Allen wrenches

[Madkoifish]

Your talking hundredths or thousands of a inch on a .05" hole it makes a difference.  Reason why I said "whatever" since you'll have to trial and error it and find what fits for you.

EDIT good example here:
crosman L wrench .046"
bondhus pinion driver 0.050" measures 0.047~8" changes across the flats
bondhus pinion driver 1.27mm measures 0.048~0.049 changes across the flats
Generic H1.3X100mm wrench 0.051~0.054 (this is a tapering)

[pirouge]

crosshairs I don't use the ball tip allen wrenches, they don't set deep enough and you round out the hex hole, by the way, you might as well get a small EZ-out, you'll need it sooner or later.     

[catapult]

my new 1377 had a semi-messed up breech screw out of the box. What was happening is the driver wasn't fully seating in the screw head, tap with a hammer and it is good to go.

Remember that few things have to be super tight. A well engineered example needs fasteners that are snug.

[millipede]

is it possible to buy set screws that DONT require a hex wrench? i want to replace all mine with slotted screws

[NorthStaR]

If anyone in the UK is after a set of allen/hex renches, I saw a cheap good enough set of imperial and metric in a combo box in Homebase.

£13.99 or there abouts. 

[Crosshairs]

crosshairs I don't use the ball tip allen wrenches, they don't set deep enough and you round out the hex hole, by the way, you might as well get a small EZ-out, you'll need it sooner or later.     

You don't loosen or tighten with the ball end it just makes it faster to remove the screw on a angle after you loosen or replacing the screw.

[millipede]

crosshairs I don't use the ball tip allen wrenches, they don't set deep enough and you round out the hex hole, by the way, you might as well get a small EZ-out, you'll need it sooner or later.     

what size EZ out should i get? a #1 or a #2? i stripped the set screw on the steel breech. (the one that holds the barrel in place, not the one under the bolt)

[pirouge]

millipede its the smallest ez out my ace hardware store had, its got a 1/8" shaft, don't know the no.