I like to use the L118A. It's bold action and that sometimes turn people away from this rifle, but, in my opinion, it allows my accuracy to increase. Mainly because I find myself focusing more and holding my breath more often so that I don't miss. Obviously if I miss, the chances of me getting killed is much higher since my second shot will take sometime, as opposed to a semi-auto like the Barrett or AS50.

This is how I use mine. I don't Q/S either, but the L118A is a very vesatile weapon that is easy enough to use while walking around or camping.

You just need to hold the button that show up as hold breath on Sniper rifles and thermal scopers while you shoot someone and you will counted as the kill.

You only need to hold your breathe while aiming down your sights (and killing someone) to get your Marksman Pro mate...

You can do it with virtually any primary...

The L118A or the MSR are the two best. I run SoH Pro so reloading and rechambering rounds is extremely fast... just practice is all I can tell you. Never takes me more than 5-6 games to finish marksman pro. Just learn the high traffic areas, and find good cover.

Another reason I never use gold camos on my rifles... I like blending in, usually use the digital camo, choco or snow depending on the map... staying hidden is a must for good snipers, that and good support from your team mates.

Like others said; just stick on the hold breath proficiency to an AR and use that; works the same way.

I used the MK14 to get Marksman Pro and it took me about 5 or 6 games.  I do not like this challenge though.