Barrel harmonics and the "Golden" pellet

Did it have a donny on it when you tested if the new one is the same it may not change. But harmonics is a fickle mistress so you will soon find out.

the way i understand tuning in respect to harmonics is getting the pellet to leave the muzzle when the barrel is flexed the least.

this is why there can me multiple "nodes" or speeds at which the rifle groups well.

so in that respect, changing the harmonics could move that "node" a little bit, or at least i don't think it would be fair to say it couldn't.

honestly, i come from powder burners and i think the weight and design of the pellet is going to be more of a factor than a small harmonics change. if your groups open up, turn the pressure (speed) up or down if you can.

Suppressor dynamics in general introduce at least two, phenomenon that could change POI. Apologies if this is all obvious and known and I don't know how much of it will carry over into airguns from powder burners.

One, as you have already noted, is harmonics. The additional weight on the end of the barrel is going to change the direction/speed the barrel "bounces" in reaction to the pressure/projectile traveling down the bore. If you're lucky, this is repeatable and "accuracy" doesn't suffer but the projectile path will be changed so old downrange dope doesn't work anymore. If you're not lucky accuracy may be unpredictable and groups may open up downrange.

Another is turbulence and air pressure around the projectile as it travels through the bore of the suppressor once the projectile leaves the muzzle. Some of the gas under pressure behind the projectile will start to pass the projectile inside the suppressor as soon as the projectile leaves the muzzle crown and this gas isn't just free to disperse willy-nilly in the atmosphere as it used to be unsuppressed. It has to go somewhere. In powder burners we sometimes get what is referred to as "free bore boost" if there's a lot of leftover pressure exiting the barrel and sometimes projectiles will chrony slightly faster through a suppressor.

One more factor which has been mentioned is what some people call "air bounce". When the suppressor bore is maybe not quite cocentric or one or more baffles are "crooked" making the clearance between the projectile and one or more baffles so close it drags or bounces the projectile and changes the path mid flight. Not to be confused with a baffle strike. A lot of pistol suppressor with boosters have a ratchet mechanism that lets you rotate the suppressor once it's mounted. For example, rotating my suppressor on my 9mm changes the POI and it shoots to POA at one position but is 2" left and down at another position.

should have tested with the donny fl on it my donny increased my fps by about 10 to 15 fps i dont know whybut that what my fx crony said it seemed like the groups were a little better with the donny SUMO

I tested my Avenger without a moderator and selected FX 25.4s as it's best pellets although JSB heavies were also good. I later added a moderator. It might have shot a little smaller groups with the moderator but it still liked the FX 25s. I only retested a few of the others it rejected before the moderator but they still did not group well with a moderator.

So my one gun experience says it will not change which pellets your gun likes if you add a moderator or switch to a different moderator.

My experience has been that the ldc can change stuff in odd ways. I have a Compatto that the poi shifts up, all else being the same, when I go from a Sumo to a 0dB 160mm. It is repeatable. I also have a Gauntlet in .22 that with a 110mm 0dB .30 cal on it is good for about 2” at 100 yds, with the same 0dB moderator in .22 cal throws them all over the place. My .22 AA S510 has a poi shift to the right going from a Tanto to a Sumo. There is also a blog by Hector at Connecticut airguns showing the effect of harmonic tuning, it’s not about mods, but shows effect of mass, and shifting mass position on barrel.

In my experience, changing the moderator changes accuracy and group size. I have a koi on a maverick, and recently picked up a tanto to make it a little shorter. No go, the groups opened up with multiple different projectiles that are all stacked with the koi. I could try to re-tune the gun, but it's so good with the koi and slugs and pellets, I am going to leave it with the koi. I've had the same experience with the sumo and ronin. Changing what's hanging on the end, changes the harmonics, and changes what happens down range.

index the barrel first