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Determining When Cases Are Fully Formed

CarlGeorge

CarlGeorge

I'm waiting on the last component to arrive for a new build - so that's giving me a lot of time to think.....which could also be labeled "obsess". LOL (It'll be a straight .284 on a Kelbly Atlas action, Brux barrel and McMillan stock. I'm waiting on the stock.)

The FL vs Neck resizing thread raised a question in my mind. Rather than derail that thread I thought I'd start a new one.

@Dusty Stevens wrote....responding to someone about some case sizes they were getting:
Your cases are not fully formed yet. Dont bump them until you feel the slight crush on a stripped bolt then bump them .002 short of that one. Some bump and some dont at this point
​
I have two questions:
  1. Stripped bolt?
  2. Is it a waste to try and do load development on brass that isn't fully formed? Or do I first focus on getting my new brass formed, and *then* do my load development? (If it matters - I'll be using 6.5x284 Lapua brass that I've necked up to .284.)
Thx.

CG
 
CarlGeorge said:
I have two questions:
  1. Stripped bolt?
Click to expand...

First of all, your Kelbly Atlas Tactical action is an excellent choice. Due to the design of the extractor and TG ejector, there is nothing putting any pressure on the case, so it is not necessary to strip your Kelbly bolt when checking for crush on the case when closing the bolt.

You didn't state if you would be neck sizing or FL sizing between firings as your standard practice. Assuming you will be FL sizing, I would start load development after the first firing/sizing cycle. What Dusty Stevens wrote is similar to my practice on sizing, I just take a slightly different approach but the same end result. I will back my sizing die off sufficiently (1/4 turn is plenty) during FL sizing so the shoulder actually moves forward slightly due to the compressing of the case without contacting the shoulder during sizing. I measure and record the case head to datum length (new brass, fired brass, and sized without shoulder bump). What I want to find is what length results in bolt contact (crush) when sizing. And once I know and record that, I set my die for 0.002" setback from that measurement.

I'm sure others will have plenty of input for you.
 
CarlGeorge said:
I'm waiting on the last component to arrive for a new build - so that's giving me a lot of time to think.....which could also be labeled "obsess". LOL (It'll be a straight .284 on a Kelbly Atlas action, Brux barrel and McMillan stock. I'm waiting on the stock.)

The FL vs Neck resizing thread raised a question in my mind. Rather than derail that thread I thought I'd start a new one.

@Dusty Stevens wrote....responding to someone about some case sizes they were getting:
Your cases are not fully formed yet. Dont bump them until you feel the slight crush on a stripped bolt then bump them .002 short of that one. Some bump and some dont at this point
​
I have two questions:
  1. Stripped bolt?
  2. Is it a waste to try and do load development on brass that isn't fully formed? Or do I first focus on getting my new brass formed, and *then* do my load development? (If it matters - I'll be using 6.5x284 Lapua brass that I've necked up to .284.)
Thx.

CG
Click to expand...

1. - Firing pin & ejector plunger removed = stripped bolt.
2. - NO (Not IMO) The first firing can provide useful information regarding what potential components that have accuracy potential and include bullet seating depth into that as well. - One "key" point is to take very good notes that you can read & fully understand in the future.
One long range BR shooter I know told me he has in fact seen match winning targets shot while the shooter was fire-forming brass & I believe it. - I've shot some pretty small groups with virgin brass during the fire-forming process.

"bump them .002 short of that one." - This is what some reloaders use as a "rule of thumb" - myself, I "bump" the shoulder more like 0.001 and I check for "feel" using a "bumped" (F/L sized) piece of brass.
 
CarlGeorge said:
  1. Is it a waste to try and do load development on brass that isn't fully formed? Or do I first focus on getting my new brass formed, and *then* do my load development? (If it matters - I'll be using 6.5x284 Lapua brass that I've necked up to .284.)
CG
Click to expand...

Your load won't vary much in once/twice fired cases vs new cases. However, assuming this is a new barrel I would not burn many rounds getting a decent shooting load (ask others that are using the same bullet/powder etc for guidance) then shoot that for 80-100rds. Then do more exact seating depth/load work as the load will usually change over that range of round count. I have done load development while forming 6.5 x55 AI brass and shot them in matches to get several hundred cases formed (roughly 4gr water capacity change in case volume). I have cleaned targets at 600 with respectable X counts. This gave me the speed that the barrel liked and I just ran a quick one/two case per load test to find that velocity in the formed cases and ran with it.
 
DJBS manages all my annealing. Pretty sure DJ would recommend you fire new brass a min 3x so it would be fully sized to your chamber.
Ben
 
I’m not talking prior to load development, just new brass on an established recipe.
I’ve hit 308 brass with a full charge and they shot fine.
 
Thanks all. This is really helpful info. I'll be FL sizing.

I've been exposed to Optimum Barrel Timing concepts from a friend/"consultant". I'm hoping/planning on the fact this will help me hone in on an optimal load without having to put too many rounds down range. (Or, at least, put less down range to settle in on a good load than I would were I not using OBT concepts.)

The bullet I most likely want an optimum load for are the Berger 184g Hybrids. I've been told (and read reports online) that H4350 works well for this cartridge/bullet. (BTW, it's a 30" barrel - 9 twist.........I live in CO at a little over 5,000 ft. And actually, I do some of my long range shooting at 6,700 ft.)

I'm also going to have a "plinking" load that I'll use on High Power Silhouette - going out to 500m. For this I've got my eye on the Sierra 150g MatchKing. Not sure what powder I'm going to use. (Although I've got a few pounds of H4831 on the shelf - and I've read this works pretty well in the .284, but I'm not sure if that's the case for the relatively lite 150g.)

CG
 
Last edited:
SPJ said:
I’m not talking prior to load development, just new brass on an established recipe.
I’ve hit 308 brass with a full charge and they shot fine.
Click to expand...
Are you saying you reduce charges for virgin brass ? If so,is it due to the quality of brass you use ?
 
My 2 cents. Seat the bullets for a hard jam with a good amount of neck tension. Use a slower burning stick powder that fills the case a little past where the base of the bulletwould contact the powder . What this does is it holds the case back against the bolt face allowing the shoulder to push forward against the chamber when firing. Also make sure the primers are flush or slightly below the base of the case
 
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