Reading the discussion about turrets vs. reticles (which I'll admit I haven't gotten all the way through yet, so if this was talked about in it I'm sorry) got me wondering about first focal point vs. second focal point.
I've thought about getting a vortex pst from time to time. There is a $200 price difference with FFP compared to SFP. Would having FFP give that much more of an advantage? Especially if turrets is where it's at for speed and accuracy. Is it just another feature that would be nice to have?
While on the subject, what about mrad vs. moa? Is one better over the other depending upon what you are use to the most? Is one easier to learn over the other? I've got a bunch more questions concerning the functionality of how they work, but I'll leave things at this for now.
Last edited by Gledeasy; 04/10/12. Reason: Changed title
Assuming you're ranging with the scope you can range at any power with a FFP. Another thing I've read about but never experienced (I'm not that great of a shot) is subtle POI shift at different powers with SFP scopes. One really nice thing about FFP scopes is as it gets late and hard to see the reticle you can crank the power up and the reticle gets bigger and easier to see. This is a huge plus when hunting. The down side to this is if you are shooting targets the reticle will cover more of the target as the power goes up. Also, some companies try to compensate for this and the result is the reticle becomes to thin to comfortably use at lower powers because the reticle is too hard to see. US Optics comes to mind concerning the last statment.
mrad vs. moa? I use a range finder and figure clicks.
It's not turrets vs reticles. It's knobs & reticles.
You can spend weeks reading what's been posted on this over at Snipershide where there are more FFP users.
Basically get knobs to match the reticle (MIL/MIL or MOA/MOA). Choose a reticle you like. Since a FFP is uniform, it doesn't actually cover up 'more' of the target, it's covering up the same at all magnifications.
I like the rangefinding element being uniform at all magnifications. I tend to do the 'math' of hash-marks while looking at the terrain as I move through it.
I do use a rangefinder and hash-marks for rise or drops. Haven't bothered with knobs for hunting. Went with MOA for the whole inches thing being easy to understand for ranging and 'felt' more precise with the closer measure than Mil-dot, but a Gen2 Mil reticle (at USO, has 1/2 Mil hash-marks) would likely be as easily finely tuned.
I understand how to use MOA, MRAD is a new to me. I understand it is 1/1000 of a measurement and 1 MRAD ~ 3.5 MOA.
If I had a MRAD scope sighted at 100 yards and had ranged an animal at 500 yards, knowing that my bullet was to drop 35" at this distance. I would need to adjust for 7 MOA's, which I then would assume means it would be 2 MRAD's for this scenario.
Is this correct and would there be a quicker/better way to calculate MRAD's than the way I did using MOA?
Gledeasy, You'll be better off doing a search / read at Snipershide for that question. It's been asked Nth times and there's many replies...start off ok, then degrade.
It will get down to something like this...you'll know your drop in Mils, period, if that's what you get. The reason I say this is because (from what I've read) is that in order to KNOW your drop is X @ Y, you have to shoot rifle+load+scope at Y distance. Calculators can help, but you should confirm X during practice, at which point, you'll be just doing Mils, not conversions.
For ranging your Mil will be like your MOA, but ~3.5 inches @ 100y, etc., and scales out at distance.
To take the mystique out of it. Neither MOA or Mils are inches, they're angles, it's just that MOA are closer to the inches we already know, while Mils are broken into 1/10th of anything.
Gled, You're correct in your example above. 7" of drop would approximate 2 mils.
Mils were explained to me on the back of a napkin many moons ago, but it's still how i best remember/understand it. A mil is the angle subtended by an item of x size @ a distance of 1000x.
Going back to 4th grade or so....... C=pi x D, therefore C=2pi x R, therefore since R (radius or distance) is always 1000 C=6283, therefore there are 6283 mils in a circle, though NATO standard rounded this up to 6400 for ease of calculation.
So, 6400/360 gives us 17.777777 mils in a degree. And 60/17.777777 gives 3.375 moa in a mil. That's rounded up to 3.5 moa, again for ease or calculation.
Hope this helps, but if your head exploded I apologize.
Pete
There is nothing made by man, which cannot be broken by woman.
It's not turrets vs reticles. It's knobs & reticles.
Basically get knobs to match the reticle (MIL/MIL or MOA/MOA). Choose a reticle you like. Since a FFP is uniform, it doesn't actually cover up 'more' of the target, it's covering up the same at all magnifications.
Exactly....
A Mil recticle and MOA knobs (which are on quite a number of scopes) is confusing to start with.
I think MIL/MIL is easier to understand and work in your head but if you go with MOA/MOA and learn that system you will be fine.
You are correct. the PST is either Mil-Mil or MOA-MOA. I have recently been working with the PST 6-24 SFP mil-mil.
