How does brass affect accuracy?

[JMW67]

I have seen the weight/ volume thing first hand with some norma brass I was weight sorting and was seeing a wide spread so I seated some spent primers in the cases and checked volume with water the volume was almost identical in all the cases I kept the 2 heaviest and the 2 lightest separate after some load development I Loaded these four cases and they shot right into the group from the other brass This was at 300 yards

 

[GrayCreed]

Can someone school me on this? Why is brass quality important? How does it affect accuracy? If I have say a 3/4 MOA rifle, would higher quality, more consistent brass knock it down to say a 1/2 MOA rifle?

If I am already case trimming, chamfer, de-burring, cleaning every piece of brass. Would I see a difference going to a more premium brand over Winchester?

While it is possible that higher quality brass would knock down group size it isn't a guarantee. Since accuracy is a combination of many factors. I think you may see a difference in consistency and brass life. You may or may not see a difference in actual accuracy (at 100y) I have shot 2" groups out of premium brass- I have also shot one hole groups with the SAME brass. Brass is the framework that you build precision ammunition on. Others have already touched on the consistency of the space inside the case. The other aspect is the temper/hardness of the brass and how consistent the temper is in the brass. A lot of this plays into not just accuracy but how easy it is to make consistent ammunition. (Think neck tension) Premium brass may/or may not shrink your groups, it may however make it easier for you to get smaller groups more often without as much work. That's why I switched from Hornady to Peterson brass. I got tired of weight sorting everything. I just get a box and load and go. Even the non fire-formed brass shoots accurate and gives single digits on SDs. About a month ago I was able to hit the 1200y target twice with loads from the non fire formed brass.

 

[Mike Matteson]

I do a hundred cases at a time. Charting their weight on paper grid out by excel sht. I set the groups of cases with there respective weight. I mark the bottom of the case with finger nail polish, I set a system that I can look at to determine case weight. I chart the weights by the marks on the case base to keep them straight. Now I never tried water to determine volume in the case. Different manufactures of cases the weight differ greatly. So I don't mix manufactures cases. The other reason is how the cases are made. Thickness of case wall can be different from side to side. A reason to turn the necks so it release evenly, but you can't turn the entire case. So I am not sure that measurement by volume is getting any further than by weight. I will have to tr that to see how they come out. Not sure on just how to do volume. I realize that a fired primer need to be placed into the case, and drying case afterward. I would think that when pouring out the water from the case wouldn't be even every time either. Go to have look into it more.

 

[Mike Matteson]

I have seen the weight/ volume thing first hand with some norma brass I was weight sorting and was seeing a wide spread so I seated some spent primers in the cases and checked volume with water the volume was almost identical in all the cases I kept the 2 heaviest and the 2 lightest separate after some load development I Loaded these four cases and they shot right into the group from the other brass This was at 300 yards

Interesting! A little more insight. Thanks

 

[DJ Fergus]

Brass makes a significant difference in my opinion. As said earlier. Its the foundation. The availability of consistent quality brass is my first item on the list when I start calculating what cartridge that I want to go with. This along with choosing a caliber that I have a large selection of high B.C. bullets in.

 

[dfrahm]

So theoretically, we could find 100 identical cases, load them with an identical powder charge, find 100 bullets that were identical and perfect, shoot them with a perfect action thru a perfect barrel welded onto an immovable bench in perfect weather and put them all thru the same hole at say, 1,000 yards? After that, find cases that were 'different' by volume only, and those would shoot differently? How much volume (room for 02 and burning and expansion and more or less pressure) makes a difference that would be statistically measurable to us?

 

[Patriot007]

I use Lapua brass, One thing you need tobe aware of about Lapua Small Primer Pockets . The Flash hole is smaller in diameter. If you use a regular decapping Die it will destroy the flash hole. I use a Redding universal decapping die. it come with the correct size decapping pin for the small flash holes. IMO, you just can't beat Lapua. Peterson Brass is stouter brass, but also has less case volume than Lapua. As far as any other brass goes, Don't waste your money if you can get lapua. I just acquired some Lapua Large Primer pockets and I'm starting to experiment with them. It should be a good test of Velocities and Primer pocket Life. JMHO.
What ever you do. Be sure to ANNEAL CONSISTANTLY after every firing.

 

[rootacres]

Well I lit a lightning rod on this one. All great info, thanks guys.

Two more questions to add to the mix.

1.) Is Bertram brass any good? Its basically my only premium option in the 7mm WSM cartridge.

2.) Whats an acceptable weight spread on brass? I just grabbed 5 at random in my prepped bin and here were there weights (223.5, 223.6, 224.4, 224.8, 222.5), is this good or bad?

