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Discussion Starter #1 (Edited)
One of the small steps in arriving at the ability to be extremely accurate in long range shooting is to develop ammo with a minimum extreme spread in velocity but to arrive at that point there are a few more steps one needs to take to get your ammo capable of performing it.

In short it doesn't matter whose name is on your rifle, who made your barrel, who made your scope or how much you paid for it. If the ammo won't do it the rifle sure won't compensate for you. This is but a small bit of info that will increase your blood flow in the brain.

OK lets take a look of just a few of the things one might consider to overcome the handicaps your brass, dies etc are going to give you.

Gov't Match 308/30.06 cases allow for I believe it is like .005" case neck thickness variation IN THE SAME CASE ! ! ! ! ! No telling what the industry allows. Case neck wall variations are not called out in the SAAMI drawings.

I set my Marquart turners two ways.

After bumping the bullet back .100" on a new barrel, (less on barrels already broken in) after the initial firing I will FL size the case (min movement)with no expander button used, then tumble clean in stainless media, and using a mandrel to the appropriate dimension I expand the neck to fit the mandrel snugly. My expander mandrel is about .3075/.3085 (have several made up) and I run the one that fits my Marquart mandrel the best and then set it to cut about .014" maximum thickness of the neck walls on my cases.

With this setting I only cut off the high spots of the case neck allowing it to center the bullet more towards the bore center line. Some cases will take the surface down only contacting outside neck surface about 30 degrees, some 45 degrees and some up to 180 degrees . Occasionally in say 100 cases I will have maybe two that the setting I used will just skim cut the neck all the way around. So basically that means in every 100 cases I have two with perfectly centered necks that did not need to be uniformed.

On this setting it will generally take off metal 360 degrees at the base of the neck so basically I have uniformed the neck all the way to the bottom removing the "dreaded do-nut" from the outside of the neck rather than the inside.

On my long range slow fire rifles with sub min necks I will set the Marquart to give me .013" neck wall thickness.

I have a 308 reamer which gives me a chamber with a .336" neck and I have to reduce neck diameters to where it removes neck material 360 and my loaded round neck measures .335". I understand some of the benchrest boys are setting up and shooting ammo .0005" smaller than the chamber neck.

Not long before my getting rear ended I had a buddy who is a tool and die maker make me two carbide expanders. I don't remember the measurements now ( due to on board software retrieval issue some folks refer to as CRS haha). At any rate the nose of the expander is cut to about 60 degree.

With this combo when the expander starts into the case neck it engraves (for lack of a better term) neck walls on the inside leaving them with a mirror finish. Literally I can run a probe into neck and see a reflection of it on the other side of the neck. I then tap the neck on a rubber mat and the residue comes out and I can tell more material is removed from one side than the other on most of them.

The name of the game in long range is fairly simple. Load ammo with the least amount of extreme velocity spread for the entire batch of ammo and logically if the inside of your case neck is grooved from a crappy factory expander loaded up with carbon that has cut grooves inside your case necks you are going to have a ridges,grooves etc wanting to grip your bullets differently for every shot which works wonders in ruining your extreme spread. The definition of "wonders" in this case his "How the **** did that shot go there?" or other choice descriptive terminology.

In other words clean your cases with stainless steel pins in tumbler and get a 10X glass and look at the inside of your case necks and if you see a number of grooves running the length of your case necks they have already been ruined for long range use so dedicate them to the 200/300 yard lines.

Look at this this way assuming you are shooting a 30 cal 180 grain bullet, a 100 FPS extreme spread dispersion is going to give you 40" of elevation at 1000 yards.

The ten ring is 20" in diameter so even if you are shooting from a machine rest at 1000 yards you are going to be trying to get a 40" group into a 20" circle.

OK the X ring is 10" in diameter which means you need ammo with an extreme spread of 25 FPS for the entire string assuming you have a zero wind change.

The NRA Targets are the not that hard but if you want to get a real eye opener do a search for F Class targets and be prepared for a real shock.

You are not going to hold that close from the sling especially but hopefully less from a bipod but still you are going to have a variation in aiming, cheek pressure, grip variation etc etc etc.

Now you are looking at about 12 FPS extreme spread requirement for your ammo.

I think the national record at 1000 yards in benchrest is NBRSA 1000yd Records | Nationals Records | Berger Bullets

The ammo those boys are using for the ten shot groups has to have an extreme spread of about 8 FPS with no aim error either from the shooter or what the mirage does to you.

Had a friend who observed a demo at Quantico 30 years ago of 1000 yard bench rest shooting a 300 Win Mag and the firer had a chrono set up and he fired 7 shots total, five for "record" so to speak and he shot about a 4" group. My buddy watched the chronograph and his shots went like 3005, 3007, 3005, 3003 fps etc. Bottom line was he had a extreme velocity spread for seven shots of 4 FPS ! ! ! ! ! !

When the new 1000 yard target was introduced at Perry (70s???)I saw a National Record set with a magnum shot by a Marine and he had 200-17Xs He had two shots cut the 10 line at 12:00 o'clock and one cut the 10 line at 6 o'clock. So basically one click elevation up or down he would have dropped a point pr two.

The middle of the target was cut out to include the entire 9 ring and left for him in the pits.

As indicated initially this is but one step to getting there and if you can achieve this then you can concentrate of putting a rifle/scope combo together that will allow you to achieve Gen. Nathan's Bedford Forrest's Order of Battle which was "Get there the firstest with the mostest".
 

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Elk Whisperer (Super Moderator)
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Even weighing individual charges to the 1/2 tenth grain and doing voodoo spells during the rest of reloading, the best I could ever do (as far as spread) was 8 fps with my sevumag. The more powder, the more apt you are to get spread I think. I've run my 30-06AI across the Chronograph but I don't have any record of what the FPS was let alone spread. The only other "long range capable" rifle would be the 300RUM and IIRC, it had a spread of over 15.

I should run the .243 .222 and .223's across just to see as I should have kept records, but never saw the need. as groups tell me as much as I need to know.

Great info Humpy, thanks.

RJ
 

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Discussion Starter #4
Mike, thank you so much. Hopefully many will benefit from knowing where they need to be as a starting point. Humpy
 
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