Slug in a break barrel

There are sorts of weight slugs out and I had no issue trying some out of my Beeman RX2 which shot them pretty nicely but only out to about 30 yds if I recall. It has nothing to do with break barrel just need enough power to push them out, they make slugs as light as 10gr in .177

Yes that is what I’ve heard too- that 700 and under FPS doesn’t work well unless the profile is less long and the weight less as well, but then you are kind of in a hybrid area between pellet size and slug size. Slugs don’t expand below 815-880fps too, so there is that too. It would probably be neat to shoot them out of a 18-20+FPS springer 
 
Hatsan 125 specs

.177 – 1,550 FPS
.22 – 1,250 FPS
.25 – 900 FPS,

Hatsan 135 specs
.177 – 1,550 FPS
.22 – 1,250 FPS
.25 – 900 FPS

these are factory specs with lead free pellets. below is with lead pellets. Hatsan tests its rifles with lead pellets and their stated fps is very close. 

.177 – 1,300 FPS
.22 – 1,000 FPS
.25 – 850 FPS

I have always been surprised when their guns perform close to and sometimes above their stated fps even before working on them.

The slugs I've used are 

26.8 Grain, .25

17.5 Grain .22
1598070303_5416543995f409e1f4cb394.08480508.jpg
1598070328_2681688455f409e387d2728.01794376.jpg

 
There are sorts of weight slugs out and I had no issue trying some out of my Beeman RX2 which shot them pretty nicely but only out to about 30 yds if I recall. It has nothing to do with break barrel just need enough power to push them out, they make slugs as light as 10gr in .177

Slugs don’t expand below 815-880fps too, so there is that too. It would probably be neat to shoot them out of a 18-20+FPS springer

A 15.5g NSA slug in. 177 absolutely expands, fully, at 55yds starting at 720fps at the barrel.
 
I know what I've seen at my rubber mat backstop at 60yds, and a few squirrel's around 30yds that contained the round. So not all that impossible, really quite predictable.

Oh nice. Thanks John_in_Ma. I read a few times about expansion with slugs being only in the 800s, but that was really before this craze or movement has taken over. That is good to know. I bet it depends a lot on the HP design and how soft the lead is. Always amazes me his soft a JSB pellet is, you drop it and it is toast. I wish a lot of my HPs had as soft as lead as JSBs.