FX Hybrid Blowby?

[jbravo103]

I’ve been trying some different pellets in my 0.22 cal Impact lately since upgrading to the MKII plenum (not power plenum) and Huma dual transfer port with matching probe.

I was slinging H&N Barracuda’s at 960 fps out of a STX liner (not superior). These are 21.14 grain pellets. Just for fun, I wanted to try the FX Hybrid slug (22 grain). With the H&N’s going 960 fps, I thought the Hybrids should be doing around 940 fps. Nope. They were only going 890 fps. I suspect that not all of the air is getting behind the slug and some is “blowing by” it. Has anyone else experienced this?

 

[Guest]

Pretty much, the skirt of the pellet is wide and is made to be shaped by the barrel. So yes it will seal better, so that's why your fps with the pellet is higher even though its heavier. 

 

[bandg]

I’ve been trying some different pellets in my 0.22 cal Impact lately since upgrading to the MKII plenum (not power plenum) and Huma dual transfer port with matching probe.

I was slinging H&N Barracuda’s at 960 fps out of a STX liner (not superior). These are 21.14 grain pellets. Just for fun, I wanted to try the FX Hybrid slug (22 grain). With the H&N’s going 960 fps, I thought the Hybrids should be doing around 940 fps. Nope. They were only going 890 fps. I suspect that not all of the air is getting behind the slug and some is “blowing by” it. Has anyone else experienced this?

Is it blowby? Is it bearing area? Is that weight difference enough to cause the drop in velocity?

 

[jbravo103]

I doubt the weight difference (0.9 grains) is enough to drop 70 fps. Likely either blow-by or slug is too tight in the liner causing increased drag. I’m going to pull my liner and push one through by hand and push a pellet by hand to see if there is a noticeable difference.

 

[oledawg]

Pretty much, the skirt of the pellet is wide and is made to be shaped by the barrel. So yes it will seal better, so that's why your fps with the pellet is higher even though its heavier.

I think that is one of the reasons NSA makes multiple sizes of slugs, so you can find a slug that works for your barrel. IMO

 

[SDellinger]

Does the hybrid have more bearing surface? Maybe more resistance.

 

[Vetmx]

My 25gr pellets were going 915 my Hybrids were 885fps. Moved the pellets up to 950 and the slugs are now 930fps. This is with a superior barrel 600mm. The key that may be eluding you is I lube my slugs. I bet you don’t. 

 

[Kevin23]

Was just chronoing my buddy's gun yesterday. He was shooting nsa 17.5 at 970, h&n 22 at ~910, avs 22gr at ~910, and then fx hybrids were 810. 

 

[jbravo103]

Update 12/27/20

I manually pushed a JSB 18.13 and a FX Hybrid 22.0 grain through my pellet liner A . I took measurements of each projectile before and after.

Before:

• JSB - 0.2175"
• Hybrid - 0.2175"

After:

• JSB - .2145
• Hybrid - .215

The pellet was fairly easy to push through the liner with slightly more effort required near the bore end, likely due to the choke. Both the head and skirt had material "shaved" off, creating shiny spots. The land marks were slightly noticeable, but not pronounced. Next, I pushed the Hybrid slug into the breech end. It got about 1.5-2 inches into the liner and jammed. I had to put substantial force on my push rod to make it budge then it went through remainder of liner fairly easy until I got to the bore end. At the bore end the slug jammed really tight and I had to point the liner up and slam the ram rod on the floor to push the slug through.

My conclusion is that these Hybrids are too large in diameter for my liner. My velocity suffers because of how tight the slugs are in the liner, not because of air blowing by the slug. This explains why the Hybrids are shooting much slower than pellets of similar weight. I could try a superior liner to see if maybe that is a little better, or switch to NSA's at .216 or .2165 diameter.

 

[Vetmx]

I’ll post an update too since I have shot 400 of them over the last week. This is for .25 Hybrids shot out of a 600mm superior. The difference between the 26gr slug vs a 25.3gr pellet is 30fps.