jump to lands

Discussion in 'Reloading' started by rclouse79, Oct 4, 2010.

  1. rclouse79

    rclouse79 Member

    Messages:
    17
    Joined:
    Apr 12, 2010
    I fear I am quickly becoming the annoying rookie who asks too many questions. I appreciate all of the replies I have recieved so far. I took some previous advice and bought a hornaday oal gauge and bullet comparator. I loaded a bullet that would just fit into my magazine and compared its length to the max oal I got from the gauge. I found that the the longest bullet I can fit in the magazine is about .050 from the lands. In the manual that came with the oal gauge it recommended .04 to .02 jump for better accuracy. I am thinking about loading some bullets that are too long for the magazine just to shoot at the range to see if they are acutally more accurate.
    I don't have a super fancy custom gun, but I did do a fair amount of research before buying my tikka. It seemed that most people claimed great accuracy with the gun out of box. I assume that the majority of them were shooting ammo that would fit in the magazine. My question is do most people find a significant increase in accuracy when they seat the bullet closer to the lands? I was also wondering if there are any tikka owners out there and what they have found to be successful. It just seems hard for me to understand why if .04 to .02 or less was the agreed upon rule, a gun maker would limit shooters by making the magazine too small.
     
  2. mo

    mo Well-Known Member

    Messages:
    432
    Joined:
    Mar 5, 2006
    You need to just try them loaded to fit in your box first. You might find you get great accuracy that way. I don't a agree with .04 to .02 statement. I know you don't sort bullets, but if you did you would see not all bullets are the same length, so at .04 to .02 you might have one bullet touching the lands, and another not. Look at the sticky right above your post, it is a great article on Berger bullets, but could relate to just about any bullet. http://www.longrangehunting.com/for...accuracy-berger-vld-bullets-your-rifle-40204/
     

  3. woods

    woods Well-Known Member

    Messages:
    965
    Joined:
    Jun 4, 2006
    I'm with mo, seating depth is very seldom the dominant factor in accuracy. I reload for over 40 different rifles and have found accuracy from .160" to .020" off the lands.

    If you are really intent on loading close to the lands then you can try different bullets with ogive shapes that will get you closer. Typically a round nose will greatly reduce your jump but we don't want to shoot them because of the low BC. Heavy for caliber TSX's typically can be seated closer. The plastic tipped and long noses on VLD's will set you back on your jump to the lands. IOW if you are looking for terminal performance only then try some Protected Point Partitions and you will be able to seat close or even into the lands.

    For me I will start at .030" for normal cup and core bullets and .050" for monometals like TSX, GMX, E-Tips etc. Vary your powder charge, case prep, primer selection etc and you can find accuracy at almost whatever seating depth you choose. There are many rifles that shoot factory ammo in rifles like Weatherby's and Ultra Mags that have huge jumps and still manage to shoot 1/2 MOA or smaller.
     
  4. zupatun

    zupatun Well-Known Member

    Messages:
    308
    Joined:
    Jan 6, 2005
    Best accuracy load for my old Tikka T3 varmint 308 was a 2.80 COAL 175 SMK fed match primers with 41.5gr Varget. 10 shot group of 3/4"--one ragged hole. This is 0.07 from the lands in my HOWA 308...I don't know how far from the lands in the Tikka, but I didn't worry because the Tikka didn't have room for a longer round.

    My Howa should allow me to get closer to the lands than the tikka, but I'm not there yet..still trying to find the optimal charge weight first...

    Didn't worry about jump but it barely fit in the plastic mag.
    Matt
     
    Last edited: Oct 5, 2010
  5. specweldtom

    specweldtom Well-Known Member

    Messages:
    1,066
    Joined:
    Jun 7, 2004
    What they said!!! Bullet jump is all over the place. Benchresters usually seat into the rifling, not just on it. But Weatherby boomers have around .250" freebore, yeah, about 1/4". Iv'e seen two .30 x .378 customs (with factory dimension chambers) shoot 5 shots under 1/4 moa, so freebore sure didn't hurt them.

    Couple of things to remember. One, as you approach the rifling, at some point the same load will start to increase in pressure, and two, some bullets like being into the rifling, and some don't.

    If your rifle is for hunting, you want ammo that will go in the magazine. Start there, and only go to single loaded ammo as a last resort. If you have a good rifle, you will find that it will shoot something that will fit in the magazine.

