Group Size opening up

[Clo61]

Hi,
Basics
Remington Sendero was printing at .331 MOA from a factory rifle. I have about 500 rounds through the gun. Shooting 168 ELDM, IMR 4064, 4 thousands jump, no crimp.

For what ever reason my group size has opened up to 3/4th minute. I can't explain why, bolts all torques, scope torqued, using quality glass. Has any one ever ran into this type of issue? Is there a significant change to the rifling once a factory rifle hits the 500 mark? Any advice would be appreciated.

98

 

[Brazo]

did you try cleaning the barrel?

 

[Ryridesmotox]

I would look into differences lot to lot in consumables first. After that, what is the cleaning regimine like?

 

[Clo61]

Cleaning process is all up to standards and by the numbers. I do believe my issue may be a new lot of IMR 4064. My last trip out I re ran my ladder test and did not find the results I once achieved.

Should I give up on the comb and move on? That change really came in the last 100 shots which went from shooting .3’s to 3/4. I have had good luck with IMR 4831 as well just in different loads for a different rifle.


Thanks for the suggestions...

 

[ShtrRdy]

Is the ambient temp or ammo temp quite a bit different from when it was shooting the 0.331 moa groups?

I had trouble with a load I developed for a .308 using IMR-4064 last fall grouping the same this summer.

 

[Ryridesmotox]

For me, IMR 4064 hasn't been temp sensitive at all. I load developed in the fall at like 50 degrees in the rain. I shot it recently at 100 degrees in the burning sun, and my elevation was within my margin of error for holding properly on target.

I would look at the bullets too. I noticed lot to lot, my hornady 178 eldms were not very consistent. They still shot alright (.3-.6 MOA), I had similar results with them. It doesnt bother me, practical accuracy under 1 moa in PRS is fine for me... so I just pressed on.

 

[Milo 2.5]

Cleaning process is all up to standards and by the numbers. I do believe my issue may be a new lot of IMR 4064. My last trip out I re ran my ladder test and did not find the results I once achieved.

Should I give up on the comb and move on?

Anytime you change lot #'s of powder, one should load 10 rds of the same charge, and just chrono for a comparison. Sometimes you can solve the problem before it becomes an issue.
I know this may sound stupid, but I have historically avoided Hodgdon's powders because of lot variations, but today now I rely on varget and H4895 for BR size cases, and it is a pain.
You can switch anything up that you please, but I'd probably adj my charge of IMR 4064 to get back where you were before doing full on load dev.
Not pointing a finger at your cleaning regimen, but dirty barrels can skew results.

 

[918v]

Maybe your cleaning regiment isn’t as awesome as you think or maybe your load, or both. Anytime you chase the lands, everything gets sensitive. I suggest you clean the bore with a bronze brush and some good solvent and redo the load so it’s farther away from the lands. There are multiple sweet spots, some close and some far away. The far ones are less sensitive to fouling and climate.

 

[6brshooter]

That's a good factory tube if it was ave .331 groups.

 

[Clo61]

Quality suggestions. I worked up a ladder of 4831 with 71 grns I got a group to print at .425 on a breezy day. I am sure I could tweak it a bit more with adjusting the seating depth. It may just be as simple as a different lot of 4064 powder which is giving me the different results. I also appreciate the suggestion of KISS and doing a great cleaning on the bore and giving the load combo another run.

I will test the 4064 on more run this week.

Thanks

 

[Clo61]

Back from the range. IMr 4831 worked great. My rifle is printing in the .388’s and velocity is 3026fps. I also picked up 100fps with the powder switch. IMR 4831 has been the ticket for 3 rifles. Thanks for all the replies and input.

 

[Lunchbox27]

I just changed lots in RL16. My first jug had my load at 40.6. Second is 42.2.

This is extreme, but not uncommon. I have had as much as .4 grains with varget and .5 with 4064.

 

[Ryridesmotox]

I just changed lots in RL16. My first jug had my load at 40.6. Second is 42.2.

This is extreme, but not uncommon. I have had as much as .4 grains with varget and .5 with 4064.

Damn that's a significant difference. I wonder why it was such a vast change. Under 1 grain I can understand. But nearly 2 grains? Its probably just me, but that seems significant amount of change anyway.

 

[Lunchbox27]

Right? I saw a 85 fps velocity swing, too.

My guess is, the first lot was very hot! I couldn’t get past 41.8 grains without pressure signs. Current jug has pressure at 42.5.

 

[culater]

Cleaning process is all up to standards and by the numbers. I do believe my issue may be a new lot of IMR 4064. My last trip out I re ran my ladder test and did not find the results I once achieved.

Should I give up on the comb and move on? That change really came in the last 100 shots which went from shooting .3’s to 3/4. I have had good luck with IMR 4831 as well just in different loads for a different rifle.


Thanks for the suggestions...

I would suggest that you find the speed node of your last load data if you have that. An take the new 8lb power and load some up to find the speed node your barrel loves. It will be different from your last load work up. It could differ up to 1 grain. But that doesn't matter the powder charge, just the speed node. I have different 8lb lots numbers in varget but take a sample of each to find the speed node so I don't have to worry about it. Everything shoots the same lot to lot. Always load to the speed node. Yes you'll have to chase the lands as the barrel wears out to keep things in optimal performance.

 

[6brshooter]

In 15 yrs of using h4895, varget, and h4350, I've not seen more than 15fps variation in lot numbers of those powders

 

[mdmp5]

Barrels sometimes speed up but should be well before the 500 mark. I could speculate more on the cause, but at this point, I don’t think it would be productive. The proposed solution is to rework the load, and it shouldn’t be very far from your current load

 

[Clo61]

I was very happy to reproduce the group I knew the barrel was producing. The first two shots with IMR 4831 were one ragged hole and the third was just off producing a group in the .3ish area. I was looking over my notes and did see a speed nod with the 4064 which is 3 grains under my previous load with the same powered.

I am going to do a ladder 1 grain under and move up in .5 increments...one last try with 4064. If this works I will report out to everyone.

Thanks