Photograph from rear of <a href="https://en.wikipedia.org/wiki/QF_2.95_inch_Mountain_Gun" class="extiw" title="en:QF 2.95 inch Mountain Gun">QF 2.95 inch Mountain Gun</a>, US Army service.
United States. Army. Ordnance Dept
1920-05
<p>Handbook of artillery : including mobile, anti-aircraft and trench matériel (1920)
</p>
<br><a rel="nofollow" class="external free" href="https://archive.org/details/handbookofartill00unitrich">https://archive.org/details/handbookofartill00unitrich</a>