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50 cal BMG
snowshoe
Member Posts: 47 ✭✭
I recently aquired a maadi griffin 50cal bmg. I am looking to put on a scope but have a concern with the recoil and short eye relief of most scopes. Is this a concern, and is their a scope with a longer eye relief without selling the farm to get.. Thank for any input
Comments
The simple answer to your question is NO... and this is why not.
Each firearm/rifle was its own unique ballistic properties with a given type of ammo... do you know what the muzzle velocity is?
Second, there will be a notable difference in where it will hit at 100 yards when zeroed for 800 yards versus 1000 yards... you need to pick one range distance and go with it.
Bert H.
Real Men use a SINGLE-SHOT!
WACA Historian & Life Member
SCOPE BASES FOR LONG-RANGE SHOOTING
By DANIEL LILJA
A common problem encountered with fifty caliber rifles intended for shooting beyond 1000 yards is not having enough vertical scope adjustment to hit the target. Usually it's not a problem to get on at 1000 yards, requiring about 25 minutes of up adjustment. But beyond 1000 yards, trajectories fall off fast. Most fifty caliber shooters that I know, and others shooting cartridges like the 30/378 Weatherby and 338/416 Rigby, zero their rifles at 100 yards and work off that zero for all other ranges.
Most internally adjustable target scopes have from 50-60 minutes of total vertical adjustment. With a normal scope base and ring configuration, a 100 yard zero will put the adjustment in about its mid range. With a total of 60 minutes of adjustment, that leaves only about 30 mininutes remaining. So we can see why we will soon run out of scope beyond 1000 yards. With the newer bullets now available, with a C1 ballistic coefficient of 1.0 or better, and fired at reasonable 50 BMG velocities, the bullet will remain supersonic out to 2500 yards or so. It takes a lot of adjustment to get zeroed out where the deer and antelope play, but it can be achieved with certain scopes and the right base.
The answer is to tip the scope down in front to take advantage of the full adjustment range. Some manufacturers of fifties provide bases with their rifles or actions that already have the slope built into them. But what if we have a rifle that doesn't have one of these bases, or it is wrong for our scope? Well, there is a simple formula for determining the correct amount of slope.
Let's say that we're using a 36x target scope and we find that with a 100 yard zero the scope still has 25 minutes of down adjustment left. This means the scope won't have those same 25 minutes for long shots where it will be needed. It's easy to figure how much to tip the scope to get that adjustment back. If we decide to leave 5 minutes of adjustment, then we want to tip the scope an amount that would move the scope's reticle 20" at 100 yards. Next we need to know the distance from the front of the forward base to the back of the rear base. Or in the case of a one piece base, its overall length. Now to find the answer, we divide the 20" of desired movement by 3600 (the number of inches in 100 yards) and multiply by the scope base distance mentioned earlier. If the base measurement was 7", this would look like (20/3600) x 7 = .039". So the rear base should be elevated that amount.
I prefer to mill the scope base on an angle, as opposed to shimming the rear base to achieve the slope. This does not put any bind into the scope as shimming would do. The base is placed in the milling machine upside-down, with the front end elevated the calculated amount. Here the front of the base is raised so when it is installed on the action the rear will be higher.
"LIFE IS NOT A JOURNEY TO THE GRAVE WITH THE INTENTION OF ARIVING SAFELY IN ONE PRETTY AND WELL PRESERVED PIECE, BUT, TO SKID ACROSS THE LINE BROADSIDE, THOUGHRLY USED UP, WORN OUT, LEAKING OIL, SHOUTING GERONIMO!!"