Kind of bored.. thought i'd post a simple but useful little tidbit. If nothing else it's my contribution to the grand repository of knowledge that is the Internets.
The airsoft Thompson is an amazing AEG. It's a solid workhorse of a gun sporting the venerable V6 mechbox. Thanks to it's hop up design, it is a reliable and accurate gun out of the box. Cybergun / KA models mean you can usually pick one up for less than 200$ new: probably one of the best value-for-money AEGs you can purchase.
One fatal flaw, however, is that due to the physical dimensions of the gun and the location of the sling mounting points: excess stress is created where the barrel meets the receiver leading to breakage.
Your options are as follows:
Don't use a sling
Attempt reinforcement (usually complex and of questionable effectiveness)
Tempt fate and use the sling anyway
I present you with another option! I have successfully used this method for some time now with no problems. I used heavy zip ties to create a mount point, but you could use anything (a hose clamp would be a good option). This takes stress off the front end (and consequently the weak connection point) and distributes it across the thicker, stronger chamber area. Add a pinch of para cord and you're in business. In addition it allows the sling to be used in a more practical manner than with the traditional configuration.