Rifle Scopes Help! SB PM II question

[Carrera]

I have an SB PMII 5-25x56 MOA/MOA with doubleturn (and 65 MOA of total travel?).
I have it on a DTA SRA 338LM, mounted with DTA 30 MOA taper base/rings.

I would expect this combination to get me nearly dead on at 100.. I have used up all of the travel and am still 6 inches high at one hundred yards!

Is there something that I am missing? Could my base be mislabeled? Is it my scope?

Thanks in advance!

 

[Thor2j]

I have srs and 30 Moa rings with nf nxs. Still plenty of travel down. I would check that the mount is facing right direction first.

 

[lowfill707]

a 30 moa base should have a pretty obvious cant to it. it would be hard to mount it the wrong way without noticing, whether it was labeled wrong or not.

 

[Carrera]

Yes, I did check the mount - definitely tapered the right direction. What I meant by mislabeled was wrong MOA...

Thanks again

 

[Captain Kirk]

Did you make sure you lifted the elevation turret enough to reset the zero stop?

 

[Carrera]

Did you make sure you lifted the elevation turret enough to reset the zero stop?

It would be two full turns regardless of setting the zero stop - it is the windowed version with the yellow and black windows depending upon which turn.

 

[lowfill707]

Yes, I did check the mount - definitely tapered the right direction. What I meant by mislabeled was wrong MOA...

Thanks again

i might be wrong, but considering that you checked and it definitely is canted and facing the right direction, even if it isnt the 30 moa stated and is something else like 20 you should still have no problem getting a 100 yard zero. its looking more like a scope issue at this point.

 

[Captain Kirk]

Understood, but the amount of elevation you have is dependent on internal travel AND the zero stop. You may just be hitting the bottom of your zero stop but still have additional MOA to allow you to obtain your 100 yd zero. I didnt understand how the zero stop worked on the first PMII I purchased years back and had the same issue.

 

[Trigger Monkey]

I doubt your scope has an issue, the 5-25 actually has closer to 100 MOA of internal travel, more than enough for just about any canted base. Try this, loosen the set screws, turn the knob to 8 MOA, retighten the set screws and then try dialing down. Chances are and it's a common occurence that you bumped the zero stop dialing down to get zeroed.

 

[19Scout77]

I doubt your scope has an issue, the 5-25 actually has closer to 100 MOA of internal travel, more than enough for just about any canted base. Try this, loosen the set screws, turn the knob to 8 MOA, retighten the set screws and then try dialing down. Chances are and it's a common occurence that you bumped the zero stop dialing down to get zeroed.

If that does not work trying dragging behind your jeep for a couple blocks!

 

[Aries64]

Importance of using the correct base/mount cant with PMIIs'

I have an SB PMII 5-25x56 MOA/MOA with doubleturn (and 65 MOA of total travel?).
I have it on a DTA SRA 338LM, mounted with DTA 30 MOA taper base/rings.

I would expect this combination to get me nearly dead on at 100.. I have used up all of the travel and am still 6 inches high at one hundred yards!

Is there something that I am missing? Could my base be mislabeled? Is it my scope?

Thanks in advance!

It's possible, but not probable, that your base is mis-labeled and/or that there's a problem with your scope. The problem is most likely the classic problem of not using a base/mount with the proper cant for the scope/application. This is not intended as a slight on you, but illustrates why people really should do their homework on equipment. It also helps to actually read the Owner’s Manual, as the Manual recommends that a base/mount cant equal to ½ of the scope’s Elevation travel be used. In a nutshell, the PMII scopes (exclusive of the Short Dots) are designed for long range shooting, and the way they are designed they need a base/mount equal to ½ out the Elevation travel in order to provide maximum adjustment travel. As stated in the Owner’s Manual, PMII reticles are adjusted out-of-center at the factory by 1/2 of the scope’s Elevation travel, and in order to compensate for the mechanical offset and re-"center" the reticle, a mount/base equal to (or at least close to) this offset must be used. The PMII-25X[56] was originally designed for the ultra long range of the .338LM (like you're shooting) and was configured with 0.1 MIL (1/10th MIL, i.e. .36" at 100 yards) click value, so 45 MOA of cant is really what the PMII 5-25X[56] is designed to use. You can download the PMII Owner's Manual may be downloaded here: Information

NOTE: Although your click increments are .250 (1/4) MOA, the Erector itself has the same internal travel as the MIL increment 5-25X[56] PMII, so a 45 MOA base/mount still works with a 45 MOA base (this has been confirmed by people with .250 MOA Turret PMII 5-25X[56]s’). The DT Dial itself limits the travel (there’s still more travel beyond the 65 MOA marked on the second turn, but you’ll break the DT Dial if you force it past the Dial’s mechanical Stop). I've posted about PMII scopes and the potential problem of running out of Elevation travel when using an inappropriate base/mount many times over the years, but since most people never need to dial to maximum travel on their PMII scopes, the blanket recommendation for 20 MOA bases for use with PMIIs’ seen on the internet tends to prevail. However, such as in your case, sometimes people run out of travel. It appears that another 10 MOA (for a total of 40 MOA) would be just about perfect for you.


