{"id":31009,"date":"2025-09-28T00:01:37","date_gmt":"2025-09-28T07:01:37","guid":{"rendered":"https:\/\/exhaustnotes.us\/blog\/?p=31009"},"modified":"2025-09-27T15:50:52","modified_gmt":"2025-09-27T22:50:52","slug":"triggershims-bolt-shims","status":"publish","type":"post","link":"https:\/\/exhaustnotes.us\/blog\/index.php\/2025\/09\/28\/triggershims-bolt-shims\/","title":{"rendered":"TriggerShims Bolt Shims"},"content":{"rendered":"
By Joe Berk<\/h6>\n

I should have known better.\u00a0 Before I tried good buddy Lance’s bolt shims (at TriggerShims.com<\/a>), I was a bit skeptical even though another of Lance’s products had worked (and is still working) very well for me.\u00a0 I installed Lance’s cylinder shims on my Model 60 Smith and Wesson revolver a few years ago and they solved a lot of ills, including excess cylinder gap, difficulty in opening the cylinder, velocity loss, and double action misfires.\u00a0 The Model 60 is completely reliable now (I’ll include a link to that story at the end of this blog).<\/p>\n

The above notwithstanding, though, I was still skeptical about bolt shims. I didn’t understand the concept of rimfire rifle bolt shimming, and that fueled my cynicism.\u00a0 I mean, on a bolt action rifle, what is there to shim?<\/p>\n

I called Lance at TriggerShims and spoke with him.\u00a0 Lance said his customers tell him bolt shims work, but I wouldn’t know until I tried them.\u00a0 I was up for it.\u00a0 I had two rimfire rifles I felt should be more accurate:\u00a0 A Remington Custom Shop Model 504 and a CZ 452 Varmint model.\u00a0 The CZ would shoot moderately well off and on (it wasn’t consistent); the Remington was a major disappointment from the day I bought it.\u00a0 It was expensive and for something coming from Remington’s Custom Shop, I expected a lot more.\u00a0 The Custom Shop 504 rifle is beautiful, its walnut stock is fabulous, but its groups were poor.<\/p>\n

The Concept<\/strong><\/p>\n

When you get a set of bolt shims from Lance, you get five in varying thicknesses. The shims are color coded so you don’t have to guess at what they are or measure them.\u00a0 The package looks like you see below.<\/p>\n

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A pack of TriggerShims’ bolt shims. Note the color coding on the shims.\u00a0 Five shims come in a package; the fifth one from the envelope you see above now resides in my Remington Model 504.<\/figcaption><\/figure>\n

How Bolt Shims Work<\/strong><\/p>\n

Most rimfire bolt action rifles’ bolts are different than centerfire bolts.\u00a0 On a centerfire bolt, the bolt locks into the receiver at the front of the bolt.\u00a0 On most rimfire bolt action rifles, the bolt locks into the receiver at the bolt handle, the forward portion of the bolt extends forward to meet the rifle’s breech, and the bolt’s locking lug is integral to the bolt handle.\u00a0 Typically (as is the case on my CZ 452 and Remington 504), the forward portion of the bolt is actually two separate and concentric cylinders, with the forward part of the bolt able to move forward on the inner cylinder (i.e., closer to the chamber) if it is shimmed to do.\u00a0 You can see it in my Model 452 CZ bolt in the photos below.<\/p>\n

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The CZ 452 bolt.<\/figcaption><\/figure>\n
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The CZ 452 bolt disassembled. The arrow points to the 0.002-inch TriggerShims shim placed on the bolt shank.<\/figcaption><\/figure>\n

Now consider headspace, the amount of clearance between the cartridge base and the bolt face.\u00a0 If there’s too much headspace, case separations can result when the brass case stretches during firing.\u00a0 Not enough headspace, and you can’t close the bolt.\u00a0 \u00a0You might wonder:\u00a0 Why not simply have line-to-line contact in the chamber between the cartridge and the chamber, with zero headspace when the bolt is closed?\u00a0 That could work if you always shot with cartridge cases from the same manufacturer, there was no variation in the cartridge cases, there was no variability from rifle to rifle, you always fired your weapon at the same ambient temperature, and you always let it cool completely between shots.\u00a0 These qualifiers are unrealistic, so rifle manufacturers add clearance (i.e., headspace) so that the bolt can always close on any rifle they manufacture when using any kind of ammo meeting the cartridge’s external dimensional specifications at any reasonable temperature.<\/p>\n

