280AI 195 Berger EOL & N560 Pressure Concern

[just_jon]

I hit the range today to test the 195 Berger EOL in my 280AI. QL showed 59.8 as a max load for N560, so I started off with five rounds at 57.8 to be safe. I got a stiff bolt, moderate ejector mark and a flat primer on the 2nd round (pictured below). Checking my notes and seeing that both QL and GRT had this load estimated just at under 59,000 psi, I continued with the rest at 57.8. No stiff bolt or ejector marking, but all had flattened primers several of which were worse than the attached. Accuracy was great at .387 moa @ 100 yards with an acceptable velocity of 2812 fps (SD 1.1). My goal in testing this combo was to find an accurate hunting load running between 2800 and 2850 fps.

My question for you all is whether I should I consider 57.8 grans of N560 as max for my rifle, back off a bit and be happy?

Specifics:
Browning X-Bolt HC Max LR in 280 Ackley
26" 1:8" barrel 263 rounds fired.
Peterson 3X bumped .002" with 1/4 turn with Lee factory crimp die.
Fed 215M
COAL 3.6" (max mag length and 0.020" from jam)
CBTO 2.8415"

 

[ADLEE2]

My GRT is showing 195s and 57.8gr of N560 is over pressure at 65,058psi. 56gr looks to be a better starting load.

 

[just_jon]

When I use my COAL of 3.6" and H20 cap of 72.6 grains, I'm coming up with 58,861 psi at 57.8 grains. QL gives me 58,117 psi.

 

[Phil Rizzo]

Looks like you need to drop your load at least a half grain, at the temperature you shot at. According to your brass.
n560 is NOT temp stable, so prepare to reduce it more in warmer temps.

 

[bomberodevil]

I hit the range today to test the 195 Berger EOL in my 280AI. QL showed 59.8 as a max load for N560, so I started off with five rounds at 57.8 to be safe. I got a stiff bolt, moderate ejector mark and a flat primer on the 2nd round (pictured below). Checking my notes and seeing that both QL and GRT had this load estimated just at under 59,000 psi, I continued with the rest at 57.8. No stiff bolt or ejector marking, but all had flattened primers several of which were worse than the attached. Accuracy was great at .387 moa @ 100 yards with an acceptable velocity of 2812 fps (SD 1.1). My goal in testing this combo was to find an accurate hunting load running between 2800 and 2850 fps.

My question for you all is whether I should I consider 57.8 grans of N560 as max for my rifle, back off a bit and be happy?

Specifics:
Browning X-Bolt HC Max LR in 280 Ackley
26" 1:8" barrel 263 rounds fired.
Peterson 3X bumped .002" with 1/4 turn with Lee factory crimp die.
Fed 215M
COAL 3.6" (max mag length and 0.020" from jam)
CBTO 2.8415"

View attachment 522092

That's showing definitive signs of over pressure. The software programs are good places of reference, but flattened primers and stiff bolts together are positive pressure signs. Me personally, I'd go down by tenths, find the beginning point of stiff bolt lift, then go down 0.5 grains for accuracy. But I'm not a speed demon either. I'm loading my 280 AI with 162 ELDX to 2875-2900 range.

 

[just_jon]

That's showing definitive signs of over pressure. The software programs are good places of reference, but flattened primers and stiff bolts together are positive pressure signs. Me personally, I'd go down by tenths, find the beginning point of stiff bolt lift, then go down 0.5 grains for accuracy. But I'm not a speed demon either. I'm loading my 280 AI with 162 ELDX to 2875-2900 range.

No doubt. You've got to trust your eyes in the end. QL and GRT max pressure predictions for cup and core bullets have been spot on with my actual results. Also, I doubt temp instability was a factor at 53 degrees. QL data was based on
preset of 70 degrees. I loaded 57.0 and 57.3 and 57.6 for testing tomorrow along with IMR 7828 SSC.

 

[orkan]

I hit the range today to test the 195 Berger EOL in my 280AI. QL showed 59.8 as a max load for N560, so I started off with five rounds at 57.8 to be safe. I got a stiff bolt, moderate ejector mark and a flat primer on the 2nd round (pictured below). Checking my notes and seeing that both QL and GRT had this load estimated just at under 59,000 psi, I continued with the rest at 57.8. No stiff bolt or ejector marking, but all had flattened primers several of which were worse than the attached. Accuracy was great at .387 moa @ 100 yards with an acceptable velocity of 2812 fps (SD 1.1). My goal in testing this combo was to find an accurate hunting load running between 2800 and 2850 fps.

My question for you all is whether I should I consider 57.8 grans of N560 as max for my rifle, back off a bit and be happy?

Specifics:
Browning X-Bolt HC Max LR in 280 Ackley
26" 1:8" barrel 263 rounds fired.
Peterson 3X bumped .002" with 1/4 turn with Lee factory crimp die.
Fed 215M
COAL 3.6" (max mag length and 0.020" from jam)
CBTO 2.8415"

View attachment 522092

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[Dmagna]

I tried 195s in my 280ai with RL23, I couldn't get it over 2700 in Peterson brass. I had mine throated for the 180eldm with I can shoot at 2850 with a 24" barrel. But it did not like the 195, I am interested to see your results.

 

[Mark37082]

I have found pressure signs well below max book pressure with Peterson brass in a 280AI. I believe Peterson recommends reducing charges by 10%. I haven't experienced this drastic of a required reduction, but I am mindful of pushing it close to max.

 

[just_jon]

I have found pressure signs well below max book pressure with Peterson brass in a 280AI. I believe Peterson recommends reducing charges by 10%. I haven't experienced this drastic of a required reduction, but I am mindful of pushing it close to max.

Excellent point Mark. I have found Peterson definitely has less capacity than others I've tried. SAAMI lists H20 volume as 74.0 grains while a 20-piece sample of new Peterson brass measured 69.7. After three firings, sized cases are 72.6 which is what I used in QL and GRT for this test.

 

[Seabeeken]

I hit the range today to test the 195 Berger EOL in my 280AI. QL showed 59.8 as a max load for N560, so I started off with five rounds at 57.8 to be safe. I got a stiff bolt, moderate ejector mark and a flat primer on the 2nd round (pictured below). Checking my notes and seeing that both QL and GRT had this load estimated just at under 59,000 psi, I continued with the rest at 57.8. No stiff bolt or ejector marking, but all had flattened primers several of which were worse than the attached. Accuracy was great at .387 moa @ 100 yards with an acceptable velocity of 2812 fps (SD 1.1). My goal in testing this combo was to find an accurate hunting load running between 2800 and 2850 fps.

My question for you all is whether I should I consider 57.8 grans of N560 as max for my rifle, back off a bit and be happy?

Specifics:
Browning X-Bolt HC Max LR in 280 Ackley
26" 1:8" barrel 263 rounds fired.
Peterson 3X bumped .002" with 1/4 turn with Lee factory crimp die.
Fed 215M
COAL 3.6" (max mag length and 0.020" from jam)
CBTO 2.8415"

View attachment 522092

When I calibrate the powder model in GRT to your actual speed, it shows pressure at 63527 psi at 70 degrees. N-565 might be a better fit giving the speed you want with better case fill. If you have it