TriggerShims.Com

Rimfire Rifle Bolt Shim Index

V2.1-BOX~BS-SIZES 8/25

Selection of Rimfire Rifle Bolt Shims Sorted by Size

BOLT SHIMS
Sorted by I.D. Size

1. .357 x .595 Remington 540X Bolt
2. .376 x .500 Ruger American Rimfire Rifle Bolt Shims
3. .376 x .565 CZ 457 Rimfire Bolt
4. .376 x .690 Orphan Bolt Shim
5. .442 x .555 Remington 5 / Zastava
6. .442 x .595 Mossberg 44 U.S. Bolt and H&R M12
7. .442 x .648 Ruger 77/22 Bolt
8. .450 x .565 Winchester 69A / 75S Bolt
9. .450 x .595 Marlin 983 Bolt & Remington 504T
10. .480 x .570 Remington 513
11. .480 x .610 Mossberg 144 LSB
12. .480 x .640 Savage B.Mag Bolt
13. .480 x .751 Walther KK500 Bolt Shim
14. .500 x .610 Kimber 82 U.S. Bolt
15. .500 x .648 Bergara B14-R Bolt
16. .511 x .648 Turbo V3 / Flash Turbo
17. .511 x .648 Winchester 52 / Suhl 150 Bolt / Flash Turbo
18. .532 x .640 Anschutz 54
19. .555 x .670 Tikka T1x - Sako / Weihrauch / Walther KK300
20. .565 x .690 New for 2025
21. .570 x .690 Remington 40X Bolt
22. .595 x .690 Lithgow LA101 Bolt / Springfield 2020 Rimfire
23. .610 x .690 CZ / BRNO Bolt ~ Also Fits: Diana R22, Webley & Scott Xocet

BARREL SHIMS
Sorted by I.D. Size

24. .690 X .900 10/22 Rifle Barrel Shims
25. .710 X .850 CZ Barrel Shim
26. .710 X .900 CZ XL Barrel Shim
27. .710 X .950 CZ XXL Barrel Shim
28. .730 X .900 2500X Barrel Shim
29. .751 X .900 Bull Barrel Shims

BOLT SHIMS
Sorted by O.D. Size

1. .376 x .500 Ruger American Rimfire Rifle Bolt Shims
2. .442 x .555 Remington 5 / Zastava
3. .376 x .565 CZ 457 Rimfire Bolt
4. .450 x .565 Winchester 69A / 75S Bolt
5. .480 x .570 Remington 513
6. .357 x .595 Remington 540X Bolt
7. .442 x .595 Mossberg 44 U.S. Bolt and H&R M12
8. .450 x .595 Marlin 983 Bolt & Remington 504T
9. .500 x .610 Kimber 82 U.S. Bolt
10. .480 x .610 Mossberg 144 LSB
11. .532 x .640 Anschutz 54
12. .442 x .648 Ruger 77/22 Bolt
13. .480 x .640 Savage B.Mag Bolt
14. .500 x .648 Bergara B14-R Bolt
15. .511 x .648 Turbo V3 / Flash Turbo
16. .511 x .648 Winchester 52 / Suhl 150 Bolt / Flash Turbo
17. .555 x .670 Tikka T1x - Sako / Weihrauch / Walther KK300
18. .376 x .690 Orphan Bolt Shim
19. .565 x .690 New for 2025
20. .570 x .690 Remington 40X Bolt
21. .595 x .690 Lithgow LA101 Bolt / Springfield 2020 Rimfire
22. .610 x .690 CZ / BRNO Bolt ~ Also Fits: Diana R22, Webley & Scott Xocet
23. .480 x .751 Walther KK500 Bolt Shim

BARREL SHIMS
Sorted by O.D. Size

24. .710 X .850 CZ Barrel Shim
25. .690 X .900 10/22 Rifle Barrel Shims
26. .710 X .900 CZ XL Barrel Shim
27. .730 X .900 2500X Barrel Shim
28. .751 X .900 Bull Barrel Shims
29. .710 X .950 CZ XXL Barrel Shim

