OzFclass

Hey fellow SAUM shooters,

Just noticed on Facebook that Bertram has now started to manufacture 7mm SAUM brass. I've been incredibly happy with my Norma cases, but I must say that there is a much stronger urge in me to support local.

Has anyone tried them ? I've sent an email earlier and hopefully I can get my hands on them and report back.

This is great news IMHO



Albert

Albert
All I can say is hope it's better than the 284 brass.
Matt

Hey Matt,

I don't think I know anyone that has used them and reading the .284 thread, most comments seem complimentary...viewtopic.php?f=5&t=8138&hilit=Bertram#p67896

It is possible that others didn't feel confident to provide criticism. Do you mind sticking your neck out ?

I'm still planning on giving them a go so you won't put me off

Albert

Albert
The pieces I got weighed poorly, the neck wall thickness variation was from 0.003-0.005" and was small in the base for a Norma based reamer.
My findings on the brass I received.
Matt

Matt P wrote:Albert
The pieces I got weighed poorly, the neck wall thickness variation was from 0.003-0.005" and was small in the base for a Norma based reamer.
My findings on the brass I received.
Matt

Thanks Matt, I hope it is a bit more consistent then. I'll try and get my hands on them and perform a decent measure and test. Will keep you posted.

Albert

Albert I have been using the 284 win Bertram brass for a while now and have found that if weight sorted and neck turned they work well. Certainly no primer pocket issues. As Matt says straight out of the bag they may need a bit of work but they can shoot very well. I would expect the SAUM brass to be heavier than the Norma stuff and long lasting.
Interested to see how you go with it.

As an update, I've received 10 cases to measure, test and report on.

First impressions were good when receiving them, I mean they looked and smelt like brass .It's obviously early days and unfortunately all my measurement and loading equipment is in Rosedale - 200 km away, so we'll have to wait until after the weekend for more information.

I did however manage to weigh the cases, using a Gempro 250. I was expecting an insignificant display of similarity to Norma, but this was not the case.

In general terms, my necked down ex 300 SAUM, Norma brass weigh 15.xxx grams while the Bertram brass came in at 13.xxx grams across the lot of them. I'm after opinions on what could have caused this... I initially thought that it could be a product of reducing neck size but 2 grams ? Interesting....

Here is the comparison of 10 Norma Cases to the Bertram. Now before you jump to too many conclusions I do buy weight batched Norma cases, so at this stage I am expecting some variation.

So in addition to all the measurements I'll be doing, I am also planning to take a single piece of brass to the range and load it repeatedly until I have loose PP. I then want to compare any other pressure signs with some increased loads and compare the web expansion against that of the Norma cases. Would there be anything else people would want to see done ?



I have also taken a few other pics to show you that it really does look like brass

I've managed to get to some further investigation completed over the weekend and have compiled a few photos that hopefully help explain.

My quick synopsis is this:
If you are planning to buy Bertram brass you will absolutely need to implement a very strict quality process and either batch or discard... MattP and others eluded to this much earlier on based on their experiences and I am able to agree to the comments through my observations. Also note that I have worked with a very small sample size of 10 cases and therefore you should take what I've seen in context of that too. Cases are not factory annealed. I would recommend doing this before any case preparation.

Flash hole and Primer pocket:
The first picture show a variation to the flash hole size as compared to Norma. I did not have the appropriate tool to measure the variation but it is visually very obvious. Both cases are unfired. I'll leave it to others to comment on what variables if any this introduces to load development but my experience was ave 30fps faster than expected, based on a known load as measured over a MagnetoSpeed v3 The known load has an ES of 13 and SD of 4
The primer pocket is deeper than the Norma. My case preparation involve using a 21st century primer pocket uni former that is adjustable in 1 thou increments. The tool had to be lengthened by 4 thou to provide the same cut as I would make in a new Norma case. That said, primers seated snugly, maybe, even slightly tighter than a new Norma. Seating was performed with a 21st Century Priming Tool, adjustable in 0.00125 increments.



OAL and Neck:
There was quite some variation in OAL of the unfired brass with 0.8mm or 31.5 thou. I use a Wilson trimmer and the quality of the trim was definitely effected by not having an annealed case. Once trimmed, there was some visual observations made on neck thickness inconsistencies. See photo below.
Using a Mitutoyo ball Mic, accurate to 0.0001 I found that the overall neck thickness varied across the 10 cases between 0.0125 and 0.018. An issue for me (maybe not for some) is that trimming to 0.125 would not have suited my chamber or load... Therefore, 30% of the cases I would have discarded, while able to turn and uniform 60% to my requirements.


The variation in OAL was a little strange as the length of the neck is shorter than that of Norma brass... it seem the culprit is a steeper&longer shoulder than that of a Norma case. In my situation only, I have on many occasion shot first fired Norma brass with great accuracy - probably suiting my chamber. Looking at the Bertam brass my suggestion would be to fire form these first. This is not a negative as I believe you really should be fire forming to gain the most accuracy out of your brass.


10 shot group @100 yards with known tuned load:



In conclusion, the accuracy on this single test was not as expected but I say again that this is likely due to the cases needing to be fire formed first. Another potential is the increase in velocity however the tuned node is about 60fps long and should not have effected it this much. I will load these again over the next few weeks and report on progress.

Please also comment and let me know if there are any processes you think I should have done differently.

Albert

Albert , I don't have a Saum , but thanks for the info ! Very interesting!
Regards Graham.