SR25 Sector gear (16 vs 19)

[Infa]

Hello guys,

I do wonder, can i use standard 16 tooth sector gear with 19tooth piston ?. In my understanding i could because the only affect this will have (not using 19tooth sector) is that piston will not be pulled all the way back - so it will reduce FPS but then this can be adjusted with higher rating spring. Or it could even be left as is tbh. Does any one have any experience with this type of setup ?

I know that using 19 tooth sector with 16 tooth piston would not be possible as the last remaining 3 teeth on sector would be trying to pull back piston that is already at the far back (and this probably would cause stripped teeth) but the other way around should be ... ?

Thanks,

[Sitting Duck]

Re: SR25 Sector gear (16 vs 19)

Yup you can do that - providing the very last tooth on 16 tooth sector is not a fat large one
(very few "normal" sectors have a larger final tooth but I've seen a few)

What you are proposing is Short Stroking but in a v2.5 it kind of defeats the object
yes L85 owners have used a 16 tooth piston + 16 tooth sector with a 9/10mm spacer between piston & piston head
(though this was mainly used to stop L85's pre cocking that wasn't always 101% lockup free)
So that is another option - but it still is short stroking

Now short stroking is fine but you need to understand that though it mainly used to reduce risk PE in higher speed guns
it does comes with trade offs eg: reduced fps which a stronger should compensate for.....

HOWEVER - another thing is that you lose volume or a shortened piston stroke as well
So if you are using a long barrel, reduce stroke by 3 teeth or 9mm you may be under-voluming so to speak
(depending on barrel & cylinder port blah blah blah)

Realistically - you should use a 19 tooth sector to keep the volume for a longer barrel setup
Though there is a shorter A&K SR-25K which has a shorter M4 363mm barrel & crane stock
if you have a shorter SR-25k type setup then yup a 16 tooth sector or SS V2.5 gearbox will provide enough volume
(provided your piston rack is half/full metal - the piston's last release tooth - now 3 teeth back must be metal or it won't last long in use)

Numerous options but I'd try & stick to a 19 tooth v2.5 setup rather than a Short Stroked one

[Ells]

Re: SR25 Sector gear (16 vs 19)

out of interest what are you trying to achieve by running a different sector gear?

[Infa]

Re: SR25 Sector gear (16 vs 19)

Yeah thats what i though that by running normal sector i would in affect reduce my cylinder volume.

Ells - nothing in particular. I just do not have sr25 sector but plenty of standard lying around and was just wondering what are the 'cons' of running normal sector against long piston and if there are any other than reduced cylinder volume