Tuning NSA 29.5 and modified avenger

[357cal]

Below is the chrono's numbers before the added Wayne Reid 16.5 cc plenum and 29 gr NSA slugs. Very soon going to see what i can get out of the 29.5 nsa's. looking to get 940-1200 fps. What had been done-Opened up the barrel and transfer port 13/64. Polished the barrel at this point.

 

[davhowrd]

Hey 357Cal,
Nice Rig. I see that you're on your way down the rabbit hole of madness. Good Luck, I know a good DR. that can help. LOL

 

[nervoustrig]

How is it grouping them? Just curious how the .25 cal barrel is doing...I tried a few different slugs and the FX Hybrids in my .22 cal and none showed any promise. Not even the slightest hint of wanting to group. It's amazing with the JSB Monster Redesigns however.

Very soon going to see what i can get out of the 29.5 nsa's. looking to get 940-1200 fps.

58 - 94fpe. The top end of the range is a pretty ambitious goal. Full bore porting can be achieved by elongating the current 0.203" barrel port to an oval 0.286" long, provided the valve has enough meat to be modified to match it.

Attaching a copy of my porting spreadsheet in case it would be useful for planning. Screenshot:

View attachment porting worksheet.zip

Diagram to clarify terms:

 

[357cal]

Today I just wanted to see how the NSA 29.5 gr slugs with a flat base preformed, Reg pressure-36-3700 psi and hammer-all the way in and 1/4 turn backed off. The thing that came to mined when I saw fps is, dished based,, i got more speed. zeroed scope at 70 yards. next get the chono's out again and see if i can get more speed. At the end of the day just wanted to make sure i was zeroed for 70 yards, here's 2 shots at 70.. 1 inch target. I was shooting from LEAD SLED shooting rest. 1st shot thru 4th i was turning up the reg from 2400psi

 

[elbeau]

How's the testing going? I've got a .25 Avenger as well.

 

[elbeau]

@nervoustrig Thank you for sharing your sheet. I just downloaded it to check out. Do you have any good resources you recommend about the "boring rules of thumb?"

 

[Glem.Chally]

Today I just wanted to see how the NSA 29.5 gr slugs with a flat base preformed, Reg pressure-36-3700 psi and hammer-all the way in and 1/4 turn backed off. The thing that came to mined when I saw fps is, dished based,, i got more speed. zeroed scope at 70 yards. next get the chono's out again and see if i can get more speed. At the end of the day just wanted to make sure i was zeroed for 70 yards, here's 2 shots at 70.. 1 inch target. I was shooting from LEAD SLED shooting rest. 1st shot thru 4th i was turning up the reg from 2400psi

View attachment 278188View attachment 278192

Is this after the new plenum? Looks promising.