Pecatonica SMR kit is $300 cheaper than Kibler kit. What does Kibler provide for the $300 extra?
More than $1000 in extra value. Every aspect of the Kibler is higher quality. The stock has excellent architecture. No thick ramrod webs or unusable lock inlets. The metal parts fit the wood as you get it with zero gaps. The difference is like a Holland and Holland double vs a Stevens double barrel shotgun as far a general quality. The main drawback with Kibler is the lack of selection.
I am not bashing Pecatonica or anyone else. They are a different thing. They make
parts sets from which you may be able to make a rifle,
may is the key word. When you buy a precarve stock you are gambling on it being usable. Most have substandard architecture. Most of the time I find that they are crudely done and finding centerlines and reference angles elusive. I have to guess and take averages. If you know what you are doing, making a really nice rifle involves a lot of "figuring". BTW, never ever get a precarve with the lock inlet done for you. Sometimes you figure out that the precarve is junk and if you have cut on it you are SOL.
Brass and steel furniture castings? Kibler does a great job. He uses only soft brass. His castings are excellent and require minimal clean up. Some suppliers send brittle bronze parts instead of the correct malleable brass. Many send rough cast junkie parts.
When you get a mass market cast part lock, it will probably need a lot of help to be usable. I have found exactly zero cast part price point locks to be OK for me as delivered. IT will never approach the CNC Kibler locks in build quality, function, or reliability.
Chambers has an excellent reputation and are a step above the part set bundlers.
As far as the effort to assemble the rifle, the Kibler
kits assemble easily and quickly. The others' parts sets are much more time consuming and frustrating. For instance I recently completed a parts set of a pre-carved stock and pile of castings in about 60 hours over a month's time. I can assemble a Kibler in one day. Finishing takes three days due to dry time and rust time. The Kibler rifle is then worth much more than I paid for the kit.
I guess the short answer is that it depends on your skill level and how you value you time.