First loads with 135gr Atip

[NY700]

Finally got around to loading some of the new 135gr Atip bullets. Accuracy was decent, was not happy with SD/ES

thoughts and input on where to go from here would be greatly appreciated.
Equipment

Rifle: Factory Tikka Tac A1
Scope: ZC 527

Temp started at 70* quickly rose to 85* with heavy direct sun

all rounds were weighed on Fxi120
Length Measurement to
Ogive
2.260 had an SD .001
COAL
2.912 had an SD .002

powderH4350
PrimerFGMM
Brass: Peterson 1x

So couple of things where would you focus your load development on charge weight?
And suggestions on tightening up SD/ES? These were my first loads on the new balance. Prior to this I had been running a charge master and my 6.5x55 routinely were single digit SD

these were fired over about a 3hr window. In between I was helping another shooter. Although not super high ambient temperatures the sun was intense and over head and I didn’t think to shield the ammo would you attribute the heat to the SD at all?

 

[skyrep]

I did not have good results using H4350 for the 135gr A-Tip. However, i did get results with RL-16. My best results was .015 off the lands. SD: 5.6 and group: .558". Avg FPS: 2813

 

[NY700]

I did not have good results using H4350 for the 135gr A-Tip. However, i did get results with RL-16. My best results was .015 off the lands. SD: 5.6 and group: .558". Avg FPS: 2813

yea that is very much what I was hoping for. They are so so expensive I was really hoping to see something that was a “game changer” stand out. They are so consistent Bullet to Bullet I loved it (helps the OCD). But it reminds me of when I had my 6.5x284. Load development is so expensive what’s the point. With that I was eating barrel I guess the advantage here is I find the right load it should be good for a while.

too bad I can’t find RL16 any where

 

[NiteQwill]

Your velocity appears all over the place. Are you doing anything in particular with the necks? I don't personally neck turn (especially with Peterson or Lapua brass) but I've personally seen that the proper sized bushing (0.001-0.002 under) and a mandrel have significantly improved my ES/SD across all my loads. As with all reloading, YMMV.

Good luck!

 

[NY700]

Your velocity appears all over the place. Are you doing anything in particular with the necks? I don't personally neck turn (especially with Peterson or Lapua brass) but I've personally seen that the proper sized bushing (0.001-0.002 under) and a mandrel have significantly improved my ES/SD across all my loads. As with all reloading, YMMV.

Good luck!

although my SD was not where I wanted it, I’m not sure that I would agree that the velocities are all over the place. Largest SD was 22fps. Am I not seeing something I should?

just in case it went missed please keep in mind those are 4 Separate loads 41.5 - 43.0gr

 

[NiteQwill]

2830 to 2896? Is that one charge?

although my SD was not where I wanted it, I’m not sure that I would agree that the velocities are all over the place. Largest SD was 22fps. Am I not seeing something I should?

just in case it went missed please keep in mind those are 4 Separate loads 41.5 - 43.0gr

 

[NY700]

2830 to 2896? Is that one charge?

yes one charge. Charge 3 42.5 had the largest ES
7 shot string 6 recorded shots
It was a slow string. You can see the velocity increase over the string. That’s why I questioned if the ammo backing in the sun may have been a factor

 

[NiteQwill]

yes one charge. Charge 3 42.5 had the largest ES
7 shot string 6 recorded shots
It was a slow string. You can see the velocity increase over the string. That’s why I questioned if the ammo backing in the sun may have been a factor

A temperature swing resulting in 66 fps difference with H4350 powder? Possibly, but uncommon with my not so scientific experience . I would get down to going over your brass prep routine again. Repeat.

Powder Temp Stability: Hodgdon Extreme vs. IMR Enduron

The goal of this field test was to quantify the temperature stability of the popular Hodgdon H4350 a...

precisionrifleblog.com

 

[NY700]

So based on my numbers from the original run I did 41.5-43gr. Where would folks suggest I start for my next batch? I would hope to limit the charge weight range 1.5 down to 1gr

I’m thinking COAL to stay the same
max mag length is 2.956. And my COAL is at 2.912
Max to Ojive is 2.315. And I’m at 2.259

 

[Doom]

I would work between 42.5 and 43. I’m suspicious of your velocity data. You ES is driven by first shot each group except the first.

Just curious, are you cleaning between groups?

 

[NY700]

I would work between 42.5 and 43. I’m suspicious of your velocity data. You ES is driven by first shot each group except the first.

Just curious, are you cleaning between groups?

good question. I am not. Last cleaning was 60 rounds ago and I usually clean in the 400-500 range historically is when I notice a change.

this is why I keep going back to the temperature. I know that H4350 is generally temp insensitive. One of the reasons I selected it. But the start of my day washigh 60s no direct sun. Finishing at 80s with intense direct sun. In the sun if I spot checked temp it was probably close to 100

I left my ammo sitting in a 100rd MTM box open.
mom just going to have to get back out there with a new batch I guess.

cartridge length seems good.

one thing I realized afterwards I did not change was the bullet weight on the labradar. My understanding is that really only impacts the ft/lbs figures. Is that correct or would it change the calculation on velocity reading?

 

[NiteQwill]

good question. I am not. Last cleaning was 60 rounds ago and I usually clean in the 400-500 range historically is when I notice a change.

this is why I keep going back to the temperature. I know that H4350 is generally temp insensitive. One of the reasons I selected it. But the start of my day washigh 60s no direct sun. Finishing at 80s with intense direct sun. In the sun if I spot checked temp it was probably close to 100

I left my ammo sitting in a 100rd MTM box open.
mom just going to have to get back out there with a new batch I guess.

cartridge length seems good.

one thing I realized afterwards I did not change was the bullet weight on the labradar. My understanding is that really only impacts the ft/lbs figures. Is that correct or would it change the calculation on velocity reading?

The bullet weight on the LabRadar only impacts your power factor. It should have no bearing on velocity at D0.

 

[fdkay]

No powder is impervious to temp changes, however H4350 is one of the best, if not the best when it comes it.
Also consider that as the temps rise, air becomes less dense and will alter velocities as well. If your getting the velocity from a radar, that, coupled with the ammo getting hot, MIGHT explain the totality of the differrence.

Powder Temp Stability: Hodgdon Extreme vs. IMR Enduron

The goal of this field test was to quantify the temperature stability of the popular Hodgdon H4350 a...

precisionrifleblog.com

I can't speak about the conditions you experienced, but you could try again, paying particular attention to keeping your ammo out of the sun.

 

[Doom]

The Lab Radar may be part of the issue. The electronics probably have a certain amount of sensitivity if it was in the sun as well as the ammo.