 

[Patriot007]

So theoretically, we could find 100 identical cases, load them with an identical powder charge, find 100 bullets that were identical and perfect, shoot them with a perfect action thru a perfect barrel welded onto an immovable bench in perfect weather and put them all thru the same hole at say, 1,000 yards? After that, find cases that were 'different' by volume only, and those would shoot differently? How much volume (room for 02 and burning and expansion and more or less pressure) makes a difference that would be statistically measurable to us?

In a perfect world maybe, but for our dimension, not so much. To many variables. If you are getting hole in hole at 1000yds, your just plain lucky, or the best shooter in the hole wide world. MOA is 1" at 100yds so if you are shooting 1000yds, your doing great to get all your shots in a 10" circle at 1000. I not saying you, or any one can't do it. I'm just being realistic. Me, if I shot 100 rounds at a 1000yd target, I'm sure I would have a couple of 1 holer's, but, that's 100 bullets on one target. LOL. If I shot 10rds At it, NOT so much luck on the 1 holler.. I'm just happy enough to keep them on target. LOL ONE more thing, Pressure and Velocity are two different beast. Pressure is not your friend.
Here's a good one for you. Are you getting GRAY hair from this, Yet??? Hey you gotta have fun with it. That's what it's all about. There's a lot of good info here in this thread, you just gotta weed out the BS. Good luck Sir.

 

[Mike Matteson]

I generally try to group in 1 gr area. Your case "Not bad". I have seen brass vary as much a 15gr+ if I remember correctly. It's been long ago, when I came across that much difference. I quickly move to Winchester brass, because I found them to be the lightest. PMC brass is or was heavy too at that time. I will store their brass, but I don't use it in reloading. I call it my rainy day supply. We didn't or I wasn't aware of any special brass manufacture at that point in time.

 

[Patriot007]

Well I lit a lightning rod on this one. All great info, thanks guys.

Two more questions to add to the mix.

1.) Is Bertram brass any good? Its basically my only premium option in the 7mm WSM cartridge.

2.) Whats an acceptable weight spread on brass? I just grabbed 5 at random in my prepped bin and here were there weights (223.5, 223.6, 224.4, 224.8, 222.5), is this good or bad?

A perfect match is always best. But, that's not always the case. Depending on the powder that I'm using determines the grouping weight. I use RL-26 in my 6.5CM. A kernel of RL-26 weighs .04... So I don't like to go over .05 on my case weight Groups. It can be hard to get 5 cases matching up identically. With your cases I'd go,,
223.5, 223.6 (just one quarter of a kernel, powder difference) (RL-26 weighs .04)
224.4, 224.8 (just a kernel of powder difference) (RL-26 weighs .04)
222.5, Fowling shot. (some would group this in group 1, but I'm OCD and that means I want, Its over my Standard.)
This is just my way of doing it. I hope some one has a better idea, I'm still looking for one my self.
Good Luck Sir.

 

[tony d willIiams]

Just a simple answer from a simple man.
If I am shooting 400 yards or less, the quality of the brass would be of importance in that I may be able to get a greater number of reloads from it.
If I am shooting at 400 and greater the difference will begin to appear, and the farther the target, the more the inconsistencies will show.
Volume inside the brass. Imagine having a different compression ratio in each cylinder of your racing V8 580 CID. Every cylinder would perform differently and a lack of repeatability would haunt you forever.
I reloaded some brass, and the difference of the volume was visible to my eye. Some loads were compressed, and some the powder was loose under the bullet. The results at 1/2 mile could not be known until after the shot was fired.
The starting base of reloading is the brass. In my opinion everything needs to be top notch and consistent. If it isn't, then it doesn't matter how nice and precise your rifle and optics are.

 

[Patriot007]

Just a simple answer from a simple man.
If I am shooting 400 yards or less, the quality of the brass would be of importance in that I may be able to get a greater number of reloads from it.
If I am shooting at 400 and greater the difference will begin to appear, and the farther the target, the more the inconsistencies will show.
Volume inside the brass. Imagine having a different compression ratio in each cylinder of your racing V8 580 CID. Every cylinder would perform differently and a lack of repeatability would haunt you forever.
I reloaded some brass, and the difference of the volume was visible to my eye. Some loads were compressed, and some the powder was loose under the bullet. The results at 1/2 mile could not be known until after the shot was fired.
The starting base of reloading is the brass. In my opinion everything needs to be top notch and consistent. If it isn't, then it doesn't matter how nice and precise your rifle and optics are.

The answer would be a broken cam shaft, bent valve rod or valve, possible blown head or broken timing chain.
20k down the tube quick. We will just build another one. A good racing motor keeps getting faster and faster. Then they blow. Next.

 

[emp1953]

This wall thickness gauge seems to do a good, repeatable job. I have troubles reading the vernier types so I had to go digital.
https://www.ebay.com/itm/iGaging-Re...rical-Anvil-Digital-0-1-0-00005-/311974653400