On a centerfire bolt action rifle, we can use tricks like neck sizing the case (instead of full length resizing the case) so that if that case was previously fired in the same rifle, a reloaded cartridge will have much less clearance between the cartridge case, the bolt face, and the chamber walls.\u00a0 This often works with a centerfire cartridge if, when reloading the cartridge, we only resize the case neck (that’s called neck sizing).\u00a0 Sometimes it’s an easy way to shrink groups (i.e., to make your reloaded ammo more accurate).<\/p>\n

We don’t reload .22 ammo, though.\u00a0 So what can we do to eliminate unnecessary headspace?\u00a0 That’s where TriggerShims’ bolt shims enter the picture.\u00a0 The idea is that instead of increasing the length of the brass case to eliminate unnecessary headspace, we push the bolt face forward (toward the rifles’ chamber) to shrink the headspace.\u00a0 In the photo above, you can see where the TriggerShims bolt shim fits between the bolt handle and the bolt’s outer cylinder.\u00a0 When the bolt is assembled with the bolt shim installed, it looks like this:<\/p>\n

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The arrow points to the bolt shim. It pushes the bolt face forward 0.002 inches.<\/figcaption><\/figure>\n
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The bolt shim is visible from the bolt underside. Because the bolt locks with a lug on the bolt handle casting, the forward portion of the bolt sits further forward when the bolt shim is installed.<\/figcaption><\/figure>\n

The package from TriggerShims contains five shims of different thicknesses, color coded by thickness.\u00a0 Lance doesn’t know how much shimming your bolt might need, and initially you don’t either.\u00a0 One approach is to go at this question as you would when developing a load for a centerfire rifle; i.e., trying different powders, powder charges, etc., except the sole independent variable is shim thickness.\u00a0 Here, the questions are how much excess headspace is there in your rifle, and how much should you remove to optimize accuracy?<\/p>\n

The best approach to answering the above questions is to take the shims to the range, and with your preferred ammo, shoot groups with no shims, the 0.0015-inch shim, the 0.002-inch shim, the 0.003-inch shim, the 0.004-inch shim, and the 0.005-inch shim, and then select the shim that provides the greatest accuracy.\u00a0 Theoretically, if you switched ammo brands, you could repeat the process and find the best shim for the new ammo.\u00a0 It’s very clever.<\/p>\n

Me?\u00a0 I’m lazy.\u00a0 I watched a bunch of YouTube videos describing the above and I decided I didn’t want to disassemble and then reassemble my bolt at the range, so I simply installed the 0.002-inch shim on both my CZ 452 Varmint and my Remington Custom Shop Model 504.\u00a0 (The Model 504 bolt shim installation is very similar to how it’s done on the CZ.)<\/p>\n

The Results<\/strong><\/p>\n

Does it work?\u00a0 In a word, yes.\u00a0 I wouldn’t have believed it without trying it myself.\u00a0 \u00a0I’m here to tell you the results are nothing short of amazing.<\/p>\n

Remington Model 504<\/strong><\/p>\n

As I mentioned at the start of this blog, my Model 504 was a real disappointment.\u00a0 Yeah, it’s beautiful, with deep, lustrous bluing and gorgeous walnut.<\/p>\n

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My Custom Shop Model 504. It sure is pretty.<\/figcaption><\/figure>\n

But the Model 504 didn’t group well with any ammo.\u00a0 That was a surprise, partly because of the rifle’s price, partly because of the Remington Custom Shop’s reputation for stellar performance, and partly because the rifle was glass bedded from the Custom Shop.\u00a0 I did my online research (ass backwards, as usual, after<\/span> I bought the rifle) and I learned that Model 504s are known for lousy accuracy.\u00a0 I tried screwing around with relieving the bedding where it interfered with the barrel attaching screw, I tried different action screw torques, and I tried different ammo.\u00a0 Nothing worked.\u00a0 I thought I had been stuck with a beautiful rifle that was essentially a paperweight.\u00a0 Here are a couple of typical groups from the Model 504 at 50 yards with Eley Target ammo (which is good stuff) before I installed the bolt shim.<\/p>\n

