The spring guide should be snug to tight in the spring. It gets loose when the spring is cocked. Shaving weight off the tophat can reduce the recoil making a smoother shot cycle but will also reduce your power as you have less moving mass compressing the air. When weight in the piston is reduced or the skirt eliminated the shooter will usually opt for a stronger spring to compensate.As far as sizing the piston seal versus breaking it in - size it!! In seventeen years my Diana 34 seal really never did "break in". I had to force it into the compression tube - it was that tight. Shooting was a bit erratic, too. I sized the seal for a couple of pounds of force to move it in the compression tube and groups shrank dramatically. Why? I have been told a too tight seal can cause a jerky start-stop motion as it travels through the compression tube. This can set up a vibration throwing your aim off. Additionally a too tight seal slows the piston travel resulting in a significant reduction in pellet speed and power.
Looks like the seal is still tight and as shown from your shot string....gains power as the seal gets warmer. Might also consider shimming from the spring guide since you took some off from the tophat.
I think RoadWorthy nailed it when he said that you do not have enough preload.Would you trade the easy cocking and smooth shot cycle for 1.5-2 pfe?-YPS you could try adding a few washers in front of the top hat.
I have a merlin its a lower power spring you might not get the power you want’I have done the same thing’ it shot fine but not fast enough’ I never size a seal betterTo be to tight than to loose’ it just makes the rifle shoot rough like it has an old seal’But yall do as yall wish’ that is a soft tune plinking spring’ that why i put it inA daisy buck for a power spring’ you needa turantula or 3650 spring’
Quote from: makarov76 on May 21, 2018, 10:49:52 PMI have a merlin its a lower power spring you might not get the power you want’I have done the same thing’ it shot fine but not fast enough’ I never size a seal betterTo be to tight than to loose’ it just makes the rifle shoot rough like it has an old seal’But yall do as yall wish’ that is a soft tune plinking spring’ that why i put it inA daisy buck for a power spring’ you needa turantula or 3650 spring’I wasn’t going for anywhere near stock power levels, was hoping to end up at a very modest 10-11 fpe by using the merlin spring. Decided against sizing the seal down any further for the reasons that you mention. I asked for advice on another forum and someone with the same exact setup minus the rear spring plastic spacer (which adds quite a bit of preload) ended up with 750 fps using 7.9gr pellets (roughly 50 fps faster than my gun which kept the rear plastic block). I’m just thinking that these lower cost guns can vary due to inconsistencies in the tube.