From .25 to .30 upgrade w/same internals - estimate potential power?

[Rdsail]

Shorty,

I would not consider change my mrod to .30 when it was shooting at 45 even 50 fpe.  I think at that power level the pellet moves too slow for my liking. It would not be worth it to me. But if the post was about heavily modifying a mrod that would be a different story. I think at that power level the pellet moves too slow for my liking.

[rsterne]

Can an MRod be made into a good .30 cal?.... probably, maybe even a great one, if you use a custom valve?.... Will you be happy with a 45 FPE one converted to .30 cal without changes, as requested by the OP?.... Not in my opinion.... I suggested what power levels might be available without major changes, you have a different opinion.... However, until you do it, it's just an opinion, so please don't call it a fact, that is misleading....

If you took the time to read my detailed response on what the OP could expect, I gave him 3 different power levels, with 3 different levels of modding, from 57-94 FPE.... If you think that is trying to "discourage" him, then so be it, I was just trying to answer his question as honestly and completely as I could, not just say "go for it, 100 FPE is easy".... cause it ain't.... If it was "easy", your .357 would be there already....

The stock MRod valve is severely limited in what you can do to it by the diameter of the exhaust port, and it's proximity to the back inside wall of the valve.... If you're happy with a 90 FPE .357 cal, then more power to you, but I wouldn't consider it a successful conversion until you doubled that.... Lobbing pellets downrange at 700 fps just isn't my bag, nor would I recommend it to anyone....

Bob

[Rdsail]

I completely agree with Bob.

[oldpro]

 EXACTLY what BOB said. You will need to get that .30 cal pellet to 880-900 fps for it to be stable and accurate(jsb exact 44.75) and thats no guess thats a fact based on over a year of testing so that means no less than 75fpe but the sweet spot is from 80-90fpe with said .30 cal pellet and if your shooting bullets you better raise that to 100fpe to get the full effect of stability from barrel twist and bullet  coef.

[crosman999]

Just buy a FLEX .30 and the job is done! Lol

[shorty]

I am satisfied that I got 90fpe with an Mrod valve and 16.5" barrel. That's pretty good for a first time around for a big bore attempt "with that platform-and barrel length". Double that, most likely not going to happen without alot of help.
Don't think I am not trying to hit 120+. I just picked up a 21" barrel and increasing the hammer to 120 grams along with porting to .2". I just can't stop running chairgun to see if 800fps is so much different than 700 fps in regards to retained energy and accuracy. It's only a 50 yard gun.

As for the 30 cal Mrod conversion. Here is one of the last posts on strings:
847   2800
841   2600
   
937   2400
928   2300
803   2200
793   2100
780   2000

(Rdsail- this might be an avenue for you to hit 150 fpe at a respectable 850/900 fps) at or below transonic speed for best accuracy.

Since tefloncoated ported already we have no idea what his max fpe/fps is. if I/we had to guess he can push the 25.39 to 70 fpe with the .156" porting on the 25.39-25 cal. With a 41% "or so" increase in cross sectional area from .25 to .30, increases the the "potential" power (fpe) to approximately 98 fpe using a proportional hammer weight/stroke/spring force.

Easy, heck yes. Buy the barrel and bolt, melt some lead and form it to the hammer, replace the HT with a set screw, and get a 12lb spring. If you want more, drill out the valve exit port to .19" or .2", make or get a polymer transfer port at .19" or .2" and drill the barrel port to .19" or .2". Run a 60+ grain bullet/pellet and your over 100 fpe all with a hand drill and your favorite hardware store.
Easier than that, buy a WAR valve, and port the barrel. Done....

Why it's not easy for me, cause I am cheap,I work 10 hrs a day, have 2 kids, a wife that "completely does not understand" the obsession. And Lastly, when I was posting about what I was doing for my .357/9mm Mrod build, the guys that know their stuff pretty much said it was a waste of time and you will not get the numbers up to their expectations. There was absolutely no advice on how to achieve the goal. I do thank QV Tom though for my "safety"manufacturing techniques. Thank you.

I sure had alot of "maybe a 30 would be better or .257"along with Travis saying "give me a call".

For what it's worth, Travis was the only big bore tuner/builder to entertain my build by asking me to give him a call to discuss. Believe me, I still have only one call and I am going to choose it wisely.

Thanks Travis.....

[rsterne]

937 fps with 45 gr. roundball - 88 FPE, and that string only has 3 shots within a 4% ES.... and the gun was significantly modified from what the OP has.... Thanks for making my point....

Bob

[shorty]

Bob,
Your welcome.

You have no idea what that guy wanted now since you discouraged him not to do it.

From 65 fpe to 88 fpe is an increased fpe of over 35% of his existing gun without the help of us.

How many +70 fpe Mrods do you read about ? There's not many of us.

I would also like to add that "and you know too" that 30 cal has much heavier than 45 round balls that seal the barrel better and make much more energy than what your trying to point out at greater velocities than 800 fps.

Bob,
It's been a great discussion with you. I think all that is reading the post should have a nay and say. There's no right or wrong but the thinking has been done.

[WHITEFANG]

Love the reading of the MAD modders. So much tallet over here for a bunch of KIDS. ROTFL
THANKS ALL for swaying me over to the DARKSIDE😈😉

FANG
JUNKYARD AIRGUN'S

[Dick Tracey]

oops wrong post.

DT