1377 barrel movement

[mcc1961]

I have just mounted a red dot scope on my 1377 with the 459MT mounts to the stock barrel and breech.There seems to be some movement of the barrel and scope away from the bottom tube ,is this normal and does it affect the accuracy of the pistol?The 459 mounts do not slip the scope and barrel move as one.

[L.O. Little]

It could be 'normal' when using the stock plastic breech... can't say for sure, as I've never used the plastic breech with the 459MT mounts. I'd check the tightness of the two screws that ties the plastic breech to the main tube before you do anything. IIRC, you'll have to remove the rear sight to get to the rear breech screw. Theoretically, if the front screw (the tiny one you see when you slide the bolt back) is loose, you very well may be leaking air when you shoot.

Regarding accuracy, since the red dot is tied directly to the barrel, it probably isn't effecting it enough to matter. Your best bet is to replace the plastic breech with a steel or SS breech, then mount your sight to it.

[hotshot]

The barrel on mine moves because the front plastic foresight allows it to and the breech doesnt secure it that well either, saying that the accuracy is not bad so cant affect it too much but Im awaiting the crosman steel breech and I know i wont have any movement after fitting that, its solid. Accuracy must improve. In the meantime I have shoved a small washer between the barrel and sight not ideal but my grouping has become more consistent.

[Madkoifish]

Those clamp mounts on the barrel and weight of a dot exp tube dots is just too much for the plastic to retain it in a fixed location. I would not recommend their use without a metal breech.

There is a chance this will wear the transfer port prematurely, since the barrel is "twisting"

You could double check the breech screw for tightness if it is really floppy. Rear slot screw and the hex inside of the loading port.

I think these clamps were designed back when the breech was metal and possibly for the old slide breeches.

[tkerrigan]

Installing the molding between the barrel and the tube might tighten it up some by providing a stop for the mounts. 
                                                                       Tom

[hotshot]

yeah? why did they do away with that plastic?

[Brighton Rock]

I have just mounted a red dot scope on my 1377 with the 459MT mounts to the stock barrel and breech.There seems to be some movement of the barrel and scope away from the bottom tube ,is this normal and does it affect the accuracy of the pistol?The 459 mounts do not slip the scope and barrel move as one.

Check the screw on the trigger guard which comes loose causing movement as well.

[catapult]

take the front sight barrel band off, heat it up and bend it down so it keeps pressure on the barrel.