Does this make sense?

hadjii

I'm experimenting with a mil-dot scope I bought. I'm not quite sure what's right and what's not, so here's what's going on. My rifle is sighted in to be 2" high at 100 yards when using the main crosshair. Using the first dot, point of impact is approximately 4.5" above the point of impact of the shot group using the main cross-hair. When I back up to 200 yards, using the main crosshair, point of impact is dead on. Here's where I'm not sure what's right and what's not. When I use the first dot at 200 yards, point of impact is substantially higher at approximately 9-10" above the point of impact of the main crosshair's point of impact. Does that sound logical, or is the operator head space out of adjustment? this is my first experience using the mil-dot, so not sure what to expect. Thanks for straightening me out.

The caliber is a 6.5 Rem Mag. The rifle is a Rem 673. The ammunition is handloaded, using a Speer 120 gr. Hot Cor bullet pushed by 51.0 grains of H4350 and win mag primers. The ammunition is accurate enough. With this rifle, I get a flyer in every group, but 2 of 3 rounds will be less than .75 moa, with one of the 3 shooting about 1-1.5" in a random direction from the other 2. Don't know what's up with the flyer. This rifle does it with every bullet I load for it. The stock has been pillar bedded, the action glass bedded, the barrel floated, and the trigger tuned to 2 1/2 pounds.

I guess my concern is that I don't know for sure what to expect for a ballistic path when using the mil dot, where I have more than one aiming point. Thanks Again.

Wolf.

Can you give us, specifically, the ammunition you are using to perform this test?

The arc or trajectory the bullet takes once it leaves the barrel, will affect its impact point at various distances from the muzzle and along its path of travel.

The data that will help, whether factory or reloaded ammo is:
Caliber:
Brand:
Bullet Data: (weight, bullet type and configuration, etc.)
Propellant Info: (may be hard to come by for factory ammo)

You may be able to find this ballistic information in some of the reloading manuals and other available references. It will be general in nature and not specific to your gun and ammo lot, but should give you an understanding as to what is going on.

Wolf.

Regards,
Wolf.

Mobuck

If there's 4-4 1/2 minutes (inches) between the main + and the next dot, that would amount to 8-9" @200 yards. Assuming a generic cartridge of moderate bullet weight and velocity, 2" high @ 100 yds would be close to dead on @ 200 yds.

4440rk

Yes it does make sense. Mil-dots are a whole nother learning experience. I would suggest you read this web site and enjoy the learning curve. Just to get you started, one mil is 3.6 inches at 100yds 7.2 at 200 etc. See where this is going?


http://mil-dot.com/

22hipower

You might want to try using a ballistics calculator (see: http://www.handloads.com/calc/) and chronograph as you learn to use your mil-dot scope. The referenced calculator seems to be quite accurate once you know the exact velocity and BC of your ammo. Then shoot the rifle at known distances. I've had pretty good results with calculated performance at various ranges once results at a couple of known distances are confirmed.

hadjii

Thanks for all the inputs. I'll definitely check out the website. Yes. A chronograph is on my wish list for Christmas. I'm sure it would dividends well paid. Thanks again.

JustC

the mil-dot or should I say, distance between them is a set distance at 100yds, and therefore will be 2X that at 200yds, 3x at 300yds etc.

tsr1965

The Mil is equal to 1/1000 of measurement. In other words, one mil, can equal one millimeter at 1000 millimeters, one meter at 1000 meters, 1 inch at 1000 inches, or one yard at 1000 yards. That said the distance between the dots, center to center, on a mil-dot scope are 3.6 inches at 100 yards, or 36 inches at 1000 yards. That is all dependant on the power setting of which the scope manufacturer states the reticle is calibrated on, if it is a variable powered scope. Of course the higher dollar the scope, the higher the quality of the resolution. Some scopes even have an FFPR(first focal plane reticle), which does not grow or shrink with the power setting.

There are some ballistics programs out there where you can input all the needed info, and get a correction in mils...NightForce has one for about $75.00, and it works fairly well. I have proven it out with a 300 RUM, and 7mm Rem Mag out to 1000yards.

The 4.5"@100 yards, to 9"@200 yards sounds about right as doubling, but it also sounds like if you have a mil-dot scope, that it either is not calibrated correctly, oryour power setting is off.

Best