Well it is beautifully done modified carbine. I see a 96 stock and blued receiver and hardware. Unfortunately not original. Others will give you more details. Dick's info on using Apple products will not apply if you are using a windows machine.
I right click on the photo to be edited and choose open with paintbrush. Paint brush will have an Icon near the upper left that says resize photo or something like that. If you are starting with a very big photo try 50 or 60 percent in place of 100%. If you need to get a small amount decrease 96% percent could work. Once you enter a number it should show up in both directions.
When finished save it as a revised name with a JPG extension (keeps prom destroying the original). After you have saved it check properties of the saved photo. If you hit it well all is good. If not delete it and try again on the original.