Weather and gas settings

[AmEngRifles]

Does warm or hot weather require more gas? This is in reference to L4's mostly.
The .303's may have had the same reaction to warmer/hot weather?

Seems it would be just the opposite. Hot weather would require a closing of the gas port?

Information

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[Peter Laidler]

We had L4's in the severe monsoon tropics and I never noticed any changes over temperate climes. Even in the coldest weather ours soon got hot!!!!! In the monsoons, the rain cooled them off and soon turned to steam

[TactAdv]

It's not the gun "temperature" mainly that is the problem, it is the ammunition that can be a serious issue.

Almost all ammunition has been designed over the last 100 or so years to be stored and consumed at some universal environmental/common standard, like International Standard Atmosphere, i.e, 15 deg C @ 1013.2 HPa currently.

Deviations from the intended temperature standard can have very deleterious effects upon both performance and safety.

For modern military ammo, a simple increase in propellant temperature of only 25-30 deg F can have extremely noticeable effects on pressure, velocity and uniformity. Increase that to an exposure or storage at anything over 100 deg F and things go wildly off the charts.

At lot of "surplus" ammunition has been surplussed out because it was exposed to storage conditions that condemned it for continued inventory and consumption. Sh*t tons of very new 7.62 M80 NATO ammo from all participant sources was immediately surplussed right after the festivities of Desert Shield/Storm ended in in the '92-'93 time frame because logistically it had been delivered and stored VERY improperly on the thinking it would be immediately consumed. Much iof it was not and logistics rules prevent anything like that from being re-inventoried so it got sold as scrap. Some of it was perfectly fine, and I and my shooting friends consumed tens of thousands of rounds of it as it came in, some if it was notoriously not just bad but extremely dangerous as it exhibited hugely increased pressure spikes. There was no real trick to figure it out which was good, and which was bad except by careful inspection and saying a prayer.

Moral of the story is be exceedingly picky about what you feed expensive guns and reject anything that even MAY have seen increased temperatures.

-Tomh

[Brian Dick]

Temperature and humidity won't affect the gas setting. Altitude will. When I replaced the gas cylinder on a Mk.1 Bren many years ago, I test fired it after refinishing back to spec and reassembly on my range here and it was so tight that the gas setting had to be set to #1 so that it wouldn't take chunks out of my shooting bench by the ejecting brass, (my bench still has them!). The #2 setting being the normal place to start, I was actually pleasantly surprised it was so good. Better than new in my humble opinion. When it was delivered back to the owner on the Blue Ridge Parkway of Virginia, he had to dial it back up to #2 for proper function. The L7 series of GPMG, (FN MAG), has a 12 position gas regulator for balancing the gun in any environment. For some reason this was omitted on the U.S. version M240B GPMG n favor of a 2 position gas regulator. I'm not sure why as it's important to adjust it correctly so the gun doesn't beat itself to death, crack sideplates, etc..

[AmEngRifles]

Thank you gentleman for these EXCELLENT contributions. It is greatly appreciated.

Wife always wants to know why I store my ammo and gunpowder IN our home and not in the garage. Heat in the Southern US is a killer in so many ways. Skin cells, rubber moldings, plastic lawn furniture, unattended gardens, live ammo and gun powder. Heck, I even keep my primers in the house, but NOT next to the gunpowder!

[browningautorifle]

I even keep my primers in the house

I couldn't imagine any other way. We do have those that store them in a garden shed and such, one used a greenhouse for storage...disused I think. Then when you come to a gunshow and find powder for sale, you have to ask...?

[Brian Dick]

I keep reloading components inside using excellent condition GI ammo cans. I'm still using some Winchester primers purchased in a bulk deal from the early 1990's with no issues whatsoever. GI ammo cans are safe and airtight as long as the rubber seals are in good shape.

[AmEngRifles]

10-4 Brian. Might I suggest one of the modern plastic ammo can copies? I tend to follow the old school powder and primer storage rule. Don’t want it in something that will become shrapnel should it end up detonating somehow. Powder stays in their original containers, plus stored in a cardboard box to simplify, and same with primers, although I use shoe boxes for them.

[browningautorifle]

I tend to follow the old school powder and primer storage rule. Don’t want it in something that will become shrapnel should it end up detonating somehow.

That's a misconception that's vastly over rated. We burned live ammo, everything from .22 to .50 cal, locked it in ammo cans and set it in the cooker to find it just popped and spread ammo around. Powder just roars into flame. There was NO shrapnel.

Yes, original containers. We were talking about primers.

[AmEngRifles]

BAR, I am talking gun powder and primers, not loaded ammo.