Reddit mentions of Galaxy Audio JIB/Y Splitter, Model:JIBY

I was actually debating picking up one of these XLR splitters as I know quite a lot of people that do it even when a feed out is possible. there are also a bunch of other models to choose from. I still might pick one up, but I think I'll probably be fine for the weddings i'm doing this summer.

Is it just one speaker with one microphone? You can split the mic and send one XLR to the board and one XLR to your recorder. You need a splitter box and 2 xlr cables (1 cable from mic to splitter box, one from box to board, one from box to your recorder. I assume the venue will have 1 cable)

Splitter box: https://www.amazon.com/dp/B00079P7T8/

There are a few good tricks you can use to get realistic gunfire recordings like the example you linked to. The first thing to be sure of is that your microphone(s) are capable of handling high sound pressure levels. With your zoom H6, the XY microphones can handle 135 dB, so that should be good for distant coverage and to get stereo perspective following the actual shot. For the closeup dialog and sounds I'd suggest a hypercardioid condenser like the Audio-Technica 4053b because of its 155 dB maximum spl. Most full shotguns like your Rode don't handle high levels impulses like gunfire gracefully (it's rated at 120 dB maximum SPL). A blend of these mics should give good results, but you still want to be sure you don't have any analog overloading happening. That way you can control the way the impulse and recovery are shaped (in post and digitally) to get a natural sound in your final product.

The next thing to do is make full use of the 24-bit recording capability of the H6. If used correctly, you can get a theoretical 144 dB dynamic range, so you can record whatever either of these mics puts out. And do not use compression or limiting during recording. This is NOT what you normally do in recording field sound for video. You want to be sure that when you fire a round the tracks you are recording don't overload--at least not very much. That means if you set recording levels accordingly, your dialog and quiet sounds will barely move the meter. You will need to use a gain plug-in during editing to bring it up to normal levels. Because of this and because of the possibility of noise to be introduced elsewhere, I suggest you use a mic splitter like this which blocks phantom power from one channel to avoid damage to the mic. Then record the mic on two channels, one set for the gunshots and the other set for maybe -20 dBFS on narration and incidental sounds. Be sure you don't limiting or compression on either of the two XLR channels.

In post, you will have two clean channels and a boosted safety channel that you can control.

You should do a lot of testing to get the best sound here. If you're lucky, you can put a fast-decay digital brick wall limiter on the boosted stereo and mono tracks and get very clean, realistic results with no pumping or unnatural sounds of compressors recovering.

Hope this helps. Let me know if any questions.