Ah yeah, the AA-12.. I swear, some days I thought mine had blanks in... made the horrible mistake of putting a silencer on it one time (since i'd had a lot of success with the silencer on the SPAS-12 and Striker)... worst move ever

I've actually posted a similar response to you in another thread... Connection certainly can have an affect, but what I've come to believe is that your tactics are the most important factor. The weapon is irrelevant if you play a smart game.  Also, a bit of luck can be a help too.

I've just put the model back into my custom classes.  I think when I started going for gold I had a KD of about 0.5 with it.  It used to frustrate me terribly and I don't think I ever had a good game with it.  By the end I'd got it up to a 0.98 and was having much better results with it.  Right now it's the only primary I have a negative KD with so I've been itching to rectify that one.

The default scope on the AS50 always seemed to give me trouble and I would get tons of hitmarkers.  It only really started working for me when I put the variable zoom on.  I'm pretty comfortable engaging at close to mid range with any of the other snipers but there's just something about that gun that just compels me to take a much more defensive posture. 

I think the CM901 is very under-rated.  I know I've a better KD with it than all of my other ARs, with the exception of the AK47 and MK14.  Have actually seen quite a few people using it recently and doing well with it.

What is it about clan guys and making excuses for being beaten eh?  Maybe that's why I've no desire to join a clan.. my subconscious mind protecting me from turning into a bad loser

I'm not sure exactly, but at a guess I'd say somewhere between 2-3 months on and off.  It was a lot more fun than just prestiging and using the majority of the same weapons over and over. Now I've done what I wanted to do in terms of prestiging and really getting to grips with all the weapons so the next 2 months until BO2 comes out are going to be just chilled without anything to grind towards.  Looking forward to it.

I think if you give the snipers a chance you may find them not so much of a grind as you might think.  I mean the Dragunov and RSASS with ACOGs aren't too dissimilar to using the MK14, so that would be 2  easy enough right off the bat.  Sniper Rifles were the class of weapons at the start of MW3 that I had least experience with and really wanted to develop some functional skill with.  I was pretty bad at the start but after a good deal of practice, trial and error, I've got pretty effective now.  I can hold down an area with the Barrett laying down cover for my team, or I can take a bolt action and play more aggressively.  I've played plenty of games of Dom and been the top scorer with the most kills and flag caps plenty of times.  If I can do that then anyone can.

I wasn't a big fan of the LMGs... in fact, before I started going for the gold guns I never used them.  I was missing out!  If you only try one LMG then make it the L86.  That gun is probably the most beastly weapon in the game.  My personal fave set up is grip and thermal.  It's got a high fire rate, very little damage drop off and with that set up it's super accurate - you can out snipe snipers with it easily.  But if movement speed is a real problem for you you can use the speed proficiency when unlocked and use extreme conditioning to get around much more quickly.  It has a drum magazine so the reload isn't too bad without SoH. 

if you can use the USAS and Striker then you should be able to do well with any of the other shotties.  The AA-12 is a destroyer once you can get close enough to your enemies, so stick assassin on there and you're good to go.  With the pump actions I had a lot of success by sticking a suppressor on.  It actually doesn't do much to the range or damage and just gives you that added stealth to flank and tackle multiple foes without giving yourself away.

I'm a HUGE fan of the FAD too... I got it gold pretty early on and couldn't wait to get back to using it again.  I didn't think it needed a buff, but I'm loving it even more since it does more damage.  Getting a lot more doubles and triples with it now.