Ruger SR9 manual says dont dry fire without an empty mag. I believe it has something to do with the mag disconnect.
So, would this be the same with all guns with a mag disconnect?
If it does involve the disconnect, since I removed mine, is it now ok to dry fire without a mag? I guess it really doesn't matter but I have wondered.
I asked Ruger and they said they couldn't give advice about an altered gun.
The Ruger magazine disconnect on your pistol operates by engaging a firing pin safety unless the magazine is inserted.
The problem is that a firing pin safety is basically a failsafe device and isn't designed to take a steady pounding. It's there to keep the gun from firing if something goes wrong, not really to act as an everyday safety that can be used on a regular basis.
When you dryfire the gun without the magazine in place, everytime the firing pin is driven forward, it is stopped by the magazine disconnect firing pin safety. If you do that once or twice, it's not an issue. If you do it a lot, it will eventually deform the firing pin/striker and/or the magazine disconnect firing pin safety. That deformation, if it is severe enough can prevent the gun from functioning properly.
If you remove the magazine disconnect firing pin safety, then when you dryfire without the magazine in place, the firing pin acts as it normally would because there's nothing to stop it from travelling fully forward.
With the magazine safety removed, I think that you should be able to dryfire your gun without any fear of damage or wear other than the normal wear you'd expect from dryfiring any other modern centerfire firearm.
With that information comes 2 cents of advice.
1st cent. If you sell/trade the gun, please restore it to factory trim before doing so. There are few things more dangerous than a gun that has had a safety altered but that appears to operate normally from the outside.
2nd cent. In the future, consider purchasing a firearm that will fulfill your needs without the need to alter the safety features of the firearm. These days, there is a truly staggering selection of firearms available. Personally, I don't like magazine safeties, so I don't buy guns that have magazine safeties. There are a couple of good reasons for taking this approach. First of all, it completely avoids the issue I mentioned above in my 1st cent of advice. Second, it avoids giving manufacturers a false sense of demand for products that customers don't want. If everyone who hates magazine safeties stopped buying guns with magazine safeties, it might just send the message to the manufacturers that they need to stop putting magazine safeties on their guns. And that saves everyone time and money.