Accuracy and barrel changes on a CZ455
CZ455 with .22 and .22wmr barrels and a Bushnell 3-9x40 Elite scope
Originally I wanted a .22 (using sub-sonics) to shoot rabbits @50m early in the morning around the farmhouse so as not to disturb family and friends (and wildlife).
I then wanted to use a .22wmr to shoot rabbits and foxes @100m later in the day and at night. I wanted to do this several times over a weekend about 12 times a year.
One solution was to simply have two rifles, however I liked the idea of one rifle doing the job of two, hence the CZ455, along with a fairly good scope. I went on to get a Tikka T3 .223 for longer range bigger game shooting, so this way I only have to take two guns with me rather than three.
When I first started considering this rifle, I asked on various forums if I would be able to reliably change between barrels and simply use a consistent scope adjustment to compensate when changing back and forth.
On the whole most people said no, I would have to re-sight it in after every barrel change, or I should have two scopes and switch between the two. The few who actually had this rifle and had changed barrels didn’t seem to have done it on a regular enough basis to confirm either way either. Some thought that this many barrel changes would cause wear and tear leading to inaccuracy down the track (the jury is out on this and only time will tell). One person said they knew of it being done but no-one with firsthand experience could confirm one way or another.
Up until recently I had only been using the CZ455 as a .22 since I also had (and still have) a Zastava CZ99 .22wmr. This was my first rifle and shoots pretty well but I decided to ‘upgrade’ to the CZ455 giving me the best of both worlds, a .22 and .22wmr.
Yesterday I finally got along to the range to do some testing under controlled conditions, trying some different types of ammo and seeing how much adjustment was needed in the scope settings when changing between barrels.
The photo show the outcome, after an hour or so testing I did the four targets as shown. I started out with the magnum barrel, took 5 shots then changed barrels and clicked the scope up 20 clicks. Took 5 shots with the .22 then changed back to the magnum, changed the scope down 20 clicks and so on.
Running out of ammo stopped any further testing, I suspect that the vertical adjustment is somewhere around 16 or 18 clicks, it seems that no horizontal adjustments are needed, and both calibres come back to about the same accuracy when changed back and forth.
Further testing needs to be done to find the best ammo, plus my shooting accuracy has room to improve, but for hunting I can probably live with the current settings and ammo choices, .22 hmr Hornady 30 grain Vmax and .22 42 grain Winchester sub-sonics.
I also want to do a similar test at a longer range, so I can get the .22wmr set up for 100m and leave the .22 set for 50m. I can then see how much drop or rise the .22wmr has at 50m.