Thanks for the info. James. I did manage to get one from someone in Germany complete with 48 newton spring and thread protector for $225.00 + shipping. It arrived in 7 days.
I asked them what the thread was and I got a different answer but I will stick with your answer.
I have decided to go with the AWC suppressor. I am also having a custom made 9mm AR-15 barrel threaded with the same thread as the P-99 barrel so I can interchange the suppressor from one gun to the other. This is why I needed to know the thread pattern.
I do have another question. Why and when should the red 48 newton spring be used ? Does the new spring reduce recoil over the original silver stock spring?
I have an AWC Titanium Abraxas that I had made with the 13.5x1 LH threads. I have only shot about 50 rounds through mine (I had only time to shoot it once while I waited for my FORM4 to clear). I did NOT have the reduced recoil spring when I shot it, so I was having some failures to feed (short stroking). This was with IMI 158gr subsonic and with Winchester 147gr subsonic.
I now have possession of it and plan to go shooting soon. I'm hoping that the reduced recoil spring will aleviate the problems. I don't have the recoil booster on mine because I was told by AWC that I wouldn't need one since the Titanium Abraxas was so light. We shall see and I'll let you know. In either case, I would use the reduced recoil spring only with the suppressor.
I can think of no benefit at all, unless you are shooting wimpy loads, low power loads or such. I would think it would not be good to shoot regularly with the red recoil spring as it might accelerate wear on the pistol by allowing the slide to cycle too rapidly battering the frame.
I would use the regular recoil spring if I wasn't using the suppressor.
Joe at SWR said that all ( sure he meant himself and the other manufacturers with whom he works or talks regularly) the suppressor manufacturers use Alabama Ammo when giving their specs on noise ratings.
Well I finally got to take my new AWC Titanium Abraxas out to the range to try again on my P99 Tactical and my USP 9mm SD Tactical.
Results with the P99 were ..... OUTSTANDING!
No failures to feed or chamber this time. At ALL. Worked like a champ. I guess the brown reduced recoil spring needed some breaking in (shot it a few times previously without the suppressor). Quiet, although not "silent" if shot out in the open. NOT so quiet when shot under a tin roof !
Some initial failures to feed properly with the USP 9mm SD, but they worked themselves out after about 20 rounds. To be fair, it was the first time the SD had been shot - period. Probably wasn't fair to shoot it right off the bat without breaking it in at all. But it worked fine by the time I was done.
Verdict: Titanium Abraxas is very nice, light, no need for the extra length/weight of the recoil booster.
Ammo Verdict: The IMI 158gr Subsonic stuff is the quietest. The Winchester 147gr Subsonic Match stuff is just a little louder.
Both worked great. Even shot some 115gr Winchester and if I freshly greased the Abraxas, it was pretty quiet too!
Fun day at the range! Also, the first time I shot my new MP5 but that's another story for another board!