Why not to trust the MV on the Ammo Box

[taliv]

I always thought 300 was short range and 400 was mid range but I couldn't say if 301 yards was mid range of 399 yards was short range.

Saying "technically " long range is at transonic .... I'm trying to figure out what group would define that?

 

[blue32]

My experiences with groups on paper do not support the SD I've been recording. If mid twenties is poor for handloads then I've been extremely lucky with regards to downrange performance.

 

[jmorris]

I've got higher MPG numbers that auto specs state for the last 4 new cars bought.

That would still be getting a non advertised number though.

I imagine the people that get "X"city and "Y" highway that matches the sticker on the window are about as rare as folks that hit the same FPS that's printed on a box of ammunition.

I can take a box of .22's out back with a few guns and get velocities below and above the "1280 fps" on the box pretty easy.

 

[Bart B.]

blue32,

A .308 Win cartridge shooting bullets with a 25 to 35 fps SD (about a 100 fps extreme spread) in muzzle velocity will have a 2/10ths inch vertical spread at 100 yards due to bullet drop differences.

To resolve and see that in actual firing, the rifle, ammo and human will have to shoot groups with extreme spreads no bigger than about 1/30th inch at 100 yards.

 

[DocUSMCRetired]

Some interesting discussion going on here, but positive compensation should be a topic for another thread. We discuss this in detail starting on page 36 of Modern Advancements in Long Range Shooting Vol 2, we also talk about it briefly at the seminars. What the average shooter needs to know, is this variable is not going to have a significant enough impact, and shouldn't even be considered by most shooters. All it will do, is send them down a rabbit hole of internet theories that can cause more harm than good.

Short, Medium, and Long Range is also going to be dependent on the shooters area of sport. For 22LR 300-400 yards is long range. For a 6.5x47L 1000-1200 is long range. For a .308 Win 800-1000 yards can be long range (lots of new high BC options here that can extend what is long range). Essentially for this discussion Long Range is Mach 1.4-1.1. (Just before transonic). Extended Long Range is Transonic - Subsonic zone. Which will vary by application. For example, a 224 at 2970 fps with a 77otm bullet. Long Range is 600-800(Mach 1.45 - Mach 1.15) ELR is around 900yards (Below Mach 1.0 or Subsonic). This gives us a good standard to go by.

 

[Howard Roark]

Bart,
I believe that this perspective is what’s causing the confusion:

When courses of fire at 300 yards use targets for the 600 yard stage of the match, their scoring rings are reduced from the standard mid-range (MR) scoring ring dimensions.
NRA No. MR-63—Reduction of the MR-1 target for use at 300 yards to simulate the 600-yard stage of the National Match Course.

Those of us who’ve been in the game for many years are used to referring to the old SR, MR and LR distances ranges. However, this changed for conventional prone when the long range was divided into mid-range and long range. High power rifle courses of fire have nothing to do with mid-range or long range courses of fire.

The rules are clear that 300 yards is included in the courses of fire for mid-range tournaments,

19.5.2 Courses of Fire used for Mid-Range Prone Classification 300 yards - When not part of an NRA High Power Rifle tournament or is part of a Mid-Range Tournament Rule 7.10 metallic or any sights.

Note that the first part of the rule explicitly excludes High Power Rifle tournaments (where the MR-63 target is used to simulate the 600 yard target). It goes on to specifically include the MR-63 through Rule 7.10 as part of a Mid-Range Tournament. The intent is not to simulate a longer distance (as it is for across the course) but to have smaller scoring rings to make the Mid-Range Prone target more challenging.

The targets for prone matches are specified for each specific yard line, not simulated yard line. There are no reduced distance mid-range or long range tournaments as there are in high power rifle tournaments.

It’s clear that mid and long range courses of fire and associated individual classifications define distance designations, not target names. The overlap at 300 yards can create a certain amount of confusion but the rules are clear. The conventional prone shooter doesn’t shoot short range targets or reduced targets, at 300 yards they shoot mid-range targets. There is a difference when the MR-63 is used as part of an across the course match and a prone match.

As Doc states above, there are many shooting games and each have their own designations for distances.

 

[Bart B.]

Howard, you're right about the rules. They're written based on what's popular and what the rules committee feels is best.

I wrote the first NRA High Power Rifle rule for Palma rifles back in the 1980s. It simply stated "Any rifle chambered for the unmodified .308 Win or .30-06 cartridge with metallic sights." That was done so folks who had only a Garand, Springfield or Enfield or any .30-06 could shoot Palma matches. The High Power Committee liked that idea.

It now reads:

3.3.1 U.S. Palma Rifle—
(a) A rifle with metallic sights chambered for the unmodified .308/7.62 or .223/5.56 NATO cartridge case.
(b) Any service rifle with metallic sites chambered for the unmodified .308/7.62 NATO or .223/5.56 NATO cartridge case.

People whose only target rifle is a .30-06 of any type cannot now legally shoot a registered Palma match.

 

[lysanderxiii]

The next question is, what does the factory test? Is it a full tilt production run or do they test handloads ? I suspect they test the handloads under controlled circumstances before they tool up production...and print ammo boxes with advertised velocity.

A good company will do some quality control testing using random cartridges pulled off the line to ensure:

-The pressure is within limits and is not drifting.
-The velocity is not drifting.
-the accuracy is not changing.

If anything starts to change, stop and figure out why. That's just good manufacturing practice.