300 rum standard deviation,HELP

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by timmyatnop, Aug 2, 2010.

  1. timmyatnop

    timmyatnop Well-Known Member

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    Hi everyone first time posting a thread,please bear with me .I have a rem sendaro 300 rum,my mv for my loads vairys mabey 45 fps from my fastist to my slowist.Iam using rem brass with 4 or 5 shots through them ,my gun loves 95 grs retumbo,with 210 vlds .5 moa mabey at 100 yards.I just annealed some brass and loaded some with different primers,havent shot them yet,is 45 fps to much deaviation. I wanna take this gun out to say a thousand yards ,but 45 fps difference seems like a lot ,that was for 5 shots ,anywhere from 3125 to 3170 or so ,does anybody have any ideas for me to try. Any help would be appreciated.
     
  2. bigbuck

    bigbuck Well-Known Member

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    I use federal 215 match primers in my .300 RUM and I shoot 210 bergers as well. I think the SD should be alot lower than that but I may be wrong I just shot my crony the other day so I can't say what my load is at this time but I have a nice group at 752 YARDS . My advice to you would be to start your load development @ 200 yards and once you have about an 1/2 inch group to 3/4 inch group ,move out to 300 and when it's nice in tight @ 300 go on out to 800-1000 yards Let the paper tell you what you need to know . my crony was the biggest lyer that i've ever seen . Not exactly what you was looking for but I atleast took a stab at it:)

    Just my opinion.

    Just noticed that this is your first post congrats and welcome to LRH someone thats a whole lot wiser than i will chime in hopefully......

    BigBuck
     

  3. kiwi3006

    kiwi3006 Well-Known Member

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    Running your load, 3125 from a 100yd zero gives 226.5" drop at 1000 yds, 3170 gives 219.1" drop at 1000 yds. So yeah you will need to get the extreme spread down to shoot out to 1000 yds.
     
    Last edited: Aug 2, 2010
  4. LongBomber

    LongBomber Well-Known Member

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    What are your groups like out at 300-400 yards. Shoot it and see what the vertical group size is. There are many things that can a do go wrong with chrony's all the time. 45fps is quite a bit of velocity change, especially if you are trying to go out to 1000. FWIW I load 95gr retumbo behind a 200gr partition with CCI primers in Nosler brass, this load holds under 0.3moa vertical.

    Is there any reloading steps that could be giving you this variation? Are you using a good digital scale? Varying powder charges will contribute to velocity differences.

    Shoot at 300 yards and try and get your loads to group under half MOA for vertical size. Try going up and down in .2gr increments, and you will find the sweet spot.
     
  5. Chas1

    Chas1 Well-Known Member

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    Welcome, glad to have you here. Lots of good folks and lots of good info. You mentioned .5 moa @ 100 yards...so at first glance one might think such wide spreads in MV are attributed to a faulty chrony, however IMHO I think you should take it out further where if you do have significant MV spreads it'll be more apparent...then again maybe at greater distances the .5 moa may hold up in which case you may have a faulty chronyor groups open up and bear out your chrony readings in which case it could be your loads or something else. Let us know how it goes at greater distances. Enjoy.
     
  6. Chas1

    Chas1 Well-Known Member

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    That's still no reason to shoot your chrony:D.

    Seriously, sorry to hear you shot it...is it beyond repair or just need a new screen or something?
     
  7. bigbuck

    bigbuck Well-Known Member

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    I posted pics of it in a thread titled 752 yard 3 shot group . You can take a look at it there . I don't know if i can fix it or if I should just hange it on my reloading room wall to get grins and giggles from all of the deer slayer friends that come over to visit :D .

    How I found out that it lied was I used my NF software to correct my drop and match up with my real world data . I'm kind of leaning towards just matching my drops with the real world data that I gather from the target and adjusting it with my NF SW if that makes any since ....

    BigBuck
     
  8. timmyatnop

    timmyatnop Well-Known Member

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    Thanks for the advice ,iam gona shoot it at a 300,600,and 900 the first cool day we get here .I will proubly give it 5 minutes between shots, I will let u all know how it did, might be a while before i get back though,wish we would get a cold front or somthing.Oh one other thing iam gona borrow a friends chrono too ,and shoot through them both and see how close they are. THANKS AGAIN FOR THE ADVICE IAM SURE I WILL NEED MORE IN THE FUTURE.
     
  9. BobbyL

    BobbyL Well-Known Member

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    There is a few things that might help. I found that getting neck thickness correct is key when it comes to getting low SD's. I replaced the pilot on my case trimmer with a neck reamer. You can tell quickly if they are doing them all the same or not. Im surprised that your got that many loads out of them i found mine blew out primers pockets way to quickly no matter what the load was.

    When i start my load development for larger calibers i look for a low SD before i do anything else. That is if im planning on shooting it long range. Next i found it useless to do load development at anything less then 300 yards and at that i do mine at 500 or farther. It just doesnt tell you anything when you dont do it at a longer range. The groups will vary from doing fairly well at both 100 and 500 to going from .25 moa to well over 1 moa. Its just hard to tell unless you do it at longer distances. Further more finding the right seating depth means a lot.