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Rookie question

Guys, I have an exceptionally accurate 7mm-08 that I have been reloading for about 4 months now. To save money, and keep my buddies 7mm-08 brass and mine separate, I began resizing some old 308 brass down. Accuracy has went to hell in a hand basket. What I am wanting to know is if the 308 brass is the problem. I suspect it to be so, since all other load components are the same. Also, if it is the problem, why is it? Any and all help is appreciated. Thanks, Mark

Comments

  • mrbrucemrbruce Member Posts: 3,374
    edited November -1
    Brass lots can and will vary a lot weight wise... The new formed 308 brass is more than likely the problem because of that... If you still plan on using the 308 brass just rework the load data and all will be well again..
  • MIKE WISKEYMIKE WISKEY Member, Moderator Posts: 9,750 ******
    edited November -1
    ALSO CHECK NECK THICKNESS, .30 CAL TO 7MM SHOULDN'T MATTER THAT MUCH BUT..........
  • JustCJustC Member Posts: 16,055 ✭✭✭
    edited November -1
    quote:Originally posted by MIKE WISKEY
    ALSO CHECK NECK THICKNESS, .30 CAL TO 7MM SHOULDN'T MATTER THAT MUCH BUT..........


    that would be my first move as well. If the brass was thicker than the original 7-08 brass, your neck tension will have changed by a fair amount.
  • sandwarriorsandwarrior Member Posts: 5,453 ✭✭✭
    edited November -1
    quote:Originally posted by JustC
    quote:Originally posted by MIKE WISKEY
    ALSO CHECK NECK THICKNESS, .30 CAL TO 7MM SHOULDN'T MATTER THAT MUCH BUT..........


    that would be my first move as well. If the brass was thicker than the original 7-08 brass, your neck tension will have changed by a fair amount.


    Get the necks turned like I did. I am shooting Lapua .308 brass and that had a lot of hold on the brass when I sized it down. Turned the necks down .003". The neck of the chamber is so tight that I still don't have to resize the neck. I just punch the primer, brush the neck, reprime, powder, stuff next bullet. Accuracy is now running in the .2" range now instead of the .9"-1.1" range. Intead of .004" hold on my bullets I'm now getting .001" hold. It helped a lot.
  • Mark LeonardMark Leonard Member Posts: 31 ✭✭
    edited November -1
    Thanks for all the info guys. Now I have to decide whether to buy new 7mm-08 brass, or buy the equipment to turn down the 308 brass.
  • Okie743Okie743 Member Posts: 2,224 ✭✭✭
    edited November -1
    You might try weighing your brass hulls on your powder scale!
    I sort my brass within about 3 grains (+ or - 1 1/2 grains) weight for a hunting rifle when reloading!
    I keep it to within 1 1/2 grains when doing target testing and working up loads and also use same brand during testing! After I find a load that the gun likes with my selected match weight brass I'll load some of my sorted light weight brass and some of the heavy weight sorted brass and do a test and see if the guns groups shift in point of impact. (accuracy is related to consistency when reloading and shooting)
    Some guns will still group ok with light and heavy brass, but some fineky guns will produce a shift in the groups point of Impact on target!

    Some of the 308 brass can vary in weight by as much as 15 to 30 grains and the brass that is heavier has smaller case capacity internally and therefore this will appear as though you have increased the powder charge and if the gun is picky about your powder charge your groups will go erratic! I have proved this shift in Point of Impact numerous times to guys by sorting brass by weight, reloading the brass with the same load and fire test groups and see the groups point of Impact shift positions on a target at 100 yards, sometimes by as much as 2 inchs!
    Military type brass is also typically heavier weight!

    The first time that my 308 brass is reloaded I also check the neck Outside Diameter of all the hulls and make sure that the OD is not larger than reload manual specs! If OD is too much this is a heads up the case necks need turned!

    I also de-burr the internal primer hole on all my cases before range testing!

    Keeping a Heads Up and making (selecting) matched brass really helps my groups! (and really will reduce the number of them flyers that tend to mess up a good test group)
  • Mark LeonardMark Leonard Member Posts: 31 ✭✭
    edited November -1
    Keep it coming guys. I have reloaded for a while now, but have never weighed or turned the neck on cases because of ignorance on my part. Much more to be learned I guess! Mark
  • OdawgpOdawgp Member Posts: 5,380 ✭✭
    edited November -1
    quote:Originally posted by Okie743
    You might try weighing your brass hulls on your powder scale!
    I sort my brass within about 3 grains (+ or - 1 1/2 grains) weight for a hunting rifle when reloading!
    I keep it to within 1 1/2 grains when doing target testing and working up loads and also use same brand during testing! After I find a load that the gun likes with my selected match weight brass I'll load some of my sorted light weight brass and some of the heavy weight sorted brass and do a test and see if the guns groups shift in point of impact. (accuracy is related to consistency when reloading and shooting)
    Some guns will still group ok with light and heavy brass, but some fineky guns will produce a shift in the groups point of Impact on target!

    Some of the 308 brass can vary in weight by as much as 15 to 30 grains and the brass that is heavier has smaller case capacity internally and therefore this will appear as though you have increased the powder charge and if the gun is picky about your powder charge your groups will go erratic! I have proved this shift in Point of Impact numerous times to guys by sorting brass by weight, reloading the brass with the same load and fire test groups and see the groups point of Impact shift positions on a target at 100 yards, sometimes by as much as 2 inchs!
    Military type brass is also typically heavier weight!

    The first time that my 308 brass is reloaded I also check the neck Outside Diameter of all the hulls and make sure that the OD is not larger than reload manual specs! If OD is too much this is a heads up the case necks need turned!