Rimmed Cartridges use the thickness of the cartridge rim for head-spacing.
.22 Rimfire Cartridges Headspace on the Case Rim.
The Actual Headspace is in the Recessed Face of the Bolt.
You Must Make Sure this Recessed Bolt Face is Equal To or Deeper Than Your Rim for Safety
Generally speaking, there is extra room left in production guns between the Bolt and Breech to accommodate a wide variety of ammunition with varying rim thicknesses.
You should first measure the depth of your bolt face pocket to ensure it meets SAAMI Headspace minimum depth.
Shimming between the two bolt halves ensures the bolt is seating the cartridge up gently against the breech with your chosen brand of ammunition.
You can use our color-coded numbered shims like a gauge to find when the bolt face touches the barrel breech face, and then calculate where you want to be with your bolt headspace depth and rim thickness measurements.
I cannot tell you which shim best works with your rifle; you decide that yourself by fitting and feel and by shooting.
Installing Bolt Shims requires fitting by hand and checking with the Bolt installed in the Rifle and Locked Down - you do not measure with the Bolt out of the Rifle.
To establish the Bolt/Breech fit, shims are installed and fitted on an empty chamber.
If possible, it may give you a better feel if you leave the extractors off some rifles while fitting shims.
Start with a 4 or 5 pack of shims, install the .0015" or .002" thinnest shim and see how your bolt closes. If it seems to close as normal, then continue to install each thicker shim until the bolt starts to close harder than normal, stacking shims if necessary.
At the point where your bolt begins to close hard, that was the amount of slack that was in your bolt, measured by whatever shim or shims combined were needed to bring the bolt up tight to the breech.
Now it is best to remove that shim and step back one number. For 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 have to force or put undue stress on your bolt to close it, you should reduce the number 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.
When you have the correct shim installed, your bolt should close normally or just (ever-so) slightly tighter than normal.
If the bolt closes slightly tight, it is best to back up one step, remove .001".
Put a very small drop of oil on the shim.
Now you can go to the range and, with the barrel pointed in a safe direction, once again check fit with your favorite ammo.
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 get to your sweet spot or required headspace for the rim thickness of your favorite cartridge.
For longest shim life, use a drop of oil or a (very small amount of) grease on your shim.
If you have to force or put undue stress on your bolt to close it, you should reduce the number of shims.
A minimum of clearance should be maintained while maintaining proper headspace. Do not put undue stress on the bolt by shimming too tightly as it is unnecessary!
At no time do you want to force the bolt to close or to crush the rim. Did I explain that clearly?
Forcing the Bolt to Close will put premature wear on the bolt shims and will not increase accuracy.
If you have any questions, use a headspace gauge to check for proper headspace.
Bolt Shims have in many instances cured light strikes.
Will they help with accuracy? Don't take my word for it. Read our Customer Reviews or ask our Customers.
Simply Chambering More Consistently Yields More Consistent Results.
Your Satisfaction is Guaranteed. If you feel you receive no benefit, you may send your shims back to TriggerShims for a Full Refund.

Click Here to Open Instructions in a Printable PDF:
LANCE'S TECH TIP: Rimfire Bolt Shim Installation Instructions

TriggerShims.com Shim Thickness Color Code

All TriggerShims Gun Shims are Made in the USA from Precision Brand American Made 304 Stainless Steel Stock and have a Guaranteed Factory Tolerance of plus or minus 10%.
Shims are marked with colored permanent marker that will wear off or strip off with oils or solvents.
If you are testing, plan on keeping your shims in separate marked small envelopes or using a micrometer.

• .0015" - Yellow
• .002" - Black
• .003" - Blue
• .004" - Purple
• .005" - Red
• .006" - Orange
• .007" - Green
• .008" - Pink
• .009" - Brown
• .010" - Yellow

TriggerShims Bolt Shim Instructions Copyright 2008 - 2025 V7/2025

The Match Chamber, and Rimfire Headspace are two different things.
Generally a Match Chamber is simply a chamber that is held to a tighter tolerance than a production rifle chamber using Premium or Match Chamber Reamers
A discussion of the Match Rimfire Chamber by Eagle Eye Shooting can be found here: (link) https://youtu.be/PzFCbOn_evE

The Chamber is in the barrel, and with a rimfire rifle, the headspace is in the bolt face. The bolt face is manufactured or machined to an average to function with many types of ammunition, both thick rims and thin, and the bolt is installed in a production rifle with additional space so as not to require hand fitting. Knowing how this works you can check and sometimes the bolt can be adjusted to better fit your favorite ammunition.

