.25 rebarrel to .30 what to expect?

[Vmaxpro]

Is there a rough guestimate? If Im making 70ftlbs in .25, is there a general guide? Say 90ftlbs?

[rsterne]

It depends on a lot of factors.... but the most you can expect, on a maximum power shot, is 44% more FPE, but that would only apply if both guns had maximum, bore diameter porting, and enough dwell that the valve was open until the pellet left the muzzle.... If your porting is not changed, then more likely a 20% increase (0.30 / 0.25) is more realistic.... say from 70 FPE to 84 FPE.... maybe a bit more....

Bob

[YEMX]

On the nose Bob...  As always! 

Read through this post Vmax- it should answer a lot of questions you have.  Lloyd did a very in depth and progressive .30 build to find out exactly what you're wondering.  Lloyd wanted to see "how low you could go"- i.e. what was the minimum required to get a usable, least expensive, easiest to modify .30 Mrod.  Ultimately, he went the route of Cothran (SS would be another option) valve and regulated the gun.  It might not be the route you want to go, but good read nonetheless.

[Frank in Fairfield]

More expensive pellets

[YEMX]

I forgot to link the post 

Here it is:

https://www.gatewaytoairguns.org/GTA/index.php?topic=118225.0

[Vmaxpro]

Great read! Thank you guys. At this point, it doesnt even seem worth it. Looks like its time for a new gun