Girodin,
Ok I hear you so lets be more specific. I have both with "many miles" under the hood and these are the are pros and cons to each:
Keltec Pros:
Light weight. Polymer is extremely hardy and will not rust or bend. receiver with integrated rail. AR bolt locking system. The piston is extremely reliable with all sort of loads. Cycles very well with all ammo including Russian junk ammo. Brass is ejected in consistent pattern and it is in good health if you reload. Holds bolt open after last round is fired. Easy to clean maintain and assemble disassemble. Chrome lined. Uses AR GI magazines out the box, plentiful and many reliable models. The folding stock, Mags in the Stock, grip/bi-pod features are unique (great for a ranch rifle). C and CA model comes threaded in the muzzle. Very accurate withing MOA, just like a good AR. It can be maintained with similar AR maintainable techniques including replacing the barrel. Affordable. Made in the USA. It is legal in some communist states.
Keltec Cons:
Keltec doesn't pay too much attention to the package and finishing. Box is totally useless and might come with some scuffs under the trigger from cutting the polymer from the mold but nothing major that will affect function.
Might be too light for some, again depends on purpose. Might be ugly for some. Not important to me. Since it uses the same bolt face as the AR but it is not actually the same Bolt carrier or bolt or pin we cannot use AR parts for replacement other than the extractor but I have been told that keltec will ship whatever you need. In my opinion every system should include at least a spare firing pin, an extractor and a few springs even if they had to pay a few dollars more. Mag well might not drop free mags so use it a lot and will open up. Also pick up the ones that work better for that purpose if speed reloading is needed. Anyway this happens with other systems.
Saiga .223 pros:
It is an AK. Super reliable!. You have the reliability of an AR with a round that shoots flatter and normally more accurate than the typical AK-47 round (not the AK-74). Easy to disassemble, clean and assemble (A cave man could do it). Perfect weight for a carbine for many uses. Not too heavy not too light. Chrome lined. Made in Russia in the Izmasat plant that are the original inventors and parent plant of the AK. Not some cheap Romanian parts kit from some junk yard over there that some are trying to sell here.
Original hand guard is nice. Factory magazines are strong and reliable, just like many old and modern AK, an important factor in reliability.
Saiga .223 cons:
It is an AK. Aks are slightly less accurate due to the Bolt carrier being slightly off center but not really that much or anyohow something that it is significantly relevant in a MBR role. Specially in this round the rattling of the barrels is reduced due to the higher density of the barrel (Smaller caliber) so it is more accurate than many standard AK-47s. I have a Saiga .308 16" that does .5 to .7 MOA all day so it is not the rifle as a whole but that specific model/barrel/round combination. No bolt hold open after last round fired. It cycles well then it chews and spits the brass (just like a Sig) so if you reload it will damage many cases. This can be resolved with a buffer by the dust cover but it is a custom job. Brass ejection pattern is good and strong though.
The trigger has some slap and this is related to the fact that these systems are "sporterized" in some sort of odd transformation form their natural AK form to this ugly stock hunting role so they can be imported here by our recent communist laws. So trigger upgrade (ie: Tapco G2 single hook) is more than desirable and with it goes dancing the whole compliance parts tango whether you need it or not. The stock magazines are great but are not plentiful. 3rd party magazines are also nice but the preban option does not exist so the communist states (ie: NY) can enjoy a higher capacity
You need to find a good picatiny rail since it doesn't come with that.
Not sure where you can get an extractor, firing pin or even a barrel or that the barrel could be replaced w/o the help of an experienced AK gunsmith. It might be worth buying several saigas now. That's what I did. It is not legal converted in some communist states (ie: NJ)
Once a conversion is completed you most likely have some of the best AKs you can buy (Again Russian made) in a popular round in the Western block that will give much enjoyment.
See some pictures of my Keltecs and saiga conversions...
Saiga .308 16" converted and accurized. including the .308, why not?...
Before and after....
Also read this thread that I created for a fellow member and friend that wanted to learn about the Keltec since it is legal in Communist NJ and not many things are legal there...
http://www.thehighroad.org/showthread.php?p=6978331#post6978331
I hope this helps someone.
Shoot often. Be safe and don't ever forget our veterans.
Cheers,
E.