Swiss Arms + DMS-1 + 200 yard question

norlandgeese

norlandgeese

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Background
I am using my PE90 as my back-up rifle for service condition matches, I used to have it sighted in by using a front rest and verified it with the bipod, strictly for 100 yard bench plinking. But since the recommendation for service rifle matches is to use the mag for support, the non-free floating PE-90 is causing a POI problem, therefore I have been re-sighting it in and testing it by resting on the mag. I go it sighted in at 100 yard, no problem there, pretty dead-on center grouping.

Issue
But when I dutifully dial the come-up for 200 yard (~1.5 MOA) on the DMS-1 (3 clicks), I am consistently hitting high. I am getting an ok 3" group consistently, however the group is also consistently about 2.5" to 3" higher than expected. Which means if I don't dial the come-up, I am pretty much on center. I am using the same support and bench position for 100 and 200.
That doesn't make laws of physics sense to me. And I don't recall having that problem with my AR (LMT MRP) which also has a DMS-1.

Questions
What could be the cause? Am I dialing it wrong?
My crappy shooting at 200 yard against a 100 yard standard orange cross target?
It has less drop than expected?
The click on the DMS-1 is more than I thought?
Something I don't understand?

Thanks in advance.
 
It makes sense to zero the rifle using the same hold that will be used in competition. You can't use the bipod in SR competition, so lose it.
If you are shooting off the magazine, carefully zero the rifle that way at 100.
Do not hold the forend. Wrap your hand including the thumb around the magazine, or the front of the magazine well. Do not have your thumb vertical, wrap it around with your fingers. You don't want lateral pressure from the thumb. Because you are not touching the forend, the floating/non-floating issue becomes irrelevant.
Zero the rifle at 200. Don't worry about clicks, how many clicks it should be. Just zero it and record the setting.
Repeat at 300, 400, 500. Establish a good base zero for short range - CQB style - shooting.
You can use tiny dabs of white paint, and fine black lines on the elevation knob and housing to make it easier to rapidly select the correct elevation.
Record your settings in your notebook.
Also record them on a sticky label fastened to the scope or the rifle. Cover with tape for waterproofing. You want to have them handy.
Find out what your actual lateral adjustment per click is.
Prepare windage charts, so you will be able to rapidly select an appropriate initial windage setting. Some SR shooters hold off for wind, others use the sight adjustments. If you need a 6 minute correction on a Fig.12 at 500m, holding off might be problematic.
Make sure the scope is mounted square on the rifle. If it isn't, cant is introduced. You can't cant. Given the height of the scope axis above the bore axis, canting will cause a real shift at longer ranges.
 
Ive noticed the same thing with my classic green. I think it's because the scope is so high above the bore, that the bullet is still rising to meet the line of sight @ 100yds.
 
Classic Green .223 said:
Ive noticed the same thing with my classic green. I think it's because the scope is so high above the bore, that the bullet is still rising to meet the line of sight @ 100yds.
Click to expand...

+1 on this. Differences in line-of-sight height above boreline seem to translate into very noticeable differences in apparent trajectory.
 
Perhaps consider a new optic? Not knocking the DMS-1, but having a BDC reticle makes sense. Also, $300 optic on a $3400 gun.

EDIT: As to your actual problem... are you sure the group is actually POI/POA at 100? Going by what you're saying, a 100 yard zero should not be POI/POA at 200 as well. It would look more like 50/250... or 75/200ish (I think?).

Also, you are shooting both at 4x, correct?
 
CarbineOne said:
Perhaps consider a new optic? Not knocking the DMS-1, but having a BDC reticle makes sense. Also, $300 optic on a $3400 gun.

EDIT: As to your actual problem... are you sure the group is actually POI/POA at 100? Going by what you're saying, a 100 yard zero should not be POI/POA at 200 as well. It would look more like 50/250... or 75/200ish (I think?).

Also, you are shooting both at 4x, correct?
Click to expand...

I would doubt the 200 POI before I would doubt the 100 zero, it has been doing <1.5 MOA grouping centered at 100 on more than one session.

Which BDC reticle scope would you recommend? Only want something with no more than x5 power.

And yes I have been staying cheap with the optics especially on a back up gun. No point so far having a more expensive scope on the back up gun.

Thanks.
 
I agree the 200 yard zero is more suspect, but it is best to consider all variables;

If I recall from my DMS-1, the centre dot is 1MOA at 4x mag, correct?
In theory, that means that you could have up to a 4MOA variance if you aimed with different parts of dot (using top edge instead of middle, bottom instead of top, etc.)

POI/POA at 200yds means you should be about 1 inches high at 100 yards (55gr going 3000ish).

That being said, what ammo are you using?
 
Thanks for going over the variables, for sure, I am not complaining about your questions.

Yes the 1MOA dot at 200 yard is not as clear-cut as with 100 yard, especially considering I was using those orange-cross 100 yard targets. The whole paper was pretty much the size of the donut and the orange cross is like an orange smudge inside the donut.
However that being said, I was getting consistent groupings at 200 yard even with the limited optics.

I was using 55gr FMJ American Eagle, red-box. With some head wind, but minimal to no cross wind.

Cheers!

CarbineOne said:
I agree the 200 yard zero is more suspect, but it is best to consider all variables;

If I recall from my DMS-1, the centre dot is 1MOA at 4x mag, correct?
In theory, that means that you could have up to a 4MOA variance if you aimed with different parts of dot (using top edge instead of middle, bottom instead of top, etc.)

POI/POA at 200yds means you should be about 1 inches high at 100 yards (55gr going 3000ish).

That being said, what ammo are you using?
Click to expand...
 
Your problem is to use those orange cross targets - they are designed for hunters shooting with cross hairs. Tell me - how can you see orange with a red reticle? Most likely your issue is inconsistency in sight picture.

The proper way to zero a reddot is to get an 8" (or bigger) black circle. Relax and put the dot in the center. Make sure that you have equal amount of black on the target to form a donut around the red dot.

This works - I used the method to zero aimpoint to hit targets at 300m.
 
I agree with Greentips;

The 4MOA margin of error I mentioned makes a huge difference when aiming at those zeroing targets. At 200 yards, those dots are half the size of the finest point on your reticle.
 
Points taken about margin of error and target choice, however I did not turn the red on, only used the black lines & dot.
 
The DMS-1 does not actually have a red dot, it merely illuminates the centre dot of the reticle red. It does not change the size.
 
Finally confirmed the reality, like someone already mentioned, the sight height is the problem. My setup gives a 3.65" of sight height, with a 100 yard zero at 200 the ballistics only call for a ~0.25 MOA of drop, which is basically no drop adjustment for the DMS's 0.5 MOA clicks. Which is exactly what is happening in real life.
 
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