Rifle Scopes Bushnell E4200 Mil/mil ffp 6-24x; Actual click val

[TresMon]

Hey guys,

I spent a lot of time at the range yesterday. As close as this machinist can possibly reconcile the actual click value of both the windage & elevation in My scope is
.367" IPHY (rounded at the third decimal place.)

My scope clicks 1.01914 x the claimed 1/10th mil clicks.

So assuming yours is the same as mine, set the correction factor in your pda to .981 in the correction field.

How I conducted my test:

I used a 165' tape measure that reads in 1/8" to measure.

I set up a metal 48" "yard stick" square & plum down range as precisely as I could possibly get it 25 yards from the center of the elevation turret knob.

25 yards is the furthest distance I could clearly & consistently reconcile the smallest fraction lines on the 48" scale while looking through the scope on 24x.

The rifle with it's optional bolt on, recoil absorbing 5 lb. weight weighs in at 21 lbs, 4 oz., just under the 1000 yard f-class 22 lb. weight limit. It was on a bipod front, monopod rear, on a 4" thick cement benchrest table top. The whole overall set up was VERY solid for this test.

The back and forth adjustments of the scope along the 48" scale was perfectly repeatable in all 20 test cycles save but one test, which was culled as a fluke/human error.

Despite the test being perfectly repeatable, I tested and retested 10 times for the elevation as well as 10 times for the windage.

I'd note the exact measurement I was looking at on the scale, move the turret 10 mils, record the new measurement and do the math.

So thats how I did it. Any critiques in the method?

DOH!! It just dawned on my I failed to actually measure the mil reticle itself.
To be so mechanically inclined I shore am dumb.

 

[sniperaviator]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click val

My only critique would be the stability of the rifle between sights. Does it come back up to where you started? I used a $300 benchrest when I did mine. Also, leaning on the table makes a difference.

I really think you have to shoot groups and measure distance between groups also as a way of verifying.

But yes, I verified my Nightforce by turning it through a 96" high brick structure at 180 yards (measured by rangefinder so some error there).

Using a tape measure is the best way for distance that is better than rangefinding or trusting the range to be some advertised distance (like 100 yards according to what? no one knows).

 

[TresMon]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click val



SniperA,
yeah it was going to and coming back to the same measurement on the 48" scale each time. The cement bench was HEAVY, and on full size cinder block columns. I wouldn't worry about an obese kid clogging on it while I was shooting for score.

I personally think reading an inch scale would be better than measuring the theoretical center of groups, not to mention the savings on components and barrel life. But not to spilt hairs, I believe either would give satisfactory results.

Thanks for the feedback.
Merry Christmas!
Tres

 

[BobinNC]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click val

Let's see if I understand this:

1) You are measuring scope error to .007 thousands of an inch, on a yardstick that at it's finest measures at .125" thousands of an inch. If I read you right???

2) What's the thickness of the reticle @ 25 yds? If it subtends 0.1 MILS (0.36") @ 100 yds, it would therefore subtend .009" @ 25 yds, which is greater than the error you noted.

3) Did you test and measure your ruler(s) to determine it's own inherent calibration error(s)? Also did you level the ruler so that it is exactly parallel to the ground. Any cant forward or back from your aiming point will induce error.

4) In short you are trying to measure something with high accuracy, using low precision devices. Tape stretch comes to mind in your initial 25 yd measurement.

None of this is to take away from your efforts, but I think you are putting too much reliance on the accuracy of your measuring devices.

Just IMHO,

Bob

 

[TresMon]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click



Bob!

I got a hearty chuckle out of your observations! Thanks.

As far as the really fine decimal places, thats what the calculator spit out so thats what I wrote down. No, I'm not trying to lead anyone to believe I pulled this off holding .007"!

However the 48" scale is calibrated to it's finest fraction and I did make sure the scale was plumb and square to the scope. And the 165' tape is a steel tape, unlike many of the cheaper fiberglass ones so not a whole lot of stretch going on there...

Great stuff!

 

[Brasscow]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click

Are you basing this off of 6283 milrads in a circle or the commonly (military) used 6200? What if bushnell uses one figure and your ballistics calc uses the other? Way to get out and do your own research... I'm just throwing some things out there for you to think about while I'm waking up.

 

[TresMon]

Re: Bushnell E4200 Mil/mil ffp 6-24x; Actual click


It's my firm belief that the 10 mils = 36" @ 1000yds & 1/10th mil clicks click .36" @ 100yards is the standard of the scope industry and thus that was what I used.

Good food for thought though. Thanks.