'Whig' - You have a very legitimate model 1902 carbine sight. Congratulations, only 1,000 of these were made.

If the 1902 top was on a model 1898 base, which has a different type of leaf spring and a lower elevation ramp, it would indicate a questionable rear-sight, likely put together by a surplus dealer.

It appears the standard rifle front barrel-band did a lot of the damage to your stock tip. It was 'force fit'.

Here's a couple of pictures of real PC 'short rifles'.

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