Help adding hopups to JG SIG 551 and FN FAL

Hello GBF.

I recently purchased JG SIG 551 and FN FAL LK-58.

These models are wildly inaccurate when using my usual Ultra Elites and Pearl Whites. Would like to be able to get hopups on them, but unfortunately, there’s no extra length on the inner barrel.

I’ve tried sweethearts, but there’s no gap between the outer and inner barrels for them to fit.

Also, I’ve heard JG have some funky, non available barrels available to swap.

I hope someone has worked out a way.

Gel blaster M4 and AK47/AK74/AK74U Hopups | Etsy

they screw onto the outer barrel.