PP-PPK-PPK/s .380 recoil springs

[MGMike]

The information below is from actual measurements of new or near-new recoil springs from German and Interarms .380 pistols. I don't have a force gauge so I didn't measure the spring rate, but assuming the spring is well-made and correctly heat-treated, these dimensions tell you all you really need to know.

I have no idea whether S&W-made Walthers are the same or not.

PP .380, c.1984: wire dia: .051", coils: 16-1/2 total, both ends closed and ground (14-1/2+1+1 coils); OAL at rest: 4.5". Outer circumference of rear coils NOT ground because the barrel boss is not counterbored in a PP.

PPK-PPK/s, German c.1980 and Interarms c.1982: wire dia.: .053", total coils varied from 9-3/4 to 10-1/4, German and early & mid Interarms are closed and ground both ends (8-1/4 [or 8-3/4] +3/4+3/4 coils). OAL 2-13/16"" to 3-1/8". Outer circumference of rear coil is ground to fit counterbore in barrel boss.

Barrel boss counterbore was omitted in late Interarms production and rear end of recoil spring is not closed and ground, just snipped off to length. (*see following post). The spring's outer circumference at the rear was left round. Note that the small diameter end of the spring goes around the barrel; the larger end faces the muzzle.

A spring that when installed extends at least 1/2" beyond the muzzle when the slide is removed can be presumed good if the spring is not kinked or obviously lame and the gun is functioning correctly.

A recoil spring that is too long (some S&Ws) makes it difficult to dismount the slide and the spring may go "solid" before the slide reaches the end of its rearward travel. If it goes solid in recoil, overstresses the spring and leads to its early demise.

M

[MGMike]

I have borrowed this from another thread, as it has a bearing on the "clipped" recoil springs found in some Interarms and S&W .380 pistols.

My suspicion --and it's only that; no information to confirm it-- that the reason Interarms introduced clipped recoil springs in PPK/s and PPK .380s might have been because, after the decision was made to omit the barrel boss counterbore to reduce manufacturing cost, it was discovered that the existing recoil springs no longer compressed comfortably in the shorter space available, especially when dismounting the slide. Then it was discovered that a goodly supply of recoil springs had already been purchased, so to avoid discarding them they were clipped to a workable length.

That's only my suspicion, but I can't think of any other reason not to use a closed and ground coil on the rear end of the spring.
If the pistol has a counterbored barrel boss, the correct spring is one with a closed and ground rear coil. If there is no counterbore, the clipped spring is not very elegant but will work provided it is not too long.

I further suspect that that little bit of Ranger's learned experience was not passed on to S&W, who proceeded according to the Walther drawings and did not compensate for the omission of the counterbore. The difficulty in dismounting the slide on some S&W guns results from the fact that the spring "goes solid" before the slide has cleared the frame rails, unless the coils are distorted by brute force into an eccentricity that allows them to stack more tightly. It is unknown to me whether S&W subsequently re-engineered the spring.

Just my suspicion, mind you.

M