Rifle Scopes Lack of elevation travel

[esheato]

Shooting a HS Precision HTR in 338 LM.

Have a 20 MOA NF base with Badger rings. Optic is a S&B 5-25 P4F.

Using my load (285 Hornady, Lapua brass, 83.3 H1000, avg velocity 2593 fps), my 100 yard zero was acquired by dialing up 7 mils.

I zero'd my knobs, but now I only have 22.5 mils of travel before I run out. Shooting to 1 mile requires 23 mils and eventually I'd like to shoot even farther.

How do I remedy my lack of travel? A more angled base? Shim the rear ring? Is there any way to get my 7 mils back from the zero'ing process?

I'd like to maintain the hundred yard zero if possible.

Thanks in advance.

Ed

 

[BobinNC]

Re: Lack of elevation travel

Ed,

You could use your reticle, plus dialing. For example dial 22 Mils with your turret, then use your 8 Mils on the reticle, to get up to 30 Mils, or any combination thereof.

 

[esheato]

Re: Lack of elevation travel

Ahh..shit.

Talk about a "duh" moment. I didn't even think of that. I just assumed I'd dial it.

 

[TonyAngel]

Re: Lack of elevation travel

You could just get a 40MOA base. I struggle shooting at distance as it is. I can do ok, holding for wind OR elevation, but not wind AND elevation. A mile is a long way too. Of course, you could just dial for wind, but I'd imagine that shooting at those distances, accounting for wind would be an "on the fly" adjustment.

 

[esheato]

Re: Lack of elevation travel

Yeah but could I still maintain my 100 yard zero with a 40 MOA base? I guess NF would know...

There has to be an S&B expert here that can get me straightened out.

 

[billyburl2]

Re: Lack of elevation travel

Yeah but could I still maintain my 100 yard zero with a 40 MOA base? I guess NF would know...

There has to be an S&B expert here that can get me straightened out. [/quote
If not, it will be easier to hold under for 100 yards, than to hold over for a mile... Just saying...

 

[cuffm4615]

Re: Lack of elevation travel

Ed I have not had a need for this but I have read of shooters taking their bases to gunsmiths and having them add cant. Perhaps a local gunsmith or one here on the hide can customize your base to add one or two more mils and still keep enough to maintain your 100 yd. zero. Just something I believe I've read but can't say I'm 100% right. Perhaps someone else can chime in and advise if I'm right or wrong.

 

[Sandbogg]

Re: Lack of elevation travel

I run a NF 40 moa on my 338 lapua, this would probably be perfect for your needs. Badger ordnance makes a 30 moa base which would also work well. Another option is Murphy precision who will make whatever you want.

I would try the NF 40 moa. My optics are Nxs 5-22 and I have no problem reaching 1860 yards. (65,moa and I have a little over 20 moa left ).

 

[Kiba]

Re: Lack of elevation travel

Going from a 20MOA to 40MOA base is going to move the POI about 5.8 mils @ 100Y-- so you should still be able to maintain your 100Y zero if you have 7 mils of down adjustment left in the scope with the 20MOA base.

 

[esheato]

Re: Lack of elevation travel

Perfect Kiba! That's what I was trying to get at...just didn't know the right way about it.

Thanks everyone.

 

[esheato]

Re: Lack of elevation travel

Ahh...just talked to Nightforce and they confirmed that the 40 MOA base would be more appropriate.

And just like Kiba said, the difference in mils between 20 and 40 MOA at 100y is less than my zero adjustment...so I can maintain my 100y zero and still get waaaay out there.

Sweet!

 

[esheato]

Re: Lack of elevation travel

Alright..

Slight problem.

The 40 MOA NF base has a recoil lug on it...and it's on the wrong side. The 20 MOA NF base that came with the gun has the lug on the proper side.

My gun is left handed so that's the problem. I guess another call to NF is in order.

Also, Kiba, how do you do the math to figure out the 20 vs 40 MOA at 100y?

 

[AnthonyL]

Re: Lack of elevation travel

The S&B scope will just barely reach 100yard zero with a 45MOA base. The 40MOA will be perfect and if you need that extra bit distance dial it with the reticle.

 

[bbw]

Re: Lack of elevation travel

The math...

Read the manual chapter 4.2. The pictures on page 19 also illustrates the issue.

http://www.schmidtbender.com/images/downloads/PMIIInstructions2006Edition.pdf

"At the Schmidt & Bender factory the reticles of PMII scopes are
adjusted out of center by half the amount of the full elevation range. This value must be compensated in the mount system."

Elevation range is 26 mils for the 5-25, half is 13 mils. 1 mil = 3.438 MOA

13 x 3,438 = 44.7 MOA. So with a 45 MOA base you basically only have "up" adjustment available and 100 yard zero may be a borderline case. A 40 MOA base should be just fine, and you do not sacrifice much "up" adjustment.

Most other scopes are delivered centered, and e.g. a 100 MOA adjustment normally means 50 up or down.