.25 Hybrid speed from Impact Power Plenum.

[DShepard]

I was shooting MKIIs at 960 fps from the pellet liner. I tried ten Hybrids for fun, and they were at about 1060 fps, with very close spread. After installing the .25/700 Superior liner, velocity dropped by about 40 fps for the MKIIs and the Hybrids. After attempting to retune to previous speeds, the best I could do was 950's for the MKIIs and 1040 for the Hybrids. This is as high as I could go. Hammerspring is maxed, reg is at 145 bar, valve adjuster is fully open. If I raise the reg, velocity actually drops.

I'm wondering what other people are getting for max velocities with the .25/700mm Superior liner? It seems that the Superior must be a little tighter than the pellet liner to slow things down like that. 

My Impact was ordered 1/8/20, setup on 1/10/20 by Utah Airguns. It should have the original longer hammer spring, not the shorter one the later Power Plenums come with. I'm not sure why I can't go over 145 bar on the reg, I know people are going higher than that. Any thoughts welcome. Thanks. 

 

[Diaz]

I was shooting MKIIs at 960 fps from the pellet liner. I tried ten Hybrids for fun, and they were at about 1060 fps, with very close spread. After installing the .25/700 Superior liner, velocity dropped by about 40 fps for the MKIIs and the Hybrids. After attempting to retune to previous speeds, the best I could do was 950's for the MKIIs and 1040 for the Hybrids. This is as high as I could go. Hammerspring is maxed, reg is at 145 bar, valve adjuster is fully open. If I raise the reg, velocity actually drops.

I'm wondering what other people are getting for max velocities with the .25/700mm Superior liner? It seems that the Superior must be a little tighter than the pellet liner to slow things down like that. 

My Impact was ordered 1/8/20, setup on 1/10/20 by Utah Airguns. It should have the original longer hammer spring, not the shorter one the later Power Plenums come with. I'm not sure why I can't go over 145 bar on the reg, I know people are going higher than that. Any thoughts welcome. Thanks.

Yes, you are right .... I have the MK II power plenum cal.25 liner Superior Heavy 600mm and I also see that difference with the previous STX Pellets ...... these new liner are very strangled (Choke) I have passed a Slug pushing with difficulty through the liner and these come out very marked from the grooving ...... for the moment after doing many tests at different speeds etc. The result is: King Heavy MKII .............1 NSA 33.5GR .............. 0

 

[nielsenammo]

I was shooting MKIIs at 960 fps from the pellet liner. I tried ten Hybrids for fun, and they were at about 1060 fps, with very close spread. After installing the .25/700 Superior liner, velocity dropped by about 40 fps for the MKIIs and the Hybrids. After attempting to retune to previous speeds, the best I could do was 950's for the MKIIs and 1040 for the Hybrids. This is as high as I could go. Hammerspring is maxed, reg is at 145 bar, valve adjuster is fully open. If I raise the reg, velocity actually drops.

I'm wondering what other people are getting for max velocities with the .25/700mm Superior liner? It seems that the Superior must be a little tighter than the pellet liner to slow things down like that. 

My Impact was ordered 1/8/20, setup on 1/10/20 by Utah Airguns. It should have the original longer hammer spring, not the shorter one the later Power Plenums come with. I'm not sure why I can't go over 145 bar on the reg, I know people are going higher than that. Any thoughts welcome. Thanks.

Yes, you are right .... I have the MK II power plenum cal.25 liner Superior Heavy 600mm and I also see that difference with the previous STX Pellets ...... these new liner are very strangled (Choke) I have passed a Slug pushing with difficulty through the liner and these come out very marked from the grooving ...... for the moment after doing many tests at different speeds etc. The result is: King Heavy MKII .............1 NSA 33.5GR .............. 0



if you are using superior liner you will need to switch switch to NSA 29.5 grain which are smaller diameter than the 33.5

 

[triggertreat]

Have you tried lubing the slugs/pellets? Especially with more barrel contact with the NSA's, or a tighter barrel, this may help.

 

[DShepard]

I haven't tried lubing, but it was my intention to do so, even if just for reduced fouling purposes. 

I've heard that both 29.5 and 33.5s work well in the Superior liner. Will it just be a velocity loss using the larger diameter 33.5s? I'll be ordering a bunch to try soon. Thanks. 

 

[Diaz]

I was shooting MKIIs at 960 fps from the pellet liner. I tried ten Hybrids for fun, and they were at about 1060 fps, with very close spread. After installing the .25/700 Superior liner, velocity dropped by about 40 fps for the MKIIs and the Hybrids. After attempting to retune to previous speeds, the best I could do was 950's for the MKIIs and 1040 for the Hybrids. This is as high as I could go. Hammerspring is maxed, reg is at 145 bar, valve adjuster is fully open. If I raise the reg, velocity actually drops.

I'm wondering what other people are getting for max velocities with the .25/700mm Superior liner? It seems that the Superior must be a little tighter than the pellet liner to slow things down like that. 

My Impact was ordered 1/8/20, setup on 1/10/20 by Utah Airguns. It should have the original longer hammer spring, not the shorter one the later Power Plenums come with. I'm not sure why I can't go over 145 bar on the reg, I know people are going higher than that. Any thoughts welcome. Thanks.

Yes, you are right .... I have the MK II power plenum cal.25 liner Superior Heavy 600mm and I also see that difference with the previous STX Pellets ...... these new liner are very strangled (Choke) I have passed a Slug pushing with difficulty through the liner and these come out very marked from the grooving ...... for the moment after doing many tests at different speeds etc. The result is: King Heavy MKII .............1 NSA 33.5GR .............. 0



if you are using superior liner you will need to switch switch to NSA 29.5 grain which are smaller diameter than the 33.5

I have tested the NSA 29.5gr at different settings and very badly.

 

[Diaz]

Have you tried lubing the slugs/pellets? Especially with more barrel contact with the NSA's, or a tighter barrel, this may help.

I have also lubricated with the same result NSA 33.5gr at 90yards

 

[Hotbrass]

I shoot JSB 33.95 Mk2s and NSA 29.5s from my .25/700 Impact PP. Shot a ground squirrel at 192 yards with the NSA 29.5`s. I am using the Slug liner, not Superior liner.

Not happy with the velocity loss. More data is needed for the difference in performance/accuracy between the Slug liner and Superior liner.

Ted, are you listening?

 

[Diaz]

I shoot JSB 33.95 Mk2s and NSA 29.5s from my .25/700 Impact PP. Shot a ground squirrel at 192 yards with the NSA 29.5`s. I am using the Slug liner, not Superior liner.

Not happy with the velocity loss. More data is needed for the difference in performance/accuracy between the Slug liner and Superior liner.

Ted, are you listening?

I do not know what happens with this new liner Superior Heavy ..... I have tried all the possible configurations and I cannot get it to work at the moment the NSA slug ...... The Hybrids behave regularly to good, the King Heavy MK II very well. In short, I bought a new liner to shoot slug no pellets.

King Heavy at 100yards

Hibrido at 100yards

NSA 33.5gr at 100yars

 

[triggertreat]

I like sizing the slugs to fit the barrels. I even size my pellets (MKIIs) for best speed and groups. Just get slugs that don't require much size reduction for best results.

Here are the results with sizing some MKIIs and finding the best speed for them in a 600mm STX barrel (the most winning barrel to date, or was it the ST barrel?).