Affects of accuracy with different brass

[Gulfcoastshooter]

Hi all,

I am new to reloading. I have been taking my time doing a lot of reading and planning. Last weekend I did some testing of 4 different loads. All loads were identical except I used 3 different types of brass and the 4th load I tested for any differences from my case length being 1.750 and 1.745 of the same brass type (yes, I'm new to reloading any might of been a little too OCD from things I read. lol)

The thing I have been wondering all week and cannot find any information about is why my groups were at different parts of the target. I was stuck with only being able to shoot from the 25 yd range since all the 50 and 100 lanes were full. At 25 yards between 2 different AR's, the windage was spread about 1 inch between the 3 different types of brass. The loads shot tight groups within each type of brass and the elevations were all close.

I was expecting some velocity and elevation differences between the different brass but would different brass affect the windage?

 

[Blue68f100]

It's the difference of the internal volume of the brass generating different pressure curve. which will generate a difference barrel harmonics. I sort all my 223R brass by head stamp. I even sort by year on LC. I use the same load but I have to tweak the OAL to get the same accuracy between the different years.

Only shooing at 25 yrds makes it harder to see the actual spread you would have had. The longer the better if you have the skill set to stretch it out.

 

[AJC1]

Es and sd are tools of long range and you are still at pistol ranges. 200 yard completion is not exactly velosity critical for vertical. The seating depth and ocw tests are way more critical at your point in the game. Cases have different internal volume from even case to case so minor deviations are not that important close. Best sanrio is you buy high quality cases like laupa, Peterson, alpha or even starline and treat them as a batch. Load them together, shoot them together etc. Jonnys reloading bench did a huge test with 10 brands at the same time and that video may be exactly what your looking for.

 

[Gulfcoastshooter]

It's the difference of the internal volume of the brass generating different pressure curve. which will generate a difference barrel harmonics. I sort all my 223R brass by head stamp. I even sort by year on LC. I use the same load but I have to tweak the OAL to get the same accuracy between the different years.

Only shooing at 25 yrds makes it harder to see the actual spread you would have had. The longer the better if you have the skill set to stretch it

I was expecting to see differences between the difference cases and then my average velocity, es and sd were within a few fps. I would have thought internal pressures would have caused a difference in velocity but it makes a lot of sense when you throw in barrel harmonics.

 

[Gulfcoastshooter]

Es and sd are tools of long range and you are still at pistol ranges. 200 yard completion is not exactly velosity critical for vertical. The seating depth and ocw tests are way more critical at your point in the game. Cases have different internal volume from even case to case so minor deviations are not that important close. Best sanrio is you buy high quality cases like laupa, Peterson, alpha or even starline and treat them as a batch. Load them together, shoot them together etc. Jonnys reloading bench did a huge test with 10 brands at the same time and that video may be exactly what your looking for.

I plan on buying brass for some good long range long range loads once I have some experience under my belt. These loads are a test to myself to see if I can make a decent load for 2 completely difference ar's for mid range shooting. Thanks for the video reccomendation. I need find it on his channel.

 

[AJC1]

If you have not watched his channel there is lots of quality content

 

[Gulfcoastshooter]

If you have not watched his channel there is lots of quality content

I found them and they are queued up on youtube to watch later. I skimmed it earlier and it's exactly what I was looking for. Thanks again. I plan on keeping all of my loads separate by headstamp but to me it's good to know why/what the differences between brass can cause.

 

[Ruger 15151]

As mentioned previously, case volume will vary with different manufactures. However, what also varies is case wall thickness which effects neck tension. If you are using the same sizing die and expander ball, you will get different neck tension as a result. Both of these factors will effect your load results and POA.

However, I don't think different case volumes, neck tension, and barrel harmonics will be much of a factor at just 25 yards. At 3,200 fps and the fact that 223/5.56 shoot so flat anyway, slight differences in velocities are going to impact about the same place at that distance. Paper will not only provide information about your loads, but it will also give you feedback about your technique. Changing things like cheek position and pressure on your stock, finger position on your trigger, shoulder pressure against your stock, finger grip on your stock.... etc... from group to group will all change your POA. To test this, position yourself on your riffle just as you normally would and take a shot, noting your POA. Now, do everything exactly the same but pull the buttock into your shoulder a little more firmly. You will likely see a different POA. Also, if you didn't cool your barrel to the same temperature between groups, you will likely see a shift in POA as well.

If you want to isolate whether your loading techniques or shooting techniques are causing different POAs at just 25 yards, load 3 sets of 3 bullets with the same load data and case manufacturer. Shoot the first group of 3, wait 5 minutes for your barrel to cool, shoot the second. Wait for your barrel to cool another 5 minutes before shoot your last group of 3. I will bet that the center of each group will have a slightly different POA. Until you get your shooting technique perfected, you may shoot tight groups but they will likely be on different parts of the target.

In long range shooting, we practice for hours just dry firing and making sure our position on the riffle is exactly the same with every trigger pull. if you are shooting for groups, you should never lift your head from the riffle until you have shot the last round in the group.

I know you original question was about different case stamps and everythign that has been suggested is correct. However, I think the inconsistency your are seeing at 25 yards is likely caused by shooting technique than anything else..

 

[Fattcracker]

If you don't mind a question or forty from a Noob... I got some?
I bought a 222 Remington that was re chambered to .223 wylde now it's a 1 in 14 twist.
that's gonna want to shoot 80+grain Boat tails Right?

 

[Bfh_auto]

If you don't mind a question or forty from a Noob... I got some?
I bought a 222 Remington that was re chambered to .223 wylde now it's a 1 in 14 twist.
that's gonna want to shoot 80+grain Boat tails Right?

Welcome to the forum.
If you're question doesn't tie into the original post. Then you should start a new discussion.
To answer your question. It will like short bullets usually 52 gr or less.

OP. I too believe your issue is from shooting technique.
In my AR at 100 yards. POI varies by <1/2" from using different brass.
Distance amplifies the POI changes.

 

[Cemetery21]

A 14 twist is old-school common for 222 back when light bullets were the norm. It's probably the slowest twist available for centerfire 22. In a 223, it would be lucky to stabilize a 60 gr. bullet, and not much chance of anything heavier. You are probably stuck with 55 gr. and lighter bullets (which is okay for a lot of shooting, just not wind bucking long range shooting).

Edit: Sorry, I just contributed to thread drift and that isn't best practice.