Funny thing during load development

S

shell_guy

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Hey guys, working on some load development for my 5r .308 and I have notice a trend with my hotter loads. It would seem that my first 2 shots in a group are consistent and tight and my second 2 shots are also tight but have a distinctly different POI. Rifle details:
700 R5 .308
Bedded in McMillan A5
Bipod
ATRS Rear pack
Vais Brake
Sightron Siii 8-32
20moa ATRS Rail and ATRS rings

Rifle will shoot .3-.5 MOA with FGMM.

I did an OCW test a week or so ago, picked my 2 best charge weights, then I added .2gn to each of those.

Taget and load details: All shoot with Berger 168 Hybrid and CCI Br2 primers
Load 1 Load 1 Load 2 Load 2
Load 3 Load 3 Load 4

Load 1 - N550 45.6gn
Load 2 - N550 46.7gn
Load 3 - N550 47.0gn
Load 4 - N550 47.2gn (over max, no pressure signs)

I would just assume that it is the shooter pulling the shots, but it seems strange to me that I would pull 2 shots so consistently.
 
I'm curious to see what the more experienced shooters have to say about this, I had the same thing happen to me a couple days ago but not as pronounced as yours. My last three shots of each 5 shot group would print left of the first two. I'm assuming it's the shooter in my case, must be something I'm doing subconsciously.
 
JayCarver said:
I'm curious to see what the more experienced shooters have to say about this, I had the same thing happen to me a couple days ago but not as pronounced as yours. My last three shots of each 5 shot group would print left of the first two. I'm assuming it's the shooter in my case, must be something I'm doing subconsciously.
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I have a pretty good idea that it's not me, but I could be wrong. Again as previously stated, I can shoot consistent .3-.5moa with FGMM. The first group on this page was a reload and measures .32".
 
Here's pics of my target's that show the same thing as Shell_Guy.




90% of the groups the first shots printed on the right, then moved to the left.

The odd thing is I shot these in 15 shot (three group) strings with the same amount of time between the last shot of a group and the first shot on the next, so that kind of rules out a change of impact due to barrel heat. Like I said earlier I think that my problem that day was the nut behind the trigger (maybe some kind of muscular tension input into the stock)?, but it could be something else at play also.
 
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manitou210 said:
If gun not bedded bed it, how long between shots barrel heat? that 550 powder is very hot
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It is bedded, McMillan a5 fully bedded.

arcticcathonda said:
It would be interesting to fire a shot and set a 5 min timer and fire again. another 5 min fire again.
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I think I am going to try this, the groups were shot with 5 mins between strings, 30 seconds between shoots all hand fed (cartridge does not fit in mag).
 
If the first group is a reload you made that shot so well, why worry about all the other loads that are obviously not to the liking of the barrel?

Barrels rarely shoot a wide range of loads well. If that first load repeats, your work is done.

Now if the question is one of consistency, I would look at your ability to shoot with a bipod (assume it is a harris or similar).

Looking at the 2 groups of load 1. The first started great. The second shows 1 out. A simple matter of poor follow through on that shot and you can pull a shot out easily.

Assuming all your ammo is loaded well and you are confident in your abilities, take 20 rds of load 1. Take your time, watch the wind (use flags). Shoot 4 groups of 5. Be very clear on where the shot breaks and how you used that bipod.

Harris and similar are not easy devices to shoot well. Set up and surface can really muck with consistency. Not sure what the ATRS rear pack is refering to but if it wiggles, that is another source of error.

See what happens.

At some point you will meet the accuracy potential of the platform - average of multiple groups using the best process possible. Good or not, that is what that set up will offer you.

Jerry
 
JC, could be something as simple as wind cycling through with the same cadence as your shots. Use wind flags, watch the mirage. Air is almost never still and doesn't take much to move a bullet 1/4".

Consider your set up and consistency. maybe you have a bad habit in your position the longer you shoot. Maybe you worry more about what has just happened then the next shot.

All of these little things will affect how you pattern in your shooting. Put a video camera on yourself to monitor your position. It is amazing what you will see.

Jerry

PS for both, consider shooting at one target and have the bullets land somewhere you cant see. If you only focus on the shot and not how the group forms, it may stop any "hedging" you unintentionally do. will also give you a much better idea of what the gun is really doing. Spot for each other keeping an eye on flags when the shot breaks. Wind can and will change which you may not see when focused on the target and reticle.
 
Some good advice there Jerry thank you. On the day I shot these it was very calm, not even a breeze, I was shooting down a road that has dense trees down both sides and couldn't even get the wheel on the kestrel to move so I'm going to say that the wind probably didn't factor into the drifting groups. It's probably the other positional issues that you mentioned.
 
Mystic Precision said:
If the first group is a reload you made that shot so well, why worry about all the other loads that are obviously not to the liking of the barrel?

Barrels rarely shoot a wide range of loads well. If that first load repeats, your work is done.

Now if the question is one of consistency, I would look at your ability to shoot with a bipod (assume it is a harris or similar).

Looking at the 2 groups of load 1. The first started great. The second shows 1 out. A simple matter of poor follow through on that shot and you can pull a shot out easily.

Assuming all your ammo is loaded well and you are confident in your abilities, take 20 rds of load 1. Take your time, watch the wind (use flags). Shoot 4 groups of 5. Be very clear on where the shot breaks and how you used that bipod.

Harris and similar are not easy devices to shoot well. Set up and surface can really muck with consistency. Not sure what the ATRS rear pack is refering to but if it wiggles, that is another source of error.

See what happens.

At some point you will meet the accuracy potential of the platform - average of multiple groups using the best process possible. Good or not, that is what that set up will offer you.

Jerry
Click to expand...

I am in search of velocity which is why I am hoping to make one of the hotter loads shoot well.
 
There is speed and then there is accurate speed. Rarely are they the same at elevated pressures.

Maybe a slower powder? Maybe a faster powder?

Barrels will do what they want despite our best intentions. Also remember that you have a factory barrel. It is only going to be so accurate. If I can get 1/2 min on a consistent basis from a factory pipe, I am all smiles.

Jerry
 
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