Load Development Check

[Rmdashrf]

Hi Everyone,

I recently completed my load development for a new barrel and wanted to check if I am on the right track with picking 42.3 grains as my node. That group shot well, but I noticed I might need to bump the shoulder back .001 as the rounds are slightly tight on close as I used brass previously fired from another barrel. Will bumping the shoulder back change the case capacity and require me to verify my node again, or can I continue to send it?

Lapua 6.5 CM Brass
Barnes 6.5 127 GN LRXBT
H4350
CCI 450

I appreciate everyone's advice and feedback!

Cheers!

 

[ShtrRdy]

I think it will change it slightly. Push the shoulder back and fire your recipe across the chrono.

 

[Rocketmandb]

42.3 looks to be on the hot side of things. I'd try playing at 42.0 - 42.1

 

[needham]

so the brass used was unsized, and fired from another rifle?

personally I would highly prefer the shoulders bumped back to the rifle I was shooting (as you alluded to as well)

I would get a batch of brass prepped for the rifle you are testing, and re shoot the test.

Chrono numbers are good to have and all, but while you are doing that I would shoot an OCW, that way you get your chrono numbers and what it is doing on target.

that way, when you go to evaluating loads there isnt much question as brass is good, and you have visual aides on target and a good set of chrono data.
If you leave it to chance now, you'll always wonder. If you're like me, just take the extra time now and you'll never have to worry about it.

 

[Steel head]

If your brass was tight a 1-2 thou bump won’t change much.

Obviously something worth looking into at 42.2 as it’s a flat spot and low es.
Next charge had three in tight and one outlier so I’d still be confident on 42.2 And do a jump test with it.

 

[Rmdashrf]

Great replies everyone!

I was using brass fired and resized based on my previous barrel (same action). I'll bump my brass back to match this new barrel and retest. I'll shoot for groups as well like needham recommended.

Will testing 41.6 to 42.6 be good enough?

 

[bax]

You appear to have a nice velocity node. The next goal would be the smallest round group you can get without flyers.

Shoot 41.8 to 42.2, 3 rounds each with a 0.1 interval - 41.8, 41.9, 42.0, 42.1, and 42.2. Based on the result above, you should measure nearly the same velocity for all shots and all the groups should make a horizontal line on your paper.

Based on consistent vertical, pick your favorite three (for example, 41.9, 42.0, 42.1) and shoot another set with a 0.05 interval, for example 41.90, 41.95, 42.00, 42.05, and 42.10. Based on flyers and horizontal, pick your favorite.

You might want to shoot all at 200 so you can see your group shape better, especially vertical. Be sure to call your flyers and don't count them.

I shoot 308 and my powder charge, developed over a lot of rounds, is 41.52 plus or minus 0.02. Charges 41.50, 41.52, and 41.54 shoot to exactly the same place within the limits of the rifle and shooter. If I don't lose my mind, sometimes I can get a 5-round four (I have a two and a couple of threes but they are flukes), I can usually get a 5-round five. I have a nice velocity node to work with but that value shoots the best round groups with my components, techniques, and weapons.

Somewhere in all this, I would play with seating depth using the same general scheme. Don't be afraid to try seating deep. Recent studies suggest that over the life of a 200-round match your throat erodes and that deep seating prevents that throat changes from screwing up your groups.

 

[Rmdashrf]

"41.8 to 42.2, 3 rounds each with a 0.1 interval" seems like a great plan! A 0.05 interval might be a bit too granular for me and my charge master lite

I already tested seating depth and i'm pretty sure 0.075, 0.100, and 0.125 all crunched the powder when seating the bullet...The groups were wild on those! 0.050 gave me good results.

 

[bax]

"41.8 to 42.2, 3 rounds each with a 0.1 interval" seems like a great plan! A 0.05 interval might be a bit too granular for me and my charge master lite

I already tested seating depth and i'm pretty sure 0.075, 0.100, and 0.125 all crunched the powder when seating the bullet...The groups were wild on those! 0.050 gave me good results.

It is obvious that weapon will never shoot and will be a perpetual embarrassment. You seem a decent fellow, in order to spare you the shame I'll give you $50 for it. It's the least I can do.

 

[Rmdashrf]

In case anyone was curious, bumping the shoulder back .003 definitely changed my results. My ES went from 10 to 40 FPS! Going to reshoot a new interval after the holidays and report back.

