Accurizing a CZ 452 varmiint in 17HMR

[DaveT]

I got my new CZ 452 varmint 17HMR and my first range session went, well just ok. I have already ordered the YoDave's trigger kit which should help the trigger. My initial groups had a lot of vertical stringing. I was advised in rimfire central to give the gun time to break in and see how it goes with a better trigger. For me, it just ain't that simple, I have to get the gun accurized to the fullest. Anyone have experience with tuning these guns for better accuracy and know someone who works on these guns? I have tried 4 different types of ammo and am still looking for more brands.
Any help would be greatly appreciated.
Dave T

 

[nhkuehl]

Vertical

Have you tried more than one brand of ammunition? - nhk

 

[Herzo]

I cannot address the .17, but here's what I did with my .22's (one 455 American and one 452 Trainer):

1. Clean the preservative from the barrel - I used a bronze brush dipped in Hoppe's followed by 3 or 4 dry patches. Repeat until the dry patches are clean. This may take a while.
2. Trigger job. YoDave works pretty well. I got mine to ~12 oz with no creep.
3. Check the crown, my 452 was good, but the 455 was off center and rough.
4. Ensure that the barrel is free floated from the action forward.
5. Glass bed the action in the stock. The factory inletting is pretty good, but bedding will insure that the action is accurately positioned in the stock.
6. Play with the torque on the action screws. The 455 has 2 screws in the action and likes ~16 lb-in torque. The Trainer has a single screw in the action and a second screw in a boss in the barrel. The Trainer seems to like 10 lb-in in the action only and NO torque on the barrel.
7. If you feel adventurous, polish the bore with Browning's #2 bore polish. I ran about 20 passes from the breech to within 3 to 4 inches of the muzzle and another 20 passes to about 8 to 10 inches from the breech. Each pass was freshly loaded with abrasive but I did NOT try to polish the 3 to 4 inches nearest the muzzle.

It required at least a brick of ammunition to bring them home, but the 455 is a solid 3/8" shooter at 50 yards while the Trainer will shoot sub 0.20" groups at the same distance. Both seem to really like Lapua Center-X. Wolf ME is my second choice, but not up to the Lapua.

When I start to lose accuracy (about every 30 to 40 rounds), I run a single dry patch through it (from the breech) and accuracy will return after 3 to 5 rounds.

Good Luck