Verticle Spreading and load development help - where to go from here?

[CONatureBoy]

Suggest you read https://precisionrifleblog.com/2012/07/13/creighton-audette-ladder-testing/ and follow it rigorously at a fixed depth. The Berger 215 is a hybrid ogive, so it shouldn't be very sensitive to seating depth. (That's been my experience.) I personally find accuracy nodes quickly taking one shot at 0.2-grain increments in very controlled conditions (shooting off a bench into no wind or light wind). Once I find a node, I confirm it with a three-shot or five-shot group. After that, if you don't like the accuracy, play with seating depth.

Seating close to the lands usually helps accuracy. Your barrel swings vertically, and when you change the charge weight, you're changing where in the swing the bullet exits the muzzle. You want the bullet to exit the muzzle at the top of the swing (when the barrel is still, just before it starts its downward excursion). That's what folks call an "accuracy node." The whip of the barrel in the middle of the swing magnifies any errors you introduce moving the gun while you shoot. That's what you want to avoid.

 

[TX Badger]

Skipping steps, not sticking to a plan, and not collecting all data wastes components. Pick a method and stick to it.

Chrono everything.

Personally I do a pressure test first. I go from rec. starting to a little over listed max in 1/2 gr steps (for large capacity cases) 3 of each. I also know I'm most likely going to pitch the very low end, but I use these to break the barrel in. I pick the best combo of low es and group size and then refine with seating depth.

Since you already know that 74gr is safe in your rifle and it liked the most jump you've tried i'd try a little further out and see if it continues to improve. Then I'd do 1/2gr steps from say 72.5 to 76.5.

Also be realistic about how far you are going to shoot and run your es numbers at that distance through a ballistic calculator. Super low es may not be your most accurate load and may not make any difference at the range you're shooting.

 

[PNWdude67]

Hi All,

So I have a Bergara Premier Highlander in .300 Win Mag that I am working on some hand loads for. I am using Berger 215's, H1000, Norma Brass, CCI 250's, and Redding Type-S Bushing Dies. Gun will be primarily used for elk hunting out west.

I followed Berger's starting point of 70.5 grains of H1000, and shot .015, .020, and .030 off the lands.

See the first imagine below - the .030 off the lands shot the best (by far). (Image without a circle)

So, 70.5gr is pretty light for H1000 in a .300 WM, and decided to bump the powder charge up to 74gr (imagine with the red circle). This caused the groups to open up. This had zero pressure signs.

Question is, from here, do I bump up to say 75 gr and keep going until I see pressure - then tweak the seating depth again? Was hoping that the powder increase would not open the groups that much. I am new to this precision reloading.

Try .080 off the lands and ensure your neck tension is consistent with a Sinclair .308 turning or expander mandrel (.001 difference) .... it is worth the time of an extra step to do this after sizing the outer diameter of the case neck down when you full length size using your Redding bushing set up.

 

[Stgraves260]

The more things you touch, the more likely you will screw it up. Take it for what it's worth.

 

[Stgraves260]

Try .080 off the lands and ensure your neck tension is consistent with a Sinclair .308 turning or expander mandrel (.001 difference) .... it is worth the time of an extra step to do this after sizing the outer diameter of the case neck down when you full length size using your Redding bushing set up.

.080 off the lands? WoW!!!! That's a lot.

 

[Roughrice]

Suggest you read https://precisionrifleblog.com/2012/07/13/creighton-audette-ladder-testing/ and follow it rigorously at a fixed depth. The Berger 215 is a hybrid ogive, so it shouldn't be very sensitive to seating depth. (That's been my experience.) I personally find accuracy nodes quickly taking one shot at 0.2-grain increments in very controlled conditions (shooting off a bench into no wind or light wind). Once I find a node, I confirm it with a three-shot or five-shot group. After that, if you don't like the accuracy, play with seating depth.

Seating close to the lands usually helps accuracy. Your barrel swings vertically, and when you change the charge weight, you're changing where in the swing the bullet exits the muzzle. You want the bullet to exit the muzzle at the top of the swing (when the barrel is still, just before it starts its downward excursion). That's what folks call an "accuracy node." The whip of the barrel in the middle of the swing magnifies any errors you introduce moving the gun while you shoot. That's what you want to avoid.

/\ /\ /\ This

Stay off the lands at or near the distance you already know worked well with the bullet you intend to use and work the ladder test.
Once node is established with YOUR barrel harmonics... THEN proceed with slight seating depth adjustment to fine tune.
I'm sure you will be satisfied with the results.

A lot of great information here from undoubtedly greatly experienced hand loaders and shooters!
Remember to take good notes and... Use the KISS (keep it simple stupid) technique or it can get confusing real quick and waste precious reloading materials.

 

[Stgraves260]

Skipping steps, not sticking to a plan, and not collecting all data wastes components. Pick a method and stick to it.

Chrono everything.

