Thanks for the responses, folks. A coupla things.
First, if that Hogue stock is the same standard as their handgun grips, it's a good'un. But,I doubt I've got 40 cents invested in this. And, right now it'll take a lot of convincing to make me invest another $40 in this. Note that I did this in a stock that fits me.It's a fair bet the Hogue won't. Most do not.
364, 350 slugs in a day is quite a lot. Sure it was that many? I've done 120 rounds of 00 and 40 slugs in a day w/o a prob other than slight soreness.
I'm quite recoil resistant, and have good form and fit. A heavy shotgun helps too, this one's over 9 lbs.
And,364,my life is simple, it's my hobbies that get complex(G).
An update....
I had conferred( A polite word for writing and begging for help) with,(uttered in a hushed and reverent tone) the TECHNOID, Bruce Buck himself. He had done similar things and urged me to use springs fore and aft in the mag, and leave the spring out of the butt and add another weight. I conformed in part. The two weighted shells in the mag aren't fore and aft as they were, both are in the middle of the tube with a workeable hunk of spring in front AND behind. The one in the stock was left just one, but it too has fore and aft springs.
I'm not working until tomorrow night, so I plan some range time tomorrow to try the new setup out. It seems(Dangerous word) to handle like it did. I'll keep y'all posted.....