Developing a load for new brass? Bump fired to match new?

[westernrover]

Can I develop a load for a rifle using resized brass and then produce the load with new brass? Should I plan on firing all my new brass? Or should I try to resize the fired brass to match the new brass?

I want to load a couple hundred cartridges for an expensive-to-shoot, short barrel-life magnum. I've bought new Nosler fully-prepped brass - not many other options for this one. I'll be developing a load and using a minimal number of cartridges to do so. I'm only going to use one powder and bullet and try to do it as efficiently as possible. Fortunately, I've got two other rifle/bullet combinations to develop loads for to get my process down before I attempt this one.

Normally, I would have fired brass and bump the shoulder with the FL or body sizing die sufficiently so the bolt-handle drops without resistance on at least 10 different cases and then resize all my cases with that die setting. Typically, I'm bumping 2 or 3 thou.

Thanks for all the replies advising me about bump gauges in my other recent thread. Since the Sinclair insert I need is perpetually out of stock, I think I'll order the Whidden because I like the one-piece design vs. base and inserts.

If I were to bump the minimal amount to get bolt drop on all cases, I don't doubt I could get a good result, but I would probably have more case volume than my new cases and the load wouldn't transfer over to the new unfired brass because the initial combustion space would be less.

What do you think of measuring the new brass with the headspace gauge and then resizing the fired brass to match it?

I measured a case fired in my chamber vs a new case using a socket (tip from Varmintterror). It looks like the new cases' shoulders are 6 to 8 thou farther back than fired (I wasn't able to be more precise with the socket). Do I really want to bump ~7 thou and then load the unfired brass with whatever load I come up with? Or should I plan on firing all my brass and resizing?

 

[AJC1]

You can develop a load for new unfired brass of the same lot or develop a load for fire formed brass, but there is a volume difference. Is your node big enough to cover that difference?

 

[JFrank]

A few years ago I put a 308 load together using new Nosler brass, the powder mid node ended up being about 43.6 gr. After a few sizings and adjusting my die a little at a time, I had my shoulder set back right where I liked it. The powder charge node was still 43.6 and the accuracy hadn’t changed. After that I quit fire forming those type of cases. Now days I’m shooting an Ackley improved so I really don’t have much choice, although fire form loads shoot pretty darn well..

 

[AJC1]

A few years ago I put a 308 load together using new Nosler brass, the powder mid node ended up being about 43.6 gr. After a few sizings and adjusting my die a little at a time, I had my shoulder set back right where I liked it. The powder charge node was still 43.6 and the accuracy hadn’t changed. After that I quit fire forming those type of cases. Now days I’m shooting an Ackley improved so I really don’t have much choice, although fire form loads shoot pretty darn well..

Makes it hard to be specific if the chambering is a mystery. 30-30, 300wm, and Ackley cases all change a lot after first firings...

 

[JFrank]

Makes it hard to be specific if the chambering is a mystery. 30-30, 300wm, and Ackley cases all change a lot after first firings...

I don’t load for a 30-30 r a 300 wm so I can’t really comment on those specifically but I did mention Ackley, most nodes I’ve seen are about 3-4 tenths wide , loading in the middle I didn’t have any noticeable variances. Certainly when I’m running the edge of a high node I run the risk of breaking out of node where the rifle begins to shoot poorly but that’s a different level.

 

[AJC1]

I don’t load for a 30-30 r a 300 wm so I can’t really comment on those specifically but I did mention Ackley, most nodes I’ve seen are about 3-4 tenths wide , loading in the middle I didn’t have any noticeable variances. Certainly when I’m running the edge of a high node I run the risk of breaking out of node where the rifle begins to shoot poorly but that’s a different level.

My post was not contention it was agreement.

 

[JFrank]

My post was not contention it was agreement.

My apologies’ my reading comprehension isn’t what it use to be.

 

[243winxb]

an expensive-to-shoot, short barrel-life magnum

Just what is this mystery cartridge? Did i miss it in the other threads? Is this a custom gun with a match grade barrel that may know the difference between good & bad ammo?

Load data, powder , bullets to be used?

Need answers

 

[westernrover]

I didn't post the cartridge because it doesn't matter to my question, but I'm not trying to be obfuscatious. It's a 264 Magnum. A custom gun and match grade barrel isn't necessary to benefit from good ammo, and bad ammo will ruin the results with the most ordinary guns. Since I haven't afforded extensive testing of this gun, I can only report that a 3-shot group with Nosler factory ammo was .75" at 100 yards. I don't have a load developed yet -- that's where I'm trying to get, without spending a fortune or burning out the barrel. I ordered the dies today and the bullets, 127 grain Barnes LRX. I haven't ordered powder yet, but I have StaBall HD or the new Ramshot Grand in mind. There is no published data and I don't even have them in Quickload, so I'll have to work it out. The data for this bullet with Retumbo should get me in the ballpark.

