How to Tune a Rifle & Maintain Tune

[treillw]

I'm relatively new to tuning rifles to precision. I have two rifles that I've got to be half minute or better by just randomly loading charge weights and seating depths. While doing that, I thought there has to be a more methodical way of doing this, but that was how I was instructed to do it. I also didn't have a chronograph at the time, so that may be why I was instructed that way. I have recently changed powder & bullet lots, my pet load has disappeared, and I'm back to square one. People on this forum have been telling me to do ladder tests, etc. I'm somewhat familiar with the process, but don't know all the details and steps.

Could you walk me though a detailed step by step guide of what you do to tune your rifle and chase that tune as time passes. What seating depth do you start at? What powder charge do you start at? What increments do you vary seating depth and charge weight by? If your rifle goes out of tune, what do you do next assuming a perfect cleaning regiment, bolt tightness, etc (ie the tune is the problem)?

Thank you!

 

[JEFFPPC]

Pm sent

 

[Bc'z]

Ladder with colored bullets shot at distance. .3gr increments in chargeor shoot a OCW test looking for same horizontal POI, I generally do these at 100, but have been thinking about moving to 300
AA2700 123 ocw test 6.5cm


After shooting charge weight test move to seating depth test.
I move in .003 increments usually 7 depths at 3 round each.
IMR4166 123 scenar seating test 6.5cm

Depending on how far you want to tune you can now run a neck tension test in .1 increments.
I quit testing primers until things normalize in supply.

 

[JEFFPPC]

Ladder with colored bullets shot at distance. .3gr increments in chargeView attachment 1297275or shoot a OCW test looking for same horizontal POI, I generally do these at 100, but have been thinking about moving to 300
AA2700 123 ocw test 6.5cm
View attachment 1297279

After shooting charge weight test move to seating depth test.
I move in .003 increments usually 7 depths at 3 round each.
IMR4166 123 scenar seating test 6.5cm
View attachment 1297291
Depending on how far you want to tune you can now run a neck tension test in .1 increments.
I quit testing primers until things normalize in supply.

Now if you go reshoot the 2.220 and it repeats your on at a good spot. It's only good if it is repeatable.

 

[darkangel_r2]

shoot a OCW test looking for same horizontal POI, I generally do these at 100, but have been thinking about moving to 300

Why do you look for horizontal POI consistency?

 

[Nick Caprinolo]

First, you must be meticulous in your powder weight. Start on the low end of the recommended powder weight for the bullet you are using. Work upwards until you find the smallest group.

Then you start testing seating depth. I load about 50 cartridges with a hard jam and then slowly reduce the depth until I obtain the tightest groups. I do this at the range but you will need an arbor press and a special die to do this. I generally reduce depth in .005 at a time. Once I find the tightest group, I then start .001 up and down until I am satisfied it can't get any better.

Horizontal consistency indicates, at least to me, your powder weight is the same in your loaded rounds. I am sure that others will have different ideas, but this is the way I do it.

 

[JEFFPPC]

How are you going to get horizontal consistency good enough at 300 yds to tune? Unless, you have a 300 yd tunnel. Revisit your powder a tenth or 2 each way and maybe a thousands each way on neck tension at 100 yards with flags and to me that would be a better way to go. Just my method but I do believe there is more than one way to skin the cat.....maybe.

 

[gtl1946]

To treillw I thank you for your post and to the gentlemen who have answered as well because you have helped me with a question that I’ve had on my mind for a while. Thank you all !

 

[Bc'z]

Now if you go reshoot the 2.220 and it repeats your on at a good spot. It's only good if it is repeatable.

Correct, these loads have produced great scores for me in my first season shooting club matches with a
395-22x average, pretty good considering the limits of my gear.
Ruger American overhauled by Zack at ODCR. We're putting together a 6br for next season.

Why do you look for horizontal POI consistency?

Horizontal POI between 2 separate charges are showing you your charge window.
Example: AA2700, 123gr scenar load
43.2-43.5.
I shot this test literally 3 days before a club shoot last month. Normally I'll just grab the charge out of the middle ground, this time I just ran the smallest group 43.5gr despite the fact it's starting to rise up from 43.2.

We shot 1 relay that day due to voting for club administrators.43.5gr load shot 198-14x.
My plan is to load 43.1 -43.6 in .1 increments and shoot those at distance using the same OCW format to find the sweetest of the sweet spot.

 

[darkangel_r2]

Horizontal POI between 2 separate charges are showing you your charge window.
Example: AA2700, 123gr scenar load
43.2-43.5.
I shot this test literally 3 days before a club shoot last month. Normally I'll just grab the charge out of the middle ground, this time I just ran the smallest group 43.5gr despite the fact it's starting to rise up from 43.2.

