Fine Tuning a Load

[treillw]

Doing load development for a new gun. I have a load that is giving me three quarter minute results. I'm wondering if I can tweak it a bit to get it down to half minute.

How would you go about this? How much would you vary the powder charge and seating depth by incrementally to explore for better results?

Tikka T3x
6.5 Creed
38.5gn Varget
143 ELDX
The lands are around 2.325" (measured with comp and anvil)
Bullet seated to 2.258" (measured with comp and anvil)
Velocity around 2710

This load is consistently half minute in another T3x I have, so I figured I'd start here and it is promising at three quarter minute.

Thanks!

 

[Jeff Porter]

Where are you at now for velocity, powder charge and seating depth ?

 

[Doom]

It will also help to know cartridge and rifle info.

 

[treillw]

Tikka T3x
38.5gn Varget
143 ELDX
The lands are around 2.325" (measured with comp and anvil)
Bullet seated to 2.258" (measured with comp and anvil)
Velocity around 2710

 

[Pete Wass]

Doing load development for a new gun. I have a load that is giving me three quarter minute results. I'm wondering if I can tweak it a bit to get it down to half minute.

How would you go about this? How much would you vary the powder charge and seating depth by incrementally to explore for better results?

Tikka T3x
38.5gn Varget
143 ELDX
The lands are around 2.325" (measured with comp and anvil)
Bullet seated to 2.258" (measured with comp and anvil)
Velocity around 2710

Thanks!

What I always do is start on an even grain number and increase the load by .02 gn up to the next grain. If you want to jump the bullets I'd start at touch and go back by .005" at a time. If you want to go into the lands, I'd go by .003" per group. I normally use .006" in and change the powder charge until I find the tightest group I can find but off the lands works also.

 

[JEFFPPC]

First bed the action and freefloat the barrel. Get some flags or hang ribbons so you shoot in similar conditions. Then take your powder charge and seat .020 in the lands. Shoot 2 shot groups. If the 2 shots touch go to next bull and shoot 2 more. If those 2 shots touch shoot a 3rd shot in the last 2 shot group.. If it touchs the first 2 you can stop and start testing powder. If the original 2 shots did not touch back out of the lands .002 and repeat the first 2 shot group. Once you do 2 plus2 plus a third shot that touches I stop and go to powder. If you have no pressure issues start adding powder .1gr at a time. If it gets smaller repeat until it opens up or you get pressure. If no improvement made going up and you have hit pressure to to starting powder number and back up .1 at a time. Get 2 shots tight , shot it again, if it repeats shoot another shot and if it stays with the first 2 your hold. Once I find a sweet spot I quit as long as it's repeatable. I 90 percent tune with 2 shot groups. If you just want to hear BANG, and lots do shoot groups all you want. I try to preserve the barrel for competition or hunting. Once you have reached this point if you want try .002 plus and minus one time to see if it tightens further.

 

[treillw]

Isn’t 143 eldx is a hunting bullet ?

A T3x might be a hunting gun too

 

[gunsandgunsmithing]

I'd change in .3gr increments of the powder and then .003 of seating depth. You might try some IMR4064, too. It's very close to Varget. It meters terribly but I don't think I've ever found Varget to out shoot it, ever.

 

[RabbitSlayer]

Is the load really consistent .5moa in the other gun? Have you fired a 20 or 25 shot group to confirm it? When the sample size goes up those small differences between the same or similar load start to go away.

 

[treillw]

Is the load really consistent .5moa in the other gun? Have you fired a 20 or 25 shot group to confirm it? When the sample size goes up those small differences between the same or similar load start to go away.

It has been shooting half minute consistently for 3 or 4 years.

 

[treillw]

Yeah that’s what mine is also. Lol
How did you arrive at your current load ?

Figure out max safe powder charge and then load up about 5 different sets with max charge and varied seating depth.

 

[jepp2]

and increase the load by .02 gn up to the next grain.

50 steps?

 

[josebd]

Did I miss what caliber is it???

 

[William Vogel]

Tikka T3x
38.5gn Varget
143 ELDX
The lands are around 2.325" (measured with comp and anvil)
Bullet seated to 2.258" (measured with comp and anvil)
Velocity around 2710

6.5 Creedmoor?

 

[Owens85]

If this is a 6.5 creedmoore . I would try h4350 or rl 16 with that 143 bullet. And I'm thinking this may be a hunting rifle. So start at max mag length and work your way back into the case as you test. Id test powder charge at max mag length first then move bullet back in case .005 at a time you will be jumping bullet at max mag length I would think. But find touch point and see. Once you find a good area fine tune it by seating bullet in finer adjustments around that area if you would like.

 

[treillw]

Did I miss what caliber is it???

6.5 creed, sorry

 

[treillw]

If this is a 6.5 creedmoore . I would try h4350 or rl 16 with that 143 bullet. And I'm thinking this may be a hunting rifle. So start at max mag length and work your way back into the case as you test. Id test powder charge at max mag length first then move bullet back in case .005 at a time you will be jumping bullet at max mag length I would think. But find touch point and see. Once you find a good area fine tune it by seating bullet in finer adjustments around that area if you would like.

What do you all typically consider a "good area" that warrants fine tuning? Three quarter minute?

 

[Keith Glasscock]

I want to help. Noting that you are getting 3/4 MOA groups with your current loading, what other loads have you shot and what did those loads look like for group size? Just for clarity, are you shooting 3 or 5 shot groups, or something else to get that group size? The reason I ask is that I'm starting to see a distinct pattern in rifle behavior overall, and might have some suggestions that differ from the standard advice given above.

If the load shoots consistently well in a nearly identical rifle design, there could be something other than load tuning holding you back.