    I also de-burr the internal primer hole on all my cases before range testing!

    Keeping a Heads Up and making (selecting) matched brass really helps my groups! (and really will reduce the number of them flyers that tend to mess up a good test group)


    That sounds like a lot of fun..[B)][:)]

    Everyone picks a hobby mine is shooting the reloading is only a means to an end. Summer is too short to spend it reloading and the winter months are to damm cold to be sitting out in the garage. The indoor range is heated [:p]

    I had similar problems with necking 308 down to 243, I turned the necks on a few and that helped. As long as I can hit the ram they are accurate enough for me

    Shoot on!
  • JustCJustC Member Posts: 16,055 ✭✭✭
    edited November -1
    I reccomend the K&M neck turning tool with the drill attachment that holds the shell holder. It makes turning necks very fast.
  • mbsamsmbsams Member Posts: 1,076 ✭✭✭✭✭
    edited November -1
    To check neck thickness, see if a bullet freely enters the fired case - all you need to buy is an inside reamer and put it in your drill. The KISS method is usually best. Take your "accurate" and "problem" cases to the range loaded the same on the same day. confirm that one batch is accurate and the other is not - I'll bet you problem is bases loose or scope.
  • Okie743Okie743 Member Posts: 2,224 ✭✭✭
    edited November -1
    quote:Originally posted by mbsams
    To check neck thickness, see if a bullet freely enters the fired case - all you need to buy is an inside reamer and put it in your drill. The KISS method is usually best. Take your "accurate" and "problem" cases to the range loaded the same on the same day. confirm that one batch is accurate and the other is not - I'll bet you problem is bases loose or scope.


    This guy is right on! You probably first need to confirm that your gun set-up is still accurate with what once worked for you!

    Keep a heads up and see if the flyers are always in same direction, like ALWAY in same direction and if so rotate the scope 90 degrees in the rings and if shift is 90 degrees on the flyers, it's the scope! Always check the base screws and if all this is ok, get some hoppes benchrest #9 and soak the barrel overnight then run a clean white patch through the bore and if it comes out severely green, the bore is copper fouled! Keep a heads up and do not soak the bore in the Ammonia based bore cleaners like Shooter choice! (read the instructions for the bore cleaner you are using! The Hoppes #9 is good to use as a indicator of copper fouling by showing the green or blue patchs!

    If your bases are loose or the scope is going bad, you will spend several dollars reloading and testing and many depressed hours trying to get the gun to produce a good group! I've seen several bad scopes such as Simmons, Bushnell and older model Redfields that would shift point of impact. Best to do a scope change test! Just keep a heads up
    for such![:0]
  • Mark LeonardMark Leonard Member Posts: 31 ✭✭
    edited November -1
    Scope and mounts are solid guys, I checked. I weighed my 7mm-08 brass today and got 19 pieces within 1.2 grains total variance, and loaded them. Now all i have to do is wait for a day to shoot and report my findings! I will also give my load info in case anyone has more suggestions. I am using CCI 200 primers, 37.5 grains of Varget, and 140 Sierra SBT in Remington brass. COAL is 2.785.
  • Okie743Okie743 Member Posts: 2,224 ✭✭✭
    edited November -1
    Good luck to Ya and have fun!

    You might also eventually consider getting a Lyman or RCBS case uniforming tool, lyman is about $15 for deburring and uniforming the brass INSIDE primer holes. This is a one time operation for the brass!
    You can review why, etc, from a google search!


    What make and model gun are you testing?
  • Mark LeonardMark Leonard Member Posts: 31 ✭✭
    edited November -1
    The gun is a Mauser 98 custom built for a friends dad, that I bought at their estate sale. It had less than one box of shells through it when I purchased it. It has a Timney trigger, custom wood stock, and 24" Douglas sporter barrel. My best group was just under an inch at 300 yards. At 100 it is less than .5". Probably the most accurate gun I will ever own except my varmint rifles(223 Savage Tactical and 22-250 Ruger MKII Varmint). My goal is to continue to tinker to see if I can achieve a one hole group at 100.
  • Okie743Okie743 Member Posts: 2,224 ✭✭✭
    edited November -1
    quote:Originally posted by Mark Leonard
    The gun is a Mauser 98 custom built for a friends dad, that I bought at their estate sale. It had less than one box of shells through it when I purchased it. It has a Timney trigger, custom wood stock, and 24" Douglas sporter barrel. My best group was just under an inch at 300 yards. At 100 it is less than .5". Probably the most accurate gun I will ever own except my varmint rifles(223 Savage Tactical and 22-250 Ruger MKII Varmint). My goal is to continue to tinker to see if I can achieve a one hole group at 100.


    You are a lucky dog!

    I own a 243 similar to yours and also had a 270! A guy seen me hunting and shooting the 270 and offered me enough to buy several newer type guns!
    Glass bedding the actions, floating their barrels, timney triggers and finding their reloading recipe was what really made them settle in on target with excellent groups!

    By glass bedding and floating their barrels I could remove the action from their stocks for cleaning and when I re-installed they were still on target! Seems to me a pressure point type barrel stock will usually slightly shift Point of Impact after the stock is removed and re-installed or have a tendency to drift off target more than a floated type barrel stock!
  • Mark LeonardMark Leonard Member Posts: 31 ✭✭
    edited November -1
    Shot the gun again yesterday, and best group was .5" 5 shot group, so for the most part back on track. I will keep tinkering and varying the load a little up and down, and have pushed the COAL up .015 to the recommended 2.80". It's plenty good for deer hunting right now, but tinkering with stuff is half the fun!
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