My Brain hurts....

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by ZombieHitman, Nov 19, 2010.

  1. ZombieHitman

    ZombieHitman Active Member

    Messages:
    36
    Joined:
    Nov 17, 2010
    Ok, gang, I've got a nasty case of information overload going on, and I'm hoping that a little intervention on your part will help me sort a lot of it out, help me make sense of it, and figure out how I can apply it to my needs.

    1) Ladder testing.
    I grasp the concept that by stepping the charge of a given powder/primer/case/bullet combination helps identify the "sweet spot" load.
    I don't understand how a chrony helps though.

    2) Barrel Break in...
    This gets tons of input, and the suggestions are as varied as the people that post them.
    My situation is that I have a brand new rifle, factory heavy barrel, chambered in 308 WIN. It's a Rem 700 SPS Varmint.
    The rifle has been test fired at the factory, but I've never put a round through it yet. Only bought it a couple days ago...
    My question is, given my specific situation, what would you recommend for the procedure of breaking that barrel in to maximize accuracy?

    3) Precision Dies...
    I've used all major manufacturer's dies for reloading a variety of calibers, but have never been in a situation where I had a rifle that was more proficient than I am on the range. Until Now.
    I am thinking that this rifle (700SPS) will outshoot me, but I digress..
    When it comes to dies, what do you have the best success with?

    4) Brass...
    I understand trimming to length, but I don't understand the concepts and principles behind neck trimming.
    I would think that it would weaken the brass, and reduce it's useful life.
    Please enlighten me!

    5) Throat gauging...
    I understand that there's a little space between the bullet and the start of the rifling, but I don't understand what's appropriate to maximize accuracy.

    6) Powders
    Having been reloading a while, I understand that different powders have different burn rates. Is there any trick to determining which powders will work best in a given firearm?

    7) Can I get some fries with all that?
    Thanks in advance!
    Dave
     
  2. justgoto

    justgoto Well-Known Member

    Messages:
    636
    Joined:
    Apr 11, 2009
    If you are ladder testing at 200 yards, and plan to shoot 600 yards or more; the chronograph is going to give you data which may translate to vertical stringing at those extended ranges. You'll want to get the extreme spread to the minimum.


    [FONT=Verdana, Arial, Helvetica, sans-serif]BREAK-IN & CLEANING[/FONT]

    You break-in the barrel to prolong the accuracy the rifle already has, without needing to clean; it doesn't make the rifle more accurate.


    You're talking about neck "turning." Bench-rest rifles shooters turn the necks to fit their perfect, tight chambers. Your rifle will not gain accuracy form it.
    "Trimming" is to trim your case to the proper length.

    That is rifle/load specific, you'll find-out when you find-out.

    I go by the book/books. Reloading manuals are our friends. :D
     

  3. FAL Shot

    FAL Shot Well-Known Member

    Messages:
    289
    Joined:
    Oct 9, 2010
    Dave,

    Regarding powders, I usually get the best results from powders that fill the case to over 90% capacity. If a powder loads results in much less than 90% capacity, flashover will cause inconsistency and possible detonation if a particularly light load sneaks through your reloading process.

    I weigh bullets and brass to tight tolerances of plus or minus half a grain. As a final check I weigh all reloaded cartridges. If there is a reloaded cartridge lighter or heavier minus or plus a grain of center, that is a no-go reload, as only a powder load screwup could make it vary by more than a grain.

    I use military ball surplus for break-in. Make sure it's good safe stuff. Avoid anything from a hot climate (Brazil, Israel ,Egypt, etc.). FNM has been very, very good for me. Some of my stuff is new, never issued, bought by the case. 200-500 rounds is a good break-in amount for standard velocity cartridges like a .308 Win.....because expected barrel lifespan is 20,000 rounds and that amount for break-in is only 1% to 2.5% of total barrel lifespan.

    A properly broken-in (smoothed out and polished) barrel IS more accurate since fouling is reduced and fouling reduces accuracy. In the case of a .22LR shooting lead ammo, shooting it will almost never break-in the barrel. You have to keep the lead cleaned out and polish the bore with something like Remington 40-X bore cleaner.

    Also, don't overdo it when cleaning out carbon, You want carbon in the pits of the bore, as copper can't stick to carbon. A certain amount of carbon makes your barrel smoother and resistant to copper fouling. M-Pro-7 takes out excess carbon with almost no work at all, while having almost no smell and being nontoxic. Use M-Pro 7 lube in the bore when the gun is sitting unused, and pull a bore snake through it before shooting. Together, the cleaner and lube makes it much harder for fouling to get a firm hold on the metal. I never use a chemical copper solvent, as it is unnecessary when using M-Pro 7 properly.

