Is it the ammo, the gun, or me?

[JA50N]

So I just recently got into shooting precision and I have a 110 Desert tactical in 6.5 Creedmoor that I am trying to develop some reloads for. I started off shoot some factory ammo to see what it likes and narrowed it down to Hornady Match ammo in the 120, 140 and 147 grain flavors.

Here is the question I am having:

When shooting the ammo above I was getting multiple one ragged hole with the 140 and 147 grain loads at the beginning of each group but it seemed to fall apart on the last or second to last round of the 5 round group. Very frustrating. So I started thinking it might be me as I have had no formal training in shooting and everything I have learned I have figured out on my own. Is there any way to isolate what needs improving when it comes to the gun or me? Obviously checking the ammo is pretty easy since I reload but the narrowing down the other seems a bit tougher to me. I was thinking maybe shooting 5 3 shot groups vs 3 5 shot groups if I had a total round count of 15 but I see mixed info on that being valid.

Anybody got any pointers for a guy just starting out it precision shooting? Here is some example groups of what I am talking about:

https://live.staticflickr.com/65535/48569174191_281bc93df8_c.jpg (https://flic.kr/p/2gZTHn2)Untitled (https://flic.kr/p/2gZTHn2) by JASON MCKIMMEY (https://www.flickr.com/photos/152932242@N02/), on Flickr

https://live.staticflickr.com/65535/48569317957_04e0381685_c.jpg (https://flic.kr/p/2gZUs6K)Untitled (https://flic.kr/p/2gZUs6K) by JASON MCKIMMEY (https://www.flickr.com/photos/152932242@N02/), on Flickr

https://live.staticflickr.com/65535/48569315532_7aa7112811_c.jpg (https://flic.kr/p/2gZUrnW)Untitled (https://flic.kr/p/2gZUrnW) by JASON MCKIMMEY (https://www.flickr.com/photos/152932242@N02/), on Flickr

https://live.staticflickr.com/65535/48569315862_f79c87f073_c.jpg (https://flic.kr/p/2gZUrtC)Untitled (https://flic.kr/p/2gZUrtC) by JASON MCKIMMEY (https://www.flickr.com/photos/152932242@N02/), on Flickr

[Robinhood]

Stay relaxed, focus on breathing. remain consistent. Do the same thing every shot. Same pressure on the stock. relax the thumb and concentrate on smooth trigger pull. Do not load a round in the chamber until you are ready to shoot. Keep the bolt open, relax get in position, chamber the round and fire. If you don't fire in 5 or 10 seconds open the bolt and get the cartridge out of battery.

[hamiltonkiler]

Looks like sub min groups to me. Bed it. Make sure stock is well away from barrel. Breath and squeeze. I like serria bullets in a factory match load.

[Monkeymaster]

Being you say it is the last to get 2nd last round, your barrel may be heating up.
Not uncommon for this to happen, with all brands of rifles, barrel makes ect.
Try giving your barrel a couple minutes or more between shots.
I have a 270 I will not shoot when it is 70 degrees or warmer.
Sun beating down on your barrel will heat it up, and keep it hot also, try to shoot in the shade.
My 2 pennies
Good luck