@JungleShooter I don’t know, I but may have an idea or two concerning the popularity of the caliber. Allow me to preface this post by saying that this is conjecture based upon what I’ve retained from reading. The 7.62/.30 has been a popular round in the United States for over 100 years. The 30-06 was used militarily and in the civilian sectors. .30 speaks to the caliber and I believe that “-06” corresponds to 1906, the year the 30-06 cartridge was introduced. It remained popular militarily, for hunting, protection, etc up until the years between World War I and World War II. During this time the .308 cartridge was adopted and replaced the 30-06 with improved range. Again after military adoption I assume that when soldiers transition into civilian life their weapon familiarity stays with them consequently the .308 became a popular round from similar reasons as the 30-06 did.
Based upon the aforementioned information it is easy to understand why bullets, reloading equipment, molds, etc are widely available. Inalso think that hunting regulations may have been shaped around the proven efficacy of this caliber. I think this is where the PB world and airgun world may intersect. I don’t know much about ballistics so other members with better knowledge of ballistics and ballistic coefficients can speak to that regarding this caliber. These are purely ideas and suspicions that I formulated based upon info I recall reading after reading your post. I didn’t Google anything before posting this. Wherever I’m incorrect I’m sure members won’t hesitate to correct me. However, considering these things it does seem plausible why the .30 caliber has a place in the airgun world. For airgunners it creates a bigger hole than .22, .25 calibers. If you can produce enough fpe with it some states allow you to hunt certain animals with a .30 air rifle. If we can get expansion like the above photo shows, even better. It should lead to a swifter death after hitting vital organs, veins, and arteries.
@estarkey7 I hope you don’t mind me posting this in your thread.