What are some over sized .25 pellets? For loose bore .25

I have a hatsan 125 in .25 with a over sized bore. My tuner says it's losing velocity because of how wide the barrel hole is. Do you have any pellet recommendations for this. I want a wider diameter skirt not the head. Hatsan will not replace the barrel. Apparently this is a big issue with hatsans. I've had the gun for 4 years and I like it. Just looking for some ammo to get full potential of power and accuracy with the gun. It's accurate it's just losing about 80fps because of the bore diameter. domed and pointed pellets are my ideal type of pellet but I won't be picky if someone can provide a good pellet.
 
What have you tried? I go overboard so don't think anything I may say is the only way, it's just A way.

I'd slug the bore without pushing thru the choke, id also slug the bore and push the the choke and compare the diameters.

If there's not a pellet diameter that just rides the majority of the rifling before the choke, id try and find a pellet with a thin skirt that would blow out and impress it's self into the rifling on the shot. After you post what you've tried, I will see if i can offer any other thoughts.

There's some nuclear options but I wouldn't go there with a Hatsan or mendoza. I've been down the mendoza path.
 
As far as I'm concerned hatsan should replace the whole gun! I know it's been 4 years but was an issue from the beginning. Luck of the draw with those Turkish and Chinese barrels. What pellets are shooting now?
I'm personally shooting h&n. I don't have a chrony. But the tuner is shooting airarms 25grain pellets and having issues with full engagement of the rifling. I'm trying to figure out what I want to do before the tuner sends it back.
 
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What have you tried? I go overboard so don't think anything I may say is the only way, it's just A way.

I'd slug the bore without pushing thru the choke, id also slug the bore and push the the choke and compare the diameters.

If there's not a pellet diameter that just rides the majority of the rifling before the choke, id try and find a pellet with a thin skirt that would blow out and impress it's self into the rifling on the shot. After you post what you've tried, I will see if i can offer any other thoughts.

There's some nuclear options but I wouldn't go there with a Hatsan or mendoza. I've been down the mendoza path.
I don't have a chrony to test. I need to get one. But my tuner has tried air arms 25 grain .25 pellets and I'm not exactly sure how good those are. I've never used them. I use the H&N 30 grain pointed pellets and had good accuracy from them. But no chrony and no tools to check engagement of rifling with pellet.
 
A few years ago when I was shooting a Sumatra 25 caliber I tried Eujin pellets
I never measured them, but can tell you that the fit tightly both in the magazines and the barrel
Hard to find these days, I expect
But there is an eBay vendor that has them.
Other vendors may also
Check out the weight and ask your tuner if they are too heavy for your Turkish Delight

just my 2 stents
Edward

 
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I don't have a chrony to test. I need to get one. But my tuner has tried air arms 25 grain .25 pellets and I'm not exactly sure how good those are. I've never used them. I use the H&N 30 grain pointed pellets and had good accuracy from them. But no chrony and no tools to check engagement of rifling with pellet.
You have to try jsb kings imho . 25 grains and I haven't found a 25 cal that didn't love them.... Yet. The skirts should blow out and seal for you. You could likely gain some of your velocity back by washing and lightly silicone lubing your pellets, and shooting a few felt cleaning pellets thru the gun with some oil on the fist couple weekly.

When you started this thread I finally looked up your gun and realized it's a springer. Make sure that piston is lubed properly and not overly so.... Too much lube causes drag and damaging dieseling if it can burn.
 
A few years ago when I was shooting a Sumatra 25 caliber I tried Eujin pellets
I never measured them, but can tell you that the fit tightly both in the magazines and the barrel
Hard to find these days, I expect
But there is an eBay vendor that has them.
Other vendors may also
Check out the weight and ask your tuner if they are too heavy for your Turkish Delight

just my 2 stents
Edward

I have 2 old tins left 45s and 30 somethings from 15 years ago, before I knew the limitations of a marauder.