Too early to do load developement?

J E Custom

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I’ve got a new C.A. In 280ai. The barrel has 75 rounds through it after the C.A. recommended break in procedure. I’ve got a couple different powders loaded up for some ladder tests but am starting to wonder if these will be conclusive. Any opinions on if the performance will change once there are 200 rounds down the tube (for example) compared to now?

Normally by the time you get a barrel broke in, velocities will stop changing due to round count. They will change with different powders and bullet loads. My experience/opinion has been that they can/will increase 50 to 100 ft/sec over the first round up to about 10 to 12 rounds in premium barrels. Factory barrels will often never peak because they will never achieve the finish of the bore in a premium barrel because of all the tool marks left in the bore.

I have seen factory barrel reach 70 or 80 rounds and still not be broke in. So these barrels will slowly increase in velocity but never more that 15 or 20 ft/sec for many rounds.

J E CUSTOM
 

denobravo

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Feb 11, 2013
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the lands are being polished by the projectile, as they wear down, more bearing surface is created.
The more bearing surface, means more pressure which means an increase in FPS.
After 200 rounds I gained 100 fps
still there after 700 rounds
gotta shoot it !
test, dont test , still gotta shoot it
 

Boatninja

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Oct 13, 2019
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I agree with A wheeler above, I have only done six barrels but have had barrels settle around 50 and some over 100. I do a round of load development loads early, around 40 rounds and record results, then get serious after 100 rounds. The early records give me a baseline for comparisons and have some fun doing break in.
 

bramlett9

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Leawood, KS
I typically do my break in procedure and then start shooting ladders to get a rough idea. Once my brass is all fire formed, I’ll fine tune it, but the load shouldn’t change that much from virgin brass to once fired. I’ve also noticed a lot of my brass isn’t fully formed after just once fired.
 

Mikecr

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It can take 3-4 firings to fully form & settle cases. Velocity will climb a lot and then less & less through this, due to this.
While considering/testing this barrel speeding notion, your brass needs to be in settled condition -to remove it from variable.
 

Arkansasdad

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In order to know when your brass has become stable and is filling the chamber can only be achieved by careful measuring. I use RCBS Precision Mic for this chore. When the brass is stable, it no longer grows either in shoulder datum to head length or do the necks elongate. Then careful sizing and neck expanding are performed. I now use Forster Comp FL dies with honed necks and polished expanders in conjunction with a mandrel turned to my specs. The FL die hardly changes the neck, it brings it back to bullet diameter and the mandrel gives me the final dimension. I like my chambers to have no more than .004” for neck expansion. I also don’t use tight neck chambers anymore either, had bad experience with excessive pressures with a tiny carbon ring and damaged an expensive barrel, it was re-usable after setting back, but it lost a full season with that trimming back...not happy.
I let my rifle barrel tell me what neck tension it likes. I start at .0015” and work up in .0005” increments until I hit .004” max, as I feel this is a lot of neck movement beyond this amount.
Usually, somewhere in that range produces the perfect tension the gun likes.
One barrel I have in 300WM likes .004”, all others are .0015“-.0025” where they like to be.

Hope this helps.

Cheers.
What???? I think your speaking of freebore. Freebore is the distance the bullet travels before it contacts the lands, neck tension is the amount of pressure used to hold the bullet in the neck of the cartridge brass. I have never heard of forming brass to ten- ten thousands of an inch. Don't even know how I would measure this.
How does using a full length die not change the overall dimensions back to the dimensions of the die and away from the dimensions of the chamber the brass was shot in? This is what fire-forming is, the forming of the brass to the chamber it has been shot in. Brass will "crawl" every time it is shot, how much depends on chamber configuration, how hot the load the primer, and etc. but it will always flow.
In my experience the brass crawls less in calibers that have sharp and long shoulder angles such as the newer bench calibers but it always crawls forward. This is why brass wears out, also this is why the brass has to be trimmed every so often depending on how much crawl or flow, as my younger brothers tend to call it, it is experiencing. As this is happening the brass is getting thinner through the body of the cartridge brass and eventually fails, this is where the brass comes from that elongates the neck.
I think fire formed brass is as good as it will ever be after the it is fire formed the first time, after tens of thousands of rounds I have shot I notice no distinguishable difference in the accuracy as far as the brass goes until the brass gets to the point it fails. Hope this helps happy shooting.
 

Zstingray

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Apr 17, 2012
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I start my processes with the first break-in shot. I want to fireform brass. Once fired brass is ok for load testing. However good virgin brass will be almost as good. I also test various loads and seating depts. during break in. These are not the final adjustments. After the break-in I will test different loads for a low SD. I don't worry about group size yet. The low SD will then be tested for seating depth. You should be good to go at this point. This is where I find the tight group. The only thing that will change your load is outside temperature if you are using a temperature sensitive power. Load development in high summer may need and adjustment in the fall and winter. If you have a good muzzel velocity with a low SD the adjustment is easy.
If you are reloading without a chromo - don't you do that get one.
I don't hunt anymore as advanced age has made this very difficult and I don't want my buddies to be slowed down and I don't want them helping me around and over fences, ditches and such. I now shoot competitive NRA long range at 300/600 and 1000 yards with a 308 Remington clone. This method has don't me in good stead. National Record Certificates on the wall can attest to that.
 

