Part 2 of 2: Testing Dilemma

[merbeau]

From Part 1 of 2 after testing the once fired brass were cleaned using a walnut brass cleaner and then the primer pockets were cleaned. Three tests were conducted. First was using neck sizing only that was accomplished with a Lee Collet neck sizing die, the second was neck sizing and then crimped using a Lee factory crimp die and third was full length resizing using an RCBS full length X sizing die.

To my astonishment the neck sizing group opened up almost triple from the virgin brass group (Fig 3). Neck sizing plus crimping was worse. The full length sizing group was not as bad but was still larger than the virgin brass (Fig 4) .

Since most of my experience is in pistol/shotgun reloading I am at a loss of what this means. According to the literature from Lee, a 0.001 less neck sizing die can be ordered. The neck size with the Lee die is about 0.001 larger than the Nosler virgin brass. Is this a possibility?

Since the original Nosler brass was pre selected by weight, neck chamfered, primer pockets reamed nothing was done to the brass after initial firing except clean. Is this a possibility?

Others?

Thanks
Robert

 

[Mikecr]

Did you load develop with brass in the stable condition(each) intended?

 

[gohring3006]

At a certain point the human element is a uncontrollable factor. Now don't take this like I'm saying you can't shoot. But are we sure we do the exact same thing over and over with as many rounds fired? Its a well thought out test. But all your figuring out is what YOUR gun likes with that particular brand of brass and bullet. Which is really all that matters with this test anyway..

 

[merbeau]

In actuality you are correct in basically I am trying to find what 'my' gun likes in terms of powder, brass and bullet which obviously all guns are different. I did a literature search on virgin brass and once fired and all seem to point towards once fired because of the case matching the rifle chamber.

I am going to repeat this experiment by first ordering the new smaller collet from Lee and test that using once fired. Then a second test using virgin brass and neck size with the Lee die. Then use virgin brass with the full length sizing die. This should determine if the rifle likes virgin brass over once fired or Nosler brass is sized just right over my own dies.

I shoot at the same range (so same elevation) and try to shoot on days having similar humidity, barometric pressure and wind (I keep records). I shoot from the same position at the range and use my own chair to sit in. The test conducted at 50 degrees cooler was designed to determine if the powder was temperature sensitive which according to Aliiant is not.

Lastly, while obviously I am not a Ramson rest, and I would expect some deviation over time, that large (to me) points to something more or this old gun just like new brass.

 

[Mikecr]

You really need to do full blown load development with the condition you intend to create and maintain.
New brass can't be maintained new

 

[tailbon3]

Once fired brass typically has a slightly larger internal volume. That can change the pressure curve even though you haven't changed the powder charge, which in turn changes how your barrel vibrates and changes where bullets end-up on the target. The previous posters are encouraging you to load develop with either once-fired brass or with fire-formed brass so you know your brass hasn't changed between loadings. I agree it is frustrating to find a sweet load on virgin brass, then find out it doesn't work with fire-formed brass. Many guys here fire-form their brass using Cream-of-Wheat or other methods.

 

[Mikecr]

Yeah, you will be fireforming your brass eventually, and you'll decide about your sizing needs eventually, and then you're ready to develop your load.
So that I'm not 'wasting' barrel life, and/or chasing my tail later, I perform Berger's seating depth testing during fireforming. With that I can go into powder testing with better seating than something pulled out of the air.

 

[merbeau]

Once fired brass typically has a slightly larger internal volume. That can change the pressure curve even though you haven't changed the powder charge, which in turn changes how your barrel vibrates and changes where bullets end-up on the target. The previous posters are encouraging you to load develop with either once-fired brass or with fire-formed brass so you know your brass hasn't changed between loadings. I agree it is frustrating to find a sweet load on virgin brass, then find out it doesn't work with fire-formed brass. Many guys here fire-form their brass using Cream-of-Wheat or other methods.

That makes sense. So do I then vary the charge up or down from the virgin brass load to see if that improves the performance with once fired brass?


Thanks

Robert

 

[tailbon3]

Yes, try fiddling with the previous powder charge. I don't know if it will result in a new sweet spot or not but it's worth a try. I think the recommendation I've read is to increase/decrease in .2 grain increments (a.k.a really small amounts).

 

[barefooter56]

Merbeau,
It is not unusual to shoot outstanding groups with virgin brass. Benchrest shooters comment on the frequently and wonder if fire forming their brass before going to a match is really worth it. Think of the new cartridge as a half empty toothpaste tube. When you squeeze it from the bottom the tube straightens itself out and reforms. Brass does the same thing in your chamber. In fact your rifles chamber is the last step in the cartridge cases formation. If you are hunting we recommend that you full length size every time so you don't have to worry about a round not chambering and so that you are not running loaded rounds through your action to see if they fit that may result in the unintended discharge of the rifle. For hunting rifles bump the shoulder back .002-.003 so you are not oversizing the brass. Also follow Mikecr's instructions on Berger seating depth testing then doing load testing. If you have any questions on any of this please let me know. Be glad to help.
Take care,
Phil Hoham
Berger Bullet Tech

 

[merbeau]

Thank you Phil for the help and insight. If all goes well next week I will be going to the range to test this load at 250 yards which is the maximum at our club. After the next round of testing I may give a shout for some help if the results do not improve. I would like to say that I have been using the Berger 155 grain hybrid in my 30-06 with equally good results. Next up will be the 250 grain 338 bullet in my RUM.

 

[barefooter56]

merbeau,
Please do! Good luck and good shooting!
Take care,
Phil Hoham
Berger Bullet Tech

 

[eshorebwhntr]

To get consistent neck tension with the collet and really test that out you should also measure the neck of a loaded round with that brass to gauge your collet size. If the finished round is .312 (example pulled from thin air) you should be running a .310 or maybe even .309 collet diameter. And if you get into testing out neck tension vs accuracy then you need to remove the expander ball in your dies so that it isn't swelling the neck back out during reloading and nulling out your test variables (the collet diameters).

If it was me, I would just stick with the full length die and work up a load that shoots. Especially if you plan to hunt with the rifle at some stage, as others have noted.

 

[merbeau]

To get consistent neck tension with the collet and really test that out you should also measure the neck of a loaded round with that brass to gauge your collet size. If the finished round is .312 (example pulled from thin air) you should be running a .310 or maybe even .309 collet diameter. And if you get into testing out neck tension vs accuracy then you need to remove the expander ball in your dies so that it isn't swelling the neck back out during reloading and nulling out your test variables (the collet diameters).

If it was me, I would just stick with the full length die and work up a load that shoots. Especially if you plan to hunt with the rifle at some stage, as others have noted.

Thanks for replying. I keep a copy of the specs for each cartridge that I load for in my Excel Spreasheet and the schematic shows a 243 cartridge with a seated bullet and a neck size of 0.276 at the top of the neck and where it meets the shoulder. My case with a bullet seated is 0.275 measured mid point of the seat. The neck size of brand new brass is 0.270 and for once fired neck sized 0.269 and for full length sizing 0.270 which means the neck size is 0.001 smaller.