Load dev - new vs once-fired brass??

Richcotte

Richcotte

Hammer Time Executive member
So, what’s your thoughts on new vs once-fired for load dev?

Assuming, high quality brass like ADG or Peterson, has anyone seen a significant difference between velocity, pressure, accuracy, etc… after the first firing? How much if any does the load change between the two?
 
I think it's more chamber specific then a brass question.

I'm driving home from Camp so no proofread and very little punctuation.

I can take brand new Bertram brass in my 300 H&H and I have to drop two grains from a safe load or it will blow the primers due to the fact that the shoulder increases .037-in upon the first firing. Definitely a reduced capacity in that cartridge.

In my 300 rum I can load the same charge weight in fired or unfired Bertram brass the specs are so close to the chamber I see no difference maybe a few feet per second but not an issue .

Joe
 
Good point @joe16

So, a little background on my question...

I've always been a once-fired until it's wore out brass reloader, whether commercial or LC brass. With that experience, I have noticed minor changes as the brass ages through the number of firings and trimmings. Not enough to make any truly significant difference in a hunting scenario, but when I was shooting long range (1K - 1400 yard) target using LC converted to 6.5CM, I would limit the cases to 3 loadings and then they went on to other rifles until they got wore out.

It wasn't until recently that I purchased some Peterson 300 WM Long that I started to ask the question.

Originally, when I bought 100 pieces of Peterson, I measured a handful for overall length to see if I needed to trim them all to a consistent length, nope, no need, so I just loaded up and went searching for pressure, found my load and ran with it.

I now have 50 cases that are once-fired, and FL resized to the same shoulder length as factory new and trimmed to consistent length, 15 pieces of virgin unloaded, and 31 loaded with my load that I worked up. (Yupp, 4 pieces of spendy brass were sacrificed to the pressure search, ending up with stretched primer pockets) That's where the question arose...Will the once-fired cases perform close enough to what they did as new, or is this load only really valid with virgin brass?

My assumption is (hunting rifle) not enough to make a significant difference, but I just don't know how much new brass really changes after the first firing. I guess I need to run a little experiment of the same load side by side in virgin brass vs the once-fired and see what happens.
 
Ok, curiosity got the best of me, so I broke out the calipers...

Comparison of the 15 virgin pieces to 15 random pieces from the 50 once-fireds....(No primer pocket measurement because they've all been primed)

Now I gotta get some more 154 HHTs so I can see if there's any difference in performance.
 

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Rich, the 300WM is prob absolutely worse case example for first during stretch (0.015 common stretch on first firing) EXCEPT for Peterson Long where I also found them to be virtually same as 1x fired. This is in comparison to first gen Sendero prob 1997 vintage. So in this case I just load new and go shoot and have not seen anything earth shaking but it wasn't at long range distance. Ha! The 154HHT with H4350 is rocket in Peterson Long brass.

I did similar measurement on Peterson Long on LRH few years back and will try to find the data.
 
Richcotte said:
So, what’s your thoughts on new vs once-fired for load dev?

Assuming, high quality brass like ADG or Peterson, has anyone seen a significant difference between velocity, pressure, accuracy, etc… after the first firing? How much if any does the load change between the two?
Click to expand...
I haven't noticed any differences. Ive heard many times you need at least 1x to at least 3x, but I haven't noticed any velocity changes starting with 0x to 1x to 3x. My guess is the amount of shoulder bump isn't critical but I size the necks on all virgin unfired brass to my die so maybe thats why I don't see anything.
I use Federal, Nosler, Starline, and Peterson brass.

Id go broke if I had to 3x fireform before I began to load develop.
 
Richcotte said:
Agreed @Koda , I definitely don’t want to manage that hassle. Mostly my brain going down a rabbit hole. But, was thinking it might be worth knowing how much if any it changes.
Click to expand...
In all fairness I cant say my observations are conclusive. Its possible that it could make a difference with cup and cores but my only experience is with Hammers which all shoot the same POI regardless of charge/velocity so how would we know fireformed brass makes a difference with Hammers anyways. All I do is run a pressure ladder, find my charge weight and zero and done. Everytime Ive gone back to measure my extreme spread the velocity has always been close to the charge weight I picked from the pressure ladder, the POI is the same. Starting from virgin brass I havent noticed anything different.
 
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