Playing with slugs?

I’ve recently been introduced to slugs and all the joys that they can bring.
As well as the frustrations of trying to get them to go where you point them and group tightly.
So I have been researching as much as I can, trying to learn from the experts and get a better understanding of these bewitching lumps of lead.

My current understanding of slugs is that:
1- They like to go fast. Very fast.
2– Different length barrels supposedly like different weight slugs. Shorter barrel = lighter slug.
3- Shorter barrels prefer sudden bursts of higher pressure air, where as longer barrels can get away with lower pressured longer bursts of air.

The barrel I have been playing with is 500mm long, and barrels of this length supposedly like slugs of 20gr to 25gr (in .22 cal).
The reg is set at 125 bar, which is probably too low for a short barrell.
I also think I’m not pushing them fast enough. Ive got a 30gr slug moving at about 750fps.

I’ve tried slugs in 24gr, 25gr, 26gr, 28gr, 30gr and 35gr, from a mix of 3 different manufacturers, with varying degrees of success.
Had a nice group from Javlin 26grainers, but I have yet to even get close to that elusive “one ragged hole” at 40m.

Then while working through another batch of testing today at 25m, I shot a pretty decent 3 shot group, with a “slow” 30gr slug… 🫢😳

So there go all my theories out the window, and I’ll continue with further testing of this 30grainer Spyda slug..
The first 3 shots were beautiful, man I got excited! And then the 4th one went and really …… the pooch.
Should have stopped at 3!

Anyone else have any experience with getting slugs to perform, and any pearls of wisdom you may care to share…?

I have dabbled ever so slightly.

Is that on a Dreamline? Does it have the extra plenum? This makes it easier to produce that extra power.

Here’s an update on my slug testing…
Spent an hour or two fiddeling around this evening with the 30gr spyda slugs.
Goal no. 1 is to get them grouping tightly, as tight as possible. I don’t care what speed they are doing, as long as they group tightly.
Goal no. 2 is once the slugs have been tuned to perfection, find an easy to set tune for the JSB hades 15.89gr pellets.

I felt the slugs were going too slow out of my 500mm barrel. Reg was set at 125bar, so I slowly turned it up to 150bar for a little more Oomph! They recommend not going past 150bar.
Unfortunately I couldn’t get my chrony to work indoors under the led lights, so I have no idea what speed they are doing out of my 500mm barrel.
I’ve heard that short barrels need a short hare blast of air to get slugs moving, where as a long barrell can use a slower, more gently push of air (and probably get higher speeds too!)
So I set the transfer port to 25/30, which I’m assuming is the largest aperture and will allow the most air into the barrel for a short hard burst of air.
Once I had the reg at 150 bar and the transfer port wide open I started testing different hammer spring settings with 3 shot groups. I got the best results with hammer spring at 5.5 and MAX.
Best group was a 9mm ctc 5 shot group at 25m. See pic. Unfortunately I don’t know how fast they are going.

Tomorrow I will test the transfer port on .177/.22 setting with the various hammer spring settings. I don’t think it will be better then today, but u never know, I might just stumble apon a setting that gives one hole groups 😉
Then re zero the scopes for these new slugs and take it out for some rabbits.

To achieve goal no. 2, I will keep the reg set at 150bar, and try the hades pellets with the transfer port on both the .177/.22 and the LOW settings. Hopefully somewhere in all of that I’ll find a tune that the hades like, and with a bit of luck it will be around the 850fps area.

While setting the reg pressure today (I was using hades pellets for that because they cheaper then the slugs) I happened to stumble across a high power pellet tune that gave a 3 shot, one hole group at 25m. I don’t know what speed they are doing, but with one hole, I’ll take it! I took note of the settings and will come back on it when I get to doing the pellet tunes.

Paul I was just using the 16 clicks on the hammer spring dial. The “micro” Allen key adjuster is maxed out and I left it there for now.

This evening I tried a few more “tunes”. With the reg still set at 150 bar, I tried the transfer port on the .177/.22 setting and went through a few of the hammer spring settings.
Logically the transfer port should be set at .25/.30 to get the most air through for the biggest push to get the 30gr slugs going as fast as possible out of a 500mm barrel, but I though while I’m into all this testing and tuning let me just see…
And what do u know… at 150bar, TP at .177/.22, and hammer spring at max, a pretty tight 5 shot group at 25m.