
Here's a writeup for my initial impressions of the WAR .30 Flex. I have previously owned 2 Marauders (.25 and .177) and 1 Evanix Rainstorm II in .357.
The Design:
The design is really excellent. I've learned a fair amount about PCPs over the years where I've modded my .25 Mrod and I can see that the Flex incorporates a "dream team" ensemble of airgun design innovations.For example, although the Flex does not have a SSG, the hammer incorporates a design that causes the hammer and spring to function similarly to a SSG insofar as there is a gap between the spring and the hammer (yes I did remove the breach from the body and take a look) which effectively eliminates hammer bounce. The cocking bolt is another example. As others have noted in their reviews, the bolt pushes the pellet forward of the transfer port before the bolt is closed and put to rest. I like that. Its not hard to get use to loading the pellet that way. So far I haven't forgot to push a pellet forward yet. The bolt itself is smooth and easy to operate. On my 80fpe Mrod I once had a problem where pellets were not being pushed over the transfer port, so seeing that the designers made a concerted effort to make sure pellets clear the port without sacrificing the FPE potential of the gun is nice.
Concerning the breach, I noticed that internally it uses a metal transfer port and oring seals like a Marauder to connect the valve exhaust port to the breech. However, the transfer port of the Flex is much more sturdy that the Marauder's and the orings look very strong. I've often bent the TP on my Marauder when the orings get shredded and I had to pry the TP out (which was a regular occurrence when running at 80fpe on the Mrod). I have no such worries with this gun. I didn't think to measure the TP but its big. It should handle moving a lot of air no problem.
Power adjustment is also easy. There is a 5/16 allen head screw in the end cap (inside of where the AR stock screws on). Here's my gun's screw set at the default power level:

The tool I use:

You need to know that there is also a set screw on the right side of the end cap that holds the hammer spring screw in place. I like this design because it will keep the tune from slipping without having to use a thread locking compound as the Mrod requires. HOWEVER, If you forgot to remove the set screw, you will strip the hammer spring screw threads when you try to adjust the power. So be sure to remove the set screw first.

I like how the bottom picatinny rail adjusts. You can slide the picatinny rail forward or back a few inches to get your bipod just right for your tastes. The gun benefits from a short bipod moreso than my Mrod does. I've tried both an 8 inch and <6 inch bipod and the shorter bipod is better for stability.

I'm tickled with how well the gun breaks down for packing. I could break it down a little bit more by removing the cocking handle and the scope but for my purposes leaving them on works fine. This is going to be a good gun for my overnight camping trips.

Finally, I like the versatility of the AR stock. The gun's endcap is threaded to take an AR buttstock. The stock that comes with it is a standard AR telescoping stock. That does mean that the stock can be a bit rickety sounding when you walk. That's not the fault of the gun, that just goes with the nature of a standard AR collapsible stock. The skies the limit as to your options to put a custom buttstock on.
Any criticisms? Only that the magazine, which is based on the Mrod design, is a tight fit for Predator Polymag .30 pellets. But they DO fit. You just have to play with the first pellet to get it positions just so or else the poly-tip of the pellet will extent too far and be sticking ever so slightly out the mag. After the first predator pellet is loaded, the rest load easy. The numbers on the mag are hard to read. That's a minor inconvenience and its something I can fix easy with a white marker. I'm an early adopter of the Flex mag so I'm sure the numbering won't be an issue on further mags.

Some people don't like the bottle design. I personally like it. Its very practical and its the only indication that a non-air gunner might have that the gun is an airgun and not a firearm. I'm personally looking forward to taking the gun to the public gun range and seeing what kind of reactions I get.
Performance:
Shooting 44 grain JSBs
Fill pressure 2800-2900psi
884
882
887
899
887
898
896
899
894
896
895
895
900
894
897
895
893
884
884
880
874
2100-2050 ending pressure.
Although I don't have my notes for it, I also shot a string with the power adjuster screwed in flush and my numbers were 19 shots with the first shot starting in the 890s, then going up to and flattening out at the 920s, to come back down to the 890s again for the last shot. Oddly, the fill pressure didn't seem to raise with the stronger spring tension. I generally got the same peak at the same PSI points as the default string, just with a little bit more air usage and 2 less shots. On my Marauder, that much change would have greatly moved my PSI curve up quite a bit. So that's good.
Accuracy is amazing. I did have to learn how to shoot the light trigger. That's not a complaint. Now that I'm used to it, I wish all my guns had the same trigger. What the light triggers allows for is for me to barely touch the gun (almost hold it in the "artillery hold") and shoot it on target with minimal pressure on the trigger. Yet it never feels so light as to be unsafe. This weekend I'll shoot some splatter targets to show its accuracy. Here's a picture of 4 shots at 30 yards. The picture doesn't do the gun justice because the target is just white printer paper and it tears bigger than the actual holes. A rigid splatter target will show the groups nicely. For scale, my finger tip is the size of a dime (small fingers) and the orange target is the size of a quarter. That's a sub-dime sized group and .30 to boot. I think the gun is more accurate than I am capable of.

I've never been super comfortable shooting at 50 yards and beyond with my Mrod. I could do it, and on occasion I would make kills at 60+ yards. But it wasn't reliable. My scopes sat very high on the bullpup which meant that sometimes the drop would be well compensated for and little holdover was necessary, but it wasn't reliable to bet on that. Never had much luck with Charigun type apps helping me accurately calculate holdover. The Flex is different. The scope mounts low to the gun. I sighted in at an estimated 30 yards and at 1 mildot hold up I was able to constantly drill a soda can dead center at 50 yards. Then when I plugged the numbers in to Strelok I was able to see that my in-field experiences matched the app. Very cool. I'll resight the gun in using a laser range finder to know my true yardages for zero and target. I could see myself learning to be comfortable with 100 yard airgun shots with the Flex.

Its also very quiet. As others have reported, the shot sounds like a quiet, deep, metallic, "thunk". Very different than my Mrod. The sound equipment is compact and doesn't add bulk or significant length to the barrel. I can't think of any criticisms for performance so far. Of course I need to but a few tins thru it to be sure but so far it seems amazingly consistent.