Home Forums Hunting & Shooting Custom Rifles & Wildcats Turrets 101....................

I've been bombed with Emails,PM's and phone calls from guys that are goin' turret crazy all of the sudden. As my typed words are of even less use than my verbal communications,I thought it prudent to Post a coupla pictures that might help those that I managed to confuse.

I just hope my text doesn't muddle the pictures!



OK,in this picture is a Leupold "regular" turret. The type that wears a cover if you should want it and I generally do. So this is the way your rifle sets after you have it on paper at your preferred "normal'' zero range. On this particular rifle I like it sighted in and zeroed at 250yds. The bullet must strike +2.3" high at 100yds to yield that desired result. After that confirmation,I loosen up the three hex head screws that affix the micrometer head to the internal elevation spindle. I align the "0" reference number,with the vertical index indicator at the base of the turret assembly and retighten the set screws.

So in this configuration,I have a "regular" rifle sighted in a regular manner,the turret is just a bump on top of the scope and from my muzzle to the 250yd line I needn't give it a thought.

Savvy?



OK,now here is the turret moved in the upwards direction and it will shift impact from my pre-established zero. It is at the 3MOA setting,which is 12 seperate .25MOA graduations from my zeroed starting point. The U- indicator at the top tells me that counter clockwise increases elevation and the opposite reduces it.

With just that subtle amount of elevation increase,my rifle's zero has now changed from the 250yd line,to the 375yd line. So at that predetermined distance(as this ain't a guessin' game),I can paste my crosshairs dead on the target and that is where that bullet will impact.

After the shot,I return the scope to "0" and I'm back to my predetermined 250yd preference.



In this picture,the crosshairs have moved even farther upwards in elevation travel. The reflection from the flash obscures the whole minute designation mark,but this is a 7.5MOA poke. That is 7 whole minutes and two .25 "clicks".

The micrometer head is marked well and easily read. It starts at "0" goes to "3","6","9","12" and 15 ='s a complete revolution back to "0". Between those numbers are hash lines,designating the whole minute values(the longest of the hash marks). The mid lengthed hash marks are .50MOA designators and the tiny ones are .25MOA graduations. With about 7 seconds practice,it becomes very easy to cypher(even for me).

So with 7.5MOA up in the glass,this rifle is now dead on at the 525yd line. I make that shot,return the glass back down to "0" and I'm back to my favorite 250yd zero for this particular rifle.

Now to find the info to feed your scope,you gotta know a coupla things. The bullet's speed,BC,sight height and atmosphere. That will yield a trajectory drop chart that will likely yield an amazingly close ballistic profile.

From there,one must ascertain that generated data and the rifle/scope combo are in perfect harmony. That is yielded by shooting at a known(confirmed) distance and comparing generated findings to actual findings and fine tuning the data. All very easy.

This game is won and lost with range determination and an accurate/repeateable scope(they call 'em Leupolds). The laser is the measuring device and the 1200LRF Leica is THE machine for po' folks like me.



So here is a trajectory data reference chart,as spewed from my PACT Ballistic Computer.

I sorta screwed up,as this printout is not in sync with the above trajectory curve,though the principles are precisely the same. This is for a different rifle and I'm guessin' you know which one,from the El Marko credits atop the ribbon.

Anyhow,we'll use this for reference and at least it uses the same 250yd zero,one which I find useful for a bunch of different chamberings.

So let's say we've done the 100yd thing(sighted +2.0") at that distance and we've confirmed that we are on the money at the 250yd line. We now loosen the set screws an index the turret's head,to correspond with our "0" designation.

No we wanna see EXACTLY what it takes to get further downrange. To start,you divide the trajectory drop in inches,by the distance of the shot which is in yards.

So let's jump right to 450yds as a curiousity. To find the MOA info you need to feed the scope,you divide the drop (20") by range in yds and I designate yardage in decimal configuration. A 50 yard shot is divided by .50. A 125 yard shot is divided by 1.25. a 500 yard shot is 5.00. An 875 yard shot is 8.75. That decimal will yield a factor that we can use to round up to the nearest .25MOA "click" adjustment in the scope. Savvy?

Soooooo...20" divided by 4.50 yields 4.44MOA. Well we haven't the graduations required to dial that elevation in as the scope is graduated in 1/4MOA "clicks". BUT,we can round to 4.50MOA. that is 4 whole numbers and 2 "clicks" of .25 per each.

Now as a curiousity,let's see how much precision we "lost" by rounding up to the nearest 1/4MOA graduation our scope allows us. Simply multiply 4.50(range in yards) x 4.50MOA(our nearest rounded adjustment graduation) ='s 20.25". The correction we dialed deviated but 1/4" from perfection,in a perfect world.

A 1/4" "click" at 100yds shifts impact 1/4". That adjustment at 200yds,shifts impact by 1/2". At 1000yds that 1/4" "click" is now moving impact 2-1/2" per "click". Savvy?

Some would think that because it is a 1/4" "click" scope,you'd have the graduations to negate that 1/4" difference between the actual 20" drop chart figure and the 20.25" correction we rounded up to,but the ''clicks" grow in size as range is extended. That is why I like toss that decimal in there and round to the nearest .25MOA graduation,because that is the finest adjustment I can mechanically make at ANY distance.

Soooooo....let's crack somethin' at 850yds. That is the drop in inches (152.1") divided by 8.50 and that yields 17.89MOA. My preference is to round up and the next 1/4 minute graduation mechanically available is at 18MOA. So that is one complete turret upward revolution(15MOA per revolution) and 3 more whole minutes. Whammo,make the shot,crank down to zero and you are back at 250yds.

See howww easy it is?.........................