I have some NRA .22LR rimfire empty chamber indicators (ECI) that are no longer sold by the NRA (through the Instructor and Trainer resource materials store). They work well enough and I like to give them away to folks, but I decided to modify the ECI I use for the AR platform for the Vudoo Gun Works V-22.
Brownells sells what is universally accepted as the NRA/CMP ECI for AR-15 High Power Service rifles. The reason why I like this specific one is because it is heat and impact resistant and can hold up to a bolt slamming onto it. It will not immediately break, cut, shatter, or otherwise be damaged as a result of accidental bolt closure (which could leave an obstruction in the bore and cause a catastrophic failure).
Note: I tested one of these specific ECIs in an M1 Garand several years ago. The M1 Garand is notorious for being hard on plastic ECIs if the bolt were to slam closed on one and I have seen an M1 Garand cut through the old CMP-designed ECIs very easily. This specific ECI held up to several M1 Garand bolt slams.
Anyway, the great thing about this specific ECI design is that it fits 22 caliber bores. The only problem is that it’s a bit long to use for .22LR rifles.
So I simply cut one down.
The stem is about 4-1/4 inches long and I cut it down to about 1-3/4 inches after some trial and error (taking a little bit off, fitting, and repeat until good).
Right at 1-3/4″, it seems like it is just the right length so it’s not excessively long and it the ECI won’t accidentally fall out due to gravity (rifle in the muzzle up position) or being jostled while inserted into the Vudoo V-22 chamber.
As you can see above, you can close the bolt onto the ECI without issue and with the bolt all the way back, the ECI will not easily come out inadvertently.
But if you want to remove it, it’s a simple pull and twist to get it to clear the bolt and ejection port.
Hope this helps. The only place I know currently to get these from is Brownells / Sinclairs. Search on the Brownells website for: AR-15 safety flag.