If they are a decent make unistrut/dobistrut
They clip in pretty tight ...
Cheap copies ...well you can guess .
We use miles of unistrut/fittings at work and there's a world of difference (and price)
Between manufacturers ...unistrut comes in heavy/medium/light gauges ...
Some of the cheaper makers only do it in £$%^ gauge lol .
See if you can get a small section to try ...if it's a tight fit like the genuine stuff is then you'll have a right job to get it off lol once clipped inYes I've gone for genuine Unistrut heavy duty channels but was thinking of the Tamlex cappings which are far cheaper.
Maybe safer to stick with Unistrut cappings then.
Rough up and use a stickall mastic, i have plastic end caps onmy home made box section bumbers and had to do this as id lost a few, see the ones on the uprights next to s wheel, end caps were also sorted.View attachment 135446
See if you can get a small section to try ...if it's a tight fit like the genuine stuff is then you'll have a right job to get it off lol once clipped in