Keith

 

[Pleistarchus]

There is nothing wrong with your scope and nothing wrong with your mount. I had an identical problem when going out to zero my brand new SB PMII 5-25. The only difference is I had a 30moa "rail" as part of my rifle which left me using 0moa mount....same thing basically. After doing some research I found out this.

As it sometimes happens with certain rifle/base/optic combinations, the zero stop can be engaged before the shooter can get a good zero on the rifle. Many shooters mistakenly think that since the knob has stopped turning, they have run out of adjustment and either something is wrong with the scope or they need another base with more cant. This is often far from the case and the scope really does have plenty of internal elevation adjustment left "underneath" the zero stop. Follow the steps below to get around this problem and get the scope zeroed to the rifle.
1.Using the reticle, measure the distance from the bullets impact on target to the the desired point of aim, point of impact.
2.Loosen the two set screws and turn the knob in the direction needed for more elevation. Since the setscrews are backed out, there will be no shift from the previous adjustments. The amount of turning necessary is dependent on how far above the desired point of impact the bullets are hitting the target. If the bullets are still 3 mil above the target turn the knob to 3 mils.
3.After that has been completed tighten the setscrews back down and turn the knob back down until the bullets are impacting point of aim, point of impact.
4.If the initial correction still hasn't gotten the desired, repeat steps 1-3.

 

[Jerry R]

Your scope should have well over 120 MOA of internal travel. It sounds as if your knob needs reset properly.

Call me at the service center if you have any questions. I'll be more than happy to help you out.

 

[Aries64]

Resetting the standard PMII DT Turret

Did you make sure you lifted the elevation turret enough to reset the zero stop?

It would be two full turns regardless of setting the zero stop - it is the windowed version with the yellow and black windows depending upon which turn.

Understood, but the amount of elevation you have is dependent on internal travel AND the zero stop. You may just be hitting the bottom of your zero stop but still have additional MOA to allow you to obtain your 100 yd zero. I didnt understand how the zero stop worked on the first PMII I purchased years back and had the same issue.

I doubt your scope has an issue, the 5-25 actually has closer to 100 MOA of internal travel, more than enough for just about any canted base. Try this, loosen the set screws, turn the knob to 8 MOA, retighten the set screws and then try dialing down. Chances are and it's a common occurence that you bumped the zero stop dialing down to get zeroed.

Oops. I read-though the thread before I posted my earlier reply, but I forgot to address the possibility that you might need to reset your DT Turret (easily done on standard “window-type” PMII DT turrets). But first, try what Trigger Monkey suggested above (see my quote of him above), and if that doesn’t work then you can reset the DT Turret.

To reset a standard PMII DT Turret:

(a) Loosen the two (2) set screws on the DT Turret to disengage the DT Turret from the Erector. Be sure that you back-out the set screws enough so that the DT Turret is disengaged.

(b) Turn the DT Turret two (2) full turns in the direction opposite of “UP”. This resets the DT Turret Indicator.

(c) Re-index the DT Turret so that the “0” line on the DT Turret coincides with the index mark (triangle) on the PMII’s base, then re-tighten the DT Turret’s set screws and you’re finished.

Underside of standard “window-type” PMII DT Turret. Here you can see the DT Indicator Actuator. Note the
slot machined into the Actuator: it is engaged by the DT Actuator Pin:
<a href="http://s155.photobucket.com/user/Louman64/media/Schmidt%20Bender/PMIIDTActuator8x6_zpsdeda9191.jpg.html" target="_blank">

This pencil in this photo is pointing to the DT Indicator Actuator Pin. The DT Indicator Actuator Pin engages
the slot of the DT Actuator at the mid-point of the DT Turret’s (marked) travel, changing the “window” color
to indicate the current turn:




Note that you can also set the “0” above the actual Hard Stop (absolute zero) if you like, allowing you to dial down below your 100-yard zero for sub-100 yard shots and/or to compensate for a load change. I know that the 0.1 MIL PMIIs’ come set about .5 MIL above the Hard Stop from the factory.


If none of the above solves the problem, I highly recommend that you take Jerry Ricker up on his invitation to call him. Jerry is a Schmidt Bender Service Technician and he knows the scopes.




Keith