I am getting ready for my second and last build (if I want to stay married), and I can't decide between 2 styles.  An A3 M-4, or an A3 midlength carbine.  I like the M-4 build page and the options from Adco.  I have several parts left over from other projects and this would help me save money by deleting certain options.  But when it comes down to it, the M-4 upper is still almost $100 more than the midlength.  I currently have a 20' A2 and 16' A3 with a shorty stock.  I am looking at this rifle just for fun shooting, with no specific purpose.

Is the chrome lining worth that?  And the M-4 barrel contour?  I can't decide.  I have never actually held a midlength upper.  What are some of your opinions out there about them?  If you were building, which would you choose and why.

Also, fixed front sight base or weaver gas block?  I may want to scope it one day.  Would the FSB cause any problems?

Thanks for the help...

If it were me and I had plans to mount a scope, I would go with the chrom-moly barrel, and maybe a 20" , I am building a M4gery with chrome lined and a red dot sight. but If I were planning to use a scope and shoot over 150 yards (accuratetly) I would go with the more accurate barrel. Let us know how your build goes once you get everything figured out.

you could leave the front sight and through the magic of refraction you will not be able to see it through your scope, or go with the weaver style gas block,( which is what I would do if it were me)

A flat top with the weaver gas block gives you the most choices for everything down the road, from optics to tac lights, etc.  The FSB won't cause any problems, but the rail style gas block would enable you to use a flip up sight, if desired.  

Personally, if you actually think this is gonna be your last rifle (HA HA), then I'd build a 16" with no muzzle brake, and take the $100 you save by not getting the M4 and put on a rail front end...the Yankee Hill one would fit in your budget, I think.  You don't *need* a chrome lining...if you're not slogging through the jungle where you can't clean and lube it for weeks at a time, then yes, you need it...but it doesn't sound like that's the case for you.  The non chrome lining should be a bit more accurate, but a little harder to clean.  

I think the 16" is the perfect size for "grab and go", whether it's to the range, popping ground hogs, or just plinkin'.  With the rail, you can mount a bipod if you need it, etc.  

Thanks for the opinions. I think I am leaning toward the midlength with the gas block.  One other question, between chrome-moly and stainless, which would be better for longevity?  I probably don't  shoot over 500 rds a year per gun, and am very meticulous about cleaning.  I plan on passing these guns down to my children.  When my son is my age, he probably won't be able to buy a replacement barrel.

I have heard that the stainless is better at resisting throat erosion.  Or is my use even enough to worry about the differences?