But, I didn't have an appropriate air rifle platform to do so.
I have grappled-with finding a repeating, clip-feed, single-stroke-pneumatic air rifle that could be readily adapted to AR-15/16 M4 sights.
To this end, a while ago I purchased several Daisy 953 Target Pro air rifles because I wanted a repeating air gun.
And, after using the Target Pro for a while, it dawned-on-me that it might be possible to adapt AR-15/16 iron sights to the receiver and barrel.
The availability of the Leaper's UTG .22/Airgun to Picatinny/Weaver Low Pro Snap-in Adaptor made my idea possible.
The rear-sight was a very straight-foreward installation.
Just fit the adapter to the UTG Detachable Compact Rear Sight w/Full W/E Adjustment and place the sight-assembly on the 11mm receiver-rail.
Tighten the quick-release sight-knob ... and, you're done.
Please excuse all the dog hair ... my Pekingese is shedding.
The front-sight installation presented a problem.
The front-sight mounting-grooves did not form a rail ... the barrel mounting surface is round.
As such, the adapter would not fit properly.
However, the judicious use of a hand-file can generate a relatively-flat surface to allow mounting of the rail-adapter.
With the flat-surface cut-on the globe front-sight mount and the adapter in-place on the Leaper's low-profile sight.
The Leaper's AR-15/16 front-sight can be put-into-place and tightened-down.
Not a perfect installation ... but, serviceable enough for my purposes. 
So, why go to all this trouble when you already own a Crosman M4-177 fitted with Leaper's AR-15/16 iron sights?
Well, it really wasn't too much trouble to make the sight conversion.
The UTG rail-adapters are the key-element in the easy installation of the AR-15/16 type iron-sights.
Also because, although the Crosman my look-the-part ... the M4-177 is airy-light.
As such, doesn't come-close the weight of an AR.
As a result, it is a challenge to hold the M4 steady for a précise shot.
And, the Crosman pneumatic-trigger does not feel like a USGI service-grade trigger.
The M4-177 trigger is light, traverses a very-long-travel and has a vague let-off.
The side-feed clip requires manual manipulation to advance the next pellet.
Although my Daisy 953 doesn't look-like an AR-15/16 service rifle.
The heft of the 953 is closer to-that of an AR than the feathery M4-177.
The one-piece plastic-stock is hand-filling and substantial.
The 953 trigger has a hint of stiffness and a touch-of creep similar to an average commercial-grade hunting rifle.
Even-so, the let-off is predictable owing to a trace-perception of stacking.
The 953 side-feed clip is auto-advanced by cycling the bolt.
While I do appreciate your efforts, the MOST accurate gun I own is a Daisy 887, which currently wears a set of Airforce 10M match sights, both front and rear. The adaptability is remarkable, and the quality is top notch. My second most accurate rifle is a Daisy 753. Both Daisys have out-shot other 10M guns that I have owned, including FWB300, Diana 66, Anschutz 250, Haenel 3.121. The Daisys with the LW barrels are some awesome sh!t.
Originally, what I was looking-for was a post, dot or cross-hair insert for the front-aperture-sight.
I couldn't find anything that was compatible with the OEM-globe.
Next, I considered an off-the-shelf peep-sight set that could be adapted to the Daisy dovetail grooves.
I couldn't find anything that was affordable ... read: justify the cost - this is a hundred-dollar air rifle.
However, the G.I. AR-15/M16 sights could-and-were easily fitted.
Moreover, there are many variations of the AR-15/M16 front-sight-post that are readily available at a relatively-inexpensive price.
Yep, I concur ... the sights are high.
And, a cheekpiece would be a practical addition.
Those little adaptors are awesome. I have one between a Burris Fastfire 3 and a Beeman P1. They are perfect for applications like this. They are inexpensive, super low, and invisible.
