Messing around with the Garmin and some 22's

[Will Henry]

I recently picked up a Garmin Xero chronograph thingy. I have to say, using this thing is so simple and convenient that I seldom shoot without it.
Anyway, I was shooting some of my 22's and set up the Garmin to gather more information.
The 22's were a Model 52 with the barrel set back and rechambered with a 52D reamer
A Model 75 Winchester with a Gaillard barrel, chambered with the same reamer.
A CZ552 varmint, factory barrel and chamber.
Ammunition was S-k standard plus, Norma Tac, and Sellier and Bellot Canadian Match.
With all ammunition, the 52 was most accurate and showed the lowest spread and SD, the 75 was a close second, and the CZ a distant third. I strongly suspect this is strictly due to chamber dimensions. The CZ is a little loose in headspace and barely engraves the bullet on chambering. It strings vertically, as one might expect given the SD recorded (over 21fps as opposed to 11 or less for the others. The other two are chambered at .041HS and engraved the bullets significantly. My next move is to rebarrel the CZ with a Benchmark barrel which was gifted to me and see what effect. At the same time, I may set back the factory barrel. The Benchmark barrel was previously fitted to a Stiller action and shot OK but not exceptionally. I re-barreled that rifle with a Lilga and it does now shoot exceptionally well for it's owner. The chamber in the Benchmark is a bit homely and I'll cut the new chamber with my 52D reamer.
By the way, the S&B ammo turned out to be slightly supersonic so I shelved it. WH

 

[grauhanen]

By the way, the S&B ammo turned out to be slightly supersonic so I shelved it.

Being slightly supersonic won't affect how .22LR ammo shoots. Shelve an ammo like S&B because it doesn't shoot.

 

[Will Henry]

Well, I pulled the CZ apart and immediately found the probable cause of the velocity spreads and the vertical stringing. The darn thing has about .011" of headspace (on a .043 gauge). I pulled the barrel, preparatory to rebarreling, and the measurement showed that amount of headspace. I expected some, but not that much!
I discovered the threads on the CZ are a 1.25mm pitch. I started to switch the gears on my lathe, to cut the metric thread, only to discover, my lathe won't cut 1.25mm, not with the gears I have anyway. I can cut 1.2, I can cut 1.3, but not 1.25. I have cut a lot of metric threads but not this one, so there you go. 1.25mm is a little less than .0008" less than 20 tpi though, so I'll just cut 20 and like it. I cut a stub to test it out and it worked ok. If it was a stainless receiver, it would probably gall but the CZ isn't stainless. WH

 

[Jonnyofalltrades]

Sounds like some fun projects.
Keep us posted, Bill.

Being slightly supersonic won't affect how .22LR ammo shoots. Shelve an ammo like S&B because it doesn't shoot.

S&B Canadian Match isn't terribly expensive, but it can really shoot.
I've gotten several 5/8" groups at 100yds with it. Considering that was from a hacked up gun with a 12 power scope, I was impressed.

 

[grauhanen]

S&B Canadian Match isn't terribly expensive, but it can really shoot.

A bit of an overstatement. Not about the price but that it really shoots. What you are likely seeing is a small number of rounds per box performing nicely.

Keep in mind that a few five shot groups under an inch out of many at 100 isn't a high bar. Similar results may be possible with SK Standard Plus and CCI SV. Ammo that gives results that are consistently good is ammo that really shoots.

 

[Jonnyofalltrades]

A bit of an overstatement. Not about the price but that it really shoots. What you are likely seeing is a small number of rounds per box performing nicely.

Keep in mind that a few five shot groups under an inch out of many at 100 isn't a high bar. Similar results may be possible with SK Standard Plus and CCI SV. Ammo that gives results that are consistently good is ammo that really shoots.

Nope.
I just finished putting 500 rounds of it through my target gun, and it always was the best performer every shooting session.
I've lost track of all the different kinds of target ammo I've tried. Nothing else equaled it in this gun. I dunno, must have lucked onto a good lot.

 

[grauhanen]

Nope.
I just finished putting 500 rounds of it through my target gun, and it always was the best performer every shooting session.
I've lost track of all the different kinds of target ammo I've tried. Nothing else equaled it in this gun. I dunno, must have lucked onto a good lot.

It must be nice to find that this ammo can "really shoot" in your "hacked up gun with a 12 power scope" (your words in post #4). What were you comparing it with?

Regardless of the rifle, most shooters don't have that experience with budget-priced .22LR ammo. (S&B "Canadian Match" .22LR ammo is about $60 CAD/brick, about 60% the price of SK Standard Plus).

 

[Will Henry]

I have to confess to never even trying the top quality match ammo in any of mine. This is because my competition is all off-hand and it is very seldom that I feel I can attribute a miss to an ammunition shortcoming! In general, S-K shoots quite well, with the occasional flier (maybe two out of ten). The fliers will generally open it up to 1 1/4 or a little more from 3/4. Lapua rifle match doesn't shoot a lot better, but the fliers are less frequent and not as far out. This fact makes absolutely no difference to my scores, however! The Norma TAC (Which might be RWS) shoots about like the S-K but shoots about 1 1/4 moa flatter over 100 meters (zero at 40). Not sure why this is. The velocity is the same
I am about done with the barrel. This is a two-groove Benchmark. I'm going with the story that the slight thread mismatch stabilizes the joint! It might be a "thing". WH

 

[Will Henry]

Well, I finished the barrel up and took the 452 out today. The SD with the Benchmark barrel was cut in half, compared to the factory barrel. I headspaced the barrel so that there is just a slight feel on most of the cartridges. Occasionally, one is a little loose and occasionally, one is a little tighter. This is usually reflected on the target with the high or low fliers. Anyway, the rifle shoots as well as the 75 but not quite up to the 52. I can hold it pretty well though, so it should work out. I'll shoot it in hunting rifle class tomorrow and see how I do. I worked my way up to AAA in that class and have not shot to that level since. Maybe this will change my luck. All I have to do is pull the trigger when the crosshairs are on the target. I don't know why I have so much trouble doing that! WH

 

[MUP]

Good luck Will, let us know how you do!

 

[Will Henry]

The CZ shot well and I had flashes of adequacy myself but was inconsistent. The 52 shot better for me but it's set up a little better. The scope is too low on the CZ. More shooting prior to the next match should help! WH