I hit a buck there the year before last hunting on a buddies family land down in Dilley.
It was not a shot I chose however he jerked and that’s where the bullet and you’re right his legs buckled and he laid there twitching for maybe a minute.

I have honestly thought about taking that shot again however I’ve never been a gambling person and stick to heart/lungs.

The learning experience from taking any shot/kill is to then gut and process the deer yourself. You then get to see exactly where you hit and what the damage was like. To see what to improve on or do exactly the same on the next shot. Once you take that shot a few times you can place that shot without thinking about it. I learned to do a necropsy from an in-the-field seminar where a deer shot was videoed way back in 1992. We then watched as the deer necropsy done to show shot placement, wound channel and other info that could be gained while cleaning a deer.

These are my shot placement preferences. I have taken these shots with a .223, 6mm, .270 and a few with the .280. All with Remington ammo except the .280 is with Federal Premium. The slightly quartering to me angle is my preferred placement. The back legs drop out from under the deer and after they hit the ground, they never move again. I have been using all three of these shots since 1991.

Do you have any other pic's of that big bodied mule deer? You're right about one thing, "magnum" alone means nothing without shot placement and the right bullet. At those very short distances it is likely that your bullet didn't open up and you punched small Ø holes in his lungs. Your whitetail that dropped at 500, what was shot placement? OP had a question, and my response was to make the point was to put emphasis on shot placement.

I hit a buck there the year before last hunting on a buddies family land down in Dilley.
It was not a shot I chose however he jerked and that’s where the bullet and you’re right his legs buckled and he laid there twitching for maybe a minute.

I have honestly thought about taking that shot again however I’ve never been a gambling person and stick to heart/lungs.

What bullet, and shot placement? I'm going out on a limb and betting it wasn't a lung shot, nor was it inside 20 yards with no chance for your bullet to expand.

Nothing is a gamble with that shot.

It’s almost foolproof with a proper caliber and good bullet.

My motto is: “ if it’s going on the wall, put it in the shoulder”. If I lose the meat on both shoulders so be it.

I have used my Remington .270 with 130 grains Corelokts to kill Red Stags and Mule Deer in Alberta/West Texas all with high shoulder shots. The Mule Deer in Alberta field dressed well over 300 lbs. I used that rifle and ammo combo since it was all I had. I just made sure I put the bullet where it needed to go. If I had a larger caliber I might would have used it but I did not at the time. So I took what I had. I have used the same combo on WT and exotics here in Texas for years. My largest WT dressed 190 lbs. Take what you are comfortable shooting and have the most confidence in.

"bigger bullets allow poorer shot placement" - for me that is the key. I think I am a pretty good shot - however things happen - get bumped, deer moves at last second, etc. Therefore I prefer (especially on trophy animals) to go with higher caliber and bullet size to compensate for potential errors

I have used my .270 with 130 grains Corelokts t.

That is where I used to aim, but on my first safari, the outfitter didn't like it when I did that and strongly suggested that I aim for the heart on the next animal. His reasoning was that anything shot in the hear will die, but there is a risk of it not dying if you aim anywhere else, and for him, there will be a lot of time spent tracking it if it wasn't a heart shot. Since it was his ranch and I was paying him for his expertise along with the animals there, I listened and shot my next animal in the heart. It ran a short distance and died cleanly. That was in 1993, and I've aimed for the heart on every animal that I've shot since then. This is also why I don't feel caliber size is all that important as long as it's in the appropriate range for what you are hunting. 130 grain bullets and up are all going to give you the same results if you take out the animals heart. Bigger bullets allow poorer shot placement, but even a 200 grain bullet in the wrong spot can lead to lots of tracking and even losing the animal. Shot placement is by far the most important concern.

This mule deer weight between 300-315 on cotton scales. Dropped him like a prom dress at 160 yds with a 7mm0i8 and 140 Accubond. High shoulder shot.

That's ridiculous. Larger calibers do not make up for bad shots, ever. I've watched big aoudad rams drop dead from a 95gr ballistic tip out of a 243, and run off never to be found from a misplaced 300RM.

I am a prime example of this. In my mid 20s I was hunting with a 375 H&H that I had become proficient with. Adrenaline got the best of me and it took 7 poor shots to take down an aoudad. That was 7 actual hits and it got back up and kept running each time. The aoudad were considered a nuisance on that ranch and I was obligated to shoot everyone I saw. The first shot was on a running animal at 285 yards. I was in control on that shot, every shot thereafter was burning up ammo and adrenaline. That proved unequivocally to me that energy will never replace shot placement. I still get “buck fever” just as bad but I’ve matured to know when not to take a shot.

This mule deer weight between 300-315 on cotton scales. Dropped him like a prom dress at 160 yds with a 7mm0i8 and 140 Accubond. High shoulder shot.

I have never said shot placement is not the key - of course it is. My point is not every shot someone takes at a live animal will be perfect placement. So if a 95 grain load and a 180 grain load both were to hit in the exact same spot the 180 grain load is going to do more tissue and organ damage than a 96 grain.

That's ridiculous. Larger calibers do not make up for bad shots, ever. I've watched big aoudad rams drop dead from a 95gr ballistic tip out of a 243, and run off never to be found from a misplaced 300RM.