By reading and understanding the information and examples on the CZ page titled;
TECH TIP PDF: Measuring Headspace on your CZ 457 Rifle by Jack Behrman (link) https://www.triggershims.com/manuals/measuring_headspace_CZ_457.pdf
you can see that:
1) The Chamber is in the Barrel, and does not affect the Headspace
2) The Headspace is in the Bolt, and it's depth can be measured
3) The distance between closed Bolt Face, and the Barrel Breech can vary several thousandths of an inch.
4) The Bolt can be adjusted to move the face forward using shims, and the Barrel can be set back using a lathe, or forward using shims.

Conditions reported to us over the years by customers on different brands of rimfire rifles but specifically CZ Rimfire Rifles range from too tight and forcing the bolt face against the breech with excessive force, to too loose by as much as 0.006" or more. It is very simple to measure your Bolt Face Headspace using a Depth Micrometer, or Caliper, and then use our shims as a measuring tool to shim the bolt to touch the breech by feel.
See my LANCE'S TECH TIP: Rimfire Bolt Shim Installation ~ A General Guide ~ for more information
Using those two numbers, you can better decide what to adjust for best consistency with the rim thickness of your preferred ammunition. If in the unlikely chance your bolt is too tight from the factory, we manufacture Barrel Shims that can be used to address that problem on CZ rifles by moving the barrel forward. A much more likely scenario is to move a slightly slack bolt forward using our Bolt Shims.
It is a fact that if you more uniformly chamber your rounds, you can expect better accuracy simply through consistency.

Accuracy through Consistency - simply put production rifles have a large headspace to accommodate a wide range of rim thicknesses. Precision shooting involves eliminating variables for best accuracy, and using a bolt shim to adjust the headspace to fit a specific rim thickness better is all this involves.
The same principal used if you were to purchase a long shank replacement barrel, you would need a barrel shim to adjust for optimum headspace.

V10/2024

Good Morning Lance,
Another testimonial from a very happy customer. As previously mentioned, I was having failure to extract issues with my CZ457 with a custom ibi barrel. At first I considered that I potentially had a very close tolerance chamber, (which I do - cut with EleyEPS reamer), that was specific for only some types of ammunition. Or perhaps there were imperfections present that interfered with extraction(?). But given the fact that extraction was 100% with some ammo, and dropped to 60-70% with others, led me to measuring rim thickness. There was a consistent difference of 0.002 to 0.003 difference. Bit of a “Aha!” moment. Perhaps there was a bolt/extractor engagement issue. After visiting several websites, chat rooms, etc. I went back to ibi to confirm that I was on the right track. Excellent customer service from these folks, and a subsequent email confirmation that I was on the right path was received. They also list Triggershims.com as the go-to for quality products related to bolt or barrel shims. I visited your site, read other folks reviews and committed to giving the bolt shimming process a try. Following the suggested trial/error fitting procedure, I was up to .007 before I noticed a definite resistance on closing the bolt. Backed off and refitted with shims totalling .0065. Resistance was less and it was time to go to the range for confirmation. Priority one was to determine if the ammunition that I was having major extraction issues with would actually cycle properly. Not one failure out of the first 10 rounds. However, I did note a stiff bolt closure on some cartridges Again, following your direction provided on your site, I backed off to .005 and tried again. Fired a full 100 rounds without one failure! Bolt engagement feels just fine. What a revelation! It would be an understatement to say I’m extremely happy with the result. Your shims are an easy install on the CZ457, and allows me to return to one of my favourite ammunition lines with confidence. Thank you again for making such a great product. Believe I will order another set, just in case lol!
Kindest Regards ~ Stephen in BC

Customer Mike from PA Writes:
Lance, just a note to share the joy :-) your shims in my CZ 457 AT-ONE cut my groups (5 groups of 5 shots including cold bore shot) from 4 inch total of all five groups to 2.065 total of all five groups, almost in half. The CZ needed .007" of shims. It was little hard to open the bolt after firing so I backed down to 006, using a 004 and 002. Still shot a 7/16, a 5/16, a 3/8, a 7/16, a 5/8. Than I put 9 shots in 9/16 at 50 yds. I used to be sure of a 3/4 inch group, with an few 1/2 inch groups. I can't wait to see what I get at 100 yds and 150yds ~ Thank you for your product!

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