Nickel brass performs different

[gamestalker]

I recently was given a bunch of 7mm rem. mag. nickel brass. As I was working up some loads with RL22 and putting them through the chronograph, I noticed that they were producing a little higher velocity. The same load specs. I recorded with standard yellow Remington and Winchester brass, were delivering an average of 2.1% higher velocity based on 20 rounds tested. Accuracy didn't seem to vary, however, primers were noticably flatter indicating pressures were probably a little higher.
An example of what I observed was with a 120 gr. Hornady PSP. Average MV velocity with the yellow brass with 67.4 grains of RL22 OAL @ 3.335" was 3318 fps. With the nickel brass and everything exactly the same, my average MV was 3388 fps. The only variation I couldn't avoid on this first test was FL sizing. I'm not sure what difference neck sizing will make, but I would venture to guess that MV may decrease slightly, we'll see.

 

[918v]

Nickel brass holds on to the bullet better than standsrd brass, thereby improving combustion. Maybe that's why you are seeing higher than normal velocities.

 

[Rokman]

That's good to know. I like the nickle ones.

 

[blarby]

So , just to make sure we have the math here correct....you are talking about 60 or so FPS difference ?

 

[Funshooter45]

Good info. I separate my brass according to manufacturer and also set the nickel aside on the rare occasions that I have it for rifle. I don't measure my velocities but I figure each brand is different, each lot is different, even with yellow brass. I don't try to keep track of lots, but it's not surprising the brass cases will produce a little bit different vels.

 

[Horsemany]

I'd be willing to be the difference is because of internal volume variations. To test this fill the nickel case and a brass case to the very top with the same powder and measure the charge. I'm betting the nickel case will hold less powder thereby increasing pressure when both cases are charged with the same weight powder.

 

[dave from mesa]

While I agree with Horsemany I would like to add that the outside diameter is also a little bigger also. After all it is just a brass case that has been nickel plated, Right?
My thinking is that this would cause the case to contact the chamber a little quicker and that added to smaller case capacity would cause the jump in velocity.

Edit:
gamestalker
After rereading your post I also believe that what I said only applies when FL resizing the case. The opposite would apply if neck sizing.

 

[snuffy]

Everybody is assuming that the nickel coating is quite thick. It is NOT! It is about .0001 thick, that's one ten thousandths. And it is on the inside as well as the outside of the case. That tiny extra thickness does nothing measurable to case capacity.

One run of a particular load over a chrono means very little. Now, go load 100 rounds of each, nickel and uncoated brass. Then see if it still holds true.

 

[gamestalker]

I'm also thinking it has something to do with case capacity. I'll bet the nickel is acting as though the bullet has been seated deeper. Less combustion area?

 

[GLOOB]

You haven't even stated the headstamp of the nickel brass. AFAIC, this thread should be titled "Different brass performs different."

You need to use the same brand of brass, nickel and plain. All once-fired. Weighed to be the same, same length, same internal volume. Reloaded together in the same lot. Then separated and shot back-to-back. At least if you want this to mean anything.

 

[Doug b]

Gamestalker do you plan on stepping on the gas with this test? I bet your MV spread is more due to a light charge of slow powder in a large casing than some nickel clad brass.

 

[10 Spot Terminator]

I have had many opportunities to load nickle plated brass for several different rifle and pistol rounds over the years. In most ( not all ) instances the cases were tighter on the throat inside diameter ( when new ) enough that you could feel the insreased pressure needed to seat the bullets on a single stage press. I too could see minor differences in both velocity and in many cases a shortening of the extreme spread on my chrony. I attribute this to the same principal stated by Richard Lee that gave rise to his reasoning for use of factory crimp dies. Having a tighter more uniform grip on the bullets tends to create a more consistant starting pressure which is the point that the bullet actually starts to break away from the case when fired. My personal load tests would agree with this and with the right powder and primers has allowed me to achieve great accuracy results in standard production firearms and some old milsurps worthy of far more exspensive custom rifles. Do note when you size these nickle rifle cases they wont be as tight on the next loading. Forgot to state I am a dedicated factory crimp die user. Reloading is an individual thing, for some it is cost, for others faster more termnal perfomance, still others its accuracy ... for me its all of these but am pretty sure I havent beaten the cost thing yet as I just keep buying more ,,,

10 Spot

 

[ranger335v]

"Nickel brass performs different"

WHAT, a component change has an effect on a reload? Amazing info! []

 

[Doug b]

Actually I think the op and a couple replies present interesting lines of thought.

 

[gamestalker]

I did shoot these loads back to back with the yellow brass. Regarding headstamp, they were Federal. The yellow was R.P. with some Win. but everything was trimmed to the exact same length, every powder charge was weighted on a beam scale, same primers, same OAL with the same bullets. Basically I've eliminated effective variables that could be responsible for a 2.1% variance in velocity. Working with combined averages from 20 rounds of nickel, and 20 rounds of yellow was enough of a spread in velocity to convince me at least that something with the nickel is causing the difference. No need to shoot 100 rounds to see an obvious trend. I did notice that the nickel had a noticable increase in neck tension. However, the yellow brass had been loaded multiple times and was necked. The nickel was on it's first reloading and not from my rifle, so it was FL sized. I'll soon have the results for nickel after it's been necked, which may be the major factor here?