The best replacement for gas tube is gas piston.

The best alternatives to gas tube are rated as following:
★★★★★  gas piston
★★  mid length

Your alternative for gas tube is not listed? Suggest!
Speaking about gas tube, one probably shouldn't forget about handguard.

Other search terms related to gas tube and their ratings are:
★★★★★ handguard
★★★ handguard sks
★ ventilated handguard
You have in mind a companion for gas tube and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of gas tube in all years. Click on graph for more.
gas tube
gas piston
mid length