Quote:
Originally Posted by lclund1946
Here is an example of the volatility of LilGun loaded just 0.1 grains under Hornady's Start load. Like the early factory rounds it is really temperature sensitive in that it does not "Show pressure Signs" at lower temperatures."A friend has been loading Lil Gun in a 17 Hornet.
9.8gr.----- 20 gr V max.
The load was developed in cool weather for shooting sage rats.
Pressure seemed normal with no ill effects on a sage rat shoot in cool (70-75*) weather.
Cases were reloaded and primer pockets were tight.
The next trip the air temp was hotter (90-95).
When he tried to reload them after that the primer pockets were too loose to use them.
He said he left the ammo in the sun and made no real effort to cool the barrel.
This leads me to believe that Lil Gun is quite temperature sensitive.
I have shot a 17 cal. for 40 years and am aware that small changes in 17 bores can make a BIG difference.
So what say you gents? Have any experience with Lil Gun and temperature caused pressure spikes?...."
This fellow from NZ found the "new factory 20 grain loads to be much slower in his CZ 527 American, than Hornady's early ammo that they claimed 3650 fps, just as I did. "factory hornady ammo 3540fps". He also had some good info on CFE BLK "CFE Blackout, Hornardy brass and WSR primer. five shots of each.
20gr v-max.
12g - 3470fps
12.3g - 3566fps
12.6g - 3738fps
12.8g - 3779fps.".
It would appear that the Hodgdon Max Load of 12.8 may be a bit on the hot side especially if the powder is a bit temperature sensitive. I would look for a "Good Load" using a pressure ladder working up in 0.1 grain increments from 12.0 to 12.5 grains which should get to 3650 which they show as max velocity. I would do this when the temperature was near the max that I would be using it. Perhaps this fellow would chime if he is on AOF which is likely as he has spent time in Northern Alberta.
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Most people that are using Lil Gun have discovered that a load of around 9.5 grains will match or exceed the velocity listed for the max load of 10gr in the Hodgdon data. Once I saw 3680fps at 20 degrees, I didn't bother trying to work up the load any hotter. If my velocity at 9.5gr exceeds the velocity for the maximum load, it only makes sense that increasing the powder charge to 9.8 or 10 gr, would produce excessive pressure, especially in hot weather.