Lots of conflicting analytic and anecdotal threads on the interweb, but I just started light loads with N320 behind 115gr coated lead and there is no question in my mind that at lower temperatures (40 degrees) the load is softer, the ejection weaker in our 9mm 1911s.
We went to the range last week with three loads (3.6, 3.7, 3.8) grains that had all previously cycled reliably in our guns. It was chilly for CA, maybe 40 degrees, and none of the loads would cycle reliably: stove pipes and obviously week ejection. The ammo cans had been sitting on our garage floor overnight so I don't doubt the ammo was actually colder than the ambient. At yesterdays match starting at a chilly 45 degrees I brought both 3.7 and 3.8 grains. My first stage I had one stovepipe and obviously very week ejection. The last six stages (steel challenge) the gun cycled flawlessly as the temperature slowly rose. This ammo we had left in the house overnight before the match. I don't believe gun lube was at issue; I'm using oil only now and the slide action was very slick at the start of the match.
Now, we're not talking about a huge temperature change, but it's almost as though with these soft loads there is some sort of a threshold that is more abrupt than one might expect from the relatively small temperature change. The good new is that I never had to open up the bags of 3.8 and I did gather some additional info. (My wife went back to our proven 3.3gr WSF behind 147gr Bayou).
If I had the time I'd drag out my chrono one of these colder mornings. I'm also dealing with the fact that my wife's gun has never been as smooth as mine, but it's going back to the factory for some rework so it will be much smoother upon return.
Long post, but setting aside that I'm running slightly below the 3.9gr VV min. for N320 behind 115gr LRN, is there a mechanism by which that 30 degF temperature difference would have such a big effect?
(and apologies for the long post)
We went to the range last week with three loads (3.6, 3.7, 3.8) grains that had all previously cycled reliably in our guns. It was chilly for CA, maybe 40 degrees, and none of the loads would cycle reliably: stove pipes and obviously week ejection. The ammo cans had been sitting on our garage floor overnight so I don't doubt the ammo was actually colder than the ambient. At yesterdays match starting at a chilly 45 degrees I brought both 3.7 and 3.8 grains. My first stage I had one stovepipe and obviously very week ejection. The last six stages (steel challenge) the gun cycled flawlessly as the temperature slowly rose. This ammo we had left in the house overnight before the match. I don't believe gun lube was at issue; I'm using oil only now and the slide action was very slick at the start of the match.
Now, we're not talking about a huge temperature change, but it's almost as though with these soft loads there is some sort of a threshold that is more abrupt than one might expect from the relatively small temperature change. The good new is that I never had to open up the bags of 3.8 and I did gather some additional info. (My wife went back to our proven 3.3gr WSF behind 147gr Bayou).
If I had the time I'd drag out my chrono one of these colder mornings. I'm also dealing with the fact that my wife's gun has never been as smooth as mine, but it's going back to the factory for some rework so it will be much smoother upon return.
Long post, but setting aside that I'm running slightly below the 3.9gr VV min. for N320 behind 115gr LRN, is there a mechanism by which that 30 degF temperature difference would have such a big effect?
(and apologies for the long post)
