Measuring scope height for ballistics program

[missed]

If wind is a big concern switch to a 6.5 of some sort. Much more forgiving in the wind.

It's not that big of a deal, I would like a 260 but it's not going to happen anytime soon

[jhelmuth]

most often charts need tweeking before a final version. first off chronagraph information is rarly
perfectly accurate. id be printing a chart and go shoot. the actual shooting results trump all other
factors at least on that day under those conditions. you will no doubt be tweeking numbers in order
to match what you actually did. that will give you a baseline to go by. your weather station can be helpfull
in updating your data on subsequent outings. another option and the one i use is sighter shots.
today there is alot of talk about first round cold bore hits even at extreme distances. no doubt in some areas
that would be more important than in others due to terrain. we shoot across wide valleys onto steep mountainsides.
sorta like shooting at a picture on a wall. misses can be quickly evaluated corrections made and follow up shots
on their way in seconds. im well aware not all areas are as easy as that. a miss may in fact be hard to detect as to why.
thats where a buddy acting as a spotter is very important.


data is simply a means of getting you on target quickly. seeing hits is far more important than data. even if you guess the yardage
and are wrong causing the shot to go 10' low. so long as you or your spotter saw it you can be on with the second shot or at least very close. my guess is you have an equiptment issue or your method needs to be scrutinized. are you shooting from your belly?

Well put yobuck. Understanding this in the big picture will gain the best results...

[thomae]

Ok, now that we are back on target:
Centerline of the windage knob to the centerline of the action.

I agree with JHelmuth that Yobuck's quotes get the big picture.

I would either go with Stangfish's statement, or would guess that the center of the reticle when properly focused and aligned with the target might be the answer, but I have no facts to back up my guess.

I realize this is still an approximation, and that's the best I believe we are going to get.

Think about the following:
Even if you have your scope mounted on a 0 MOA base, the angle (from horizontal) of the light path from the target through the center of the reticle to your eye is at the same angle as if the scope were mounted on a 20 MOA base.

So, the rhetorical questions I would ask are:

1. Is it really the height of the scope above the barrel that is important or is it really the height of the actual light path above the barrel that we should be measuring?

2. If the answer is the light path, then where along that light path do we measure "scope height?

This is a good academic question and discussion, but, at least for me, at some point I accept approximation as "good enough." I don't think I can consistently and deliberately change my POI by .25 MOA, so I have no problem accepting a reasonable "area of probability" in which my bullets will impact the target.

[yobuck]

Ok,

This is a good academic question and discussion, but, at least for me, at some point I accept approximation as "good enough." I don't think I can consistently and deliberately change my POI by .25 MOA, so I have no problem accepting a reasonable "area of probability" in which my bullets will impact the target.

that sums up the whole discussion. we should attemt to use as accurate data as possible. but we also need to accept that data alone
wont improve what we lack in ability and or equiptment. this stuff can be learned very easily by average shooters who are willing
to listen.

[yobuck]

If wind is a big concern switch to a 6.5 of some sort. Much more forgiving in the wind.

im sure youd agree that their are 6.5s and then their are 6.5s. the wind will be more forgiving on the one driving a 140
@3300 than it will be on one @2800.
so now what happens if we drive a 284 180 berger at 3200?
or a 300 gr berger in a 338 @3200?
their all gonna be door to door to a point, after which the bigger bullet will prevail.

[stomp442]

What happens then is a considerable increase in recoil and cost. Most shooters are not going to get that kind of velocity out of a 284 bullet without jumping to a large magnum caliber which uses more powder and probably requires the installation of a muzzle brake to be able to shoot comfortably. Same can be said about the 338. At over a dollar a round most shooters are not willing to drop that kind of coin. We would all like to have one I'm sure but most of us don't.

My point about switching to a 6.5 even one that only goes 2800 fps is that it will still provide much better results in wind versus all but the heaviest of bullets out of the 308 and will do this using pretty much the same powder charges with less recoil. This means no costly muzzle breaks or 70+ grain powder charges.

[jhelmuth]

Just for the purposes of "easy" to calc. centerlines (scope to bore).

[Note: this only work for a 0 MOA base]

[(Action Diameter)/2] + top of action to bottom of scope tube gap + [(Scope Tube Diameter)/2]

Example: 1.351/2" (Action) + 1" (measured gap between action and scope tube) + 30/2mm (Scope Tube) ---> 0.6755" + 1" + 0.595" = 2.2705"

I've only measured the PTA, but I think it's an OK assumption that all Savage actions are same diameter ~ 1.35". The example above does not reflect any actual values regarding any particular mounting. YMMV....

[yobuck]

What happens then is a considerable increase in recoil and cost. Most shooters are not going to get that kind of velocity out of a 284 bullet without jumping to a large magnum caliber which uses more powder and probably requires the installation of a muzzle brake to be able to shoot comfortably. Same can be said about the 338. At over a dollar a round most shooters are not willing to drop that kind of coin. We would all like to have one I'm sure but most of us don't.

My point about switching to a 6.5 even one that only goes 2800 fps is that it will still provide much better results in wind versus all but the heaviest of bullets out of the 308 and will do this using pretty much the same powder charges with less recoil. This means no costly muzzle breaks or 70+ grain powder charges.

your points are valid ones. these are things that need to be considered before deciding how far is far.
it also depends on wether your interest is in some type of target or shooting at animals.
most hunters dont need to be told when they need more gun. its something they usually find out on their own the hard way.
as for the muzzel brake. take your 260 out and shoot at a small rock at 500 yds and then tell me where the bullet hit.
if you cant tell me then your simply sending lead in the hopes something falls over.
a muzzel brake will enable you to see every one of your own hits. of secondary importance is that they also help felt recoil
on the larger cartridges.