15x or 20x (max) for a .308 bolt gun

[EvolutionGSR]

Can anyone say if there is a downside to having a higher max power on a scope? Scopes are about the same size. Would there be any reason to go for the 15x over the 20x?

[Black Majik]

The biggest downside I can think of for a SFP 20x is needing to subtend correctly at that high of a magnification. Depending on the distance you're shooting it may be more difficult to spot hits on higher magnificationd due to smaller FOV.

[Matt P]

Several issues,
Higher power, the stability of your rifle becomes more of an issue. What you use to stabilize your rifle may not allow you to use max magnification. Bags are more stable then a bi-pod for example. Consider the type of rests you will more then likely use to shoot off.
When you will shoot and where. Mirage will become more of an issue as we get into summer. Again, lower power will be better if you will be shooting in field conditions and during the summer.
Those are just two I can think of quickly.

[EvolutionGSR]

Matt thanks, I understand. Ill be shooting off bags at the range and bipod in the desert.

Blackmajik - what do you mean by subtend correctly? I bought a glock from you many years ago....didnt I?

[CSACANNONEER]

There are pros and cons to more magnification. I'm not against putting a 12-42X scope on a .22 or a .308 but, sometimes a 4X scope is the right choice. It really depends on the type of shooting, the rest of your equipment, your ability, etc. The higher the magnification, the more mirage you are going to see. This can be a good or a bad thing depending on your abilities. Internal windage and elevation adjustments seem to be less for high magnification optics. Will this be a problem?

[Black Majik]

Matt thanks, I understand. Ill be shooting off bags at the range and bipod in the desert.

Blackmajik - what do you mean by subtend correctly? I bought a glock from you many years ago....didnt I?

Yes you did, a G23 if i remember correctly. hope it treated you well.

Most scopes will have some sort of reticle you can use to range targets, such as Mildots for example. For second focal plane scopes the reticle is "correct" at a certain magnification, usually at the highest power unless otherwise stated by the manufacturer. If For example you're using Mildots on a 5.5-22x Nightforce NXS in SFP it is required to have the magnification at 22x for the Mildots to measure correctly 1 Milradian center to center. As such any other magnification will not measure true 1 Milradian. If you need lower magnification to say... spot hits because your FOV at 22x is too high, you can turn it down to 11x, however your Mildots now will read 2 MIL instead of 1 MIL. Turn it down to 5.5x and you have 4 MIL per each Mildot center to center.

First Focal Plane scopes eliminates this issue, as it now subtends correctly at all magnifications. However, the reticle will now grow and shrink as you lower and increase magnification. So, lets say for example we get a unicorn 5.5-22x F1 NF (yeah right). At 22x your Mildot reticle will be true 1 MIL. At 11x, a SPF scope will be 2 MIL, with a FFP it is still 1 MIL. At 5.5x with a SFP will be 4 MIL, with FFP it is still 1 MIL.

Hope that sort of makes sense. Hopefully brando can chime in since he's better at explaining these things.

[Matt P]

Milling is a beast all to its own.
Understand to use that feature on ANY scope, you have to not only be able to break the retical down in size/measuring, but also have a pretty good idea of the size of things at distance. Meaning a rock, a tree, a building, whatever. Unless you will be shooting at known sizes of targets, then less of an issue.
Additionally, due to the rock like drop of that rifle cartridge, your ability to mill and do it well will be even more tested as that cartridge is not very forgiving in its trajectory at longer ranges.
Unless you are going to be dedicated about learn how to mill and take the time to learn it and practice it, I suggest not to worry too much over first focal vs second.
Most importantly, be very realistic at what distance you want to shoot to. When you start shooting past 500 yards, things get difficult real fast.
We all want to shoot to a 1000 yards and more, but few realize just how difficult that is.

[EvolutionGSR]

Csa - i want to hit small targets at long distances, thats why im going for this higher magnification.

Blackmajik- sold the g23...haha. I decided I didnt want to stock .40 for my pistols. Just 9 and .45. But i know what you mean now by that explanation. I have already read into the ffp and sfp differences.

[EvolutionGSR]

Matt- Im going to take it incrementally. I had experience with a rem 700 about 8-9 years back, when I used to shoot at fish canyon. Problem was I only got to shoot at 100 yards and I was unaware of angeles at the time, so I sold it. I was capable as a shooter to group it sub .75 moa right away with federal gmm. I would zero it at 100 and strat paper punching at 200 at angeles. After that move it out to 300 in the desert. I'll try to strt milling after that.

