Unfired ADG brass - Headspace question

[Deleted member 107666]

Have new/unfired ADG brass in 300wm.

Just taking some initial measurements and headspace is on average .0117 under SAAMI.

Using the RCBS precision MIC...

Min SAAMI is 2.2791
Unfired ADG is averaging 2.2674

Yes, they are not fire formed yet...just trying to understand why they would be almost .020 under SAAMI max...that's alot of room to grow.

Would there be a benefit to running these all through a body die (not bumping) to uniform the cases?

Also, is it safe to shoot to fire form with them .011 under SAAMI?

Maybe a sanity check for anyone who also has the RCBS precision Mic...it reads 38 to 39 with new case, the way I understand it that is 11-12 thou under saami as zero should be saami min

 

[sedancowboy]

Yes the ADG brass is fine. Just load it and shoot it and them use the shoulder datam line to determine headspace from then on. I have seen belted cases as much as .016 off. No worries.

 

[J E Custom]

Have new/unfired ADG brass in 300wm.

Just taking some initial measurements and headspace is on average .0117 under SAAMI.

Using the RCBS precision MIC...

Min SAAMI is 2.2791
Unfired ADG is averaging 2.2674

Yes, they are not fire formed yet...just trying to understand why they would be almost .020 under SAAMI max...that's alot of room to grow.

Would there be a benefit to running these all through a body die (not bumping) to uniform the cases?

Also, is it safe to shoot to fire form with them .011 under SAAMI?

Maybe a sanity check for anyone who also has the RCBS precision Mic...it reads 38 to 39 with new case, the way I understand it that is 11-12 thou under saami as zero should be saami min

If you measure from the datum line to the case head the dimension should be 2.270 to 2.263.

The belt dimension should be .220 to .210.

Subtract the .220- from the 2.270- and that is the SAMMI case length.

Belted cases always have minimum case size/length to fit any chamber the belt to case head is the important dimension on new cases. head space is measured from the front of the belt to the bolt face and should be .220 to .223 with a go gauge. Example: if your belt face to case head is .218 and your chamber head space is .002 you will have almost .004 thousandths head space in the chamber.

I recommend using a go gauge to find the actual head space of the chamber and after fire forming, size only enough to close the bolt easy.

J E CUSTOM

 

[Deleted member 107666]

I was just planning to fire form the brass...drop it in my RCBS Prec Mic...note the new measurement (should be my chambers actual headspace) as my new "zero" reading and then us that same MIC to then measure as I bump the shoulders .002.

I'm using the min/max headspace listed on the instructions page from RCBS for the .300wm...they say the MIC measures from datum line...not sure why the numbers they list are slight different than the ones you posted, can you clarify?

Does that all check?

I'm starting to get the feeling there are 1.1 million ways to skin that cat

 

[MagnumManiac]

Have new/unfired ADG brass in 300wm.

Just taking some initial measurements and headspace is on average .0117 under SAAMI.

Using the RCBS precision MIC...

Min SAAMI is 2.2791
Unfired ADG is averaging 2.2674

Yes, they are not fire formed yet...just trying to understand why they would be almost .020 under SAAMI max...that's alot of room to grow.

Would there be a benefit to running these all through a body die (not bumping) to uniform the cases?

Also, is it safe to shoot to fire form with them .011 under SAAMI?

Maybe a sanity check for anyone who also has the RCBS precision Mic...it reads 38 to 39 with new case, the way I understand it that is 11-12 thou under saami as zero should be saami min

The belt controls headspace on the initial firing, then the datum to shoulder controls headspace thereafter.
My own 300's have between .018"-.024" to shoulder datum prior to firing. This is no problem and the brass fireforms with no issues.

Use your Precision Mic to bump the shoulder about .001"-.002" and use that dimension to keep the bump consistent after each firing.
My headspace runs 2.271" after bumping.

Don't worry too much about how much the shoulder moves on the first firing, only how much you move it after the initial firing.

Cheers.

 

[Deleted member 107666]

Thanks fellas, as always.

 

[Okanogan]

I have some ADG 300 WM brass that I am working with for load development alongside my usual Norma brass. I was surprised to see -0.030" between fired and unfired brass for the ADG. I just went ahead and fire formed the new cases and have had no issues.

The ADG brass has been every bit as good as the Norma brass and maybe better for primer pocket depth and initial case length consistency. I had to drop back about 1.5 grains with RL26 for the ADG brass but had no problems achieving the same velocity. I was surprised that I could use the same neck bushing for both Norma and ADG 300 WM. (That wasn't what I had seen for Norma and Laupa cases for other calibers.)

 

[Deleted member 107666]

I have some ADG 300 WM brass that I am working with for load development alongside my usual Norma brass. I was surprised to see -0.030" between fired and unfired brass for the ADG. I just went ahead and fire formed the new cases and have had no issues.

The ADG brass has been every bit as good as the Norma brass and maybe better for primer pocket depth and initial case length consistency. I had to drop back about 1.5 grains with RL26 for the ADG brass but had no problems achieving the same velocity. I was surprised that I could use the same neck bushing for both Norma and ADG 300 WM. (That wasn't what I had seen for Norma and Laupa cases for other calibers.)

Good to hear. Thanks.

How thick were the neck walls on you ADG?

 

[Okanogan]

I measured the necks but didn't trust it completely even though I remember getting the same caliper reading for both Norma and ADG. I ended up loading a bullet and checking with my bushings. 336 bushing just started to slip on so went with 334 bushing for loading. Math would suggest that (336-308)/2= 0.014

 

[bushmotornv]

I was just planning to fire form the brass...drop it in my RCBS Prec Mic...note the new measurement (should be my chambers actual headspace) as my new "zero" reading and then us that same MIC to then measure as I bump the shoulders .002.

I'm using the min/max headspace listed on the instructions page from RCBS for the .300wm...they say the MIC measures from datum line...not sure why the numbers they list are slight different than the ones you posted, can you clarify?

Does that all check?

I'm starting to get the feeling there are 1.1 million ways to skin that cat

Hello,as a work around fo short cases,here's what I have done.A, seat the bullet long so it is just touching the lands with a light load. And B,you can size up the case neck and then resize the case partially and use the enlarged neck at the shoulder to hold the case against the bolt face. I have found that not all short cases will completely fire form to length.