The Evil Within: Ch13 - The Freezer Room. NG/No Upgrades/No Keys/AKUMU. A safe-ish strat.

A strategy that works repeatably for me. Requires 5 explosive bolts (so 15 parts if you don't have any already) , 5 bullets, and 1 shock (from the previous room.) The video has several runs to show some of the variations depending on where he/the roomba spawns. The health script is a little wonky, but hopefully gives you an idea about what damage the weapons are doing.
1. First attack is always across the room 45 degrees. Plant the explosive bolt, change to shock, then shoot with handgun. An easy kill.
2. A roomba will start up. If lucky it will be on right hand side and you can shoot the shock bolt near it. If you can't see it, then either shoot the bolt close to you or into the middle-ish of the room. The roomba will be the only thing that should have a chance to kill you here if the shock doesn't take it out. I hate the roombas!
3. Second attack. If the enemy spawns:
Near right side: run to far right, turn and plant 2 bombs at what looks like a drainage cover. Restock while you wait for the explosions, and run back to the alcove after the explosions kill him.
Far or mid-right side: Another easy kill. Plant the bombs and wait for him to run into them. Duck and restock while you wait.
Unseen (Left hand side): If you can't see where he spawns - its the left hand - usually the mid-left - side. You'll hear him bang his head before he does an aggressive b-line for you. Before that happens, shoot 2 bolts close together a bit further around to the left than the first attack path (see video). Move against the alcove wall to remove chance of shrapnel killing you (akumu), and restock
4. Final attack. Standing in the alcove, this always appears to be the near right side. As 3.1 above.
5. Pick up bullets and shotgun shots if required.
6. Escape.
Tips
As always, expect the game to do something random. Be ready to run and shoot if the 2 bombs don't do it for whatever reason, but always go back to the alcove to keep things consistent.
Shotgun can do 0 damage while he is on his knees if you hit him head on. The handgun can be better in that situation.
Don't shoot the Executioner's head (zero damage taken.) And watch out for the meat getting in the way of your shots.
You can use the handgun (or shotgun) method again by restocking, and if the Executioner goes down on his knee, or your willing to do some running around the meat in circles, turn shoot, repeat.
Don't go through the hanging meat if you don't have to - it really slows you down.
Avoid the traps.

[@xymox12]

See the description for info on the strategy. Update: From initial tests it looks like 3 of the 6 Executioners will "take the knee" with 1 explosive. The first one, the far right, and near left. You can force the far right one, as the last one to spawn of the 3 needed, if you run up to beside it and wait for it to spawn, picking up the bullets, then run back to the alcove. Plant an explosive bolt and start shooting as soon as his spawning animation is complete (otherwise 0 damage.) That reduces the bolts required by 1. It might be possible to force the near left to spawn as number 2 but yet to figure that out.
All the others will hardly pause with 1 explosive, so best to use 2 to be sure, or in use 1 in combo with a higher powered weapon.
The roomba is still the my worst enemy in this room if it doesn't launch from the right hand side or runs into my shock bolt quickly.