 10% burn rate spread, so as was said, always check your load with a new lot, especially if it's a warm to hot load.
 

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