Dumb barrel replacement question on a MP 40

[Nicksterdemus]

I was over at the Storm Lake site looking for the 357 sig barrel that's not available yet. I noticed they offered barrel lengths in various sizes. I've seen the extended length barrels w/threads for attachments and I wondered how far the extension could be taken. I don't want the threads, but the extra length seems appealing. So could a 4.125" MP barrel be stretched out another 1.5 or 2" w/same slide and still be supported? Or am I experiencing yet another weird dream?

 

[Nicksterdemus]

I was over at the Storm Lake site looking for the 357 sig barrel that's not available yet. I noticed they offered barrel lengths in various sizes. I've seen the extended length barrels w/threads for attachments and I wondered how far the extension could be taken. I don't want the threads, but the extra length seems appealing. So could a 4.125" MP barrel be stretched out another 1.5 or 2" w/same slide and still be supported? Or am I experiencing yet another weird dream?