Too hot?

[Mtneer]

Now that I finally have a suppressor for my Glock 17, I'm looking at HD ammo and suspect I may have a problem. For my altitude (6700 ft), speed of sound is about 1090 fps. I have 300 rounds of Federal 147g HST +P that I bought several years ago. It's rated at 1050 fps out of a 4" barrel but I have a 5" barrel so that adds about 50 fps. Hence I think this ammo is just over the sonic crack limit. Alas, I can't test around here (at least at room temp).

I'll buy some good ammo I'm sure will stay subsonic. But am I correct in thinking the stuff I have now is too hot and defeats the point of a suppressor?

[Gman]

The 147g HST non-+P perform quite well. Have you given that some thought?

[Tim K]

For ultimate quiet, yes supersonic ammo is not ideal. Still gonna be a good deal quieter through the can, though.

[whitewalrus]

Should still help a lot to bring the noise down. Subsonic will be the most quiet you can get, so you may want to look at the standard pressure load like Gman mentions. But I wouldn't stress over it if you have plenty of the +P.

[ray1970]

For ultimate quiet, yes supersonic ammo is not ideal. Still gonna be a good deal quieter through the can, though.

Should still help a lot to bring the noise down. Subsonic will be the most quiet you can get, so you may want to look at the standard pressure load like Gman mentions. But I wouldn't stress over it if you have plenty of the +P.

What they said. Suppressing even high velocity stuff takes a lot of the bark away.

I have very little experience shooting suppressed but I've mostly shot 5.56 and 7.62x51 and even those rifle calibers at normal velocities were much more enjoyable suppressed.

[Mtneer]

Cool, thanks guys. I'll pick up some standard pressure and keep the +P in reserve. The hot stuff is probably subsonic at Denver altitude and certainly if I go lower, just not up here. Probably overthinking this but that's what nerds do ;-)

[Zcsdkr]

Is not speed of sound mostly dependent upon temperature and a tiny bit on humidity?

[00tec]

Is not speed of sound mostly dependent upon temperature and a tiny bit on humidity?

Speed of sound depends on density. Barometric pressure (including the lack of pressure at altitude), temp, and humidity can all change the speed of sound.

[Jayhawk]

Then Speed of sound is mostly effected by temperature, my E-6B flight computer aka, wiz wheel will prove, also my college aerodynamics class.