Mainspring Guide Mod.

It is easy to copy the dimension of the of the factory mainspring guide, but the benefits of using the guide are unclear. With the guide the Max velocity was 4fps higher and the average was 2fps higher than with the preload only. The guided spread of velocity was 2 fps larger and the standard deviation was 4 points higher than with proload only. The main cluster of shots seems to be a bit tighter but it is hard to credit that to the spring guide. Easy to make; but of questionable benefit.

Here is a factory mainspring guide next to a Poorman mainspring spring guide.

This guide is made from a #6 nylon machine screw with a 3/4 section of 3/16OD & 1/8ID vinyl tube.

This is the group from the 2240 shot from a rest with .066 preload on the mainspring. The product of the main cluster extreme spread (HxW) was 1.330 inches.

This is the group from the 2240 shot from a rest with a guide on the mainspring. The product of the main cluster extreme spread(HxW) was .977 inlches.

Shoot Smart. Shoot Safely.

Poorman Plinker