No. 10 & 11 cap sizes?

I have a small older pistol I wanted to test with only a cap. I only had some no. 10 caps. They didn't want to fit the nipple very well...didn't want to go forward on the nipple. They would actually protrude back into the recoil shield, such that I couldn't turn the cylinder. I wound up rotating a chamber under the half cock position and sticking the cap on. I fired only one! The question what is the actual difference in sizes...that is length, width, etc,?

Someone else will chime in on the exact sizes , but in my experience a CCI No.10 is too small for most nipples. Remington No.10 is just right especially for revolvers. No 11 CCI usually work fine for rifle nipples but are loose on my revolvers unless crimped between the fingers before using.......................Bob

The above information is the arithmetic average of measurements from at least 20 samples of each size and brand. Although the results are presented to 3 decimal places (thousandths of an inch) please understand that you do not get 0.001" precision for 4 cents. The opening diameter is especially difficult to make reliably with a vernier caliper; those numbers should be considered to have an error term of at least 0.002" and probably more like 0.004" when considering any single cap.

You will no doubt notice that the 'size' number is essentially meaningless. CCI No. 10 caps are not the same size as Remington No. 10 caps; the same applies to No. 11 caps from the two companies. Also, please notice that Remington No. 10 caps are actually larger than Remington No. 11 caps.

Finally, there is evidence that the above information varies considerably from one batch to another within a given brand and size.

In short: cap sizes are a manure shoot. What fits today may not fit tomorrow.:idunno: :surrender: Have a nice day.

Thanks for taking the the time to post the data! Good to know when trying to get a good fit. I did read somewhere, the no 10's were supposedly a good fit for the Italian replicas, but not originals. :v

Even that is a definite maybe :youcrazy:
My Uberti made '58 Remington in .44 would not take #10 CCI caps on the factory-fitted nipples. It would misfire constantly & the fix was to re-strike the nipple a second time to ram it down onto the nipples enough.
I replaced the factory with some SS aftermarket ones & went to #11 CCIcaps & the problem went away.

Imagine what it must have been like in 1860! The wagons circled, bad guys attacking, and your hammer just went 'Click'...get out the horn fill each chamber, put in a ball, ram the lever...do it again,then wrap your fat little shaking fingers around a wee, tiny cap and try to press one on each of six nipples...perhaps having to squeeze them to stay on...Wow! Now, with all the modern machinery, CNC driven, and we still gotta screw around............where's my 9mm?