M4 Build Buffer and spring question

[target4fun]

I have everything to build my m4 except 2 parts buffer and spring.... I have a mil spec size tube and stock, my question is will the following parts work:

https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=287&CFID=20263870&CFTOKEN=20424892

AR0072A 72 - Action spring, CAR $4.00
and
AR0107A 107 - Buffer assembly, CAR $11.00

Rock river doesnt list if these are mil spec or commercial or does it matter. I would think the spring and buffer need to be not commercial but mil spec size, but there doesnt seem to be any other options from RR.


Thanks for your input.

[markm]

That part doesn't matter. It's the Outer dimensions that differ between commercial and mil spec.

But I'd get an H-buffer if you're running a carbine gas system.

[target4fun]

Thanks for the quick reply, I did end up going with the Heavy buffer.