Real world drop

[Bones]

I have a hard time thinking the MV is that far off as well. I have a .280 ackley that I am shooting Nosler factory ballistic tip ammo out of. I just got the gun and took it to the range, ran the numbers and took it to 800. I did estimate the MV being a bit slower than advertised, but my 200 yard zero and 16.3 MOA correction at 800 was correct. Since I confirmed my numbers, I adjusted the zero to 100, and showing about 9” drop at 300. I know this is what you already know, but I am in agreement that something doesn’t add up

 

[MuleyFever]

Come to think of it I tried a box of the ELD-X factory ammo a little while back and the drop at 300 was a few inches more than the calculator as well.

 

[rayporter]

if you can ask around and find a guy with a labradar you can get velocity at muzzle and 100yd on each shot.
I have seen some unusual things with mine.

 

[MuleyFever]

I have watched a few comparisons on the radar and magneto and Caldwell and they have all been actually pretty close.

I still just can’t accept that my MV is only about 2800fps.

What if my scope is not parallel to my bore? If the scope tilted slightly up from the line of the bore would it cause excessive drop in bullet trajectory? Maybe a variation on my bases or scope defect.

 

[ChrisAU]

I have watched a few comparisons on the radar and magneto and Caldwell and they have all been actually pretty close.

I still just can’t accept that my MV is only about 2800fps.

What if my scope is not parallel to my bore? If the scope tilted slightly up from the line of the bore would it cause excessive drop in bullet tragedy? Maybe a variation on my bases or scope defect.

The way I understand it is as long as you were able to zero your scope it wouldn't matter; zeroing your scope aligns the erector with the bore, not the external mounts.

 

[Muley Buck]

@ChrisAU is right. Drop is drop. Doesn't matter where the scope is pointed if zero was already established.

 

[MuleyFever]

Ah yes, I see.

 

[MuleyFever]

I ordered a box of 160ABs to try. Does zeroing at 100 or whatever actually matter if I am just shooting at multiple distances to find my curve? I don’t want to waste ammo zeroing at 100 if I can just shoot from 400-100 and then adjust the calculator until the drops all line out.

 

[ChrisAU]

I ordered a box of 160ABs to try. Does zeroing at 100 or whatever actually matter if I am just shooting at multiple distances to find my curve? I don’t want to waste ammo zeroing at 100 if I can just shoot from 400-100 and then adjust the calculator until the drops all line out.

Again, I am no expert, but I imagine all the calculators will need a known input, whether its a 0 at 100, 200, or 1000. Then it can work from there when you input drops at various yardages. I'd zero it where you want your zero to be, then shoot a couple more distances to plug into the calculator to get your curve.

 

[id260]

Tell us about your scope, no one's talked about that yet. If it's under tracking your impacts will be low. Has the scope been tested against a precise MOA grid or a box test performed?


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Your velocity seems inflated based on the nosler factory ammo ballistic data. 24” barrel would be approximately 80 FPS less too. I think this would account for some of your results.

 

[AirborneEScouter]

Nice holes on the target? Maybe jacket coming apart due to velocity? Just a random thought

 

[Wrench]

When trying to determine bc or velocity, use 0-600 yards to validate velocity, use 600 and beyond to validate bc.

It will drive you nuts trying to get it correct if you do otherwise.

 

[204guy]

Maybe I missed it but, how many shots in the group to establish 100yd zero? How many shots per group to check drops? What I'm getting at is was your sample size big enough 5 is good 7 is better. Measuring from center of group to center of group?

Also as has been mentioned 3270 would be an extremely hot load for 140gr.

 

[MuleyFever]

Man those drops in meters are awfully close to what I am getting. The RF is in yards though. I am also within a yard or 2 of the markings on the range.

Holes on target appear good but I have heard of people complaining the polymer tip can deform in flight. Not sure how likely that is.

Zero was done with around 6 shots. Height was spot on. I only had enough ammo to shoot 4 shots at 200 and 300. There was more horizontal spread than vertical. At 200 only about an inch of difference in height on the 4 shots. At 300 about 2 inches variance. I know its not a lot of shots for a group but I don't see a few more shots moving the average very much.

 

[ChrisAU]

Man those drops in meters are awfully close to what I am getting. The RF is in yards though. I am also within a yard or 2 of the markings on the range.

Holes on target appear good but I have heard of people complaining the polymer tip can deform in flight. Not sure how likely that is.

Zero was done with around 6 shots. Height was spot on. I only had enough ammo to shoot 4 shots at 200 and 300. There was more horizontal spread than vertical. At 200 only about an inch of difference in height on the 4 shots. At 300 about 2 inches variance. I know its not a lot of shots for a group but I don't see a few more shots moving the average very much.

More horizontal than vertical? And low? Scope canted? Watch this:

 

[Cahunter805]

Could be canted rifle or scope like Chris alluded to.
Was this all fired from a bench? Prone? Bipod/bag? I’d confirm your velocity on a sunny day also just to see what your chrony reads then also.

 

[rayporter]

it was the 100yd velocity I was alluding to with the labradar. you can back figure the bc if you have both,

 

[16Bore]

This thread makes me scared to shoot...

 

[MuleyFever]

I will make a point to watch for cant. I don’t think it would be causing as much variation as I am getting but it may be contributing.

While my horizontal spread is greater than my vertical the shots are not all hitting to one side like if I was canting the rifle consistently. I am .5” left of center then .5” right then .75” right and 1.25” left at 200. At 300 similar just slightly larger spread.

I did make sure to torque everything. I am shooting off bags.

I have produced the same excessive drop results on 2 occasions now and with 2 types of ammo. It may just be me I guess.

 

[16Bore]

Left/right is parallax and drift. Shoot 100 rounds at distance and the group will be oval.

What has other ammo done?

This is why I take run of the mill chamberings over something with limited factory availability.