The receiver extension (buffer tube) is mil-spec, so after-market parts will fit. Here's a link to a "how-to" video at Brownell's
Changing Standard AR15 Rifle Butt Stock into a Collapsible A-4
dots and scopes
The choice of an optic, like most everything about AR carbines, depends on what you plan to do with the carbine and how much you want to spend.
As a starting point I suggest this review of optics
Fighting Carbine Optics - A Short Guide to Picking The Right Optic - AR15.COM
Well, that hole in the gas block is for a QD (quick detach) sling swivel. And while you can find qd rail mounts to attach a sling swivel to a rail, I haven't seen any rails with a qd used for attachment.
Second, you might be interested in a GG&G UFIR (under forearm integrated rail) - see Under...
More on heavy buffers
from Defense Review article
" A benefit of the additional spring/buffer weight is that it slows down the unlocking and extracting tempo, increasing the locked chamber dwell time and allowing for much more reliable extraction and ejection. This is because the longer dwell...
new Buffer
My impressions of changing the carbine buffer in the M&P-15 to a Spike's Tactical ST-T2 buffer:
a) There is a lot less noise in the receiver extension/buffer tube (no weights to bounce around inside the buffer)
b) The recoil impulse is smoother (again, because of powdered metal...
AR carbine comparison
Start with "The Chart" found at this link
https://spreadsheets.google.com/ccc?key=pwswheghNQsEuEhjFwPrgTA#gid=1
Then you may want to read "So you want to buy an AR-15, huh?" at this link
Links to other forums not allowed. Phil
and, finally, for a discussion of the...
Recoil in MP-15 v M16
There is more felt recoil with an MP-15. All of the following affect felt recoil:
The MP-15 is 6.5 - 7 lbs empty (depending on which one). An M16A2 is 8.3 lbs.
The MP-15 uses a commercial lightweight carbine (3.2 oz) buffer . The M16A2 uses a heavier rifle (5.2 oz)...
buffers
I've ordered a Spike's Tactical ST-T2 buffer for my MP-15. You can read about it here
“Oh” AR-15 Products Vuurwapen Blog
It will arrive tomorrow and sometime next week, after a range visit, I will post about it here.