New barrel lowered power?

[accused]

I just fitted a brand new barrel on my HW80 and noticed a big drop in power, do they need an amount of pellets through to bed in?

[angrybear]

Did you clean any protective grease from the bore ?
Is it the same length & the same calibre ?
Have you tested different pellets as your previous brand simply may not be as efficient in this barrel, they may be too tight or too loose.

[PCPShooter]

And apart from above - breach seal fit

[accused]

It had a .22 barrel and I fitted a .25 today, in .22 it made 11.7, in .25 first shot was 7.5 now settled at just over 10ftlb. I expected the exact opposite, mk1 HW80 HN FTT in both sizes. Both breech seals are new.

[BC312]

Normally if you had a .177 air gun and swapped the barrel to .22 the power would increase. I swapped my barrel over years ago on a HW 80 from .22 to .25 and to .30 but found i had the same problem as you.

[angrybear]

Standard, 'try other pellets' reply
They cost a bit, but JSB lead free at 16.4gn are 'interesting' pinpoint accurate in my scorpion se, but too hard for hunting/vermin, they go straight through with zero expansion.

I've actually dug them out of the sandbags and shot them a second & even third time, although third time they were markedly less accurate.

[luap]

i did the same on a 95 .20 to .25 big power drop i thought it was because i had a short stroke piston

[evert]

The .25 is rumoured to be less efficient than the .22

[Shed tuner]

The .25 is rumoured to be less efficient than the .22

yes..and no...
it's more efficient if you have enough volume to maintain pressure.. but the big bore .25 causes big pressure drops as the pellet moves down the barrel, due to it size.

this is why hw80s shoot nice in 25 at 12 fp.. they dont piston bounce half as much, and the spring can be upped, speeding up shot cycle.

short stroke noses are a bad idea for .25, or any low swept volume guns.

you lost 1.7 fp, sounds about right. also using hn ftt in both doesn't mean its a good comparison.. they may be brilliant in .22 for your .22 barrel, but crap for the .25 barrel.

so in summary, try a few other pellets, but its much as expected. and remove a short stroke nose if you have one.

[accused]

Thanks for the replies, yes I assumed power would increase. I have lots of springs to try if it stays below 11 but I think definitely a good idea to try a few pellets. The new barrel is a K so about 50mm shorter.

[ian321]

Thanks for the replies, yes I assumed power would increase. I have lots of springs to try if it stays below 11 but I think definitely a good idea to try a few pellets. The new barrel is a K so about 50mm shorter.

That’s the difference, you need more energy for a shorter barrel. That’s why carbine pcp’s produce less shots per charge

[Murphy]

Every time I read a .25 thread I always think I would love a .25 HW80.

Then I remember I have all the bits to make one but I’m lazy.

[simona]

Different barrels often give different power. I have 4 different 0.177 barrels machined for my Steyr rifles. If I set the gun to 780 fps with 8.4s with the quickest barley twist barrel then the FWB barrel makes about 750 and a standard factory barrel makes 700 fps. That's with the same pellets and not touching anything else. For the record the barley twist barrels are slightly shorter than the others.

I just changed from a 0.177 hw98 barrel to a 0.177 hw95 barrel and gained 30 fps with the same pellets. Same length.

[Mr. Gen]

light lead free pellets are the quick answer to get the power up in .25

[angrybear]

The .25 is rumoured to be less efficient than the .22

So how come .25 gets more shots per fill in a PCP, That would indicate it's more efficient not less

The issue is that he has the same amount of air energy trying to accelerate a heavier pellet so it takes longer to achieve max velocity,
having switched to a shorter 'K' barrel he's lost the final bit of push, a 'K' barrel in .22 would also have lost power.