The last thing you want to do with a scope of this nature is conversions. Either get the MOA reticle and work with minutes, or get the Mil-Rad reticle and work with mils exclusively. Mils are even easier to work with if you set your range finder to read in meters.
An easy way to define the radian, it is the angle which will subtend an arc equal to the range. At 1000 meters, a radian will subtend 1000 meters. A mil-radian is 1/1000 of a radian. So a mil will subtend one meter at 1000 meters range.
It is also convenient that the mil-radian will subtend one yard at 1000 yds range.
One can handily use the SFP reticle to determine range to a target of known height. For example an elk will measure very close to 24 inches from back to brisket,
So, if an elk subtends vertically one mrad in the reticle of your Viper PST 6-24x50 scope at 24X, he is 667 yds away.
If he subtends one mrad at 14X, he is 389 yds away.
If he subtends one mrad at 6X, he is 167 yds away.
Do not forget to check with Doug at Cameraland for the best price available on the Viper scope. Just mention you want the Campfire price.
People who choose to brew up their own storms bitch loudest about the rain.
I understand how to use MOA, MRAD is a new to me. I understand it is 1/1000 of a measurement and 1 MRAD ~ 3.5 MOA.
If I had a MRAD scope sighted at 100 yards and had ranged an animal at 500 yards, knowing that my bullet was to drop 35" at this distance. I would need to adjust for 7 MOA's, which I then would assume means it would be 2 MRAD's for this scenario.
Is this correct and would there be a quicker/better way to calculate MRAD's than the way I did using MOA?
Gledeasy for me the beauty of a FFP reticle is you dont need to know a conversion of inches to moa or mil, you simply know what the drop is in moa or mil. To top it off I can shoot at whatever magnification works for me, I am not stuck being at a specific power to make sure any special reticles are accurately. If I choose to hold off with a mil dot reticle I can use it just as accurately at 6x and 9x.
Here is an example: if I am facing a shot at 525 yards in a 5mph full value wind I dont care how many inches of drop or drift there are, all I need to know is it will be +2.3mil of elevation and .4mil of wind. With that information I can simply hold or dial to connect.
Attached is a copy of the chart I used for my .270, you will notice I dont even have inch values for anything, it is all based on mils that can be used to dial or hold.
Hunt hard, kill clean, waste nothing and offer no apologies.
"In rifle work, group size is of some interest...but it is well to remember that a rifleman does not shoot groups, he shoots shots." Jeff Cooper
One can handily use the SFP reticle to determine range to a target of known height. For example an elk will measure very close to 24 inches from back to brisket,
So, if an elk subtends vertically one mrad in the reticle of your Viper PST 6-24x50 scope at 24X, he is 667 yds away.
If he subtends one mrad at 14X, he is 389 yds away.
If he subtends one mrad at 6X, he is 167 yds away.
While maybe seeming like a good idea in theory, this really does not work in actual use. Besides ranging with reticles being horribly inaccurate on living objects, very, very few scopes are actually on the exact power that the ring states. What happens to your range when instead of 14x it is really 15.7x? Unless one is going to map the reticle and power ring on paper to know what the actual values are this is not the way to do it.
No, it does work with limitations. Keeping in mind thaty deer and elk vary a good bit in chest depth and keeping in mind that any up or down hill angles change that as well, it works in that it avoids the large errors in range estimation of the shorter long range shots, say 300-400 yds. or so. Take the Leupold 6X scopes for instance. The thin opening is 9 inches at 100 yds. That nice looking, 5 pt muley is nice enough to stand broadside at 200 yds. or is it 300 yds. ? If he fills the thin opening, he's about 200 yds. But if he only fills half of it, he's 400 yds., not even 300 yds like you once thought he might be. Oh.... Gee, I thought he was alot closer than that. A very common mistke in the clear air of the western mountains. Now I realize that a range finder cuts down on all of this guessing. Happen to have a well used one myself. I know enough about dials to like them too. Nothing like being precise. The trouble is that the darn breeze makes shooting out where I really need a LRF a real guessing game. If guess wrong, I gut shoot something and off it goes. To places that are anything but fun to track him in. Assuming of course he's nice enough to bleed or leave tracks. So much for the 15 min wonder long range shooters. No, range finding reticles really do not only work, they can also prevent us from trying to make shots that we really shouldn't. E
One can handily use the SFP reticle to determine range to a target of known height. For example an elk will measure very close to 24 inches from back to brisket,
So, if an elk subtends vertically one mrad in the reticle of your Viper PST 6-24x50 scope at 24X, he is 667 yds away.
If he subtends one mrad at 14X, he is 389 yds away.
If he subtends one mrad at 6X, he is 167 yds away.
While maybe seeming like a good idea in theory, this really does not work in actual use. Besides ranging with reticles being horribly inaccurate on living objects, very, very few scopes are actually on the exact power that the ring states. What happens to your range when instead of 14x it is really 15.7x? Unless one is going to map the reticle and power ring on paper to know what the actual values are this is not the way to do it.