Personally I do a pressure test first. I go from rec. starting to a little over listed max in 1/2 gr steps (for large capacity cases) 3 of each. I also know I'm most likely going to pitch the very low end, but I use these to break the barrel in. I pick the best combo of low es and group size and then refine with seating depth.

Since you already know that 74gr is safe in your rifle and it liked the most jump you've tried i'd try a little further out and see if it continues to improve. Then I'd do 1/2gr steps from say 72.5 to 76.5.

Also be realistic about how far you are going to shoot and run your es numbers at that distance through a ballistic calculator. Super low es may not be your most accurate load and may not make any difference at the range you're shooting.

I like it, and at the end of your statement, is why I don't use a chronograph do to just because you have a low extreme spread doesn't make it the most accurate set up. I all ways tell people that paper doesn't lie. It physically shows you your bullet impact each and every time. My chronograph sets in my closet and I pull it out for the kids to play with when we go to the range. It just doesn't match my cal forum at extended ranges. Like the corona virus test sometimes it gives off a false positive. LoL!!!

 

[Mike Matteson]

Whether the load is low or high, use the chronograph. It add more pieces of info.

 

[lightshooter]

Hi All,

So I have a Bergara Premier Highlander in .300 Win Mag that I am working on some hand loads for. I am using Berger 215's, H1000, Norma Brass, CCI 250's, and Redding Type-S Bushing Dies. Gun will be primarily used for elk hunting out west.

I followed Berger's starting point of 70.5 grains of H1000, and shot .015, .020, and .030 off the lands.

See the first imagine below - the .030 off the lands shot the best (by far). (Image without a circle)

So, 70.5gr is pretty light for H1000 in a .300 WM, and decided to bump the powder charge up to 74gr (imagine with the red circle). This caused the groups to open up. This had zero pressure signs.

Question is, from here, do I bump up to say 75 gr and keep going until I see pressure - then tweak the seating depth again? Was hoping that the powder increase would not open the groups that much. I am new to this precision reloading.

I think you need to keep going with the searing depth test.
I don't load for .300 WM but for everything I do load for, I've found reducing the max load by 10% (as long as its higher the starting load, always is in my experience) this is the load I use for searing depth test, then for my starting point for charge weight testing.
good luck!

 

[QuietTexan]

.080 off the lands? WoW!!!! That's a lot.

Not really. Berger's VLD test recommends shooting intervals at 0.080" and 0.120" off the lands. My 300 RUM's mag length is 0.229" off with Berger 210VLDs, and 210 ABLRs shot best at 0.070" off. He's shooting similar length bullets in his Win Mag. Being snuggled up to the lands is not always best and it's very common for bullets with secant ogives to shoot well with a jump.

Interesting read on jumping. While a short jump might be the most precise in absolute terms, it might have the least forgiving margin of error, so you're better off with a wider node sat further away:

Bullet Jump: Is Less Always Better?

About 2 years ago, Mark Gordon shared some preliminary research he’d conducted with the Applied Bal...

precisionrifleblog.com

 

[grry10]

Are you shooting off a lead sled? If so, try just bags front and rear. I've seen a lead sled cause this problem with a Browning A-Bolt in 300 Win Mag. Worked weeks on loads before removing the sled. Once removed groups tighten right up.

 

[fnlights]

Are you shooting off a lead sled? If so, try just bags front and rear. I've seen a lead sled cause this problem with a Browning A-Bolt in 300 Win Mag. Worked weeks on loads before removing the sled. Once removed groups tighten right up.

Interesting - I was shooting from a sled

 

[Deputy819]

I was shooting from a sled

None of my rifles ever shot worth a darn in one of those things.

If so, try just bags front and rear.

^^^THIS^^^

 

[MontanaJack]

Distance off the lands depends on the bullet design in my experience. I shoot Berger VLD's 0.010 to 0.020 off the lands with best results from 6mm up to 30 caliber. The new Berger Hybrid design offers an option for chambers with long jump. My Christensen 6.5-284 drove me crazy until I tried the new 156gr Hybrid hunter. At 0.030 off the lands, I'm only using 3/4 of the neck of the case for bullet contact, but I'm finally getting sub-minute groups. I couldn't seat VLD's long enough to get sub-minute groups. I start at minimum load with 3 rounds and then prepare 3 rounds in 0.5 gr increments up to max. Then I take the interval with tightest groups, and ideally, lowest extreme spread, and load 3 rounds in 0.1 grain increments to find the holy grail load for the rifle. So much influences getting that single hole group: brass uniformity, neck tension, concentricity. Those topics and the means to achieve them hare continuously shared in this forum. PS: another recent discovery, we where using "lead sled" type rests but were getting vertical scatter in groups. Went to a tripod and rear support UNDER gun butt with recoil pad tight to shoulder and solved that. It appears that the gun was "bucking" when held too rigid by the mechanical gun butt stop. Guess that's what makes this fun and relaxing. So many details. Nice escape for a mind overloaded in today's 24/7/365 work place.