Just curious...which one would you buy and why?

M7 or M9?

Depends what you want it for.....

I have both, but I collect bayonets.

The M9 is much heavier and can be used as a wire cutter.

If you are looking for a survival knife, there are lots to choose from.

What are using it for? If you are specifically looking for a bayonet then the M9 always seemed nice to me. If you are looking for a Survival / General Purpose Knife I would not recommend either of them as there are alot of other better choices out there

I just want to get a bayonet for the AR15.

I was looking briefly at a couple of sites and saw something about:

1.  Stay away from Chinese junk.

2.  The M7 has superior metallurgy and was better made; the M9 was meant as a 'throw away'...


Didn't know if any of that was true, so I asked first about preferences here.

Any info / opinions would be helpful.
Thanks.

Just remember that the bayonets won't work with the 16" Barrel AR's. They only work with the 20" and 14.5" Barrels that the military uses. To make it work with the 16" AR it requires an extension piece to lock in place properly.

You might also look at the Marine Corps OKC3S Bayonet made by Ontario Knives. For a Bayonet only knife I always thought it looked pretty tough compared to the M7 or M9.  

If you just want a bayonet to have one, I would get the M7 due to the cost.
I mean, you can get one for less than half the price of the M9.
And you do have to be careful with the M9's as there are cheap import copies out there.

ETA:
I don't know about 'throw away', but the army considers them expendables... but then again, they consider helicopters expendables as well.

Thanks.

Someone here showed a shortened bayonet on a 16" bbl. ––- cool, but took a bit of work!

I'd be interested in a 'no work' type of attachment, though.  What is it and where do I find one?

They also fit on a 16" mid-length albeit in a slightly different location on the FH but they do fit fine. The main issue with the 16" mid-length is that the bayonet ring ends up over the FH just forward of the actual threads on the barrel - if this difference "makes the difference" then you have far far worse problems at hand. Military length barrels allow for the bayonet ring to rest on the FH directly over the threads of the barrel.

Although it was not listed as one of your choices I personally went with this:

http://en.wikipedia.org/wiki/OKC-3S_Bayonet

It is a little longer and those serrations just look cool.  

if you really want a bayonet for your 16" barrel you still have a couple choices, well two anyway that i know of.

1. the clamp on bayonet lug. iirc cheaperthandirt.com and dpms amongst other sell these. they simply bolt on around the barrel with allen screws and are a seperate(from the integral lug attached to the front sight post) bayonet lug which relocates the the lug forward allowing proper seating of the standard bayonet on the flash hider. they're running about $20 here at dpms and $25 here at cmmg(scroll about a third of the ay down the page).

2. your other option is an extended handled bayonet. these bayonets have a handle slightly longer then the standard bayonet handles and will facilitate proper seating of the bayonet on the lug of the front sight base and flash hider of a stardard 16" barrel. the down side is that the handle is about as long as the blade and look kind of odd. the only ones i've seen are altered m7s or longer versions patterened off of the m7. here's one, but a barrel swap may be cheaper.

or you could always swap out your 16" barrel to a 14 and 1/2 inch barrel with permanently attached flash hider for a more accuratelly configured m4 carbine clone.

hope this gives you a few ideas. K.

Apparently, THIS is the answer I seek:

OKC-3S

OKC-3S

The internet is awesome.

im looking for one as well. im going to go with the new marine corp bayonet. its basically a combat knife , designed to be sharpened, plus its a bayonet.  keeps you from having to carry a knife, and a bayonet. its something to think about. i guarantee a bayonet is not something many people would like to have coming at them.