Changing brass - Do I need to rework the entire load?

[M1Amen]

Hi guys,

I have a question about hand loading. Finally, after much labor, I have developed a hand load that gets a certain gas gun to hold 1/2 MOA. All of the load data and experimentation was done with Remington brass, but now much of that brass has passed it's useful lifespan.

Now that I am done with this certain Remington brass, I will begin to organize my other brass by head stamp for consistency when I'm reloading. My question is, now that I am changing brass manufacturers, how much should I expect my group sizes to change? Should this simply be a small change, or possibly no change at all? Or should I expect to need to rework the load for each different brass manufacturer.

My instinct tells me it will likely be very small and that my results will remain consistent as long as I don't mix head stamps in the same shooting session, but I am new to the search for extreme accuracy and would like to hear from those more experienced than myself.

Thanks in Advance,

M1Amen

 

[zuke]

Yup,you'll have to rework the load.

 

[McCrazy]

Is always prudent to back down your powder charge a bit and work back up so you don't hurt yourself or your rifle.

Some brass (Lapua especially) tends to have a smaller volume so dumping in the same amount of powder increases pressure.

 

[M1Amen]

Do you think sizing, trimming and weighing the cases would be a good indicator of case capacity. If they are trimmed to the same length after sizing, the weight should at least point to the case capacity, right?

 

[Hogshooter]

Once they are full length resized and trimmed to the same length case weight is a pretty good indicator. The heavier cases will have less capacity. I would still back down my charges a bit and work back up to be safe. If you weigh the cases from different manufactures you will see quite a variance.

 

[M40_A1]

I would work up new loads and compare the new reloads with a sample lot of the old ones using a chronograph. As long as the barrel time is the same, you should be getting similar results (assuming nothing else is changed). Otherwise, just changing case capacities will affect velocities, barrel time, and your harmonics. That's my understanding anyway.

 

[M1Amen]

I was afraid of this. I guess I will back off about a grain and work up again. Do you think a grain is enough?

 

[pawprint2]

Do you think sizing, trimming and weighing the cases would be a good indicator of case capacity. If they are trimmed to the same length after sizing, the weight should at least point to the case capacity, right?

The smart answer is NO! With that said, "good indicator" who knows? Brass from different mfgs is not the same "mix", therefore;cases from different mfgs even with the same case cap. will have different weights. Using some ball powder, fill one of your old cases (vibrate it a little to be sure it's full), dump the powder and note the weight the powder (weigh the case before and after to be sure you got it all) then dump the powder in one of the new cases, does it overfill? is there room left? If room is left, there is a good chance you can start with your old load, if not, back off and work back up. Of course, I'm suggesting using the ball powder Only for capacity check and nothing else, and in the interest of the math minded readers, you may want to do this with 5 cases or so, picked at random, to be sure. You could (in theory) skip the scale, just dump from one old full case to one new case, however; using the scale you can be sure you are leaving any powder in the old case. Good luck!

 

[M40_A1]

Do you think a grain is enough?

That would depend on the case capacities, type of powder, and how close to maximum you were running the loads to begin with.

 

[turbo54]

Jeez. You'd think this was brain surgery based on some of these posts...

If it makes any difference at all, it'll be small. Yes, it's conceivable a max charge in notoriously thin brass like winchester will be overpressure in notoriously thick brass like Lapua or lake city. If you're switching from Remington to winchester, or vice versa, etc etc etc, these will be a minor difference.

for a cartridge that takes ~45gr powder, backing off 1gr witha new head stamp is HUGE!

For example: in a 260 I worked with, 43.5gr H4350 and 140hpbt hornady in RP brass gave 2850fps and shot great. That same load in Lapua brasswent 2880 and showed a bit of pressure. I backed it off to 43.2gr to achieve 2850fps, equal accuracy, and no pressure.

If you're really concerned, measure the water capacity of your different head stamps:

Get 2 or 3pcs of each kind and seat a spent primer. Fill a cup with water and add a drop of soap. Put a piece of brass on your scale and zero it. Then fill the case up when with the top with water, dry up any spillage, and weigh it.

 

[M1Amen]

Thanks Turbo, I am glad to hear this. I will try this method with a couple of cases and adjust accordingly. I am not anywhere near a max load with 40.6 grains of RE-15 and a 168 grain Nosler BTHP pill.

 

[glassbeaver]

What brass are you moving to?

 

[M1Amen]

I have an assortment of different head stamps. I do have some more Remington in storage, but I have a bunch of Winchester and Federal too. I am not a fan of the Federal stuff though because I have found that even with light loads near minimum, the primer cup will sometimes pop right near the edge of the primer pocket. It looks like a tiny pinhole in the very edge of the primer cup and can score a bolt face.

Some have suggested the primer manufacturer might be at fault for making a batch of primers with cups that are too thin, but I don't think this is the case. The Remington brass I was talking about replacing in the post above just had its fourth firing and on the last range trip, three of the cases had the same kind of pinhole right at the edge of the primer cup.

Before the last range trip, I noticed when priming them that a few of the cases had started to feel a bit too easy to seat, and I wonder if those were the cases that had a bit higher pressures during the load development experimentation. After this last trip, a few primers had also started to set back a bit, which is a sign of pressure. Like I said, 40.6 gr RL-15 under a 168 pill, so I don't think I am loading anywhere near hot, but I do think this brass has seen it's useful life.

 

[turbo54]

Pinholes in primers aren't caused by high pressure. Its a manufacturing defect.

Loose primer pockets also don't cause leaking primers either. The pressure blows the cup outward and seals it against the pocket, the same way the case mouth blows out and seals the barrel off.

 

[EddieNFL]

Another vote for water weigh. Done so numerous times over the years.

 

[Greg Langelius *]

Low pressures may leak more due to insufficient pressure to fully seal the primer to the pocket, and will usually exhibit no primer flattening. Leaks from flattened primers are warning signs of excessive pressure.

If the primers from the old brass show significant flattening, then stepping down and working up is wise. If no flattening, just try the same load with the new brass and see how it performs.

1/2MOA is gratifying, but may prove frustrating to maintain as conditions and components vary.

A more realistic approach may be to step back a step or two and ask oneself just how much accuracy is truly necessary. As I have aged, I have asked myself this question frequently, and I now shoot and handload to a different accuracy standard.

If I shoot for score, I seek an MOA accuracy standard that is equivalent to the diameter of the X or V ring, and recognize that such targets were never intended to permit perfect scores. Otherwise everyone would be shooting perfect scores and where's the fun in that?

If I am not seeking a number value score, I assess my percentage of misses. If it's a respectable percentage, I'm content.

This approach has changed my shooting experience from the "cup half empty" frustration of the BR shooter, to the "cup half full" acceptable degree of satisfaction of the recreational shooter.

It's either work or it's fun, and you even get to choose.

Greg

 

[insight3b]

I rework a load if powder lots change. I load close to or over max so any change requires rework