Hey everyone, I'm trying to fit a magpul forearm on my 590m. And fitment charts don't really include the 590m for aftermarket parts of most any sort. This forearm is made to fit the 590a1. And claimed to fit all 590 models. I probably should've done a bit of measuring first. But instead took the internet's word that it'd fit, with only a bit of relief cut in for the heat shield. I was ready for that slight modification, but substantial modification won't work for me. It's actually about an inch too long for the slide tube mount. I remember seeing somewhere, that there's two different size tubes for the different models. And IIRC, there's about an inch difference between the two. Here's the question, do I look for a longer action tube? Possibly there's a longer nut that'll reach down in there? Or look for a shorter version of the magpul grip? I'm thinking that replacing the magpul grip with the shorter version would be easier, and probably best. Since it would continue to use the specs as designed. And would likely only be a swap return. Or if the longer nut is a possibility, that'd work too. But I have no idea what other models have the shorter tube. Since I'll have to know what to ask for from magpul. So what model comes with the shorter tube? And is the tube the same circumference?