You can get the Safeguard achievement most easily by playing locally and setting max health and fast health regeneration.
Loot rounds always last 25 seconds and give you 8 care packages.
The more teammates you have the more enemies there are each wave. Playing solo wave 2 has 13 enemies, but with 4 players wave 2 has 20 enemies.
Your loadout: MP-443 Grach w/ ext mags, 1 IED, 1 concussion grenade, 1 support squadmate
1 - Loot round
2 - Shotgunners
3 - Shotgunners
4 - Shotgunners
5 - SMG + shotgunners + dogs
6 - Loot round
7 - SMGs + shotgunners
8 - SMGs + shotgunners + dogs
9 - SMGs + riot shields
10 - SMGs + riot shields + dogs
11 - Loot round
12 - SMGs + riot shields
13 - Noob tubers + SMGs
14 - Noob tubers + SMGs + dogs
15 - Noob tubers + SMGs
16 - Loot Round
17 - Noob tubers + SMGs
18 - Noob tubers + SMGs + riot shields
19 - Noob tubers + SMGs + riot shields + dogs
20 - Noob tubers + SMGs + riot shields
(this is my first pass at the wave contents, I may update this if I find I've made a mistake)
Safeguard Extended and Infinite
A loot round followed by 4 waves of enemies most of who wield noob tubes and SMGs.