Hello Birdslayer. I got off to a rough start with my .22 Streamline, but did eventually start getting what I consider excellent accuracy from the gun. In my case, I was getting decent groups from the 15.9 JSBs, but horrible groups from the 18.1 JSBs. By taking chronograph readings at 50 yards, this was tracked down to a stability problem with the 18.1 pellets. Extreme spread at 50 yards with the 15.9 JSBs was around 30 fps, but much greater than that with the 18.1s. It seemed the Smooth Twist barrel was providing very marginal stability, at least with the heavier pellets. I tried cleaning the barrel, with no improvement, so decided to stop cleaning the barrel altogether. Just as with rimfire shooters, many airgunners find that accuracy improves with a seasoned barrel. That seemed to do the trick. Accuracy improved until after shooting a couple tins through the barrel without cleaning, half inch groups at 50 yards were the norm with the 15.9 JSBs, and the 18.1s were not far behind. It is my understanding that a lot of people have found that their Smooth Twist barrel needs to be shot in to obtain best accuracy. That was certainly the case for me.

​At this point, I can count on moa or better accuracy at 50 yards under low wind conditions. To verify, I just shot a couple groups today at 50 yards in the rain using unsorted 15.9 JSBs. Both groups measured 0.52", which I consider typical for the gun, although it is not unusual to get groups measuring 0.04" or less. I have not shot extensively at 75 yards, but groups at that distance typically range from 0.78" to 1.02". Wind seems to be a much bigger factor at 75 yards. I would think your Impact would provide similar accuracy. What groups sizes have you been getting?

​When I am intent on getting the very best accuracy from my rifle, I do sort the pellets for weight to make sure I am eliminating that variable. I also single load, and use lightly lubed pellets. Since I am not cleaning the barrel, the lube is mostly intended to prevent excessive leading. Although hard to prove, these additional steps seem to improve accuracy a bit.

Chuck
 
Birdslayer,

No question at all these rifles should be sub moa (1/2") at 50yds.

My Royale 400 was NOT accurate enough when I first received it new and it annoyed the **** out of me. I have shot a lot, and know it was not my shooting, or scope or loose screws causing this - although these are things to make sure of of course.

I tried every type of pellet imaginable - very expensive, and in the end the JSB 18gr was the best although not good enough. I would get the occasional 5 shot group under 1/2" at 50yds but the next one could 3/4" and at 100yds forget about it 4" if I was lucky. Weighing pelets made no significant difference.

On YouTube - and the main reason I got this rifle - Ted was shooting a "new" Royale with pellets out of the tin not even trying and getting 1/2" at 50 and 2" at 100yds. He is a master and I bow to his skills... but as people have said in the thread above there is an element of luck in what you get (and he was no doubt sent a tested rifle - not rigged just tested), and I think the difference is in tiny discrepencies in the barrel that you get.

I can now get 0.34"-0.4" (8mm-10mm) groups pretty consistently at 50 and best yet at 100 is a full mag in 1 3/8" (34mm).

I have tried everything I could think of / read about including adjusting the reg to increase velocity which was a very lengthy process to learn from scratch.

The two things that made a night and day difference were:
  1. Polishing the barrel - Automobile type chrome polish, or polishing paste on a cotton mop; stick that in a power drill and polish the crown (last inch at the muzzle end) of the ST barrel with it ... a lot.
  2. Pellet sizing - using a Pelletgage I discovered my barrel only works as it should with pellets 0.03mm - 0.04mm smaller than they tend to come in the tin (although that varies more than you might expect). Then resizing tool and a bit of patience and you have pellets that work.
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    Final thing is that it may be that the reg takes longer to break in than expected so that's only settling down after 5000+ shots, I don't know how much of a factor this was for mine.
    Other final thing is my ST barrel defintely loves being cleaned and often... some say never but it just may be for yours as mine that is not going to help.

    These are my experiences so not rules for all, but if I'd known these sooner it would have saved me serious heartache... on the other hand I learnt a lot in the process!

    Don't give up.