I don't know how to make U tube Videos but I am a CMP GSM Master Instructor.
GSM means Garand-Springfield-Military Rifle. The "Military" part is just that, Other Vintage Military Rifles such as 1917 Enflieds, Mauser's, Swedes, Krags' or basically any other vintage military rifle INCLUDING the Mosins.
The CMP started this program to train instructors to put on Clinics to get people shooting these rifles in matches. They put on a instructor course for experienced instructors in shooting these old war horses.
Ok now with that out of the way, a GSM match has rapid fire stages, which consist of shooting 10 rounds in 80 Seconds, but not just to see how fast you can get the rounds off, but to shoot 5 rounds, reload and shoot another 5 shots and "hit the target" at 200 yards.
In these clinics we teach the loading for rapid fire, INCLUDING loading the Mosin. Sure its different, but its doable. Just requires a different technique.
Shoot your pre loaded 5 rounds, drop the butt from your shoulder, (other then that stay in position) take your 5 round clip and drop it into the clip guide slot, take your index finger and pull up on the "bullet" part of the top round as you put your thumb on the body of the case. Pull up on the tip as you push down firmly with your thumb, all five rounds will go into the magazine with out undo effort.
The real trick of shooting bolt actions rapid fire operation of the bolt, not the loading, that only takes a few seconds. The main thing is loading is don't panic, relax, take an extra second or two to do it right.
The ideal is not to take your rifle out of your shoulder while operating the bolt, Keep your position.
This may be hard for Mosin shooters, seems mine is longer (from the bolt to the butt) then my Springfield or Enfield, I do have to drop the stock to work the bolt.
Many people teach bolt manipulation by the numbers........forget that, its ONE number, one smooth operations not 1, 2, 3 but just one.
We've all played as a kid the game where we hold our hands out flat, someone else puts their hands over ours and you have to try and slap their hands before they can move them.
This is the same movement used in operating the bolt of a bolt action rifle.
Start with your hands flat, palm up. As you roll your hands to slap, you catch the bolt knob, flipping it up pulling it back as you continue the roll ejecting the spent case.
As your hand flips and you come down for the "slap" you are pushing the bolt forward and down chambering the next round.
Again this is one smooth motion. This is best learned by dry firing, get into a good prone position, operate the bolt as mentioned above without getting out of position, (preferably without taking the butt of the rifle from your shoulder).
While dry firing keep it slow and smooth. Speed up as long as you can keep it smooth. Speed with follow. It it gets sloppy or ruff, slow down to "smooth" again.
You have plenty of time to work the bolt, and reload a second clip, IF YOU KEEP IT SMOOTH. Spend the time concentrating on your front sight and trigger control.
Last year I put on a GSM Clinic followed by a Match. The guy who won the match had just bought his Mosin and some surplus ammo the night before. His first shots were the sigher's for the match.
He didn't win because the Mosin is a superior weapon compared to the Garand, Springfield or others, he won because he paid attention in the clinic and didn't panic and rush the loading. He spent his time concentrating on the fundamentals.
I'd recommend that if you want to learn to shoot a Mosin or any other vintage military bolt gun, that you attend a CMP GSM Clinic. They are put on through out the country, and listed on the CMP Website. They don't cost much, just a couple dollars to cover the cost, (I charge $5 for mine).
They are taught by CMP GSM Master Instructors.
Most clubs have a GSM Match in conjunction with the clinics