    Phil
     
  4. ZombieHitman

    ZombieHitman Active Member

    Messages:
    36
    Joined:
    Nov 17, 2010
    Ok, I've heard the term vertical stringing, but I don't understand what it means or what I am looking for to identify it.

    On throat gauging, is there a basic rule of thumb I can start with?
    I'll be doing my initial detail cleaning and sighting in tomorrow, using ammunition that's not quite world class IMHO, but it's a good start. Gander has Remington PSP ammo on sale for $8/box of 20. I can't buy brass for that price, let alone factory ammo. I'm on that like ticks on a dog!

    I heard someone mention fire lapping the barrel today. From what I have read, it's using lapping compound on the bullet to essentially polish the bore.
    Is there any value to this concept?
     
  5. Loner

    Loner Well-Known Member

    Messages:
    599
    Joined:
    Apr 14, 2010
    Don't fire lap your barrel , not now and hopefully not ever. It's for rough barrels that
    don't shoot or clean well and is used as a last resort by most. Your barrel is good for
    maybe 4000 rounds, so 200 to 500 to break it in is a bunch. Bartlein Barrels website
    has a great article on break in that agrees closely with Krieger's.
    I like forster dies.
    Until you've read and reloaded enough to understand the concept of seating the bullet
    near the lands don't worry about throat gauging. If you are lucky your gun will shoot a
    variety of loads well and you won't ever have to deal with it. Certain bullets seem to
    be temperamental as to how far of a jump they like to the lands.
    Neck turning is another facet of reloading best left for the future. One of those things
    you may never do. It makes the neck brass the same thickness which makes the tension
    on the bullet more consistent. It will make more accurate ammo but your time will be
    better spent shooting and working up loads that shoot well with some forgiveness in
    the process.
    There are known loads that shoot well in many popular rifles. Federal Gold Medal Match
    308 shoots well in most 308 rifles as a for instance. Google your rifle model and loads
    for it.
    Fries are bad for your heart, caffeine is bad for your groups, laying off the coke and
    coffee can do more for your shooting than hours of case prep at the reloading bench.
     
  6. Trickymissfit

    Trickymissfit Well-Known Member

    Messages:
    4,072
    Joined:
    Jun 11, 2010
    one thing you can do with a factory barrel is to hand lap the tight spots. Lay a strip of masking tape ontop of the barrel, and then mark all the tight spots in the barrel (do leave the one at the muzzel alone!). Nothing can be done to the loose spots, so don't loose any sleep there. Now you'll need a very ridgid cleaning rod (I like Proshot), and a VERY tight patch soaked in 800 grit lapping compound. In the tight spots, stroke the patch five to eight times (just in that area). Now clean the barrel, and run a clean patch with a very light coating of oil on it to see how it feels. You may have to do this a couple times (I've had to do a couple Remington barrels a half dozen times in the past). You want the muzzel to be tighter than the rest of the barrel, so you pretty much are stuck with that end result.

    Bill Calfee has written several papers on how to select barrels and lap them, and everyone of them is worth the read. Funny thing is that 50% of the gunsmiths laughed at him, but none of them have built winning international target rifles on a regular basis. I highly recommend reading his book! As it's a wealth of information on everything from barrels to triggers. Bill is mostly known for his rimfire rifles, but he does do a center fire on occassion, and readilly shares all his data banks with the masses.
    gary
     
  7. bigngreen

    bigngreen Well-Known Member

    Messages:
    5,841
    Joined:
    Nov 24, 2008
    Fire lapping is, IMO, a last case ditch effort to get some usable accuracy out of a factory barrel till you can get a good one installed. Some have used it with good results but it is for after you know it need help.
    Good luck and welcome to LRH!!
     
  8. SBruce

    SBruce Well-Known Member

    Messages:
    1,786
    Joined:
    Oct 31, 2009
    Vertical stringing has different meanings to different types of shooters. What I mean is: A competetive benchrest shooter would probably call a 1/3 or 1/2 moa group that was mostly vertical.........vertical stringing. A long range hunter would probably call that same 1/3 or 1/2 moa group.............good to go, because 1/2 minute or less is plenty good enough for most long range hunting, especially on big game.

    Guys that are trying to hit very small targets ie prarie dogs or such at distances beyond 600 yds require better than 1/2 moa to make consistant hits.

    You can get an idea of how much vertical you'd see in long range groups by chronographing the loads that you're shooting at 100 or 200 yds. If there is a large amount of "extreme spread", the groups will have alot of vertical dispersion at long range.

