HW/Weihrauch Barakuda spring

[JayDee24ca]

My EL54 'kuda shoots around 630fps, and is really boingy. I can fix the noise easily enough, but I have on hand a virtually new HW35 main spring that I though would be a straight swap for the old tired and bent on in the gun. However, when I fit it into the gun, along with the HW35 rear guide, the gun will not cock.
The old spring measures 210mm in length, but I assume it is compressed over the years. The HW35 spring is 222mm.
The wire on the old spring appears to be 3.52mm, and the HW35 is 3.62.
They both have 27 coils.
I understood, from reading various posts, that they were a direct swap, Can someone help me on this please?
JD

 

[JimBentley]

The difference in wire diameter is equal to 2.7 mm or 0.106". That could be enough to prevent it to cock. Is the flange thickness on the two guides the same?

 

[MDriskill]

There was also some differences in the metal thickness at the head of the piston on many HW rifles over time, which affect the space available for the spring.

 

[JayDee24ca]

The difference in wire diameter is equal to 2.7 mm or 0.106". That could be enough to prevent it to cock. Is the flange thickness on the two guides the same?

Flange thickness is slightly larger on the new guide, so that might be my problem, along with the extra 2.7 mm due to wire variance. I think I might try clipping half of one coil.

 

[JayDee24ca]

There was also some differences in the metal thickness at the head of the piston on many HW rifles over time, which affect the space available for the spring.

Not sure if I understand what you are saying, but I did not swap pistons, just spring and guide.

 

[Chuck-in-Ohio]

Not sure if I understand what you are saying, but I did not swap pistons, just spring and guide.

What he is saying is-

Over the years of production, the thickness of the head of the piston has varied in dimension.
If you look at the interior of the piston through the cocking slot, at the very front, there is a bearing surface for the end of the spring to seat on. Over the years, through design change, or machining tolerances changing, that area can vary in how deep the spring seats in relation to the piston head.
IF you have a model that has a thicker section at the front of the piston, it will decrease the free space that you have available for the spring to compress. Couple that situation with a spring that is a smidgen longer when compressed, and you could be running into a coil bound spring.
Be sure that there are no thrust washers lodged in the piston, or that there is no tophat in there from someone else kitting up the rifle at some point.

@MDriskill can competently comment on just how much variation he has observed in piston head thickness hopefully, and this can give you a better idea of what compressed spring dimension that your rifle will tolerate.