I recently had the opportunity to buy a Crosman TR77 NP .177.
Since I already own a metallic-spring TR77 .177.
Rather, the
Stealth version, I thought it would be a very-good direct comparison - metallic spring vs gas ram.

I purchased the NP for
New England Airgun.
John Swenson is the owner ... a good-guy to do business with.
He even does lay-away purchases ... helpful to me.
For me, my springer TR77 has proved very accurate for my purposes.
I was very impressed with the performance of this less than $100 air rifle.
So much so, I purchased a second TR77 from New England Airgun along with the Nitro Piston model.
The TR77NP is accurate.
But, it takes a lot of effort to extract good performance from the NP.
First, it is harder to cock than the springer TR.
Exasperating the cocking effort ... the NP has a shorter-barrel that provides less-leverage for the cocking stroke.
This didn't make sense to me.

Standing Position, Off-Arm Supported on Window Sill
Off-Hand Lightly Braced Against Window Frame
3-Shots, 20-Yds
CPHP 7.9 grs
However, the first group I shot ... after a little warm-up ... proved to be promising.
The next day, I tried to sight-in the TR NP ... and, everything went to pot.
Nothing I was doing was producing any level of acceptable accuracy.
In frustration, I resorted to resting the TR NP on a padded surface.
As such, the TR NP was fully-rested on a soft-surface while my only contact was at the pistol-grip.
This holding technique resulted in a sub-dime, 5-shot group.

Standing Position, Only Trigger Hand Making Contact
Rifle Fully-Rested on Padded-Surface
5-Shots, 20-Yds
CPHP 7.9 grs
Right then and there, I knew my TR NP could shoot.
But, resting the TR NP on a well-padded surface in-the-field was out-of-the-question.
As such, I struggled all afternoon trying to find the proper hold for my TR NP.
So, I went back-to-basics ... isolating the rifle system from any supporting surface.
The only contact the rifle would have would be with the shooter - period.
It worked.

After taking a break, I anxious to see if I could repeat the process.
It was a great relief to see my TR NP sending pellets down-range ... accurately.

Standing Position, Off-Arm Lightly-Supported on Shooting Stand
Off-Hand Lightly Braced Against Shooting Stand
Light Hold on Forearm and Pistol-Grip
3-Shots, 20-Yds
CPHP 7.9 grs
But, the TR NP is not an easy rifle to shoot ... it demands much effort from the shooter to achieve serviceable results.
In this vain, the TR NP would not be a fun-gun to plink with.
This being the case, I do not see my TR77 NP as a go-to gun for casual shooting.
But, as a specialized shooting platform where the air rifle will need to remain cocked-and-loaded for an extended period-of-time.
Such as in rodent hunting, where sitting-still for a rat or squirrel to expose themselves for a shot would be a routine practice.
Otherwise, I don't think my TR77 NP is gonna see much use.
That is, in comparison to my springer TR77.