#1
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OT: saw my first major lot to lot powder variation
Finished up a pound of N160 this week and cracked open another one to shoot in my 22-250 behind some 80gr berger VLDs. I've read many times to start over with your load when you switch to a different lot of powder but i never really took that to heart........until now.
That is after I ruined 4 neck turned lapua cases tonight. I was shooting 35.6gr N160 this week into nice small groups and I ran that pound dry. So i broke open another one and moved down to 34.8gr and started to work back up. Couldn't find that node right away so i kept going 35.4 started feeling like a hard bolt lift. I've experienced this before but usually it was due to the fact that i run my cases tight and probably don't shoulder bump as often as i should. 3 shots into 35.6gr and I knew something wasn't right. Didn't get any noticable flat primers but the bolt lift got worst, I'm now getting a sharp crack at the top of the lift. The forth shot wouldn't open, I could not get it to crack. After beating it upwards and finally extracting the case i couldn't believe my poor brass survived that. You can't even hardly make out the words lapua .22-250 and my primer looks like it was smashed with a hammer. Viht shows a max load of 41.0gr with a 69gr sierra MK. I don't think this batch of powder would come close |
#2
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It happens often enough that it should always be a concern especially if the load is at the upper end of things to begin with. That's why I always buy favored powders in quantity . In sub .22 caliber rounds that spike pressure differently anyway we need to be particularly careful.
Glad ya only messed up a few cases.
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"Shoot safe!!" montdoug |
#3
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Lot variation
I had a lot of RL 22 that was a shocker just about 15 years ago. Good thing I always work my loads up. Some guy blew the guns up with that lot from what I heard.
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NRA Lifetime Member NBRSA Member |
#4
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Interesting report, thanks for sharing.
I haven't done enough reloading/shooting to get through any of my big jugs yet but this is something that I will definitely be aware of when I do. |
#5
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Interesting. I have always shot Hogdon and IMR powders and in 40 years I have burned a pile of powder. I have never seen a substantial difference in lot to lot, though I have read and heard about it many times.
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#6
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Bullets matter as well. Going from one lot to the next in bullets can change the relationship of the ogive to the lands which can affect pressure also. I've see one lot of bullets have an oal off the ogive that's 10 or 12 thou different than the next lot of the same bullet. That can take an oal from close to the lands to jammed in em with all the attendant pressure spikes that can cause . Whenever finishing one box of bullets and starting the next I measure seating depth before continuing loading.
Some call me a fanatic.....ok so a lotta folks call me a fanatic ....."BUT"! I always stay with same lot cases, primers, bullets and powders. Any variation of a load matters, some only in accuracy or consistency but some affect pressure to one degree or another. Powder lot variations probably being the most significant. Just the personal opinions of an old fanatic .
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"Shoot safe!!" montdoug |
#7
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One of the main reasons I NEVER EVER crowd max charges knowingly.
Only one I've ever blown up was that NEF .17x28 a few yrs ago when increasing just .2 of a grain. Been loading since 1958 14y/o. Quite a pile of jugs and old "kegs", can's as they used to ship it in before jugs came along.
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George "Gun Control is NOT about guns, it's about CONTROL!!" |
#8
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batch to batch variations
in loading for my 17A/H with Vit 120 i loaded up 12grs behind a 20gr V/Max now this is almost a full gr behind advertised loads and it got me 4,085ft/sec ,case head expansion rim expansion and a case jammed in the chamber so i finaly settled on 10.8grns for a vel of 3,637 ft/sec with that batch of powder
I have now finished that lot and started another batch and with ref to my ruined pants the first time i started at 10 grns and worked up in 0.2grn steps i am now up to 12.0 grns with no pressure signs at all but feel that i need to go up a little more to get it up to the 3,637ft/sec of my old load cause it drops a bit short at 160yds compared to the other one ( my crony is playing up again ) but accuracy is a bit better no doubt to the fuller case . Wally |
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