    Good luck and good hunting, Tom
     
  6. cva54

    cva54 Well-Known Member

    Messages:
    297
    Joined:
    Dec 24, 2007
    I am going though the same thing with my 700 .06 I just pick up one of them RCBS precision mic's. Just got back from the range didnt work to well. I started at .010 jump thinking about .015. What do you all think.
     
  7. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,264
    Joined:
    Aug 10, 2003
    In contrast, I cannot think of any single thing that has a larger affect on accuracy than seating depth. Maybe this thinking applies out there at 1moa+, but you can't just pick any old seating depth and work your way below 1/2moa. You'll need to identify the BEST seating for your bullets/barrel.
     
  8. woods

    woods Well-Known Member

    Messages:
    965
    Joined:
    Jun 4, 2006
    Hey Mike

    In several of my rifles that is exactly what I have done. IME any difference in group size that you can get by varying seating depth you can also get by varying the powder weight minutely. Exact case prep like consistant seating depth and bullet release will keep your groups small.
     
    Last edited: Oct 6, 2010
  9. cva54

    cva54 Well-Known Member

    Messages:
    297
    Joined:
    Dec 24, 2007
    here is what I got. 30.06 Using 150 gr FMJ/BT hornady trimed to 2.484 49.0 gr BLC-2 powder coal 3.193 it shot a moa. In the mean time I got seating depth gauge So now with 165 gr SP/BT sierra every thing els the same. I checked the FMJ and set up the 165's with the same seating depth 0.010. I all so loaded some up with IMR4350 48.0 gr. Like I said didnt work so well 4"moa. ANY input would be great yes I am new at this
     
  10. specweldtom

    specweldtom Well-Known Member

    Messages:
    1,066
    Joined:
    Jun 7, 2004
    CVA, I shot a Rem 700 stainless .30-06 about a month ago that was putting the factory 150gr Rem ammo into 1" AT 100 YDS. I don't know what their load is, but it's their cheapest factory ammo, so nothing special. This doesn't mean your rifle will do that, but it might be worth trying! You'd end up with 20 rounds of brass at worst.

    Unfortunately, I have found that most factory rifles don't shoot but 2-3 moa. Every once in a while, you find one that will shoot 1 moa, or sometimes better. Not the norm though.

    Good luck, Tom
     
  11. Mikecr

    Mikecr Well-Known Member

    Messages:
    4,264
    Joined:
    Aug 10, 2003
    This is a 'long range hunting' site.
    Accuracy for this is not what you FIND in a shooting system, but what you develop.
    It's not what you GET merely cutting checks, or haphazardly failing in every regard.

    "Hey Bob, I tried this and it didn't work at all"
    "Jerry, the other day I tried that and shot terrible". "It's how guns are I guess."
    "Well fellas, I do anything under the sky, and it's always sun-shiny over here..."

    Is anything humanly achieved from such a progression(beyond perpetual voting in of Satan's finest)?
    NO
    You need to pick up & read a few books, think independently, develop a plan, and stay on it.
    Otherwise, you will never be a long range hunter. You'll be lucky to get your basic reloading badge..

    Off the shelf, 'good enough', isn't for long range hunting.
     
  12. cva54

    cva54 Well-Known Member

    Messages:
    297
    Joined:
    Dec 24, 2007
    FYI this rifle I am talking about I have had acurized/redone to shoot. It shoots sub MOA with factory win ammo. The same with MY hand loads in 150 gr FMJ it is a 1951 721 .06. If you all must know cut & recrown laped lugs reset head space set to 2.0487 replaced triger (timney). B&C stock floated. So there it aint the rifle! My 700 7RM shoots a base ball at 300 Y with my loads Yes I am new at reloading thats why I am asking. It sounds like some of you came out of your moms woom and started reloading and new every thing sorry thats not me
     
  13. Forester

    Forester Well-Known Member

    Messages:
    436
    Joined:
    Mar 23, 2008

    If your bullets are varying in length by twenty or forty thousandths then I think I would find a home for them in the trash.

    But for the OP, If you are familiar with ladder testing, I have had success with that method for figuring out seating depth too. If the gun shoots best with a length that does not fit the mag then just use it as a single shot. If you are shooting over a few hundred yards then it will never matter that you need to single feed.
     
  14. mo

    mo Well-Known Member

    Messages:
    432
    Joined:
    Mar 5, 2006
    Guess I shouldn't assume what I thought he was trying ask. He had is magazine measurement of .050. I thought he might have been trying to say 2 thousands .002 or four thousands .004. Sorry for assuming, and thanks for correcting me.