Which
weapon is it?
Sound works on a logarithmic scale. For each doubling of distance between yourself and the weapon, subtract 3dB*.
Calculate the expected SPL, and set the H6 to an appropriate setting, that leaves some overhead.
*Note: This is also effected by surroundings. If you are in an enclosed space, you may only want to subtract 1dB, to be on the safe side.
edit:
Looks like the
rated Maximum SPL using the XY mic, is 136dB.
Judging from the data above, the
minimum SPL you will encounter is 150dB.
Best case scenario, you need to be at least 32 meters away.
The -20 PAD won't fix compression of the mic diaphragm.
Don't use any of the compression or limiting settings.
Can you describe the recording surroundings?