I've run hundreds of pellets over the chrono. JSB and AA 10.3, 8.4, 13.3. Ironically, I'm getting very consistent results with spreads of 11-12 and SD of 2 or 3. That's outstanding in my book, but why the accuracy problems? I've cleaned the barrel, polished it with JB paste and when I slugged it, the rifling marks look perfect. The crown appears fine. I've run it with no moderator, 4 others with different exit hole sizes, all the same. This is becoming a complete mystery. This is what I'm getting at 10M.
This is a new gun and barely 3 weeks old. Unfortunately, I didn't buy it from Martin so if I send it to him, it costs me $$. I'm dealing with RAW (Air Force) currently on the problem and I'm hoping they correct it under warranty.
I am dealing with the exact same issues with my Micro Hunter, and have been in email discussions with RAW support for weeks. But I still get some fantastic 10-shot groups at 25 yards, only to be spoiled by 1 or maybe 2 flyers.
1) I have tried many pellet weights and brands from 8.44 to 13.43 (yes, mine is a .177 cal gun). (RAW has told me that they tune the guns at the factory with domed JSB 8.44 and/or 10.34 gr pellets). I have had best luck with my personal gun with 13.43 Monster Re-Designs and have been told by RAW to just experiment with those for now;
2) I have tried many different pellet velocities achieved by adjusting hammer spring tension only (I have not revised the regulator, which seems on my gun to be set around 150 bar). Latest info from RAW is to tune the HS for a velocity of ~720 fps with the 13.43's;
3) I have tried many different positions of the air stripper. I was told by RAW to start with it at the full out position. Then I adjusted it by 1/2 turn increments, sometimes 1/4 turn increments if I felt I was getting close to consistent performance;
4) At first I was using a moderator with a .30 cal hole (STO Brevitas II), but to take issues with the mod out of the equation, I have since removed it and am shooting all of my test groups without any mod;
5) I changed scopes on my gun just to make sure that wasn't the issue;
6) I have been asked by RAW to take some of my testing out from 25 to 50 yards, and that might show improved performance. But all that did was add any of my technique inconsistencies into the mix. No better groups, and still random flyers.
7) My ES and SD values are quite low - almost always in the single digit or maybe low double digits for ES for 10, 20, 30 shot groups;
8) RAW asked me for photos of the pellet probe and its interaction with the barrel breech, and said that based on the photos all was good;
9) RAW asked me for photos of the removed air stripper from different angles, but didn't see anything wrong with it;
10) I'm shooting off a Caldwell Stable Table bench, using an Accu-Tac bipod at the front and a bean bag at the rear of the rifle;
11) Based on an issue seen in the Wisconsin AirGunners video review of the gun, I checked my threaded shroud collar at the base of the shroud. Mine had not come loose, so wasn't an issue.
This gun is really starting to frustrate me, now with perhaps nearly 1,000 test pellets fired and seemingly no closer to the RAW claim of '10 meter accuracy in a compact hunting rifle." Mine was purchased directly from RAW as a blemished product (I had assumed a cosmetic blemish - but maybe I got a 'performance blemished' gun?)
(terrible punnage)!! - only thing is everything is essential!
