Spare Parts to keep on hand?

Just would like some expert opinions on the spare parts I should keep around. I already have several extractors, but curious as to what others I should stock up on. I’m referring to backups for my shooter inland, which is already a mix master. 

And would you recommend a round bolt for my shooter, or does it not make that much of a difference? And would I need to purchase a headspace gauge to check it out on a new bolt?

And what about another slide? 

I’ve caught the bug big time and def need to slow down. I’ll heed your advice and buy them when I see a good deal. Mine functions great, but wanna make sure I don’t get caught with my pants down. I have TONS of ammo for it and am currently accumulating the items needed to begin reloading 

Nope, don’t waste your money. A gauge only gives you the limits. You can exactly measure your head space with an empty sized case. See if the bolt closes and rotates on the case. Add strips of scotch tape one layer at a time trimming it neatly to match the base until you reach no-go. Measure this case with the tape attached and you have your true head space. Depending on who’s field gauge is discussed, out-of-spec. can be 1.299 to 1.302. If you are under that…...it passed the field gauge test.

In reality, SAAMI allows from 1.280 to 1.302. Thats .022 of slop. Many here will support the fact that the carbine will be perfectly ok with head space exceeding 1.302 and I’ve handled some that would rattle on a 1.302 gauge. I have handled commercials that routinely left the factory at as much as 1.310.

You can find head space threads all over the forums. Collectors condemn carbines that close on a field gauge, but they can have lots of life left, particularly if you reload and keep brass length on the longer side.

That is a whole ‘nuther discussion. 

Before I get too far and risk getting beat-up, always consider short head space to be more dangerous than long head space. One should always insure the bolt will rotate and lock at no less than 1.290 and most like from 1.292-1.295. You can use the same method for that too.

Think I paid $32 for the Forster gauge from Midway. Paid much more for my USGI gauge when I finally found one.

The round bolt will contain all the updates/changes implemented during manufacture. The general rule-of-thumb is to use the latest issue (type) of any component to get the safest and most reliable version. But, parts interchange forward and backward. The only time I suspected a round bolt might have been superior to a flat bolt was the increase in size and shape of the chin on the round bolt. Maybe it will help feeding issues, but I can’t actually prove it. I did find a round bolt seems to have solved a problem once, but a fresher flat bolt might have worked just as well. I usually don’t prefer one over the other in a shooter. The price, fitment and condition dictates what I use.