We shot 1 relay that day due to voting for club administrators.43.5gr load shot 198-14x.
My plan is to load 43.1 -43.6 in .1 increments and shoot those at distance using the same OCW format to find the sweetest of the sweet spot.

Most people including myself who do load dev at closer range look for similar vertical POI to limit vertical dispersion at range. Is there a reason to do horizontal POI instead of vertical POI? Is one better for short range or something?

 

[INTJ]

How are you going to get horizontal consistency good enough at 300 yds to tune? Unless, you have a 300 yd tunnel. Revisit your powder a tenth or 2 each way and maybe a thousands each way on neck tension at 100 yards with flags and to me that would be a better way to go. Just my method but I do believe there is more than one way to skin the cat.....maybe.

We do it all the time at 1000 yds. In fact, there isn't a better way fine tune the load for a match than to shoot a round robin ladder at 1000 yds and then look for overlap.

300 yds probably isn't far enough to see the changes in a LR BR rifle. 500 might be. Here is the 1000 yd ladder that resulted in three 10-shot screamer groups over the next three matches.

 

[Bc'z]

Most people including myself who do load dev at closer range look for similar vertical POI to limit vertical dispersion at range. Is there a reason to do horizontal POI instead of vertical POI? Is one better for short range or something?

I'm looking for horizontal POI in groups over the various charges, not each shot. I'm also looking for a nice round grouping not vertical or horizontal in the way the shots print.

 

[darkangel_r2]

I'm looking for horizontal POI in groups over the various charges, not each shot.

I get that you are looking for POI consistency in the center of each group between charge levels. That part is SOP. The question is why horizontal POI instead of vertical? Or even just minimum total movement of group center between charge levels? Is there a reason for looking specifically at horizontal POI instead of other metrics?

I'm also looking for a nice round grouping not vertical or horizontal in the way the shots print.

I get this part.

 

[JFrank]

@Bc'z
Brett
When you refer to Horizontal I interpret that as a horizontal format, is that a fair interpretation?

 

[RegionRat]

Could you walk me though a detailed step by step guide of what you do to tune your rifle and chase that tune as time passes. What seating depth do you start at? What powder charge do you start at? What increments do you vary seating depth and charge weight by? If your rifle goes out of tune, what do you do next assuming a perfect cleaning regiment, bolt tightness, etc (ie the tune is the problem)?

Note that some of the answers you seek, depend on giving a few more details about what you are trying to accomplish.
For example, some games like BR are single feed, while others require magazine feeding. That makes a difference in the advice on seating depth starting points as an example.
The type or style of gun we are discussing makes another big difference in the initial advice. Bolt gun or gas gun? The chambers and expectations can run different.
The type of shooting you are trying to perfect? Are we talking BR or F-Class, or other?

 

[darkangel_r2]

@Bc'z
Brett
When you refer to Horizontal I interpret that as a horizontal format, is that a fair interpretation?

Yeah perhaps we just have different definitions. The top line has the same coordinate in the y axis. Groups that fall along the top line I would say have the same vertical POI as they have no variation in the vertical direction.

The bottom line has the same x coordinates. Groups that fall along bottom line I would say have the same horizontal POI as they have no change in the horizontal direction.

Is this terminology correct?

 

[JFrank]

At one point I’ve used the Horizontal format while actually drawing a line to set the red dot so I could observe the “sin wave” or barrel oscillation and point of impact shifts. This works fairly well but leaves a few questions as to the bottom of the barrel swing or top being better or worse whereas the single point of aim at a greater distance creates separation that seems easier to identify the overlap ( optimum exit timing) just before breaking out and becoming erratic.
Blaine and Brett have posted targets but here’s another example where the second charge ( green) overlaps blue prior to black and red starting to go away.

 

[newbieshooter]

[/QUOTE]

..... test looking for same horizontal POI

.....Horizontal POI between 2 separate charges are showing you your charge window.

I'm looking for horizontal POI in groups over the various charges, not each shot.

.... as they have no variation in the vertical direction.

maybe i'm missing something - but seems like you two are talking about the same thing - just using different terminology?

 

[RegionRat]

+1 @newbieshooter

 

[darkangel_r2]

maybe i'm missing something - but seems like you two are talking about the same thing - just using different terminology?

View attachment 1297393
[/QUOTE]
The only reason I questioned it was the example he gave was 43.2-43.5 on his target which clearly have one group much higher than the other.

"Example: AA2700, 123gr scenar load
43.2-43.5."