The patented CST Auto Bolt Stop Kit is the world’s only last shot bolt hold open device currently available for the Ruger 10/22 rifle. It is designed to automatically stop the forward travel of the bolt upon its full retraction if and when there is an absence of another cartridge. Upon the discharge and ejection of the last round loaded in the rifle, the auto-bolt stop mechanism will detect the absence of a fresh cartridge and automatically stop the bolt's forward travel upon an empty chamber. To load the rifle with the bolt locked open, insert a loaded CST modified magazine (supplied in the kit) and simply pull rearward the bolt and let go. The cartridge present in the magazine will trip the auto-bolt stop mechanism and allow the bolt to carry the cartridge forward into the chamber. The auto-bolt stop tab located next to the magazine latch is designed to manually release the bolt from a locked position. Manual bolt stop release is primarily needed to close the bolt on an empty chamber or can be used to clear a jam during a firing session. To use the manual release function you should pull back on the bolt to relieve tension on the bolt stop, and then push forward the auto-bolt stop tab, and while holding the tab forward, release the bolt.




The CST 10/22 Automatic Bolt Stop Kit
10/22 Parts
TF1 Action


To unload the rifle, remove the magazine and pull back the bolt until it automatically stops in an open position. This will clear the chamber of a live round and lock the bolt open, exposing an empty chamber. Some tight chambered match barrels may not extract a live cartridge.

The CST Automatic Bolt Stop is fully compatible with most aftermarket products for the Ruger 10/22 rifle, including magazine latches, triggers, sears, hammers, etc. Fitting may be required when using Volquartsen trigger assemblies or bolts. MOST IMPORTANTLY, FOR THE AUTO-BOLT STOP MECHANISM TO FUNCTION CORRECTLY ONLY CST MODIFIED MAGAZINES CAN BE USED.

CST Auto Bolt Stop, .22LR with new 10 round modified magazine for standard trigger assemblies. $59.95 #1001

CST Auto Bolt Stop, .22LR with new 10 round modified magazine for Volquartsen trigger assemblies. NOTE: Fitting may be required for proper function with Volquartsen TG2000 trigger assemblies. $62.95 #1001V

CST Auto Bolt Stop, .22MAG/.17HMR with new 9 round modified magazine for standard trigger assemblies. $67.95 #2001

CST Auto Bolt Stop, .22MAG/.17HMR with new 9 round modified magazine for Volquartsen trigger assemblies. NOTE: Fitting may be required for proper function with Volquartsen TG2000 trigger assemblies. $70.95 #2001V

About CST Modified Magazines:

The CST Auto Bolt Stop works by a lengthened ejector/lever relaying directly on the cartridge rim. If there is no cartridge rim present, then the bolt gets stopped. This simple concept requires a clearance cut in the magazine to expose the cartridge rim.

Unmodified magazines will not work with the CST Auto Bolt Stop. Without the necessary clearance cut in the rear of the magazine mouth, the bolt stop mechanism will be put in a bind and will not allow forward movement of the bolt, rendering the rifle inoperable. This can also lead to damage to the auto bolt stop mechanism. All CST modified magazines are completely compatible with factory 10/22 rifles, with or without the auto bolt stop installed. Although a modified magazine is supplied in each Auto Bolt Stop Kit, CST also offers extra magazines
New CST 10 round Modified Magazine, .22LR. $19.95 #1500

New CST 10 round Modified Magazine, Clear 40th Anniversary, .22LR. $21.95 #1500-40

*(5 round Ruger magazines available upon request)

New CST 9 round Modified Magazine, .22MAG/.17HMR. $21.95 #2500


Customer Supplied Magazines:

In addition to offering new CST Modified magazines both individually and with the Auto-Bolt Stop Kits, CST will be happy to modify your existing Ruger magazines. This can be a very affordable option for any extra Ruger magazines you may have on hand. Also remember, as with new modified magazines, once your magazines are modified they will still function fine in any 10/22, with or without an auto-bolt stop installed.

The warranty covers a new modified magazine as well as a modified customer supplied magazine, as long as the supplied magazine is found to be free of defects. Every CST Modified Magazine, new or customer supplied, has been identified by "CST MOD MAG" stamped clearly on the bottom of the magazine. Using unmodified magazines or anything else won't work and voids the warranty.

In addition to the standard (BX-1) .22LR magazines, CST will also modify the Ruger 40th Anniversary and 5-round magazines. The Ruger 77/22 magazines are not compatible with the 10/22 and should not be used or modified.

All CST Modified Magazines are completely disassembled and rebuilt in 6 steps:

1) If the magazine is customer supplied, it gets inspected and completely cleaned.
2) The magazine throat has the necessary clearance cut CNC machined in place and then it is completely deburred and polished.
3) A clearance cut is also cut in the rear plastic plate and then it is completely deburred, including the common burrs left from the factory underneath the hex nut.
4) The socket head screw is carefully turned in a lathe and 100% inspected for correct height. It is then deburred and reblued.
5) The magazine body is stamped to identify it as an authentic CST Modified Magazine.
6) Each magazine is then reassembled with the correct spring tension on the follower (2 to 2 1/2 turns) and properly snugged for reliable function.


Customer supplied magazines can be modified for $10.95 each plus $5.75 shipping for under $100.00 orders. (See shipping rates.) To have your magazines modified simply ship them with a check or money order along with your return mailing information to the following address:

CST, Inc.
8794 Elmburg Road
Bagdad, KY 40003



Aftermarket 10/22 Magazines:

Several attempts to modify aftermarket magazines were all found to produce unsatisfactory results. Most companies have departed from the steel throat configuration that Ruger uses with their rotary magazines. This usually orients the cartridge incorrectly and creates incorrect geometry for the auto bolt stop device to work properly. High capacity aftermarket magazines yield a greater range of spring pressure on the cartridges from fully loaded to the last few rounds making proper function of the auto bolt stop device problematic. Also keep in mind that some aftermarket magazines function unreliably right out of the box.

CST Auto Bolt Stop Return Policy:

Custom Shooting Technologies, Inc. guarantees the Auto Bolt Stop and Modified Magazines to be free of defects for a lifetime of use. For any reason a customer becomes unhappy with our products, simply return the item for a full refund.

However, any damage to the 10/22 auto bolt stop caused by using any other magazine other than CST modified magazines voids this lifetime warranty. All CST modified magazines have been identified with "CST MOD MAG" clearly stamped on the bottom of each magazine.