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A Model 504 typical pre-bolt-shim-installation 5-shot group at 50 yards.<\/figcaption><\/figure>\n
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Another pre-bolt-installation group at 50 yards from the Model 504. Before installing the bolt shim, I would have considered this a good group from this rifle.<\/figcaption><\/figure>\n

As you can see, they are what we in the engineering world would call lousy.\u00a0 The groups would vary, seldom going as low as that 1.041-inch group you above.\u00a0 \u00a0Mostly they were awful.<\/p>\n

I then installed a 0.002-inch trigger shim on the Model 504 and I tried it again.\u00a0 Wow! Look at this!<\/p>\n

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A dramatic and immediate improvement with the 0.002-inch bolt shim. This first group with the bolt shim installed was shocking. It got even better (see below).<\/figcaption><\/figure>\n
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The next group from the Model 504 with the bolt shim. I’m a believer.<\/figcaption><\/figure>\n

When I saw those groups through the 12X Weaver scope on my Model 504, I couldn’t believe what I was seeing.\u00a0 In my mind, I could hear Lance’s calm voice in our recent telephone conversation telling me there’s no guarantees, but folks say they work.\u00a0 \u00a0Indeed they do!<\/p>\n

CZ452 Varmint<\/strong><\/p>\n

I was blown away by the Model 504’s improved accuracy with the addition of the 0.002-inch bolt shim, so I wanted to try it on the CZ.<\/p>\n

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Another pretty rifle: The CZ 452 Varmint.<\/figcaption><\/figure>\n

The CZ has always shot better than the Model 504.\u00a0 Here’s a typical 10-shot group with the CZ452 before I installed the bolt shim:<\/p>\n

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I meant to shoot a 5-shot group before installing the bolt shim, but I shot 10 instead. It’s a typical group from the CZ before I installed the bolt shim.<\/figcaption><\/figure>\n

What you see above is what the CZ would do at 50 yards with Eley Target ammo in my hands.\u00a0 Sometimes it would do a little better.\u00a0 Sometimes it would do a little worse.\u00a0 \u00a0I’m not that great a shot; other people could probably do better.\u00a0 But it’s typical for me.\u00a0 I wanted it to do better.<\/p>\n

The TriggerShims 0.002-inch bolt shim went into the CZ and again, my response was:\u00a0 Wow!<\/p>\n

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One little tiny 0.002-inch bolt shim and voila!<\/figcaption><\/figure>\n
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Someone once said only accurate rifles are interesting. These two rifles suddenly became much more interesting with the addition of TriggerShims<\/a> bolt shims.<\/figcaption><\/figure>\n

The Bottom Line<\/strong><\/p>\n

As the saying goes, your mileage may vary.\u00a0 But I’m convinced:\u00a0 Bolt shims work.<\/strong>\u00a0 I might be able to improve my groups even more if I experimented a bit with different shim thicknesses, but I’m more than pleased with what I saw after trying my simple and unscientific “install the 0.002-inch shim and see what happens” approach.\u00a0 This really is a great product. If you want to improve a bolt action .22\u00a0 rifle’s accuracy, check out TriggerShims<\/a>.\u00a0 You can thank me later.<\/p>\n

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Pretty Wood<\/strong><\/p>\n

People sometimes ask how I find guns with exceptional wood.\u00a0 It’s easy.\u00a0 I can’t pass a gun shop without stopping, and I spend a lot of time on gun forums.\u00a0 Every once in a while, I’ll see a rifle with walnut that speaks to me.\u00a0 The Model 504 you see here came from First Stop Guns (they’re in Rapid City, South Dakota) when Susie and I were out there touring that part of the country.\u00a0 I spotted the CZ 452 on a forum post and I sent a message to the owner asking if he would sell it to me.\u00a0 The first answer was no, but a year later the owner contacted me and asked if I was still interested.\u00a0 You know the answer to that one.<\/p>\n

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Pretty lumber indeed, and now they are both shooters. The CZ 452 is on the left; the Custom Shop Model 504 is on the right. You don’t often see .22 rifles with wood like this. For that matter, you don’t often see centerfire rifles with this kind of wood, either.<\/figcaption><\/figure>\n
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About that Model 60 cylinder shim story I mentioned…<\/a><\/p>\n

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