Trying to set zero's and testing loads on....

[Pond, James Pond]

... a rainy day. Waste of time?

I want to try and sort my AR's zero before my dad visits so he can have a go, unhindered. I also may try to test my new 170gr Lockbase load for the CZ seeing as I'm driving all the way out there.

But, the forecast is shocking. Rain and/or snow and a miserable near freezing. I'd be shooting at 50m, 100m and 300m.

Is all that precipitation going to skew my results?
Should I just do one of the two and if so which?
Or should I just let it go and wait for decent weather?

[Art Eatman]

IMO, the weather will affect you more than it will affect your rifle's behavior. If the sight-in conditions are anything like the possible weather during a hunt, I'd guess that you're ahead of the game.

If, later on, actual shooting conditions are warmer, it's possible that your point of impact might be off by an inch or so--but that's a guess.

My sight-in history, I vaguely recall, has been done with temps of 80F or more. That never seemed to matter at 40F. All went well.

[Pond, James Pond]

I'm more concerned about the falling water drops/flakes interfering with trajectories.

[AK103K]

If youre testing loads, I wouldnt bother messing with the zeros, until I settled on a load that shots well. No need to drive yourself crazy.

I personally think shooting year round, in any and all weather is a must, if you really want to know your gun. Some guns and/or load combos, can act very different in warm and dry, than they do in damp and cold. Shooting year round tends to help you work all that out.

[Pond, James Pond]

I want to know if rain will interfere with POI to the point that playing with zeros or doing OCW in rainy/snowy weather is not a waste of my time, ammo and therefore money (about €20 of range time, €20 of .223 and €45 of .308).

As outlined in the OP, the zero is for my AR, and the OCW is for my .308 CZ.
Two different goals with two different guns.

Both potentially affected by precipitation.
Should that last possibility give me pause?

[kraigwy]

I'm more concerned about the falling water drops/flakes interfering with trajectories.

Ain't going to happen.

As Art said, rain/snow affects the shooter not the rifle/ammo.

[Pond, James Pond]

Ain't going to happen.

As Art said, rain/snow affects the shooter not the rifle/ammo.

Cool!!
So off shooting I go tomorrow morning!

[4runnerman]

The best Match I ever shot in was raining on me. As Art said- The rain will affect you not your rifle... If you have a deck table with a umbrella- Bring it with and stick it in the ground. The cold, I must agree with-It bites to shoot in it.. I am one of those that needs skin on the trigger,can't wear gloves. Beifet is - barrel cools down faster.