Mikecr

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Brass does not 'flow'.
Everything brass does -we did to it.

I run a fitted chamber with cases having ~70 reload cycles on them now. These are not sized, annealed, trimmed, etc.
Zero changes from fire-formed.
But they did change during the fire-forming, all cases do,, and you can measure & watch the changes settle.
If your cases never settle, it's because you won't let them. No doubt with your excess sizing.
 

GW Hunter

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Orangevale, Ca
Brass does not 'flow'.
Everything brass does -we did to it.

I run a fitted chamber with cases having ~70 reload cycles on them now. These are not sized, annealed, trimmed, etc.
Zero changes from fire-formed.
But they did change during the fire-forming, all cases do,, and you can measure & watch the changes settle.
If your cases never settle, it's because you won't let them. No doubt with your excess sizing.

These are not sized, annealed, trimmed, etc.

Please enlighten me...
 

RDRNNR268

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Jan 27, 2009
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Texas
I’ve got a new C.A. In 280ai. The barrel has 75 rounds through it after the C.A. recommended break in procedure. I’ve got a couple different powders loaded up for some ladder tests but am starting to wonder if these will be conclusive. Any opinions on if the performance will change once there are 200 rounds down the tube (for example) compared to now?
The break in takes about 10 shots if you follow the procedure in The Book of Rifle Accuracy written by Tony Boyer one of the greatest bench rest shooter of all time. He sometimes fires 20 shots in one string. Coat the barrel with Lock Ease and shoot. I use colloidial graphite for mine. Just heavier than lockease.Usually all it takes. None of this shoot and clean crap. I shot for 20 years. Life Member NBRSA. I broke mine in like this and do others i know that still are active. Ready to start load development in a hurry.
 

Okanogan

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May 5, 2015
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Riverside, WA
Gotta agree with the advice from Alex Wheeler. I am still working on load development for a new 6.5 SAUM. The barrel definitely sped up about 50-75 fps right around 150 rounds. That didn't mean that all the work determining bullet seating depth, barrel harmonic, etc was lost though. I'm in the process of going back and tweaking loads lower to get back to the velocities that were shooting best. In some cases, I'm trying a different powder because I don't like the new ES/SD with the revised charge weight. If you have a chronograph and keep records of what your are doing, it isn't wasted effort. It isn't like you can skip the break-in process without putting rounds through the barrel so as long as I'm spending the money on bullets, I want to get the most out of it. Getting fire formed brass out of it is just a side benefit to me as I'm doing the initial work with virgin ADG brass.
 

Alex Wheeler

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Many in short range br never shoot over a chrony and tune for every target. A lapped barrel shooting long for caliber bullets that does not speed up is rare, but I have owned them. I have no doubt it's in the surface finish and I have spent the money to test and hopefully fix it.
 

J E Custom

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There are so many opinions on velocity changes that I decided to do a test that would actually show real world results. I have since done many this way and some valuable information was gained from the test.

This is just one of the test with results and since then I have fire formed over 100 rounds in this rifle and the velocity has remained within 10 ft/sec once break in is done. The fire formed AI cases have retained this 10 ft/sec average difference even though the load is over 100 ft/sec faster and rifle has over 200 rounds through it including the fire forming loads. SD's have been 3 to 5 for 5 shot strings of this load.

What this test has showed, is the quality of the different barrels by the speed that they break in and settle down from the very first shot to the point they level out. The longer the break in takes, the longer it takes to reach it's peak velocity. Some barrels and loads showed lower spreads in the total difference from the first to the break in completion. So the comparison has to/must be made with the same load and condition of the case. (Fire forming, or formed). any change will void/skew the results.

I have not done a factory barrel yet but intend to the first one that I break in. I don't expect a lot from factory barrel because in the past they never seem to break in.

https://www.longrangehunting.com/threads/new-barrel-break-in-and-cleaning-methods.160450/page-2

post #20 has the details of this test if anyone is interested, and has led me to begin working up loads once brake in is finished to speed up the process and so far I have been able find accurate loads within 20 or 30 rounds.

So far it has been very predictable.

J E CUSTOM
 
Last edited:

6.506ai

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Oct 5, 2017
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I’ve got a new C.A. In 280ai. The barrel has 75 rounds through it after the C.A. recommended break in procedure. I’ve got a couple different powders loaded up for some ladder tests but am starting to wonder if these will be conclusive. Any opinions on if the performance will change once there are 200 rounds down the tube (for example) compared to now?
My 280ai i noticed sped up after about 100 rounds. I found best results with rl23
 

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