Improve Your Accuracy With Bolt Shims From TriggerShims.com

| August 18, 2022 | 2 Comments

What are Bolt Shims?

After the first video I got a lot of questions about the install of bolt shims and overall principle of the idea.

Bolt Shim Installation ~ A General Guide By Dayattherange.com

Rimmed cartridges use the thickness of the cartridge rim for head-spacing, the actual head space is in the recessed face of the bolt.
Shimming between the two bolt halves ensures the bolt is up gently tight against the breech, therefore adjusting headspace.

Due to rifle to rifle, manufacturer and ammunition brands it is just about impossible to tell you which shim best works with your rifle. That is one of the great things about bolt shims you get to decide yourself the ideal headspace by fitting, feel and shooting examining your results and deciding what’s best for your rifle.

Installing Bolt Shims requires fitting by hand, and checking with the bolt installed in the rifle in the closed position. Without the right tools which most will not have at home, there is no way to determine headspace with the bolt out of the rifle.

I started with a 5 Pak of shims, install the thinnest shim, reinstalled the bolt into the rifle closed it to test for fit, if it seems to close as normal, then I would move up to the thicker shim until the bolt starts to close harder/tighter than normal. At the point where your bolt begins to close hard/tighten against the breach face you are now starting to approach the proper headspace. This process is removing slack that was in your bolt, measured by whatever shim or combination of shims needed to bring the bolt up tight to the breech.


At this point I would remove that shim and back down by .001 or one number. Example if a .005″ Red shim causes the bolt handle to close harder than normal, then take it out and install a .004″ Purple shim. If you are concerned about about the length of time it takes don’t be. Across the 3 rifles, Lithgow LA101, CZ452 and CZ455 it took me all of 15 minutes combined, so about 5 minutes per rifle. For my results the outcome was worth the investment. I only wish I could get this sort of return out of the stock market.

If you have to force or put undue stress on your bolt to close it, again reduce the number or thickness of shims. You will generally only use 1 of the 4 or 5 shims in the package, but you can stack shims together if needed. The best way for me to explain if you have it right is by feel. When you have the correct shim installed, your bolt should close just (ever-so) slightly tighter than normal. I would not go to tight because you still have to test this with your ammunition. Because of the variation in rim thickness by manufacturer and lot number you do not want this feel EXTRA tight.

On your final shim put a very small drop of oil on the shim after installation and move on to the critical testing stage. Test the closing of your bolt with your ammunition, while at the range or with the barrel pointed in a safe direction. If at home remember a 22 will still penetrate walls, a 5 Gallon bucket filled with play sand works great.


Again due to variations in rim thickness, you may have to reduce the thickness of shims, remember you have already removed all the excess headspace from the bolt/breech, so now the only thing to do is remove thickness (shims) if/as needed to find your sweet spot. At this point if you have to force or put undue stress on your bolt to close it, you should reduce the number or thickness of shims. What was right for me was testing the closing of the bolt with different brands of ammunition, Eley, Lapua, RWS, Norma, SK and Federal for what felt right. Testing across a wide variety of brands of ammunition made sure I would get the best results for whatever ammo I had on hand and would always just be able to grab a box of ammo and head to the range for a session. Shimming where you need to force the bolt closed causes undue stress and potential damage to your rifle and is unnecessary!

Why Bolt Shims?
Bolt Shims providing the proper headspace can cure light strikes and improved accuracy just by providing a more consistent chambering and improving upon the headspace.

In all honesty when ordering this product I really was not expecting much. I mean I understand the criticality of headspace for rimfire so the overall principle made since, but in no way did I expect the results I got down range on target from three different rifles.

TriggerShims.Com made a believer out of me!

See For Yourself

Other Customer Testimonies

I’m happy to write a review on the shims that I received. I was having trouble with my CZ 457. It’s a custom build with a Bartlein barrel. It shoots lights out, but I couldn’t get it to shoot more than 60-70 rounds without having a failure to extract, followed by multiple per magazine. I called the builder, and they said to try new ammo. Well, I was already shooting Lapua Center X, and bought 5,000 rounds of it, so I wasn’t about to switch that easy.  I have over 1,500 rounds through the gun and it still jams. Yesterday,  lost an NRL22 match due to 3 FTEs in one stage that crushed my score. I was fed up with the rifle and ordered a new Proof barrel. On that same day, I received your shims. I found that I can fit a full .007 shims before the bolt was stiff. After I backed it down to the .005 shim, I took it to the range and was able to shoot 350 rounds without a single failure to extract! Definitely cancelling that new barrel! Your shims have saved me $600 and hours of work breaking in a new barrel. Thanks for the great simple product and the easy instructions. I will definitely recommend you to any others having this same problem.

Chris in AZ

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2 Comments on "Improve Your Accuracy With Bolt Shims From TriggerShims.com"

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  1. L.C.Shively says:

    Excellent Blog Post on the Description and Installation of Bolt Shims!

  2. james says:

    wow, what a coincidence, I just tested the same trigger shim kit in my LA101 and shot 250 rounds of ELEY Tenex to test it. I found that no shims shot best!

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