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FFP and SFP and ranging

 
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  #1  
Old 01-03-2011, 03:09 PM
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Join Date: Nov 2010
Location: Port Elizabeth, South Africa
Posts: 22
FFP and SFP and ranging

Maybe this has been asked before so please be patient. I am anticipating my 308 Howa M1500 heavy barrel 24" in a few months and need to finalise scope choice. Rifle will be used for hunting (0 - 400m approx) and target shooting (to about 300m officially but will shoot further for fun).
This is what I want to do and need advice on:

I want to zero at ONE range (say 100m), then (for hunting and target shooting), range find using rangefinder, then consult range drop card (in MIL), use scopes MIL reticle to adjust holdover (let's ignore windage for now), hold over using reticle and shoot. I do not want to fiddle with adjustments/dialing in/out etc as after a few shots at varying distances (as hunting is) I will be so confused (or hire someone to keep track of all the up/down changes) that I will have to spend half the day re-zeroing my rifle after every session. Call me stupid or lazy, take your pick.

So my question is:
If I want to do the above, do I need a FFP or SFP scope? ie will the (as the majority of scopes are SFP) SFP reticle change the MIL distance as I change magnification? (assume I will in the hunting field as prey is closer or further)
So if I shoot at 10x and 100m (zero) - all fine. Next shot is at 200m and I change mag to 16x, now I need to hold over (say) 1 MIL. Is the SFP scope's reticle still 1 MIL at the 1 MIL point (assume a multiple MIL reticle like the enhanced mil dot marked in half MIL increments) at a different mag or is 1 MIL sitting somewhere else on the reticle than where it should be?
I know a FFP scope's gradients stay the same for all maginfications so this should be fine for the above? (Did I just anwer my own question?)

Thinking of the Falcon Menace 5-25x50 for FFP or MTC Viper 6-24x56 (you do not get this scope in the US).

Thanks for sorting me out.
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  #2  
Old 01-03-2011, 03:50 PM
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Join Date: Oct 2009
Location: Thunder Basin, WY
Posts: 1,788
Re: FFP and SFP and ranging

I've been a fan of FFP for many years, however; they are just catching on here in the US in high quality optics. Only downside I've seen in some FFP scopes is that sometimes the subtension (reticle thickness if you will) is not as fine as I'd like it to be.

Yes, you answered your own question. 2nd FP optics Have to be on a particular power for the reticle to work as advertised. Sure, you can change the magnification, and still use it as needed. We just have to realize that the spacing will change as we change power, and calculate how much.

In my case, a 1/2 mil mark/dot at 25X changes to 3 IPHY at 15X......less power = more spacing.
(25/15=1.667...........1.667 X 1.8 IPHY (1/2 mil) = 3 IPHY)

If I want the spacing to be 2 IPHY (basically 2 moa), then the scope needs to be on 22.5X
(1.8x = 2, so x=1.111...........25/y = 1.111, so y=22.5 power)

This of course is in algabraic theory, and obviously should be verified at range on an actual grid; because not all scopes magnifications and zooms are exactly as advertised.......It does work out very well on the particular scope I have.

Last edited by SBruce; 01-03-2011 at 04:10 PM.
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  #3  
Old 01-03-2011, 06:19 PM
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Join Date: Apr 2010
Location: NW Mt.
Posts: 600
Re: FFP and SFP and ranging

I don't understand why you would want a mil dot if you are not going to range with
it? There are much better reticles out there for holdover. I would think a reticle in
iphy ( ffp ) would suit your needs to a t.
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  #4  
Old 01-03-2011, 06:48 PM
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Join Date: Aug 2003
Location: NC, oceanfront
Posts: 3,369
Re: FFP and SFP and ranging

+1 Loner
I also can't stand FFP/reticle changing, nor the coarseness of MILs and MILDOTS.
I'd take SFP, and either IPHY, or MOA hashes for holdovers.
But that's just me.
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  #5  
Old 01-03-2011, 06:59 PM
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Join Date: Oct 2009
Location: Thunder Basin, WY
Posts: 1,788
Re: FFP and SFP and ranging

I too much prefer the moa marks that some scopes have.

That's why I learned to do the conversion with a TMR reticle. Only reason I bought the TMR is that Leupold doesn't offer a MOA reticle in the Mark 4.

Nightforce does, and I love my NF scopes. I've got 3 of them.
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  #6  
Old 01-03-2011, 08:27 PM
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Join Date: Jul 2009
Location: GEORGIA
Posts: 1,211
Re: FFP and SFP and ranging

Hi Vleder,

Since you are living in Port Elizabeth, South Africa are you more accustomed to the metric system of measurement. If you are it is my suggestion that you stick with it.

I am accustomed to feet & inches so I decided to stick with it.

What I did was to have a custom turret made in (yards) so I could use my laser rangefinder in yards and not have to mentally convert to mils. Both systems work equally well.

If you decide to go with a custom turret for elevation do not trust a computer program to give you the drop distances from your zero. Every rifle shoots differently. Once you field test your rifle then you can give the maker of the custom turret YOUR drops at the different distances.

Since most laser rangefinders will display the distances in both feet & meters you can go with either when making your Custom turret. If no wind all you need to do is range your target, turn your custom elevation turret to that distance and shoot. IT IS THAT EASY!!!

This is how I went about having mine made. I think it will help you. I am an advocate of a custom elevation turret. I hold for wind with the hash marks on my reticle.

Drop chart. - Georgia Outdoor News Forum

Testing new Vortex custom turret. - Georgia Outdoor News Forum

Field test: Vortex Viper 6-24x50mm PST MOA FFP scope. - Georgia Outdoor News Forum

joseph

Last edited by joseph; 01-03-2011 at 08:32 PM.
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  #7  
Old 01-03-2011, 09:51 PM
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Join Date: Dec 2009
Location: NW MT
Posts: 2,668
Re: FFP and SFP and ranging

vleder, I am doing just as you want with my scope 6-20 mark 4 mil/mil FFP.I shot mil dots for years so I love TMR RETICLE. Many mil reticles are out. I used the reticle to get me right to 825 w/200 zero. Or I could go up the reticle to get farther. I will typically dial at further range, but like option for speed.under 7 mils takes me to 1000.TMR IS MARKED IN 1/2 M AND HAS A SECTION that is 1/5's.I have been ranging elk and marking mils for a back up system, need more data right now,going to play w/scope on winter range w/lazer
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