Any of them will fit in your rifle. The difference is in the size of the latch knob itself. 3-large,4-medium,5-small; are the sizes. Some people like them really big, for gloves etc. I sling mine over my shoulder with a reg. Padded leather sling like a bolt gun, over my right shoulder. I have/had the tac. Latch(upgraded latch on the existing charge handle, done simply by removing a roll pin and remove/replace) and now i have the BCM medium and small latches. They are worth every penny of the $50. Anyway, the tac latch upgrade was way to big for my liking and jabbed me in the back and made lots of noise when slung(it catches on pant/coat/belt when walking) so i quickly when for the BCM medium(seems to be the most common) and it is way better than the tac latch but still made noise when walking with it slung. Bought the small BCM and it is the one for me. No digging in my back so its quite when walking. I tip the gun so ejection port is up and then reach under scope with right hand to charge. This allows me to see the round chamber and to see the bolt is fully closed. II personally think the small latch is plenty big and has giving me no issues, gloves or not.