You don't because the Mosin Nagant M38 doesn't have one. You are probably thinking about the M44, which has a fold over bayonet.
Removing the bayonet from a Mosin Nagant M44 is as simple as removing the screw that holds it on.
See the instruction at SurplusRifle.Com here:
http://www.surplusrifle.com/mosincarbine/rifledisassembly/index.asp
if you mean the M38 carbine, they can go for about $60 on average in re-arsenaled condition (I.E., forced match numbers, counter bored barrels, dropped into M44 stocks minues the bayonet) and sometimes close to about $100, but that's about as high as the prices from them go.
Comparable to a .308 or .30-06 hunting rifle.. not particularly hard in the M1891, M91/30, M39, etc. rifles, although with the short carbines (M38, M91/56, M44) it tends to be hellacious.
The M1891, 91/30, M38, M91/56, M44, and all the Finnish variants all fire the 7.62 x 54mm Rimmed cartridge. Usually known as 7.62x54R, or 7.62 Russian. The only Mosin Nagant rifles which fire a different cartridge are the M1891 rifles captured by the Austro-Hungarian Empire during the First World War. These were converted to fire the 7.92x57 cartridge, and are extremely rare.
If none of your local stores are carrying them, AIM Surplus and J&G sales probably have the best deals going on them right now. You may want to check Gun Broker and Auction Arms if you're looking for rarer/specific models, as the MN 91/30, and maybe some Finnish variants, such as the M38 or M39, will likely be the only models available at retailers.
M38
If you mean the SVD Sniper rifle manufactured by the Soviet Union, no, it is not a .50 caliber weapon. It fires a match grade version of the 7.62 X 54R cartridge- the same round used by the Moisin-Nagant 91/30 rifle (and the M38 and M44 Carbines). Wikipedia has a good concise article on the Dragunov sniper rifle. Enjoy.
Nope
M38 and M151 depending on the year.
M38 (th350)
A M38 Hardstock Automatic Air soft gun is smaller then a standard magazine. If you are looking to fit the gun inside a magazine Harper's Bazaar magazine is the thickest magazine.
In the past couple of years, the Russian government was put thousands of 91/30 rifles and M38 and M44 carbines on the market- most in excellent condition. Due to the numbers, prices on these are very low- $100 or less. However, they can be great shooting rifles.
One made for it.