Plasterboard fixings - plastic vs metal

[r_c]

I need to hang up some pictures on a plasterboard wall so I bought some self drilling plasterboard fixings. I didn't know if I needed the plastic sort or metal, so I bought a tub with both of them. I hope these are the right fixings for the job - please let me know if you think otherwise.

But when should I use the metal fixings and when should I use the plastic fixings? (I did try Google but couldn't find the answer.)

[GALLERY=media, 100936]20171231_113519 by r_c posted 6 Jan 2018 at 5:19 PM[/GALLERY]

 

[endecotp]

Use the metal ones only with the screws provided; the plastic ones can be used with your own screws.

See page 91 of https://www.rawlplug.co.uk/media/filer_public/2017/07/20/rawlplug_product_catalogue_uk_07_2017.pdf

Either shold be OK for most pictures unless they are very heavy.
It's important that you don't hit the wooden studs behind the plasterboard when using these fittings as they won't screw into them.

 

[lostinthelight]

Today I fitted some curtain rails using the metal fixings and after experimenting with a soon to be replaced plaster board stud wall, I ended up tapping threads in the fitting with the supplied screws first then drilled a 3mm pilot hole and wound the fixing in with a cross head driver. It seemed to place less stress on the hole and the screw could be undone easier if needed without winding out the fitting.
litl

 

[lostinthelight]

.

 

[^woody^]

Either or. Plastic is just a cheaper version of metal and both do the same job.