The ICAO regulations govern transport/shipping of loaded ammunition and firearms on commercial passenger aircraft, not TSA. That said, it is still up to each airline if they want to allow firearms or ammunition onboard their aircraft. If they do, they can NOT exceed the limits established by the ICAO. A significant number don't allow firearms or ammo at all. The limit for ammo is 5 kilograms (just a shade over 11 US pounds) of loaded ammo per passenger. The actual ICAO regulation does not include the weight of the locked transport case. I have been a little over the total weight limit checking in a couple of times. Discussed it with the check-in agent and took the boxed ammo out of the case and weighed it by itself.. The loaded/boxed ammo was under the 11 pound limit. Agents accepted and continued on just fine with it all back in the locked transport case.
It's not just the airlines having ammo and firearm entry restrictions. THEORETICALLY, a non-hunting traveling companion could get extra ammo on the aircraft. The trouble becomes when you try to enter the country without bringing in an accompanying firearm and temp import permit and invitation/motivation letters from the PH/Outfitter.
NAM VAT tax can only be refunded for items purchased in Namibia and taken out of the country. It can NOT be refunded for good/services and restaurants and lodging. VAT on exported taxidermy can be refunded. However, they require you to have any items the refund is requested for be with you at the airport, where you apply for the refund, the day you depart. Makes taxidermy refunds unlikely, unless you do what I've done several times, bring the previous years taxidermy back with you as excess checked luggage on your return flights. You do still need to have all the proper Nam export and US import permits in your hands to process thru/out of the airport in Windhoek.
They do have a process where you can email your taxidermy receipts into the tax office after your stuff gets home and they say they will mail out a check (in Namibian Dollars). I tried this once. Emailed copies of the proper forms and receipts/invoices to the email address I was given, multiple follow-up emails to multiple other individuals and offices and....nothing.
I've made a LOT of trips to Namibia starting in 2007. Sometimes three a year. Only years I didn't make at least one trip was 2018 and 2020. Didn't go in 2018 because the drought was so bad and we went to Australia for a month of sightseeing and a week of water buffalo culling in the NWT. Didn't go in 2020 due to the Rona lockdowns. A very sever drought started there in 2012-2013 that effected nearly the entire country with the exception of the Caprivi Strip area. It finally broke about 3-4 years go. It devastated the game and and domestic livestock populations. They are both still recovering and will take years to get back to pre-drought populations. Cull hunts will be difficult but not impossible to find because most operations are letting everything live they can to restock. That is why I agree with agree with IvW above that 40 head is optimistic in Namibia.
I was in the Tuli block of Botswana this past Aug-Sep where PG populations are at least 50x (not exaggerated) what I saw in NW Namibia last June 2022 for 14-days. In 10-days of culling on Bots, I took 40 head combined of impala, blue w/b and zebra. I don't think I even saw that many head on 50,000 acres of low-fence, free range land in Namibia the entire 14-days in Nam. I took 100 rds of 9.3x62 ammo and had 52 rds left. Are or will there be perhaps a few high-fence operation in 2024 with some culls to take....possibly.
Also something to be sure to ask about before you book a cull/management hunt with ANYONE, ANYWHERE - what are the "rules" regarding wounded/lost game. In trophy hunting, the general "rule" is if you wound it and it's not recovered, the TF is still due and payable. Just because your doing a cull/management hunt doesn't mean wounded/lost game doesn't mean you don't pay the cull/management fees. Some places MAY even charge an extra fee for the wounded/lost game based on the average weight of each species for the lost income from the meat sales either directly neighbors or to commercial butcheries. SOME do. SOME don't. It's just something you need to ask upfront so you don't get an unpleasant surprise. My point being, just because it's cull/management hunting it not just taking willie nillie shots at everything you see. Every animal possible is still recovered an eaten/utilized by someone.
Just my opinion - take it or trash it as you wish.