It would be absolute co-witness if I didn’t have the 1/2" riser. Instead I just live with lower 1/3.
Primary arms has a nifty little micro RDS… just got mine today…will let you know how it works!!
duh, what was i thinking?
i’m going to post this here, then reference it in the ‘front sight’ thread
i had a stupid experience that i don’t mind sharing so others can potentially avoid this stupidity
i mounted a red dot on a 45deg m-lok. and tried to zero it (and yes, i was aware of the difficulties and methods necessary to properly center it, and compensated for them).
i went through 130 rounds! omg, how? each time i would carefully make adjustments for one distance (let’s say 15yrds at first), it would move at another distance (let’s say 25yrds). and the adjustments for the longer distance grew greater. and dare i say, more unpredictable?
what the heck was going on. only this morning did it dawn on me (shoulder and face aching ;))…the red dot is out-of-parallel to the bore! of course! in both directions, vertical & horizontal. slightly.
this out-of-parallel ‘opens up’ with distance. so when i finally zero at 15, out at 25+ its’ way out.
leading to the remarkable discovery lol that with an out-of-parallel situation, one can only zero at ONE distance.
why do i need to post in ‘front sight’ too? because, i’m the OP who had run out of windage with the stock sights (gen2) and I (and later KT too!) resolved it with a front sight rotation (so much so the front is now rubbing against the cutout/recess in the stock upon folding). so now i’m thinking: rotating the sight to solve this is folly too, no? this will create the analogous issue with steel, that is, the sight line will be out of parallel with the bore, and consequently only zero’able at one distance?
stupid? am i thinking clearly about this now? opinions?
i now see that a/ this is much more complicated than i thought (eg, arc of trajectory, etc) and b/ many others have faced and dealt with it with varying degrees of success. call me naiive
sighting is simply Trig at work.
easiest way ive found to square sights, on everything from a Winchester to a Kentucky long rifle is a vise and a laser. now i have it easier than most, i use my mill bed/turntable vise, and a C.A.T. alignment laser, but you can mock up a rig using a simple laser to do the same.
light doesnt lie. if your front sight is to far to one side or the other (and ive had some beaut’s) you need to center first, dead center on pin, and move sight base till its on your beam, then dial in fine tune. that help you any or confuse you more?
So you are saying you have a defective mount? How is you sight not parallel to the bore?
I have that problem with lasers (why I seldom use them) and of course the ballistic trajectory of the bullet’s arc of travel is intersecting at various points with your eye-line, hence the need for elevation adjustments. And with a 9mm the come ups can be pretty drastic. For SDMG I am usually sighted for 12 yards, at 25 yards I have a full 3" of elevation.
But erratic and inconsistent shots like you are describing is usually due to either a loose/defective mount or poorly loaded ammunition.
hi goblin , i’ve mounted a dozen or so sights and scopes so i’m v familiar with the process. i believe you may have missed the whole point of the post. it had to do with out-of-parallel in two dimensions. the laser has nothing to do with it (ps, i have boresighters too which are largely useless)
no, the mount is not ‘defective’. you might look at some of the m-lok posts. they highlight a range of issues, many of which arise from the polymer of the rail, and looseness of the fitment. theoretically, the rail ought to be parallel in windage, with the bore, but it’s not with the mount on it, correctly. and, in elevation, it’s almost impossible to achieve parallel. thus two dimensions. i know i can zero it at only one distance, but if these dimensions are significantly off, then other distances become a shooting problem, each with it’s own new POA.
i hope i explained this
@500c Is it possible that your picatinny rail still has the “hump” on the top from the factory. I had similar issues until I took a file and made the top of the rail flat where I mount the scope. As a matter of fact I have that very same TruGlo 2X red dot and now after “Fixing” it, I have no issue at 10, 25, or 50 yards.
this is not rail mounted, it’'s m-lok mounted, thus the issues i outlined. and ps, yes my rail is crowned and is being fixed too.
@500cc you keep stating it is not parallel. Can you explain how please?
@500c I’ve been following your posts Tom but I’m pretty confused now. Could you post a picture of your optic mounted on the sub?
I’m not @500c, but I have felt his pains. When I explored mounting an offset rail to my mloc slots, I invested in a quality mount by Arisaka. I discovered that the mloc slots are a poor choice where precision is desired. They may work for a flashlight, but I strongly suggest investing in Performance Services Forend Stabilizers, praying and spending any accumulated karma if you hope to achieve a stable platform to mount an optic or laser. Minute of man is achievable but enough precision to execute Mozambique Drills is elusive.
@500c is telling us that a rail mounted to his mloc slots is either convergent or divergent with the barrel plane, but that it is not parallel. Parallel planes are required to extrapolate/predict POI changes with distance using calculations we can process without overly complicated and burdensome mathematics.
then it lies with the company that casts the m-lock rail, on how true to parallel it is. I went thru the same issue with the claw-lock H&K mounts. non locked parallel til I got a German STANAG. price hurt, once, but it fixed my drift.
please read dred’s post below
don, sorry, it’s been removed…but it’s simply the magpul 45deg m-lok picattiny w a trs-25
dred, this is perfect, thank you
i’m sorry i just learned i can reply to multiple posts at once. ouch. will do from now on
for anyone interested in doing the math for mounting a 45deg, this might be useful
Hey Brothers!! Thinking I have an issue with the Primary Arms MD-ADS and the Midwest Industries G2 S2K mount.
There seems to be a little play between the optic and the mount…It isn’t much and the optic seems squared on the mount…
Any suggestions will be appreciated !!
Does the Primary Arms Microdot Sight (Gen II) MD-RBGII co-witness at 100% with the sights when using the MI Gen2 SUB 2000 Mini Picatinny Rail Optic Mount from Midwest Industries, or do I need to purchase a riser?