If I had enough Trailboss, I might be able to fire-form the new brass with that and some cheap Matchburners. I only have enough to fill a dozen cases. Hodgdon publishes a Titegroup load for 223, but I don't feel like trying to come up with one for this rifle. It's not worth a squib or worse.

Once I have a load, I'd like to have as many as 200 or 250 pieces of it, but I don't want to fire that many to get there. I did consider just developing a load for new brass, and just discarding the fired cases. I wouldn't need to resize or trim at all. I decided not to do that and I've ordered the FL bushing die, bushing, and mandrel setup as well as the seater.

Now my dilemma is whether I should resize the brass bumping the shoulder as much as 8 thou to match new brass (which seems kind of lame) and develop a load for that. I would hope to put that load into the new brass. Otherwise, I need to figure out a way to get enough brass sized for my chamber. That's the solution I prefer, but haven't figured out yet.

 

[Nature Boy]

A few years ago I put a 308 load together using new Nosler brass, the powder mid node ended up being about 43.6 gr. After a few sizings and adjusting my die a little at a time, I had my shoulder set back right where I liked it. The powder charge node was still 43.6 and the accuracy hadn’t changed. After that I quit fire forming those type of cases. Now days I’m shooting an Ackley improved so I really don’t have much choice, although fire form loads shoot pretty darn well..

Ditto my experience

 

[JFrank]

I’ve spoken more than my share on the last few threads, forgive me for being repetitive.

Unless you are loading for a long range target rifle, new brass to once fired and resized brass won’t make a noticeable difference. Resizing to .008 under a chamber is pretty extreme and likely lead to early brass failure.
minimum component load development is fairly simple. I’ve used as little as one round per charge for powder but never more than three to get a basic idea of my node. Currently I use two shots per charge for powder and three for seating. Bullet hold and primer testing can be two or three or no testing. Hunting rifles need cold bore accuracy not extended barrel heating test strings.

 

[westernrover]

Ditto my experience

So you're saying you developed a load in unfired brass without resizing, and the same load worked in resized brass? How much was the difference between the new brass and the resized brass? How much did you resize it?

 

[westernrover]

I’ve spoken more than my share on the last few threads, forgive me for being repetitive.

Unless you are loading for a long range target rifle, new brass to once fired and resized brass won’t make a noticeable difference. Resizing to .008 under a chamber is pretty extreme and likely lead to early brass failure.
minimum component load development is fairly simple. I’ve used as little as one round per charge for powder but never more than three to get a basic idea of my node. Currently I use two shots per charge for powder and three for seating. Bullet hold and primer testing can be two or three or no testing. Hunting rifles need cold bore accuracy not extended barrel heating test strings.

So you're saying that if I develop a load with minimally resized brass, say bump the shoulder 2 thou or the least amount needed for bolt drop, then I can put it in the undersized new brass and it will still be good, or maybe good enough.

 

[243winxb]

I tested new factory brass. Used a boatail bullet as the expander. Just added primer & powder, bullet, nothing else.
Then compared to same brass after Bench Rest prep. Difference 1/4" @100 yards.

The load had been worked up/used before. Rem 40x in 243.

dilemma

Fire, size, bump .002" load.

Once I have a load, I'd like to have as many as 200 or 250

50 is plenty. I have not had good luck with stored ammo. Neck tension, bullet weld can change, over time. Any remaining residue. from previous firings, may attack the brass.

 

[243winxb]

Long bullets may need more twist? Barnes data 264 magnum 127 grain Barnes LRX

Recommended twist 1:8 or faster.

 

[westernrover]

I tested new factory brass. Used a boatail bullet as the expander. Just added primer & powder, bullet, nothing else.
Then compared to same brass after Bench Rest prep. Difference 1/4" @100 yards.

The load had been worked up/used before. Rem 40x in 243.

Fire, size, bump .002" load.

50 is plenty. I have not had good luck with stored ammo. Neck tension, bullet weld can change, over time. Any remaining residue. from previous firings, may attack the brass.

Thanks for the feedback. Your comments have been helpful. It looks like I will plan on firing the brass and being content with fewer pieces.

 

[AJC1]

My apologies’ my reading comprehension isn’t what it use to be.

Your node covered your increase in case size.... in the big changes your lower wider node helped. It's hard to help him if we're guessing what he is loading.

 

[AJC1]

Thanks for the feedback. Your comments have been helpful. It looks like I will plan on firing the brass and being content with fewer pieces.

A barrel usually takes 100 ish rounds to break in and be at full speed. That's 50 pices of working and loaded ammo. If you shoot 10 a year at game after development that's 5 years worth. Keep the other cases stashed away. That's how I'd approach this situation.

