Share your results with various POI shift solutions

[AlanMcD]

I doubt that there is much change in the breech block, as it actually attaches to the valve in front and to the hammer spring plug in the rear, both through the tube. There is no high pressure air under the area where the breech attaches. So I expect that the tube would not be changing at all in this area and thus the breech should be stable from front to rear . . . .

[Doc]

Another idea if you dont want to do the set screw mod or loktite you could simply cut a groove or channel on the bottom of the breach barrel bore. This could be done by broaching, end mill, four jaw lathe, or even a round file. This would give three points of contact on the barrel two of which would be full length just like sitting in a v-block. I have stated before that I dont think this is an issue but I only have the .25 and some say the barrel to breach fit is much looser in the .177 and .22

[Springwater 808]

i have stated this many times...loctite the barrel in...add set screws

These discussions of POI shifting have me concerned about the rifle I just bought (a .25 cal Marauder with synthetic stock, BP2564S). So I've been following these posts with a great deal of interest.

Some have suggested using Loctite to secure the barrel in the receiver. I was thinking if I ever needed to go that route, I would use a lower-viscocity epoxy that's normally used to laminate fiberglass since it will easily flow into the tight gaps, yet set solidly without shrinking. The epoxy could also be used to lock the rear shroud mount in place. Everything would be assembled without having to use a great deal of torque, and this would help avoid any distortions excessive torque might cause.

When the epoxy cures, the barrel, rear shroud mount and receiver will be a single, solid assembly. Soaking it in acetone might eventually soften the epoxy enough to allow the assembly to be taken apart, but for all intents and purposes it would be considered "welded".

Is there a reason to ever have to separate the barrel from the receiver?

For now I haven't experienced any POI shifting with my all-stock Marauder. The first day I shot more than 70 pellets. Once the Leupold EFR scope was zeroed, it stayed zeroed while shooting Benjamin domed pellets. All shooting was done at 15 yards. Not far, but enough to detect anomalies. It wasn't unusual to get all eight shots in a single hole.

When I shot Beeman Silver Bear pellets there was a POI shift of about 1/4" to the right, but the grouping remained tight. When I switched back to the Benjamin domes, POI went back to where it was.

This is the latest Marauder that comes with a de-pinger as standard equipment in the air tube. Other design changes may have been made with this latest series, including a simplification of breech block to make servicing easier. The breech block is also supposedly a little larger to accomodate larger scopes.

[SHOOTINIT]

must have been built on a wednesday.

[PB_Matrix]

read somewhere about using brass shims cut from .005, .008, or .010 flat sheets for various reasons on fire arms, like shimming triggers and such...

Anyway, I made shims from the brass stock for the shroud mount and receiver instead of drilling holes for set screws. These shims are cut as big as can be press fit into the gaps between the shroud mount and receiver in tri-angle shapes. Once I have them snug, the set screws are used as a final lock. The barrel band is left alone and the barrel is free floating. I have not had any POI changes from day to day shooting with these shims. My .22 and .25 SRods get moved around a lot and the barrels are occasionally bumped or grabbed by mistake. I think this is much easier than lock-tite or epoxy ideas, and as the shims get a bit worn (loose) it doesn't take anything to cut another one the same size with common scissors.

The brass shim material was found in a local Ace hardware store for about $8.00 for a package with four various thicknesses in it.

I can post pictures of the shims if anyone is interested in this method.