Mosin Magic Part 3 - Professional Work

Action Blueprinting

This is a simplified explanation.
Action Blueprinting is simply truing the barrel to the action, then lapping the bolt lugs to fit properly.  It is actually a little more complex than that, as it involves removing the barrel an placing it in a lathe to true up the mating face where the barrel threads into the action and meets the reciever. A corresponding amount is machined off of the threads, and once the barrel is mounted properly in the action, a chamber reamer is used to create the proper sized chamber. On non-rimmed cartridges, headspace can be adjusted at this time.

While the barrel is removed, the action has a mandrel mounted in it and it is chucked up in a lathe to have the barrel mating surface trued up. The final step to this process is lapping the lugs of the bolt to their new position in the action. This amount should be very minor. Depending on the condition of the barrel, it may need to be replaced at this time.

This is my understanding of the Action Blueprinting process. It is not a cheap process, but it will give you a very accurate firearm, if the proceeding modifications have been completed.

Here is a link to a more in depth Action Blueprinting process by a custom firearms manufacturer.
http://www.aquilafirearms.com/RifleOptionsAndComponents/AccurizingProcess.htm

Muzzle Brake/Porting

A muzzle brake will help with recoil abatement and muzzle rise, but the report of the rifle is actually louder due to being deflected to the left and right sides as well as up instead of being projected to the front of the barrel. There are various styles of muzzle brakes out there, but most will require cutting and threading the barrel, unless you wish to add up to four more inches to the overall length of your rifle. Not something I would like to do with a 91/30.  Select or search for a service provider near you, or to ship to. Be sure to call ahead and discuss what options are available to you for the Mosin-Nagant. This would be a perfect time to have that barrel shortened to a more manageable length. A partial list of companies providing these services follows.

Sources:

Accurizing
Lots of good info on Mauser's and Mosin's - Action Blueprinting
http://www272.pair.com/stevewag/

accurizing a mosin nagant M91/30 part 1
http://www.youtube.com/watch?v=dcITHYnRiSs&feature=related

accurizing a mosin nagant M91/30 part 2
http://www.youtube.com/watch?v=58rLbsG_mso&feature=relmfu

accurizing a mosin nagant M91/30 part 3
http://www.youtube.com/watch?v=fQvcs58gHKg&feature=relmfu

accurizing a mosin nagant M91/30 part 4
http://www.youtube.com/watch?v=Rz6e3HYkhlU&feature=relmfu

Muzzle Breaks
Vais Arms Inc.
http://www.muzzlebrakes.com/Prices.aspx

E. Arthur Brown Company, Inc.
http://www.eabco.com/cssmb.html

Aquila Precision Firearms
http://www.aquilafirearms.com/index.htm

There are more, just do a keyword search on muzzle breaks!