RANGE RESULTS, speed or accuracy if you have to choose?

[Derek M.]

I was able to chronograph my loads today with a Chrony Alpha. Don't know if it is good quality or not but it reads velocities. Odd things happened today.

Checking my new 270 with Krieger barrel with New Win brass, Federal 210M primers, 150 Berger VLD seated to COAL 3.260 and H4831SC. I'll have to double check how far from lands.

56.0 grains x 3: 2892, 2905, 2909. One inch group at 100 yards
56.5 grains x 3: 2871, 2920, 2913. 3/4" group
57.0 grains x 3: 3012, 3005, 3007. 5/8" group (I totally dig this group and will work with it).
57.5 grains x 3: 3026, 2998, 2982. 3/4" group [why would I get 2 slower than 3000 with more powder)?

All charges weighed one at a time. All brass sorted to w/i 0.5 grains.

My 280 with Shilen pipe, 150 btips, 57.5gr VV N165, Norma cases, Fed 210M primers. This load prints very well in the 1/4 minute and very consistent but velocity is lacking. Shouldn't matter with a Btip. I've had tremendous success with this bullet when slowed down. The first 5 were what I had left over with a deeper seat. Then I shot a few more with the correct depth for best accuracy:

1. 2683
2. 2715
3. 2699
4. 2703
5. 2686

Seated closer to lands and a cold barrel start again:

1. 2741
2. 2763
3. 2760
4. 2755
5. 2761

The 270 is pushing the 150 Berger VLD at 3000 fps but I will have to play with seating to match the accuracy of the 280 which is pushing a 150 Btip in the mid 2700s. Of course I've ONLY tried the one powder in the 280. It just did so well I stopped playing for this season.

The 270 and 280 both have 24" barrels.

7mag/Krieger, 168 Berger VLD, Win brass, 215M primer, 0.010 jump:

1. 3036
2. 3055
3. 3060
4. error
5. 3020

The 6.5-284 with 24" Bartlein had some disappointing speed but I have a lot of work to do with it as well. 140 Berger VLD, new Lapua brass, 210M, Retumbo, 0.010 jump:

1. 57.5 grains, 2878, 2840, 2862 (sticky bolt lift)
2. 57.0 grains, 2814, 2756, 2807, 2813.

The last time I was testing Retumbo, I got a 1/4 minute group at 100 with 56.0 grains and reverified it today and it was still 1/4 minute but I didn't get to chrony those loads dang it.

So, for the 270, how do you add only a half a grain and go basically from 2900 and some change to 3000 fps? I'm not complaining and I can live with a better than half inch group. I'll have to retest it at 200 yards and alter seat depth to see if I can enhance accuracy of course.

I loaded everything in one sitting and weigh each charge, sort brass, etc. Scale calibrated yada yada yada...

Thoughts?

 

[Lefty7mmstw]

Derek, your rifle is telling you where to quit with the odd velocity add- first 100 fps on a half grain then nothing on the next half grain. Drop down to before you started noticing oddities and you'll have a more stable load. Tweak your seating depth if you need better accuracy at this charge. A 270 and 150's should be 2800-2900 depending on barrel length.

As for your 280, try something like rl19 or 22 in it. My brother runs 280's all the time and he's using a 140 nos tipped and one of the rl's depending on what the pipe likes; I think he's using 22 lately. 3K+ in a 22" barrel with 140's is normal with good loads.

 

[Derek M.]

I have 18 new 270 loads ready to go to range right now all with 57.0 gr H4831SC but varying seats. I'm actually pretty impressed with 3000 fps with a 150 from a 270. Of course I'm trusting the chrony to be correct. When I get to take the rifle where I can verify drop at some distance to JBM I'll be in good shape.

As to the 280, I know I can get it faster, but for now I am leaving it as is. 150 grain Btips going 2750 are fine with me for now. I'm taking the 280 for KY opener this Saturday. I've never had exceptional velocity with any of the VV powders and didn't expect it, but this recipe sure does shoot well! I'm out.....heading to range right now.

 

[J300UM]

I agree with lefty on the load developement aspect. I'll add that my chrony is very sensitive to light conditions. Even something as minute as a cloud going over my shooting position causing a momentary shade spot has caused me to scratch my head a bit. I built a small 2 sided shelter that sits over my chrony so I would have consistant light conditions throughout my session. Not sure if my simple minded logic has made a real difference but my ES went way down!

 

[royinidaho]

I built a small 2 sided shelter that sits over my chrony so I would have consistant light conditions throughout my session. Not sure if my simple minded logic has made a real difference but my ES went way down!

I build a cover for the chrono out of a white plastic 50 gal barrel. It shades the entire chrono regardless of sun angle.

Same results as your device.

Added about 200 bucks of value to the chrono.

 

[Derek M.]

Re: RANGE RESULTS, PICS ADDED

270 At the range today, as well as the 280

 

[Derek M.]

those 3050 avg velocities are from the 270, 150 VLD, and 57.0 gr H4831SC.

 

[FEENIX]

I build a cover for the chrono out of a white plastic 50 gal barrel. It shades the entire chrono regardless of sun angle.

Same results as your device.

Added about 200 bucks of value to the chrono.

I have a couple of EZ pop up canopy tents (IIRC, I paid $49.99 for it ) that I have for many years that I'll use over it, if that issue arises.