 

[westernrover]

Long bullets may need more twist? Barnes data 264 magnum 127 grain Barnes LRX

Recommended twist 1:8 or faster.

Yes, 1:8 is Barnes general recommendation. I determined I should be good on twist because I live and use the rifle at high altitude. I live at 5000 feet. I can use a stability calculator like the one from Berger or JBM to factor in atmospheric pressure. Barnes has to consider customers at sea level.

The lower the altitude and temperature, the denser the air is, and the more gyroscopic stability is needed. Berger's calculator will also show how much a lower Sg compromises the bullet's BC. For JBM's calculator I needed to use an atmospheric pressure calculator to determine the pressure in mmHg

Twist Rate Stability Calculator

Our newly updated Twist Rate Stability Calculator not only tells you what your SG is, but it also lets you know if you are reaching your optimized BC.

bergerbullets.com

JBM - Calculations - Stability

www.jbmballistics.com

https://www.omnicalculator.com/physics/air-pressure-at-altitude

I won't be able to expect these loads to work in Alaska in winter at sea level, but they should be good for antelope in September at 4000 feet, and for mule deer in October when it's cold but at higher elevations. The last deer we took was at 9300 feet (my son took it at 200 yards with a 127 grain LRX albeit with 1:8 twist). It had been -5 when we woke up, but it was warmer by the time the sun rose. My 1:9 twist should be good with a comfortable margin all the way down to -5 deg. F at 6000 feet or 30 deg. F at 4000 feet. I'll lose about 6% of the BC in those conditions, but it's still better than shorter bullets.

The main reason I want to use the 127's is for elk. This isn't primarily an elk rifle -- I can very rarely get the tags. I'm not going to get a 338 to shoot one elk every 10 years, but with this bullet I can take pronghorn and mule deer, and should I be fortunate in the tag lotteries, bighorn, mountain goat, the small black bears we have, and elk.

I didn't pick this rifle or chambering. It's been around a long time. It seems like both the rifle and the cartridge could be awesome, so I'm going to see. I think this is the best bullet to do what I want with it. I'll have to prove that it's stable by taking it out when it's really cold this winter, so we'll see.

 

[Varminterror]

What do you think of measuring the new brass with the headspace gauge and then resizing the fired brass to match it?

1) What you’re doing doesn’t dictate the level of concern you’re applying to it. You’re not moving brass and forming cases, you’re just fireforming cases to match your chamber. The difference in case volume response for the fired case vs. virgin case won’t make a difference for what you are doing - and may not make any difference at all for anything anyone is doing.

2) Bumping the shoulder back to match the virgin brass headspace length doesn’t actually ensure you are matching the original volume, so it’s pseudoscience to assume doing so would be meaningful. Unless the original brass was formed with your sizing die, then you have no assurances that your die is putting the internal volume back where it was originally, even if you do restore the shoulder datum relative to your specific comparator.

As described in your other thread - don’t sweat the small stuff here. The detail you’re chasing is stuff that will only matter if you’re trying to shoot in the 0’s and 1’s instead of shooting in the 2’s, which simply isn’t pertinent for your application, and doesn’t align with the philosophy you have described for the rifle and ammo. Work up the load, consistent ES/SD, it’ll likely be ~1/2-3/4moa unless your barrel is a drain pipe, in which case, change the barrel. It’ll survive coming back to your virgin brass.

 

[Nature Boy]

So you're saying you developed a load in unfired brass without resizing, and the same load worked in resized brass? How much was the difference between the new brass and the resized brass? How much did you resize it?

I run new brass through the sizer, chamfer and deburr, in order to uniform the necks before I begin any load testing.

Like @JFrank , the load work I’m thinking of was also .308 win. I don’t recall an appreciable difference between new and subsequent fired brass relating to the accuracy node.

And like @JFrank, I’m also running an Ackley Improved cartridge that requires fire forming. I developed a specific load for this task that I actually shot in a match. It was surprisingly accurate and scored a 592 (that’s 52 out of 60 rounds inside a 1 MOA circle at 600 yards).

ETA: the reason for a different load when fire forming an Ackley cartridge vs a standard cartridge is because the case volume between pre and post formed brass is significant enough to warrant a reduced powder charge.

 

[Walkalong]

As likely already covered, bump to fit your chamber, not new ammo, which has to fit in any SAMMI spec chamber.

 

[OS/N]

Magmun or other hp big cases don't last many cycles. I generally load new the same as bumped brass with same charge and OAL. It will size to your chamber and pressure end up about the same is my opinion.

They aren't as accurate in my rigs but the only way to get them the right size is to fire in your chamber. The loser fit case doesn't position the bullet as close to the same way each round. About the only way to get around this is to have a saami minimum chamber that is .002 longer than your new brass and then different makes or lots of brass still may be a little different in headspace.