SF Ryder 9Ti to MP5 fit question

[JPB]

Okay so I ordered the SF-SPCR-9 (fixed barrel spacer). It's backordered, but they stated that it should ship by mid March"ish". I also ordered a 1/2x28 piston as I bought the can with the metric piston for use on a Sig P226. Just for fun it threw it on my MP5 to get a feel for it vs. the Octane 45/three lug set up that I have been using. Spinning it onto the threads, the system tightens up against the muzzle vs. the barrel shoulder. Is this going to be a problem? I seem to recall that it is preferable to index off the barrel shoulder vs. muzzle. Thanks.

[JPB]

Despite the overwhelming response, I think that I've had an epiphany! On pistol barrels, the pistons actually bottom out on the muzzle as well. No shoulder on threaded pistol barrels. I still wonder if the same rules apply to MP5s?

[MegademiC]

I don't thing many people have them.

My silencer sits on the shoulder, but it's not the one in question. Maybe SF does it different than griffin.

[interfan]

Sorry for the underwhelming response. I have a Surefire Ryder 9ti, the fixed barrel spacer, and the std piston. On my own MP5s and MP5k, it threads down to the shoulder (converted HK94 with a Navy barrel and a POF for the full size, MKE/Zenith K) On my Kriss Vector 9, it does not thread to the shoulder and indexes on the barrel end. I asked Surefire's CS and Barry Dueck about it and both said that the Ryder 9 can index off of either the shoulder or the end of the barrel. You should be fine

My only complaint is that it does get very hot when your volume of fire is high and rapid. There's not much gas volume there.

[JPB]

Thanks for the responses. That's odd both of my MP5s are MKE/Zenith SBRs (Z5P and Z5RS). You're saying that on your Zenith it threads down to the shoulder?

[interfan]

Thanks for the responses. That's odd both of my MP5s are MKE/Zenith SBRs (Z5P and Z5RS). You're saying that on your Zenith it threads down to the shoulder?

Yes. The Zenith is a Z5P purchased in 2015.