Accuracy Improves when Barrel heats up

[Endyo]

Help me understand this phenomenon.

Groups have been averaging in the .3s, .4s, .5s. During load development groups would sometimes start grouping in the .1s and .2s and I never understood why.

At the range yesterday I was fine tuning a new lot of powder. I was also testing other trivial things such as uniforming primer pockets. I've done 600+ rounds of load development on this rifle at this point (90% of my shooting is perpetual load development..). The sun was setting on me so I cranked out 33 rounds in about as many minutes much faster than I normally shoot.

To my surprise in fading sunlight with a slightly hazy sight picture my last 3 groups came in the mid .2s when the exact same loads that were shooting in the .4s, .5s earlier in the range session.

The last group was the control group which normally shot in the .3s-.5s. So no it wasn't from uniforming primer pockets that groups shrunk that group shot average in the .4s

I did a pair of 3-shot groups when I tested seating depth. All groups on the left were shot on a cold barrel and after 30 rounds the groups on the right were shot with a moderately warm barrel.

I went back and started studying my old targets. I found another instance of this phenomenon more pronouced. Attached is the same phenomenon on a different day.



The velocity and ES are very close between the groups on left vs groups on right.
The barrel is floated I tested it before writing this.
Is it possible the barrel is contacting the stock during the harmonics while the bullet is traveling?

I understood that groups generally open up with a hot barrel secondary to vertical stringing or other issues.

My groups have been getting drastically smaller. I have not heard of this. I'd love to diagnose this and replicate so my rifle starts grouping in the .1s and 2.s consistently

 

[Sheldon N]

The sun was setting on me so I cranked out 33 rounds in about as many minutes much faster than I normally shoot.

Any possibility that the faster shooting was done in a more relaxed consistent manner, improving your general shooting technique?

I've observed the same thing in my own shooting.... try too hard, concentrate too much, tense up and shoot poorly. Get frustrated and rip out a couple 5 shot groups just to finish up the day and the rounds stack on top of each other. I've always chalked that up to me just relaxing and being consistent in my technique once I stop trying so hard.

 

[BenPerfected]

Any possibility that the faster shooting was done in a more relaxed consistent manner, improving your general shooting technique?

I've observed the same thing in my own shooting.... try too hard, concentrate too much, tense up and shoot poorly. Get frustrated and rip out a couple 5 shot groups just to finish up the day and the rounds stack on top of each other. I've always chalked that up to me just relaxing and being consistent in my technique once I stop trying so hard.

Might be the different in the SD. You show some jumped from .013-.030 and some jammed .030.

 

[Endyo]

Any possibility that the faster shooting was done in a more relaxed consistent manner, improving your general shooting technique?

I've observed the same thing in my own shooting.... try too hard, concentrate too much, tense up and shoot poorly. Get frustrated and rip out a couple 5 shot groups just to finish up the day and the rounds stack on top of each other. I've always chalked that up to me just relaxing and being consistent in my technique once I stop trying so hard.

I kept the same pace during the entire range session yesterday 2/3/16.

The target posted above was from a slow fire day 1/29/16. These groups just happened to be the first of the day (left-cold barrel) and last of the day (right-warmer barrel) and conveniently on the same target.

I didn't feel any change in focus. I did notice velocity increased 5-8fps every 12 shots. All velocity changes were still within my known accuracy node.

In the Texas State match last year on the last relay of the shoot my rifle shot it's best in the worst mirage conditions all shoot. I thought it was me improving, lol, it may have just been the rifle...

This very well could be a mental thing or purely coincidence, but I've noticed it on more than one occasion.

 

[Endyo]

Might be the different in the SD. You show some jumped from .013-.030 and some jammed .030.

Sorry my handwriting is poor.

The groups on the left and the groups on the right would have both been the same jump/jam.

I loaded 6 rounds total to fire two-3 shot groups. I started with these particular loads and finished the day with the same loads some 30 rounds later.

 

[LHSmith]

The thread could also be titled " Accuracy Improves With Fouling". I don't suppose any type of wind flags were employed?

 

[joshb]

My groups always seem to get better after I settle in. IF you actually do have a barrel that shoots better hot? Run with it!

 

[Endyo]

The thread could also be titled " Accuracy Improves With Fouling". I don't suppose any type of wind flags were employed?

Very possibly. The bore had 36 rounds on it prior to it's last cleaning.

That would be a drastic change in accuracy between 36 dirty rounds and 60ish dirty rounds.

No wind flags.

 

[LHSmith]

Very possibly. The bore had 36 rounds on it prior to it's last cleaning.

That would be a drastic change in accuracy between 36 dirty rounds and 60ish dirty rounds.

No wind flags.

IMHO without some type of wind reading aid, your quest to shoot consistently small will be a long one.
Try again without introducing so many variables. Nail one thing down at a time.

 

[Fotheringill]

Two questions-

How often were you cleaning the barrel?

How warm is warm?

Someone at my range gave me a heat sensor stick on strip for my barrel. He said he got it from McMaster-Carr. I can' find the product at its website and the guy disappeared.

Another Q- does anyone know the link to the product?

 

[Homerange]

Hmmm it appears your POI is set sightly right although not all groups demonstrate that so yes wind would seem to be a factor. For better results I've gone to different targets... a small white square surrounded with a thick black border. Quarter it with the scope cross hairs for an extremely precise aim point.

 

[LHSmith]

Two questions-

How often were you cleaning the barrel?

How warm is warm?

Someone at my range gave me a heat sensor stick on strip for my barrel. He said he got it from McMaster-Carr. I can' find the product at its website and the guy disappeared.

Another Q- does anyone know the link to the product?

There was a "Bulletin" on these.....do a search

 

[LHSmith]

If you look real close, the bullet holes on the left are oblong, the ones on the right targets are smaller and round. What was the time interval between targets?. Always record time, temp., RH%, and light conditions on your targets. Are those chrono's avg?

 

[Dusty Stevens]

Shooting faster lets you get more in before the conditions change and a warm barrel always shoots better- ask any br shooter if they heat their barrel up before they shoot a group. Some call it fouling some call it heating. Works in all barrels from rimfires to the biggest centerfires

 

[KMart]

McMaster Carr
Temperature indicating strips
http://www.mcmaster.com/#temperature-indicating-labels/=10zgch0

 

[Endyo]

I believe we are shooting different disciplines based on the advice that I've been receiving.

I'm willing to learn from it and borrow techniques if there's room for improvement.

We aren't allowed to use our own wind flags.

We also shoot a high volume of rounds so I consider a barrel with less than 100 rounds since last cleaning "clean". I've noticed groups start to tighten up after 150-200 rounds.

I believe my groups opening up a bit as of late may be partially due to this.

 

[LHSmith]

It's usually helpful for the OP to state what his shooting objectives are so that answers can be geared to certain disciplines. As to flags, when your doing load development you're free to use whatever tools necessary in order to gain usable information. IMHO without flags, it's just plinking.

 

[1shot]

This thread is of great interest to me, although I shoot sling/prone LR. I used to be meticulous in cleaning after every days shooting at the Nationals. Without going into why I changed, one year I shot all four days without cleaning the bore, just cleaning and greasing the fire control system. My scores got better with every day regardless of conditions. I used to shoot 2 maybe 3 sighters then go for record. More times than not the 1st shot for record was a 9. I started taking an extra "warming shot" and started shooting 10's or X's on the first record shot. I tend to shoot very fast for 22-25 rounds in about 16-18 minutes weather and good pit service not with standing. My barrels get extremely hot to the point you can't touch them but they sure do shoot well in that condition.
I hope this helps,
Lloyd