I used a set of feeler guages to find the size of the breeching washer I needed. You'll also need locking shoulder gauges and head spacing gauges to set the head spacing. I used a couple of blocks of wood in a vise to hold the receiver when I did the final barrel tightening.
I can't think of any real problems I had putting it together.
MNs: M91/30, M91/30 SNPR, M38, M44, M39 (VKT) 91/59, Mausers: K98k, Swede M1896, Argnt. M1891 Engr's Carb,Yugo 24/47, M48, Persian, LEs: No.1 Mk3., No.4 Mk.1*, No.4 Mk.2, No.5 Mk.1, Carcanos: M38, M91, M1903, M1917, M1 Garand, M1 Carb., Steyr M95, VZ52, Arisaka T99, Hakim, FN-49, Rasheed, Vetterli M78, K11, K31, MAS36, SKS (Tula), SVT40, Martini-Henry, Hanyang88, KAR88, Ishapore 2A, Sprfld Trpdr, P08 Luger, Makarov (DDR), Enfield No.2 Mk1*, Nagant M1895, P64, P83, Rom. Tok TTC, CZ27, CZ52