Rim Sorting 22LR

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After testing weight sorted cartridges of Federal Champion 22LR LRN and finding that they produced 60% smaller groups than non weight-sorted cartridges, I decided to test the other big old-school 22LR accuracy technique: sorting cartridges by rim thickness.

The thickness of the a 22LR rim can effect the amount of headspace of the bullet in the chamber. And presumably, the thickness could also effect the amount and burn rate of the primer inside it. Both of these factors could effect the velocity and stability of a .22 bullet.

For the test used a batch of weight sorted 22LR cartridges from which to draw my rim sorted samples from. All the cartridges I measured weighed between 51.3gr and 51.5gr. I put 50 aside as a control group and measured the rim thickness of the remaining cartridges and sorted them by rim thickness. A friend from my rifle club lent me his Neil Jones Rimfire Gauge tool which made the measurement process relatively quick.

For my testbed I used my same CZ 457 VPC that I used for the weight sort test. At the range, I set up 2 rows of 3″ paste up targets at 100yrds. I fired 5 rounds into each target for a total of 40 rounds of rim sorted and 40 rounds of my non-sorted ammo.

Upon inspection the target groups were each a bit different from each other but overall appeared relatively similar in size. Just how similar surprised me after I ran a photo through my phone’s Range Buddy App. On overage both the rim sorted and the randomized control group produced a 1.27 MOA average size. Identical.

RIM SORTED
1.03 1.28 1.61 1.16 MOA
Avg 1.27 MOA

RANDOM CONTROL
1.83 0.99 1.14 1.14 MOA
Avg 1.27 MOA

So it would appear that rim thickness plays an insignificant role in 22LR accuracy and performance. At least so far as Federal Champion LRN is concerned. My buddy who lent me his Rim Gauge told me as much when he tested his Match Grade 22LR for competitions. Were it not the case, I doubt he’d be lending me his gauge.

Coyote Point 100y Rimfire Match: Nov 14, 2021

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We had twice as many competing at this match. Still plenty of room for more next month. If you’re an experienced or competitive rimfire shooter and would like to compete at next month’s match, reach out to the Rifle Executive at the Coyote Point Rifle and Pistol Club website. https://coyotepointrpc.org/cprpc-board

https://youtu.be/SpTZ7H4dGW0 #22LR #rimfire

CZ457 Varmint Precision Chassis

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With the success of the Ruger RPR and Savage Precision B-22, CZ has come out with their own factory built precision rifle based on their new 457 action. They paired an all aluminum chassis of their own design, with a LUTH-AR adjustable buttstock to create a competition ready rifle straight out of the box. I test out that claim by taking this new CZ 457 to a 100yrd competition practically right out of the box. 

I had been eyeing a CZ 457 MTR but none could be had anywhere, so I ordered the VPC (Varmint Precision Chassis) from Coyote Point Armory and 3 weeks later picked up the rifle (after the idiotic mandatory 10-day CA waiting period but don’t get me started). It was the Wednesday before the Sunday Match, so I had time to film a short unboxing video. You can mount 11mm dovetail scope mounts on the rifle but I chose a Trigger-by-Scar 25MOA Picatinny adapter rail for more commonality with my scope mounts for future reviews.

I attached a spare pair of UTG M-Lok bipods and borrowed a 6-24×50 Athlon Argos from my AR. I took it to the range Friday night to zero out the scope but I didn’t do any prior seasoning, breaking-in or adjusting of the rifle. I kept the trigger set at it’s 3lb factory set pull. I didn’t even lube the shine action (which was very smooth out of the box).

I also didn’t an opportunity to test match-grade ammo. I have a few partial boxes of match-grade ammo from prior testing of Eley Edge, Eley Target, and Federal Gold Medal, but not enough to complete the match, which would require a minimum of 40rnds.

I opted to try out the best quality LRN 22LR I had supply of: Federal Auto Match and CCI Standard Velocity. While zero’ing the scope, I tested out 5rnds of each ammo type. CCI grouped the best (a sub 2″ group at 100yrds) so I chose to run with that for Sunday match. I noted that the CCI standards took a bit more effort to seat into battery. To keep to “out of the box” spirit, I didn’t clean the barrel out but bagged it up waited for Sunday morning.

The Sunday 100yrd match was non-sanctioned casual club event open to all members and guests of the Coyote Point Rifle and Pistol Club. All types of small-bore rimfire rifles were allowed. I had participated only once before with my Glenfield 60, which is a fine plinker but to be competitive I had to bring out the CZ.

The course of fire had 40 scoring shots with a total maximum score of 400:
4 targets
10 shots per target
10 minutes per target
3-minute free-shot period between targets
Shooters were allowed to re-zero and test on a non-scoring target during the free-shot period.

The CZ performed flawlessly. The action was smooth and the only effort was the additional pressure required to seat the CCI standards. The factory set 3lb trigger had a clean, crisp, break with zero over travel. It was pleasantly lighter than any of my other rifles.

My only issue was the need to re-load half-way through each target because the CZ only came with a single 5-round magazine. For the price and for the US market, CZ should have included 2 magazines or better yet both a 5-round and a 10-round magazine.

At the end of the match, I came in 4th among the 22LR shooters and 6th overall. My smallest 10-shot group was 1.6″ at 100yrds with a total score of 347 out of 400 (though it would later turn out after reviewing video that one of my targets had holes mistakenly shot by my buddy in the next lane). While this is not sub-MOA performance, I still give this rifle very positive marks because I can easily improve its performance in two simple ways: find match-grade ammo it likes and lighten the trigger.

AFFILIATE LINK
Order this rifle at Palmetto State Armory: https://bit.ly/3BmmHE5

SPECIFICATIONS

Product Name CZ 457 Varmint Precision Chassis

SKU 02361

Firearm Type Rifle

Purpose Competition

MSRP $1,039.00

Chambering 22 LR (optional 17 HMR)

Twist Rate 1:16 in

Magazine Capacity 5

Magazine Type Detachable Box

Stock Aluminum Chassis

Sights None,. Integral 11mm Dovetail

Barrel Heavy Tapered Cold Hammer Forged

Barrel Length 16.5 in or 24 in

Weight 7.65 lbs

Trigger Mech Fully Adjustable

Safety Two-Position, Push-To-Fire

YOUTUBE REVIEWERS ARE USELESS
YouTube continues to annoy and perplex me. This is the 2nd edit of this video. YouTube reviewers rejected the first longer edit which contained a full unboxing and additional commentary about the features of the rifle. Their reviewer comment was:

Use of guns outside a controlled environment; display of homemade, 3D-printed, or previously modified guns; use of airsoft or ball bullet (BB) guns against others without protective gear.

YouTube Manual Reviewer Team

This, despite the fact that the original video had both text and audio stating that the shooting portion of the video was filmed in at a gun range. In fact, the Sheriff’s training center! So, I edited out much of the unboxing footage and removed any mention of the bipod and scope (which some un-informed reviewer might have deemed as a “modification”?! ) This shortened video was approved.

This is not the first time their human reviewers have misclassified one of my videos and probably won’t be the last. Here below is the original edit (the title was amended by me after the Reviewer rejected it):