Does opening impact probe helps?

[2fast2furious]

The hole on the probe is already bigger than pellet itself. Does making it any larger really help? Anyone who opened up their probe can you please let us know if it give more fps and by how much? 

Anyone who opened up their probe, can you post a pic of your mod?

Mod Edit: moved to PCP Airguns forum

 

[Hyperdave]

The velocity improvements vary somewhat with caliber, see the long thread on Impact mods for more fps/fpe. I would only do these kinds of porting mods if you are comfortable with precision metal grinding/shaping and really want to get that last little bit out of your rifle. The Impact pellet probe mod is really done as a companion to the porting mod of the transfer port in the barrel breech (see long thread on Impact Mods for more FPS for details). If you have re-shaped the roof of the transfer port (elongated the round TP hole forward and tapered in), the top of the pellet probe is then in the way of the air flow, so you will see photos where the top portion of the pellet probe is carefully reduced to match up with the re-shaped barrel transfer port.

There is the drawback of removing too much material and having the pellets get out of alignment with the breech as they are loaded and creating a pellet jamb, or at least a noticeable drag during loading. Both the transfer port section of the barrel and the pellet probe are readily replaceable parts, but you have to ask yourself whether the risk of ruining these parts is worth a 2-5% velocity improvement.

 

[Fire_at_will]

This is a gun I am setting up right now. 22 cal 700mm shooting 30grn slugs at 928fps. Before this mod, it maxed out at 890. But this will vary with caliber and slug weight.

First picture is the transfer port after mod.

Second picture is factory probe vs mod probe.

Third pic is probe in breech, make sure hole in probe is a little larger than transfer port.

 

[Glem.Chally]

Yes helps.

 

[heavy-impact]

This is a gun I am setting up right now. 22 cal 700mm shooting 30grn slugs at 928fps. Before this mod, it maxed out at 890. But this will vary with caliber and slug weight.

First picture is the transfer port after mod.

Second picture is factory probe vs mod probe.

Third pic is probe in breech, make sure hole in probe is a little larger than transfer port.

A 7mm port feeds the brass port so it will do better if you flare the brass to match.

 

[2fast2furious]

This is a gun I am setting up right now. 22 cal 700mm shooting 30grn slugs at 928fps. Before this mod, it maxed out at 890. But this will vary with caliber and slug weight.

First picture is the transfer port after mod.

Second picture is factory probe vs mod probe.

Third pic is probe in breech, make sure hole in probe is a little larger than transfer port.

A 7mm port feeds the brass port so it will do better if you flare the brass to match.

What's the benefit of cutting away the opposite side like that? Does air flow better that way instead of just larging the original probe hole?

 

[Fire_at_will]

I'm not saying my way is the best, or it gives max fps. Its just what gives me good reliable results, and is how I will continue to do it.

 

[heavy-impact]

What's the benefit of cutting away the opposite side like that? Does air flow better that way instead of just larging the original probe hole?

It flows better and you make the probe hole larger than the port. Pellets and slugs still feed the same.