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Old January 15, 2013, 10:44 PM   #1
Dannyboy303
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Case preparation Tips to help achieve the most accuracy out of your rifle!

Ok i'll start by saying i have been reloading for about 6 years now and by no means am i a "proffessional". In saying that i thought i'd share my tips on case prep in hope of some feedback or extra steps that could be taken.

Case Prep:

1: Fire form Quality factory brass
2: De-prime the fired brass
3: Uniform primer pocket(this cuts the primer pocket to the correct depth to help produce better flash consistency)
4: Trim cases to minimum length(i believe this will create equal holding pressure on your projectiles)
5: Uniform and deburr flash hole (most flash holes are punched out in the factory leaving an uneven surface with excess brass protruding on the inside of the case which can result in uneven ignition)
6: Outside Neck turn your brass slightly only to remove high spots on the case neck as no case is perfect(taking too much off the neck can result and case neck separation VERY BAD!! and also reduce the life of your case by overworking it)
7: Clean your brass.. many ways to clean brass but the best i have found by far is ultrasonic cleaners as they remove all the rubbish out of the inside of the case.
8: Sort all your cases into groups by weight with say 1/2 a grain increments.(For me i don't bother with this step unless i absolutely have nothing else at all to do.... or im loading some for benchrest)


Now you only need to do steps 3, 5 and 6 once as once the excess brass is removed its gone forever....

So have i forgotten anything? are there any other tips with case prep that can be shared to help squeeze that last bit of accuracy out of your rifle?
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Old January 15, 2013, 10:52 PM   #2
reloader28
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You could also measure the chamber length and trim the cases so that they are only .003-.004 under that length.
Everything I've checked, that means the case is going to be longer than factory specs (over max), so it has to be for THAT gun.

You dont have to trim to min, but you need to trim so that they are all the SAME length.
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Old January 16, 2013, 12:18 AM   #3
Dannyboy303
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Quote:
reloader28 You could also measure the chamber length and trim the cases so that they are only .003-.004 under that length.
Everything I've checked, that means the case is going to be longer than factory specs (over max), so it has to be for THAT gun.

You dont have to trim to min, but you need to trim so that they are all the SAME length.
Wouldnt i have to do a chamber casting for that or is there an easier way?
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Old January 16, 2013, 07:45 AM   #4
Bart B.
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I've had zero problems reloading ammo with absolute zero case prep. Even brand spankin new cases will shoot 1/3 MOA at 100, 1/2 at 300 and 3/4 at 600 and at 1000 yards 1 MOA; all with half way decent brass. Good brass will shoot even better. Case weight can have a spread as much as 2% and great accuracy is still easy to get, but sorting to less than a 1% spread's a waste of time. There's a greater spread in the energy exact powder charge weights or primers have than what a tiny difference in case volume has.

All that's needed with bottleneck cases is to full length size fired cases with bushing dies that reduce case body diameters and set fired case shoudlers back no more than about 2 thousandths and have their neck diameters a couple thousandths smaller than that of a loaded round. Use a case headspace gague (RCBS Precision Mic or equivalent) to measure case headspace; set fired case shoulders back no more than 2 thousandths.

Case length from head to mouth needs to be at least 10 thousandths less then chamber length; don't go over SAAMI specs. And cases can have several thousandths spread in their length; a 5 thousandths spread is common in good commercial .308 Win. match ammo that shoots unde 4 inches at 600 yards.

Regarding the issue of trimming case length to all having the same exact length to get consistant neck tension, consider the following. With a bullet that's held by 2/10ths inch of the case neck length, for every .002" difference in that length, that's a 1% change in how tight the neck grips the bullet. How many readers have actually measured the force it takes to pull a bullet out of turned case necks with exact dimensions, then looked at the percentage spread form least to most amount of force to do it? Once you've done that, you'll feel just fine with a .005" spread in case/neck length.
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Last edited by Bart B.; January 16, 2013 at 09:23 AM.
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Old January 16, 2013, 07:44 PM   #5
Dannyboy303
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Hi Bart, i agree with what you say in almost every respect as all this case prep plays only a small part to accuracy in the reloading process... though for some people(like me) they're obsessed with getting the absolute best out of their ammo

In regards to case neck turning i was under the impression that by turning the high spots off the case necks it helps to align the projectile true with the bore, even though yes it will be a very very miniscule amount.

Happy shootin!
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Old January 16, 2013, 07:50 PM   #6
hooligan1
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Well Dannyboy ole Bart B. would rather probably shoot than load, (like he needs the practice) but what he's not doing is spending time fiddling with brass. I really don't either if it's long I trim, if it's dirty I clean.
But not everybody spends a lot of time fiddlin with brass.
Now don't get me wrong ITS IMPORTANT to PREPARE BRASS CORRECTLY, but it really doesn't require intense attentions.
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Old January 16, 2013, 08:12 PM   #7
Bart B.
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Dannyboy, the case neck's dimensions have nothing to do with how a rimless bottleneck case centers its neck in the chamber neck when loaded and fired.

When chambered, if the bolt's got an in line ejector, that pushes the round full forward into the chamber where its shoulder centers in the chamber shoulder. Its back end gets pushed where the extractor presses it against the chamber wall, usually. When the firing pin smacks the primer, that further drives the case shoulder hard into and well centered in the chamber shoulder before the firing pin dents the primer enough to crush the pellet against the anvil and finally fires the round. And there's typically a bit of clearance all around the case before and when fired except at its back end that's pressed against the chamber wall. Rounds do not lay in the bottom of the chamber except when they're in it and the bolt's open and not touching the case head whatsoever.

So, all that's needed is to have the case neck well centered on the case shoulder after resizing that fired case. It floats in the chamber neck untouched by anything except the bullet in it; there's clearance all around it. Full length bushing dies center sized necks on shoulders better than neck sizing dies. Doesn't matter if the neck's .001" thicker on one side than the other. The bullet will well align itself in the rifling when it gets there. Or seat bullets out far enough to jam gently into the rifling when loaded.

All this aside, one will get better accuracy if their barrel's groove diameter is right for the bullets used (.0003" smaller or more than the bullet diameter), very uniform dimensions and twist rate and the receiver's properly epoxy bedded in the stock; totally free floating the barrel. Sloppy handloads will shoot very accurate in such rifles. If the rifle's not up to par, really tiny groups may well be a dream.
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Old January 16, 2013, 08:13 PM   #8
Dannyboy303
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Yeah i know what you mean.... 5 years ago i was a professional kangaroo harvester shooting from 20-40 rounds a night, sometimes every night. My slapped together reloads were plenty sufficient in getting head shots at a max range of 200yards so i definitely know where you're coming from when you don't want to spend much time with brass haha.

Now that i've moved away from the farm i get hardly any time to shoot which i guess is why i spend so much time trying to achieve the most accuracy out of my loads, think it keeps me keen on shooting as with alot of shooters.
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