Tree analysis

[merbeau]

I am starting to build a load for my 7mm-08 that I plan to shoot in local 600 yard competitions. I am using Lapua brass necked using a Redding S die to 0.310 inches, CCI BR2 primers and Cutting Edge MTH 130 bullet. COAL to start was just fitting into the magazine at 2.808 inches. Cutting Edge sent some initial load data and Alliant RL 17 looked promising.

I have attached pictures of my recent tree analysis. At 44.0 grains an equilateral triangle is produced Fig shown for 44.0 grains and showed the same result for 45.0 grains and 45.5 grains (pictures not shown). At 44.5 grains a tightened group is produced (Fig shown). At 46.0 grains a tightened group is produced but different shape (Fig shown). At 46.5 my last test the group opened up to 3 inches.

Should I concentrate on the 44.5 group or the 46.0 group. Keep in mind the 600 yard distance. Also are these results suggesting I should vary the seating depth.

Thanks
Robert

 

[Remmy700]

Any chrono data?

 

[merbeau]

Any chrono data?

Yes
For 46.0 grains 2961 FPS ES 12
For 44.5 grains 2876 FPS ES 8

 

[Mikecr]

COAL to start was just fitting into the magazine at 2.808 inches.

Is this the best place or worst place to seat before load developing?
What is a 'tree analysis'?

 

[J E Custom]

I would also recommend trying H 414 and Varget I have had great results with them for accuracy, and Varget will exceed 3000 ft/sec @ 50,000 CUP's.

Just a recommendation using CCI Br 2 primers.

J E CUSTOM

 

[86alaskan]

Was this at 600yds? or 100? The 44.5gr load would probably be a good tuning point. looks to be very little vertical. That flyer may come right in with a seating depth adjustment or charge fine tuning. RL17 has a tendency to give excellent speed but be tricky with temp change. I used it for a while in my 284 and was getting excellent speeds, but as the temp rose the powder got faster and would take me out of a node.

 

[merbeau]

I would also recommend trying H 414 and Varget I have had great results with them for accuracy, and Varget will exceed 3000 ft/sec @ 50,000 CUP's.

Just a recommendation using CCI Br 2 primers.

J E CUSTOM

I tried Varget, CFE 223, BLC(2), N540 and N150 powders. All except N540 gave groups 2 inches and above at charges tested. N540 at 42.0 grains provided initial promise was with a 0.8 inch group. Did not try H414.

 

[merbeau]

Is this the best place or worst place to seat before load developing?
What is a 'tree analysis'?

I have seen Ladder also used for charge testing. I typically follow Tobby Bradshaw's regimen for my testing. Basically anything less than 30-06 the initial charge should be in 1 grain increments and the final should end with either zero or 0.5 behind it (e.g., 44.5 RL 17 powder. Anything above 30-06 should have initial test at 2.0 grains and the final should end with a zero (e.g., 88.0 grains). So I tested initially at 1 grain increments to find a load providing a group of 1 inch or less and then went back and tested at 0.5 increments. around that load.

I typically seat my bullets out near the lands to start with which tends to keep pressures lower. I will then try various seating depths to see if there is any improvement.

 

[merbeau]

Was this at 600yds? or 100? The 44.5gr load would probably be a good tuning point. looks to be very little vertical. That flyer may come right in with a seating depth adjustment or charge fine tuning. RL17 has a tendency to give excellent speed but be tricky with temp change. I used it for a while in my 284 and was getting excellent speeds, but as the temp rose the powder got faster and would take me out of a node.

That was my initial reaction. Testing was at 100 yards. After initial development I will move to 300 to see if the load holds; should be able to see around 1.0 inches at that distance which would hopefully allow a move to 600 yds. Supposedly RL 17 is moderately temp sensitive and rated for 0.5 fps velocity change per degree F of temperature change. Of course according to the manufacturer. N540 also gave some promising accuracy. I may work that up too. I believe it is not supposed to be temperature sensitive.

 

[okie man]

I ran h-4350 with 130 grain bullets in my 7mm/08 with good results.

 

[jjmp]

Be nice to have more info on your rifle , bbl length , twist , I run mine 27 inch bbl 1/9 tw,cm/#3 conture Lilja for fun . Q , does your bullet mfg advise a jump to lands ? Thks

 

[merbeau]

Be nice to have more info on your rifle , bbl length , twist , I run mine 27 inch bbl 1/9 tw,cm/#3 conture Lilja for fun . Q , does your bullet mfg advise a jump to lands ? Thks

Barrel length 26 inches, twist 1:9, Douglas premium heavy varmint contour, target crown, and PTG one piece bolt blueprinted. Set in Stockeys LRT stock with aluminum block and pillars. Cutting Edge claims the bullet is not very sensitive to seating depth.

 

[jjmp]

Ok nice, what's your opinion on bbl brake in , personally i believe in it ,and it's more relaxed from a stand point of reloading , and it lets your barrel tell you what it likes . Granted your excited ,and that's normal. I'd suggest trying some Sierra tipped match kings in 130s & 160s , a great friend of mine ran the 130 sierras threw his target 708 rifle and he almost won his first 600 yard match . He traded me a leftover box of 20 count 160 tipped match kings my 708 loved them ,best 3/shot group was 1&1/16 at 300 yds ,followed up at625 with a 3 shot 2.75 group measured with a tape bullet holes not subtracted , have picture also . Tmv tested muzzle velocity 2780 fps powder h4350 ,cci/200 ,col 2800 ish . Never shot the tipped Sierra 130's but their on my to do list . H414 is very good powder , don't forget to try Sierras normal 150 match king it likes the 1/9 twist , happy testing , happy loading , your Rifle was made for these components ,gd on you !!!.

 

[Greyfox]

I have gotten good results with Varget in 7mm08.