Burnside Carbine Box?

[FrankT]

Hello I am looking for some assistance. I have seen this identified as a Spencer and a Burnside box. I also had a question related to the straps being cut. I saw one example online that said it was a period modification. Curious as to this. The maker I am pretty confident is Dingee & Lorigan. Any insight to this box in general is appreciated. I am fairly confident it is legit , but if something jumps out at you please let me know. There is a star type mark on the back and I seem to remember that was an inspection stamp from the Army? TIA

 

[Salterr]

What's the measurement on the drilled holes?

 

[FrankT]

I don't have a precise measurement tool. But about 10/16 of an inch. I have a Burnside cartridge, and I just noticed the front holes are deeper than the rear holes.