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Old June 3, 2001, 07:46 PM   #1
Jamie Young
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How does your choice of Brass effect or is it Affect a rounds performance?

If its trimmed to the same length and its not deformed how is it different?
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Old June 3, 2001, 08:01 PM   #2
Contender
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SodaPop,

The quick and dirty answer would be that some brands of brass can tend to run thicker than others especially in the head/web area.

A stark example can be with Military brass which in most cases tends to be thicker in it's walls. Thus, requiring charges to be reduced, due to less internal volume, with max charges reached sooner.

From brand to brand, the difference can be substantial at times.

That's why when changing brass brands or lots, it's best to reduce your charge and work up again if you are into a max loading.

Some brass also tends to be "softer" and others "harder". However, affects performance to a lesser extent than wall and web thicknesses.

There are other variables such as primer pocket depth, rim thicknesses, annealing quality in the neck area that can also have an effect on performance of the brass/loads.

Regards
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Old June 3, 2001, 09:51 PM   #3
labgrade
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Contender's right. Mainly it's due to case volume based on internal dimensions.

All things being equal & a given that the exterior remains constant (i.e. you size the brass to exterior dimensions) thicker brass means that the internal volume is the variable.

Basically, progressive powder burns as a function of internal volume, heat & pressure. Decrease volume & the other two go up.

A quick study is the 9mm pistol cartridge. Again, all things being equal, if you seat the bullet a tad deeper = presures go way up & quickly. All due to internal volume.

There is a lot more to it regarding accuracy, etc., but for pressure relateds, that'll do ya (for starters).
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Old June 4, 2001, 10:07 AM   #4
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Between commercial brass, the difference is nill. I have some 5.56 Malaysian brass that is quite heavy and needs a one grain reduction to commercial data to get acceptable pressures. (Blew a primer this weekend getting rid of 50rounds of that stuff that I loaded up with normal brass data-stupid me!)
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Old June 4, 2001, 04:05 PM   #5
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Also keep in mind that some brands of brass are much more uniform with regard to case wall thickness, etc... i.e., you don't have to turn the necks with Lapua 6BR brass (if you have a .271 or therabouts chamber), etc...

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Old June 4, 2001, 06:25 PM   #6
Jamie Young
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Ok I get it now. I reload 5.56 ammo all the time. I have never had any problems with blown primers but I do mix various types of once fired brass together. Everything I reload is pretty much Military brass because they all have the primer crimps I have to ream out. I don't really reload super hot loads so I think I'm ok?
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