Well, maybe in light of current technology.... but there was a time not too very long ago when one had no choice,there being no LRF's at all and you were left with the skill,discretion,and intuition reserved today for guys reading wind....and the same way some become very good at that,so too did we become accustomed to looking through the lenses of a 4X or 6X scope,and gauging distance. You had to do a lot of shooting and hunting to cement this stuff in your brain, but it could pay off.
Counterintuitively,a SFP variable did not work very well for this,the changing powers constantly giving a different "read"to the minds eye,and effectively shortening distance...but if you used (say)a 4X leupold for a lot of this, you "knew" that the reticle subtended about 8" (the books say it is 7.5")at 100 yards...and I always used 32" as the hairline to hairline measurement of a big bull elk....telling you that if he filled that space between intersection and bottom post,he was about 400 yards away.
Knowing your trajectory cold is also helpful here.
I used this "trick" to kill a couple o bull elk at the 450-475 yard mark, and one mule deer buck at about 500.There were others.
None of this is to suggest the method is as precise as a modern LRF,and it certainly had its' limitations...but even today it is not a bad skill to acquire,lest you find yourself in the situation I did 3 years ago,where I was nailed down on a stalk in knee high brush for a pretty nice mule deer in Wyoming,and unable to use a rangefinder.Using the scope I guauged distance at over 300 yards ,not much over 350, and was able to kill him.We lazed after the kill,and came up with 340 yards.
The reason I will use an LRF when and if I can, but have a backup plan if for some reason, I can't use one. A reticle estimate may save the bacon.
Bob and E- I'm with you on the fixed power deal and field expedient it works. Just like mil dots when used correctly and I believe that any competent hunter should know how to get a rough range without LRF's. I was addressing the advise of using a variable at different powers to bracket an animal and get a range. That = no bueno.
In general I agree. Heck, I'm seriously considering buying another 6X42 with a Mil-Dot reticle as I post this. Either that or a custom retilce with 2 MOA spacing of the dots. However, I'm also of the impressions that anybody with a scope that he might use for quick ranging should actually test the spacing of whatever his reticle has. That way, it doesn't matter what the actual magnification of the scope is or just what the spacing is as long as the user knows just what he has at what setting. E
I'll never forget what my gunsmith told me about longer range shooting in the field many years ago now. He said, "It takes just the right sort. The kind that has a bit more than a passing interest in mathematics."
I never realized just how right he actually was, or how that comment would influence my shooting career thereafter.
The two most important concepts to learn are--
1) The mil-dot mil-ranging formula defines rangefinding and downrange zeroing with any multi-stadia reticle or turret, and should be understood completely to be able to calculate any of the other variables once the others are known.
2) Reticle subtension is ~inversely proportional to magnification. Yes it's true that most power rings are incorrectly calibrated for the optic's true power, but it seems they're close enough. In fact many ballistics programs use this concept in their calculations.
Here's an example of how this stuff worked just yesterday while i was out shooting prairie dogs with this little 22 LR Ruger Mk III--
While walking back to the truck i saw this little rock on the side of a dirt bank at a lasered 100 yds. I thought to take a shot at it and see if i could hit it. That optic on top is an el cheapo 2x Barska. The plex reticle in it measures 15 MOA. Now that's an awful big subtension to try and interpolate a zero off of, but i wanted to try it to see if it would get me close. I knew tht at 100 yds. the bullet drop was 6 MOA. So by applying the mil-dot mil-ranging formula [actually a simplification of it], i could calculate the interpolative zero along that reticle for that distance. But i didn't have a calculator with me so i didn't know how to really do it, but i could sort of figure it out since i knew that 4x1.5=6 [the simplification of the true mathematical formula that defines it--the "mil-ranging formula"]. That meant that the correction [the "mil-reading"] needed was 40% of 15 MOA PPT or .4 PPT [plex post tip]. So i got setup tight in my stadium seat with pistol braced on my knees, and interpolated the .4 reading along the reticle. 1st shot was a miss and i couldn't see the impact at that range. At the 2nd shot the rock disappeared and i thought i saw the 2 pieces roll down the hill after a distinct "meat report". I walked up and found where i'd actually hit that little tgt. as seen in the pic. below. This is the reason it's important to know these MIL/MOA concepts for in-the-field improvisation and application...'CAUSE IT'S REALLY FUN, AND IT WORKS!!
but there was a time not too very long ago when one had no choice,there being no LRF's at all and you were left with the skill,discretion,and intuition reserved today for guys reading wind....and the same way some become very good at that,so too did we become accustomed to looking through the lenses of a 4X or 6X scope,and gauging distance. You had to do a lot of shooting and hunting to cement this stuff in your brain, but it could pay off.
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