Ill also be going for the small swingers at 300 and 400 at angeles.

[Hk996]

Get the 20x. I have a mark IV SFP 15x that I thought I was happy with till I started shooting with Blackmajik! Now I also have a 5-25x FFP and couldn't be happier... the way I see it, I can still scale down to 15x or less if I want to (rarely happens) but if you have a 15x, then that's it.

[CSACANNONEER]

Csa - i want to hit small targets at long distances, thats why im going for this higher magnification.

Blackmajik- sold the g23...haha. I decided I didnt want to stock .40 for my pistols. Just 9 and .45. But i know what you mean now by that explanation. I have already read into the ffp and sfp differences.

I can hit clay pigeons at 1000 yards with my 5.5-22X NXS but, I do prefer using my 8-32NXS instead. Are you going to be shooting a set distance or a large variety of ranges? This will make a difference. My 5.5-22x has the ability to allow me to zero it at a wider variety of distances than my 8-32x does. If all of your shooting will be done at one range or close to one range, that's one thing but, if you are planning on shooting from 50 yards to one mile, you are going to have to look into scope adjustments, etc. Also, higher power optics can go blurry (due to mirage) under certain conditions. Last summer, I was shooting in Coalinga and having issues with conditions. One second I could see the target crystal clear at 32X and the next second, I had to drop the power down to 8X just to get an idea where the target was.

[Matt P]

I can hit clay pigeons at 1000 yards with my 5.5-22X NXS

Please offer to support this,
What Cartridge are you using?
What rifle manufacture are you using?
What type of rest is this level of accuracy from?
How many shots does it take to just hit one on average?
Having just been on the private 1000 yard range last Sunday shooting, please understand that I would not be the only one to feel that level of shooting near impossible. You seemed to throw that out like some pretty basic feat in your effort to prove another point. Shooting to that level of accuracy is incredibly above average. Shooting like that would allow you to easily dominate at High Power matches.

[IrishPirate]

the ability to go higher magnification is usually pretty useful, but the knowledge of which magnification to use in a situation is always useful. Just because you can go 25x on a target, doesn't mean that 25x is best. Sometimes, 10x is better than 25x. But without a 25x scope, how would you know???

[EvolutionGSR]

I am looking to shoot at different distances. I too use clays when I'm out in the desert for targets, but going past 600 yards with a .308 probably won't happen anytime soon for me. Sounds like a 15x will be good. Also looks like the FFP scopes cost a little bit more, I'll probably steer away from them.

[CSACANNONEER]

Please offer to support this,
What Cartridge are you using?
What rifle manufacture are you using?
What type of rest is this level of accuracy from?
How many shots does it take to just hit one on average?
Having just been on the private 1000 yard range last Sunday shooting, please understand that I would not be the only one to feel that level of shooting near impossible. You seemed to throw that out like some pretty basic feat in your effort to prove another point. Shooting to that level of accuracy is incredibly above average. Shooting like that would allow you to easily dominate at High Power matches.

You're welcome to come to a FCSA match and witness this for yourself. Consider this a personal invitation to show up at our match this June in Coalinga on site in day. As long as I know in advance, I'll load some ammo for you to do it yourself. OK?

Rifles are a FAB10 with an ALS upper and an AR50.

I use an Action Gun Works rear reat that Randy slapped together for me the night before a match and, I think he used whatever culled parts he could scrounge up. I'm not complaining though. The very first 5 shot group I shot off it measured 6 7/8". My front rest has morphed into a Franken rest using a Sinclair style top (off a rest I bought at Angeles) and a Whitchita Magnum base.

It took me about 4 or 5 matches (2 per year) to hit my first one. Of course, we only shoot them on sight in day. I've run 3 in a row and stopped before too. It depends on conditions and how well I'm shooting that day so, I really can't give you and average. Some guys can do it more than 50% of the time. I'm probably closer to 35-45%. That's starting with an unsighted in gun and a cold bore though.

Anyway, I agree that it does seem near impossible until you start doing it. It takes a little know how, some homerolled ammo that takes me about 15 minutes per round to load and a bit of luck. IMHO, quality trigger time and quality ammo are really the key.