    Throat Gauging; I recommend the RCBS Precision Micrometer. They make one for most factory cartridges, they are not expensive, they will help you gauge your throat and set up your loading dies, they will give you an idea of the headspace in your gun too. Very good little tool, I've been using them for around 15 years or so on my factory guns.

    I start my load development (when possible) by seating the bullets .000" to .010" back from engaging the rifleing (using the Prec Mic to get this info).
    I do not seat bullets "jammed" into the rifleing. I did once upon a time, and ended up leaving a bullet in the throat when I unloaded the gun and ejected the case. Left 36 grains of H380 powder in every crack and crevice in my rifle action.....bolt wouldn't even close after that........ruined my day and took alot of time to get it cleaned out!!!!

    If I change my seating depth, I only have to move it back out farther. Don't usually have to reduce powder charge because of moving bullets back, but sometimes do when moving bullets out. Another reason for starting close to the rifleing and working up with powder charges.

    Good luck to ya!:)
     
  9. ZombieHitman

    ZombieHitman Active Member

    Messages:
    36
    Joined:
    Nov 17, 2010
    Ok gang, I think I have some new concepts to apply here, in my endeavor to grow into the finest shooter and handloader I can be!

    First, my thoughts for my rifle:
    After rooting around for a sound starting point for my load development, I think I'll be going with, excerpted from the Sierra Load Map...
    IMR 4064 - 39.7gr
    F210m
    168 SMK
    2.800" COAL.
    I have had a lot of success across the board with 165-168 grain projectiles, and use them in multiple rifles. It seems to make sense. I haven yet to decide whether or not I will lighten the load slightly, say a grain or two. I'm still pondering the pros and cons in my head. If anyone has input on this concept, I am all ears.
    I'll be making up 100 rounds for the initial break in. My current break in plan is:
    25 rounds - swab bore after each shot.
    50 rounds - swab every 5th shot
    25 rounds - swab after the fact, zero the scope, and get the full feel of the trigger.

    A good cleaning and lubing job will be done once I get the bore guide.
    I have a Dewey Nylon coated one piece I adore, with the brass jag & nylon bore brush. It serves me very well, and I keep it religiously clean, and in it's protective tube. I read someplace that crud gets into the coating on some of these rods, which can abrade the bore while cleaning, so I do what I can to prevent it.

    I found someone who has a chrony, and once I've gotten past the break in and start really developing the loads for this rifle, we'll see about that vertical stringing thing. Hopefully I can understand it a little better by then, what causes it, how to identify it on paper, and solutions in dealing with it. I suspect it has something to do with pressure variations in each load, as that's the only thing I can conceive of that would be indicated by impacts lining up vertically.

    I've ordered Lapua brass and a neck turning tool and related bushing die (backordered) Forster Hand Held Outside Neck Turner - MidwayUSA
    The reviews on it are very good, and I keep hearing the Forster name. Figured it was a sound decision, even with Lapua brass being very consistent.

    Ordered some Cerrosafe too, as I'd like a true method of understanding the chamber and throat, and the 3 gunsmiths I spoke with each recommended this method. I figure this will assist me greatly in getting myself dialed in as quickly and easily as I possibly can.

    I also found a range nearby that has a 500 yard line...that I can drive my truck out to post targets. Happy....

    More to follow....
     
    Last edited: Nov 21, 2010
  10. trueblue

    trueblue Well-Known Member

    Messages:
    2,127
    Joined:
    Feb 18, 2008
    biggreen's post is right on. I would add that the first thing I would do is find your top end of pressure for your powder charge, then back off and work on your load developement. Need to use a chrony if you have one.
    175gr SMK seems to be a popular bullet for the 308 for target., and out to 1000yards. If you are not going to shoot that far, the 168's will take you to about 800yards. I would look at shooting Nosler AB for hunting , or maybe even Barnes.
    Since this is a factory barrel, I would not spend forever on barrel breakin, just shoot it and clean it and you will be fine. It wil break in on its own with some rounds down range. I would not bother with 100 rounds to do barrel breakin.
    If you are going to shoot this rifle past 500yards, there might be some benefit to cleaning up the necks, or spend alittle more and buy Lapua brass for the 308.
    As far as powder, I strickly use Hodgdon extreme powders as I don't want velocity changes due to temperature changes.
    I use Forester dies. I would recommend a bushing die so you can partially resize the neck when reloading, leaving a small part by the neck/shoulder area unsized. This will help center your loaded round in the chamber.

    There are better ways to measure your chamber length and ogive measurements than using cerrosafe on the chamber.