So I am working up a subsonic 115gn 9mm load for my Glock 19.

Range Brass
xtreme 115gn fmj
CCI Small Pistol Primer
4.45gn of 231 (+/- .05gn)
Nothing over 1.165 OAL (1.155 avg)
.45 Osprey suppressor

1066fps avg. 1011 low. 1111 high.

The speed of sound is 1135fps. (77 deg)

I don't want to break the sound barrier. Should I worry about the fps down the road in the winter when the speed of sound is like 1100 fps?

I have read the for each degree of temperature, fps goes along with it (1 fps per degree). Has anyone found this to be true? Or can provide any info?

Thanks

all depends on powder used... some powder is much more sensitive to temperature swings than others....

much easier to accomplish this with 147 grain.


4.3 grains W 231 will give you about 1030 fps depending on your barrel with JHP.


3.5 grains for 147 lead.

+1 for the 147's. I was using 3.7 grains of 231 with the zero 147 and getting great accuracy. Hope this helps

Thanks for the input on the 147's. I could see myself doing fine with 124's.

But I have ~3600 115's from when before I had a suppressor. I love the super low recoil of them. The .45 Osprey acts as a muzzle brake hehe.

I may just do 4.4gn of 231 (1040fps avg, 1000 low, 1085 high) and use a 15lb ISMI recoil spring. I already have a 18lb ISMI spring in the gun.

I *probably* had some issues using titegroup and 124 gr's in the cold.
I chronod them around 1090 fps ... at 80-85* F
But, we were shooting them in 30 * weather. They were feeling way slower, but I didn't chrono them for obvious reasons. But, there were some problems that day.

Didn't want to get DQ'd

Just don't use WST. Quiet through a can but very high inverse temp sensitivity.

I would go 147's for subsonic 9mm. There is a load with IMR4227 and a 115 grain bullet that is subsonic, will not cycle in a pistol but may in a rifle. 8.9 grains of 4227 is the load.