TheOtherErik Posted April 4, 2004 Share Posted April 4, 2004 Just started using imr 4756 and gone through a few 1/2 pound cans with good suscess untill now. The tail end of one can was left in the powder measure . Opened up another and poured it in. Threw a few charges, right on the money where I left it. 100 rounds later...check the charge weight, one grain low?!?! Check again same.... bust out the old beam scale thinking my digi went belly up. same... one grain low. My load is 8.8g of 4756 under a 124 and which filled a super case to about 1/8'' below the top. I adjusted the powder measure to throw the same chage weight that I had started with and it filled the case right up to the top. So, were my first two cans heavy with mositure or is my new can of powder jacked? The first two cans were pretty consistant but the third was way off. what gives? I've never seen any powder varry this much lot to lot. Link to comment Share on other sites More sharing options...
shred Posted April 4, 2004 Share Posted April 4, 2004 4756 is notorious for lot-to-lot variations, though I've never seen a swing quite that wide. Link to comment Share on other sites More sharing options...
TheOtherErik Posted April 4, 2004 Author Share Posted April 4, 2004 4756 is notorious for lot-to-lot variations, though I've never seen a swing quite that wide. Mostly you hear of velocity differences, not density. Now I'm leary of buying large quantity. I could end up with 5 pounds of somthing that I can't reproduce my origonal load with. Link to comment Share on other sites More sharing options...
shred Posted April 4, 2004 Share Posted April 4, 2004 Yeah, I've seen pretty large density variations, but nothing that would overflow a Super case with 9.1gr (some come very close though) I have had OK luck with "close" lot numbers being pretty consistent from one to the other. Link to comment Share on other sites More sharing options...
Too_Slow Posted April 4, 2004 Share Posted April 4, 2004 I had one time when I was loading 44 Mag with 2400 and when I changed Lots on the powder it changed by 1.9 to 2 grains for the same charge volume. Now thats a scary change on 240 HP's. Luckily I caught it... FAST and did not need to dump any rounds. Link to comment Share on other sites More sharing options...
TBF Posted April 4, 2004 Share Posted April 4, 2004 Wonder how much of the diff is due to humidity ? I once did an experiment with Blue dot, and found it indeed does suffer from " water retention " under extreme conditions. Travis F. Link to comment Share on other sites More sharing options...
Bill Schwab Posted May 14, 2004 Share Posted May 14, 2004 I've had to pretty interesting things going on with 4756 lately. In early winter I started load development for my Open Gun I decided to just go with 4756 becuse it's locally available, whereas nothing else that is worthy of Supercomp Major loads is. So anyways, I'm using Starline brass, WSR primers, Zero 125 JHP and 1.250" OAL. In early winter my 170 PF loads settled out at 8.85 grains of 4756, no pressure signs. Okay, so fast forward to now, I have since opened a new 5 lb can of 4756 and I decided to chrono my ammo, just to check it. The ammo is not making major. I bump up my load little by little until I get to where I am now: 168 PF (which is a little too close to 165 for me, I like to not worry when getting chrono'd at a match), but this is with 9.4 grains! Everything else has remained constant: gun set-up, die settings, powder storage environment. Well, okay, the weather that I'm chronoing in is hotter, I think most powders increase pressure, and thus velocity, with temperature. So to make a long story even longer I concur with the statement that 4756 has huge lot to lot variations. Link to comment Share on other sites More sharing options...
Patrick Sweeney Posted May 14, 2004 Share Posted May 14, 2004 I can't lay hands on my powder books right now, but isn't 4756 a shotgun powder? In which case the manufacturer is looking to reproduce a certain power level for a given volume, weight being a secondary consideration. If so, it is also engineered to be burning at something like 12,000 to 14,000 psi, not the 35+ we'd be running in a Super. Be glad it works at all. But switch to something else or be certain you're buying powder from the same production lot. Link to comment Share on other sites More sharing options...
redmercury2 Posted May 14, 2004 Share Posted May 14, 2004 switch to one of the VITTY POWDERS fast 340,350,3n37,3n38,105 all work well and consistently with 115s and 124s . Link to comment Share on other sites More sharing options...
sargenv Posted May 24, 2004 Share Posted May 24, 2004 I can't lay hands on my powder books right now, but isn't 4756 a shotgun powder? In which case the manufacturer is looking to reproduce a certain power level for a given volume, weight being a secondary consideration. If so, it is also engineered to be burning at something like 12,000 to 14,000 psi, not the 35+ we'd be running in a Super. The thing is yes, 4756 IS a shotshell powder but then so is clays... (did you ever wonder which "clays" they were thinking about?) Almost all of the powders that we burn for pistol have some correllation to shotshell powders. The bullseye, red dot, green dot, select, unique, herco, blue dot, and 2400 powders are all utilized in some way for shotgun gauges from 10 gauge down to the .410 as are the Hodgdon line of clays, Univ clays, International clays, titegroup, titewad, HS6, HS7 and H110 in some capacity. In the IMR line there is 700x, 800x, PB, 7625 and 4756. I'm sure you could use some of the VITT powders as shotshell powders as well as some of the Accurate arms powders. You'd probably get good results with the VITT powders though it would be pricey.. (imagine using 18-33 grains of powder per shell of that stuff at $20+ a pound). When you read the data manuals, they say in there that you SHOULD back down 5-10% of your powder charge and work back up when changing LOTS of the same powder. This comes mostly from Rifle powders and inconsistencies, but it applies as well to the higher pressure pistols that all of us shoot here. I tend to buy all of my powder in a minimum can size of 4-8 pounds unless I'm working up a load. Fortunately, I load shotshells as well and if I buy a larger can of powder that I turn out not to like in my pistol(s) I can then turn around, and find data for my shotshells and burn it up there. I've had powder given to me by people who wanted to try something only to find they couldn't use it/didn't like it and I turned around and made a small run of shotshell loads that worked for me. That's the way I see it anyway.... Vince Link to comment Share on other sites More sharing options...
eric nielsen Posted May 26, 2004 Share Posted May 26, 2004 IMR 4756 is a powder that gives a lot of different Open pistol shooters a lot of different headaches and hassles. If you use it without any trouble, count yourself lucky. Anyone remember Blue Dot? Link to comment Share on other sites More sharing options...
kdj Posted May 26, 2004 Share Posted May 26, 2004 I'd been thinking of trying 4756 but I've been put off! The idea of not being able to trust that I was in the same ballpark from batch to batch just wouldn't work for me. I need life to be simple OK - so back to considering VV N350, 3N38 and maybe TrueBlue for the new gun. Choices, choices ... Kevin Link to comment Share on other sites More sharing options...
Steve RA Posted February 6, 2012 Share Posted February 6, 2012 If you buy quite a bit at the same time the odds are you will be able to use the same load data for a long time. Just be sure if it is in multiple containers that it is the same lot #! Link to comment Share on other sites More sharing options...
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