aa_limited,
Since it is a dead calm day here, I'd be happy to answer that for you, and give you a few more hints on the poly barrel from RAW. I've been off working on another accuracy experiment with my gun, so it wasn't sighted in for "normal" pellets at 25 meters. I had to start from scratch with sighting back in JSB 13.4s on target #3. By the initial POI (highest) with my first 13.4, you ought to be able to guess what I was playing with
I walked the 13.4s back down into the center of the target then shot 10 JSB 13.4s on #4. I added 1/8 MOA up then shot 10 13.4s on #5. I then added another 1/8 MOA up figuring I would be back on center.
Big hint #1 : I was not sorting pellets for this. These were pulled straight from the tin and just lubed. No weight sorting and no head size sorting up front. I know I could coax better accuracy out of the 10.3s, 8.4s, and 7s with a sort. I had the AZ air stripper / flip compensator on the gun for this test as it is more accurate than my moderator or naked barrel.
I started on the right of the paper on target #10 with 10 JSB 13.4s. They all went through the same hole (like 4 and 5). Big hint #2 is on the right of the target (my fps). I then moved to #9 and shot 10 JSB 10.3's, #8 is 10 AA 10.3s, #7 is 10 JSB 8.4s, #6 is 10 JSB 7.8s, #11 is 10 JSB 7.3s.
Big hint #3 is the 13's aren't the most accurate because of their weight. They are the most accurate because of their average
head size which is .453 on average.
I am shooting the 13.4s in my poly at just under 18 fpe to get those single pellet hole groups. I did not adjust the power up or down for the other pellets. My rifle is shooting an extreme spread of 5fps over 10 shots, so you are seeing the speed, poi, and group size changes as a result of the head size and weight. The 7.8's shot really well, but they had an advantage over the other pellets - and you should be able to tell what that is. I'm betting I could get a single pellet hole out of 10 shots of the 7.8s - just like the 13.4s - by slowing them down. I'm guessing the 10 7.3s were a bit more open than the 7.8s due to speed. They should have shot closer to the 7.8s.
So now, I've told you my barrel length, lube, fps, what works best on end of barrel, and given you a really big hint (basically the answer) on the final piece to get serious accuracy from the RAW poly with other pellets. I'll take a +1 on accuracy for all that homework and sharing the info.
I'll give anyone a +1 if you are the first to tell everyone why the 8.7s shot the worst from my barrel. Another +1 if someone gives me the exact number
To answer about the barracudas, don't bother if you are chasing best accuracy from this barrel. I pitched my tin.