[MGMike]

You may be letting your hand ride the slide to chamber the first round. The soft lead bullet is engaging the rifling before the slide is fully closed, and tends to hold the slide slightly ajar, which cushions the fall of the hammer.

The same situation arises if the chamber is dirty, especially at the front where it meets the rifling, and in the annular recess for the cartridge rim. Thoroughly clean both out with a a bronze brush rotated like a drill, and see if that helps.

M

 

[MGMike]

A new .22 brush would probably work okay, provided you used a rotating motion to scrub out the front end of the chamber where it meets the rifling. Lead and powder residue (and with some ammo, bullet wax) tends to get wedged in there, and a normal back-and-forth cleaning often does not remove it. If in doubt, try a .25 rifle brush inserted just far enough to fill the chamber.

I should have added in my post above that the reason your malfunction only happens on the first shot is that in semi-automatic operation the slide generates more velocity and its momentum overcomes whatever resistance is offered by the lead, dirt and wax in the chamber (unless it gets too fouled to function at all). Chambering the first round is also when stripping pressure from a full magazine is greatest, and impedes slide velocity. That's why it's important, when chambering the first cartridge by racking the slide, to let the slide snap smartly shut, and not slow it down by riding it closed.

M

 

[MGMike]

If I needed a new trigger spring, I'd call Walther USA.

But that may not be (and probably isn't) the cause of the problem.
I would suspect that somewhere along the trigger-trigger bar-sear chain, something is binding. Remove the right hand grip to get a better view of it.

M

 

[MGMike]

I think uvarmint and Malysh and MN Swede may be describing somewhat different problems. Misfires in DA mode on the first shot are often due to a slide that is incompletely closed, which in turn may result from incorrect charging technique or a dirty chamber. Misfires in DA mode later in the magazine following a decocking may indicate an insufficiently strong hammer spring. On Interarms guns, at least two different hammer springs were tried in attempts to cure misfires, with varying degrees of success; the brand of ammunition in terms of primer sensitivity and rim thickness, turned out to be critical. The basic problem is that in a gun so small, there is only marginal mass in the hammer. A stronger hammer spring can be substituted, but it adversely increases the DA pull, which is already pretty stiff. The German guns were in fact no better, and often would not shoot at all in DA mode with American ammo. Walther partially compensated by keeping the headspace at the very minimum--which had the unfortunate result of occasional slamfires when the gun got dirty. The headspace was opened up slightly on the Interarms guns, which improved the safety but at the cost of occasional DA misfires.

SA misfires are rare in a clean gun. I have an Interarms TPH that was subjected to a controlled 1,000 round nonstop test with Remington Hi-Speed 40 gr. solids, SA only. There were exactly five stoppages-- which is better than the reliability of that ammunition in ANY gun. Three of the stoppages were misfires, probably due to duds. At a malfunction rate of 0.5%, that's better than most 9mm service pistols.

M

 

[MGMike]

The TPH was introduced just in time to be banned by the GCA '68. That cut off 90% of the potential market, and not much further development effort was expended by Walther to cure the DA misfire problems that soon showed up. The technicians at Ulm had always regarded the TPH more as a toy than as a serious weapon, and did not think the DA problem was particularly serious. Much later, when the gun was put into licensed production in the USA, the complaints resumed and had to be addressed by Interarms.

I had a German-made version also, which I preferred because it had an alloy frame and was not much heavier than my key set. Simply dropped in a pocket, it was unnoticable and better than being unarmed. My solution to the DA misfire issue was simply to shoot it only SA, cocking the hammer manually when assuming a two-hand hold. In hundreds of rounds it never failed to fire even when filthy, and I could consistently hit a silhouetta pig at a 100 yards with it. Nice gun; wish I still had that one.

M