Same Powder Different Lot ??(Please read)

[bigbuck]

Last time I had shot long range was during the summer. I have all of my data recorded.

Rifle 300 RUM

Powder retumbo
Primer Fed 215M
210 Berger .
MV 2900 FPS
Now for my questions

1. I bought a new pound of Retumbo powder so what should I expect when I run the same MV into my ballistics soft ware, this being a different Lot ?

2. What about the Temp. change ? It will be colder when I try and shoot tomorrow than when I was shooting back in the summer ?

I will have all of my answers tomorrow but I just wnated to hear your experience .

Thanks for taking the time to read ...........,

 

[SBruce]

I haven't yet changed lot#'s with Retumbo, cause I bought 8#. I don't know what to expect when I change lots the first time either.
Interested to read what comes of this.

 

[barnesuser28]

i changed lots of retumbo in the 338 Lapua and had to go from 84.4 grains to 82.4 grains to get back to were there werent ejector marks and i got accuracy back. My velocity dropped 150 fps.

 

[nddodd]

There was a thread 3-4 years ago on here about this same thing on the same powder and the same thing happened new lot was hotter by a couple grains. That's why I always buy 8lb jugs, I know that doesn't help you much but if your gun likes retumbo buy 8lbs and drop down a couple grains and work your way up and hopefully you'll keep your velocity before pressure hits.


Nathan

 

[backwoods83]

If your old lot of Retumbo has a lot# of 5026 or lower it is the right burn rate, if the lot# is 5027-5098 your velocity will likely be higher or be the same with more pressure, I found this out in my 6.5x284, had to back off 1.5 grns and lost 30fps, so I went to another suplier and got a bunch of the older lot. The powder between the lot numbers I mentioned is closer to H1000 than Retumbo, about on par with RL25.

 

[JeffVN]

+1 find a lot that your rifle likes and buy 8# jugs, more than one if you can. The lot-to-lot variance is not isolated to Retumbo or H1000, but is also true for RL-25 (the three powders that I am most familiar with). When I get new jugs, I run them over the chronograph to match the needed velocity, if I can. I recall a major lot-to-lot variance problem with Varget a few years back also.

Jeffvn

 

[bigbuck]

Thanks for the replies. my impacts where high at 556 yards today .

 

[brentc]

If your old lot of Retumbo has a lot# of 5026 or lower it is the right burn rate, if the lot# is 5027-5098 your velocity will likely be higher or be the same with more pressure, I found this out in my 6.5x284, had to back off 1.5 grns and lost 30fps, so I went to another suplier and got a bunch of the older lot. The powder between the lot numbers I mentioned is closer to H1000 than Retumbo, about on par with RL25.

I just bought 5 lbs of 5026 made in December 2011. I hope it's similar to what I have been using.

 

[moombaskier]

I can't imagine only buying 1lb. of Retumbo for a 300RUM. For your bullet weight it's just about the best pick and if it has worked in the past do yourself a favor and buy it 8lbs at a time. You would also be better off to buy enough of your 210's in the same lot# to launch with that 8lbs. The Berger's can vary quite a bit from lot to lot too.

 

[backwoods83]

Brentc, I have a pound of 5026 lot# it is the same as my recent 3lbs of 4986 lot, its where it should be in my rifle.

 

[Cornfield Flats]

A person can't get away without chronographing loads with a new powder lot.

 

[bigbuck]

A person can't get away without chronographing loads with a new powder lot.

I have a CDM 2 I didnt chrono this new powder because I have found my chrony to say one thing and my actual field impact shows different . I would start with a chrony then let the software match my real world data as far as impacts on my target . I thought I would be close enough then select the target validation mode and go from there. just my opinion.

 

[meat head]

I haven't yet changed lot#'s with Retumbo, cause I bought 8#. I don't know what to expect when I change lots the first time either.
Interested to read what comes of this.

this may sound stupid as long as i have reloaded but where is the lot num. on the h1000 one can has a num. the other one doesn"t thanksgun)

 

[Dr. Vette]

this may sound stupid as long as i have reloaded but where is the lot num. on the h1000 one can has a num. the other one doesn"t thanksgun)

Here you go.
5023 is the lot number on this one.