 

[bax]

In case anyone was curious, bumping the shoulder back .003 definitely changed my results. My ES went from 10 to 40 FPS! Going to reshoot a new interval after the holidays and report back.

This is what I do. It works for me.

Sinclair sells reloading die shims. See the "reloading die shims" here. The thinnest shim is 0.003. While using the 0.003 shim, set your die to a three thou bump. If you want brass with a 3 thou bump, put in the 0.003 shim - same as your setup. If you want a 2 thou bump, put in the 4 shim - the die is now 1 thou higher so you get less bump. If you want a 1 thou bump, put in the 5 shim - the die is 2 thou higher. The 6 shim will give you chamber length.

When installing your die and shim, make sure the die and shim are clean and use a torque wrench - results will be consistent, I use a crows-foot and 60 in-lbs.

If you anneal, then your shoulders will have the same hardness and they deform the same every time. That helps consistency.

When I set up for full-length sizing I start with a a guideline like above then I check to see what bump I am getting with one of these and adjust the shims. The case gauge has a zero mark but your mileage may vary so you have to measure several fired cases to calibrate. My chamber is SAAMI minimum (2 thou short, on purpose) so I know that if a case measures 2 thou short, that is just chamber length. I full-length size my brass but my setup sets the shoulder to be the same as chamber length or just a tiny bit of a bump. The die is reducing neck diameter and body diameter but doing little to nothing to the shoulder. In my rifle, with a stripped bolt, when the bolt handle is fully down, the brass is just kissing the bolt face and the chamber shoulder. You can close the bolt with one finger but you have to close it.

 

[supercorndogs]

I don't think .003 shoulder bump caused it.

 

[Rmdashrf]

I'll read up and try to troubleshoot any common offenders to high ES.

 

[Dthomas3523]

I'll read up and try to troubleshoot any common offenders to high ES.

Powder drop/charge weight and neck tension.

 

[Rmdashrf]

Neck tension definitely changed. I realized my bushing was engaging an unknown amount of the case neck. It's now set up to size half the case neck. That might explain an overall increase in FPS as well.

 

[Rmdashrf]

My cases are now fireformed for my new barrel and bumped back 0.002. Any thoughts on the new test below, what would you do next?

This test was in .03g increments. 42g had the best group on paper.

My reloading process was previously:

1. Clean
2. FL Resize, decap, and expander ball
3. Clean
4. Trim, Chamfer, and Deburr
5. Prime
6. Charge
7. Seat

My reloading process is now:

1. Deprime
2. Clean
3. Anneal
4. FL Resize
5. Expander Mandrel
6. Clean
7. Trim, Chamfer, and Deburr
8. Prime
9. Charge
10. Seat

I appreciate everyone's advice and feedback.

Cheers!

 

[Rmdashrf]

Here is a bit more info:

 

[KnowNothing256]

Frankly, it looks like 42 gr is still your huckleberry.

Don’t worry too much about crunching powder, some can like to be compressed a little, esp extruded powders like H4350. I pretty much always end up with a bit o’ crunch with H4350, although I watch very carefully for pressure signs as I ease into it. If you saw pressure signs with more jump, so be it, you’re at your limit. You could potentially increase jump in smaller increments, but I wouldn’t jump less than 0.050”.

 

[ZY100]

Your node is 42.2-42.6. Its a little warm but 2900 for 130 class bullets in 6.5 is not unheard of. Personally I would do a seating depth test at 42.4, watch for pressure and find the sweet spot for accuracy. You have a nice wide .4 velocity flat spot—at least for your sample size.

PS. Thats quite a reset you did on your loading process. Looks solid.

ZY

 

[Rmdashrf]

Your node is 42.2-42.6. Its a little warm but 2900 for 130 class bullets in 6.5 is not unheard of. Personally I would do a seating depth test at 42.4, watch for pressure and find the sweet spot for accuracy. You have a nice wide .4 velocity flat spot—at least for your sample size.

PS. Thats quite a reset you did on your loading process. Looks solid.

ZY

I see the flat spot but would you be concerned with the high ES of 31 in that range?

 

[ZY100]

Re: ES....not so much. a) sample size is way too small.....b) an optimal seating depth can tighten that up too.

Finalize an accurate load and shoot a larger sample size and I think you will be fine.

ZY Opinion: We all love single digit SDs....but an SD in the 10-ish range is more than good enough for hunting or PRS type comps out to 1000-ish.

PS--what neck tension are you running?

ZY