6BR AI load development

[Blue68f100]

Does the brass you using have the std 0.062" flash hole, or one that's reduced 0.059"?

 

[Nature Boy]

Does the brass you using have the std 0.062" flash hole, or one that's reduced 0.059"?

Reduced flash hole

 

[Blue68f100]

The reduced flash hole according to Lapua says it's suppose to make the burn more consistent. I can see it working to restrict the explosiveness of the flash and reduce the shock to the cup when pressure builds. In my test with the 6.5 CM, my load was developed with the Rem 7.5 and Starling brass. I was getting single digits SD with the ES in single digits most of the time. The Starling brass has the larger 0.062" std size flash hole. I'm going to test again using my Starline brass and see if every thing is the same. May run some #41 too, just for info. In a few occasions I have had better groups with the 41's but normally the Rem 7 1/2 preform better. If I remember the right the Starline and Lapua had the same internal volume, the reason I did not do a load workup. If this is truly the case, the difference is the flash hole.

 

[Nature Boy]

Took the 31.6 load with 205M primers and -0.040 off the land to the match. Posted a 592 with 26 X’s



Most of my 9’s, particularly on the 3rd string, were missing the wind switchs. Still, I think there’s more tweaking to do with this load

 

[Walkalong]

I think there’s more tweaking to do with this load

But you are definitely in the ballpark. Nice shooting.

 

[Blue68f100]

Took the 31.6 load with 205M primers and -0.040 off the land to the match. Posted a 592 with 26 X’s

View attachment 799025

Most of my 9’s, particularly on the 3rd string, were missing the wind switchs. Still, I think there’s more tweaking to do with this load

The strive for perfection. There is no end.

Nice shooting

 

[Nature Boy]

I’m getter better at reading the wind and holding off for it. Not doing very well at catching the changes.

The wind was not every strong during this match but it blew from every direction

It was interesting to watch the effect when scoring because you can watch several targets at once

I saw 3 shooters all dropped shots, all in the same direction and at the same time, because they were holding for wind and missed it when it let off

Then it happend to me in my third string. I’m holding off for a wind from the right. Starting at shot #7 I’m hammering the X and going as fast as I can manage and still be in control. Then it let up and “hello 9, where did you come from?”

 

[taliv]

nice shooting!

and yeah, watching your wind dogs to the left and right of you is a time honored tradition. find a new shooter who has young good eyes and doesn't pay attention to the wind yet haha shoot right after they do

 

[Walkalong]

90% of Benchrest was reading the wind. Difference is we used wind flags and only shot out to 200 yards.

 

[z7]

Shot a PRS match on Sunday and the know your limits rack was tough for folks, we had swirling wind at about 3mph, looking down range you saw 2 different winds and felt a 3rd. a 4” target at 440yds is unforgiving

 

[taliv]

That’s the whole point of Kyl lol

 

[Nature Boy]

Life has gotten in the way of my reloading and shooting lately but I had some time to test some loads with 2 new bullets with H4895.



As the preceding posts indicate, I’ve been working with the Berger 105 Hybrids and Varget but haven’t been satisfied so I worked up some loads to test using 107 SMKs and 108 Berger BTs

I used the same load ranges for both starting at 29.0 and ending at 31.5. I also seated both to touching the lands.

Here are the results, 3 shots per charge weight at 100 yards. My notes: Average FPS left of the target, charge weight on top and group center vertical distance from target center line on the right



Looks like a wide node with the Bergers from 29.5 to 30.5 (maybe to 31.0) and a smaller node with the SMKs between 29.5 to 30.0

I also noted on the berger target the increase in FPS with each increase in charge weight. It flattened out (+33 fps) between 30.5 and 31.0. I think I’ll take 30.5 and load some for a seating depth test test then take them to 500 yards and see how they do.

 

[Nature Boy]

Here’s my seating depth test for the 108 Bergers

0.005 into the lands came out on top. I’ll stick with the 205m primer and take it to 500 and see if it holds up

 

[MCMXI]

Great shooting there @Nature Boy and it looks like you have an outstanding set up. Out of interest, do you have velocity data to go along with that last target? Looking forward to seeing you get all Xs at 500 yards!

 

[Nature Boy]

Out of interest, do you have velocity data to go along with that last target?

I tried to but it’s usually difficult to get data at my range early in the morning due to low light conditions and today was no exception. The chrono was throwing off odd numbers and not recording about half the shots.

If I go by my load test it’s running 2,875fps

 

[MCMXI]

I was curious as to whether you would see any velocity patterns resulting from the bullet being into the lands or off the lands. The pressure curve would most likely be different so the velocities might be different. No big deal though and well done on such a good set of tests.

 

[Nature Boy]

Finished off the load testing for the Berger 108s this morning at 500 yards.



Began with 10 shots on the 1st target



The three at the bottom were where the ballistics app put me. Made an adjustment and put the next 7 where you see them. Vertical looks great but I was struggling with the rifle tracking straight. It kept wanting to kick to the left, which I’m sure was causing the horizontal variation.

I went ahead and put 20 into the final target. The 10 ring on these 8” shoot-n-see targets is 2.5”, approximating the X ring on a 500 yard F class target. Here’s the results



I think I’m calling that good enough. Even with the flyer that would have scored a 200 19x

 

[Bayourambler]

Awesome job! It doesn't get better than that!

 

[WelshShooter]

I like reading your threads Nature Boy. Detailed information, lots of pictures, excellent shooting and no BS! Thank you for your contributions

 

[horsemen61]

I agree with the above statement by welshShooter!

 

[Superiorfirepwr]

I love the "Black Arts" of working up a load - the wife thinks I'm crazy (well she's prob right) Awesome thread!!!

What dies are you using and what neck tension are you going with .001 .002?

 

[Nature Boy]

I love the "Black Arts" of working up a load - the wife thinks I'm crazy (well she's prob right) Awesome thread!!!

What dies are you using and what neck tension are you going with .001 .002?

I’m using a set of Widden custom dies with the sizer honed out to match the reamer that cut my chamber. It’s configured to deliver 0.002 of neck tension.

Like you, I enjoy the load development process and observe the results down range. Good or bad, you always learn something.

My wife already knew I was crazy long before I got hooked on this absurd hobby

 

[Superiorfirepwr]

Very cool, I'm using Redding type S dies with "stock" Remington 700's and getting some excellent results, as you know I could go down the "rabbit hole" on describing all the bits and pieces, process, and my fickle OCD steps and documentation rituals, I'm just happy I live in a place I can enjoy this and practice my "dark arts" lol..... More to come!! Keep up the excellent posts, it helps us all stay inspired!!

 

[Superiorfirepwr]

The next batch to test out back in the 6.5 Creedmore 5R with Varget, H4350, Rl-15 140 and 130 RDF Nolsers .005 - .030 off the lands best so far at 100 is .362 in a 5 shot group