Started getting signs of overpressure with my primers flattening and cratering. Rifle is a Rock River AR. 7th loading on my .223 Lapua brass. Annealed them after 3 loadings and again after the 6th. Minimum loads of 25.5 gr. Varget pushing a 65 grain Sierrra. Was curious so I checked the neck thickness of my reload against a quality Winchester round. Winchester measures .246 and my hand laods measure .248. Is my brass thickening in the neck and causing the neck to be tight in the chamber and causing slight overpressure. Also had a loss of accuracy with my last loading and when I used the factory round I'm back to nice little 3/4 inch groups. Hate it when my handloads aren't up to factory loads. Thanks
Do necks thicken?
- Thread starter timvv50
- Start date
Gonna risk a first response so the trolls can jump on it and say any thing can happen.Brass flows there are no absolute answers so explore all options.Could have a carbon issue.Also I have experienced a pressure change from new to fired brass.
CatShooter
timvv50 said:
Lapua and Winchester do NOT have the same neck wall thickness. You cannot compare them.
Necks do not "thicken"... if you have a headspace problem, and are constantly pushing the shoulder back, then the base of the neck, just at the shoulder junction can get a little thick, but by that time, your cases are ready for the trash bin.
CatShooter
DBailey said:
Where does the metal come from to make it thicken?
I shoot several rifles with turned necks - si I know thwir exact thickness to 0.0001"... I have never seen a neck get thicker.
So where does the metal come from to make a neck thicker??
I've had it happen with a tight chambered 6.5-284. I didn't ask the brass where it came from, I just trimmed it off.
If I had to guess I'd say it comes from the same place as the brass that makes trimming the case neck length necessary.
I'm not here to have an internet expert debate. The OP asked if it was possible and it is, although it's very unlikely that it is his problem with a factory chambered AR.
If he'll just stick that bullet in the fired case he'll know for sure.
If I had to guess I'd say it comes from the same place as the brass that makes trimming the case neck length necessary.
I'm not here to have an internet expert debate. The OP asked if it was possible and it is, although it's very unlikely that it is his problem with a factory chambered AR.
If he'll just stick that bullet in the fired case he'll know for sure.
there is a difference in neck thickness in the Lapua brass over Winchester. the Lapua's are thicker to start with.
But yes I have seen necks thicken with as many as three fireing. I don't know why. have you ever seen a case grow in length and have to trim them. i'm sure that's why the sell case trimmers. most of the time that is what you will experience is case length growth. but for some reason you can experience neck's that thicken up. I have seen it happen once or twice where it became a problem.But case length and a carbon donut can also cause poor shooting and high pressure. in the rifle you are using I would check that also.
But yes I have seen necks thicken with as many as three fireing. I don't know why. have you ever seen a case grow in length and have to trim them. i'm sure that's why the sell case trimmers. most of the time that is what you will experience is case length growth. but for some reason you can experience neck's that thicken up. I have seen it happen once or twice where it became a problem.But case length and a carbon donut can also cause poor shooting and high pressure. in the rifle you are using I would check that also.
CatShooter said:
where does the brass come from. I have asked this before. from brass flow under pressure. when does this happen. maybe soft brass in a large chamber can make it happen. but when a case grows in length where did it come from. if FL sized the body of the case is sized back to normal but the case is longer so you trim off the neck length. I have seen the necks get thicker..I sold that rifle...lol...it does not seem to be normal in my experience but yes it can happen.
I agree with Jim. The first thing I would check is carbon buildup. I would get the barrel borescoped. You also need to check trim length. My brass usually gets thinner with repeated firings. This is checked by measuring necks with a neck micrometer. In the area of the junction if you have a donut and putting the bullet through the donut they will get bigger there. Matt
Like Jim and Matt said clean the carbon out of the necks before you check them for thickness. I've clean the brass and run them over the neck turner and have gotten very little if any, Might leave marks from the turner. I could have taken more of with 0000 steel wool! But thats with my 300WSM that doesn't grow much at all. But my 308 Baer that I just neck size grew all the time. So I'm thinking it depends on the caliber and the chambering.
Joe Salt
Joe Salt
Joe R
Gold $$ Contributor
First of all, general statements are generally wrong. It always comes down to details. What brass are you using? How are you measuring the neck thickness and in how many places on the neck?
I totally agree. I can only speak for the .308, but the Lapua, like the Federal, start out about .001-.003 thicker than a Winchester case. I have seen neck brass being re-distributed. Search for "peening", but that is not relevant to this discussion.
I do believe that brass gets redistributed. If you don't think so all you have to do is look at a steel mill flattening rolled steel. They use heat and pressure to flatten steel. Guess what we have in our chamber at the time of firing? You guessed it, heat and pressure. So, in conclusion, Catshooter and .338 Mollet are both right.
So, if brass is being redistributed because of chambering issues or variability of brass, then some parts are going to get thicker and others thinner, the exception is the corners. It is my opinion that they always get thicker; think about it. The case mouth could be a corner depending on several factors.
My feeling about annealing is very simple: if you do it once, you have to do it every time. Otherwise you're changing the brass hardness characteristics from firing to firing so you're not going to get the same pressure. However, if you're not shooting long range you probably will not notice.
Overpressure and loss of accuracy. I had the same problem with my .308 Federal brass when I first started to reload (3 years ago, yes I'm a newbie). The answer is simple: turn the necks. Like most people I resisted until I was forced to cross that bridge. You may be there too.
Kindest regards,
Joe
I totally agree. I can only speak for the .308, but the Lapua, like the Federal, start out about .001-.003 thicker than a Winchester case. I have seen neck brass being re-distributed. Search for "peening", but that is not relevant to this discussion.
I do believe that brass gets redistributed. If you don't think so all you have to do is look at a steel mill flattening rolled steel. They use heat and pressure to flatten steel. Guess what we have in our chamber at the time of firing? You guessed it, heat and pressure. So, in conclusion, Catshooter and .338 Mollet are both right.
So, if brass is being redistributed because of chambering issues or variability of brass, then some parts are going to get thicker and others thinner, the exception is the corners. It is my opinion that they always get thicker; think about it. The case mouth could be a corner depending on several factors.
My feeling about annealing is very simple: if you do it once, you have to do it every time. Otherwise you're changing the brass hardness characteristics from firing to firing so you're not going to get the same pressure. However, if you're not shooting long range you probably will not notice.
Overpressure and loss of accuracy. I had the same problem with my .308 Federal brass when I first started to reload (3 years ago, yes I'm a newbie). The answer is simple: turn the necks. Like most people I resisted until I was forced to cross that bridge. You may be there too.
Kindest regards,
Joe
I would think for a factory gun there would be ample space in the chamber to allow for case necks to expand and let the bullet go. They have to make sure it fits all factory brass including the thicker stuff. The brass that gets trimmed off comes from the brass being worked and is getting stretched out. That usually means it is getting thinner. If the accuracy went away and the pressure went up my guess would be carbon in the throat and neck area of the barrel. Another possibility is that since he annealed before loading is that they were annealed properly. Matt
Joe R
Gold $$ Contributor
Just a heads up.
If you start to anneal every time, you will find that the force required to seat the bullets increases. As Catshooter put it the brass gets "grabby". I believe that heat changes things: during the annealing, the heat softens the brass but also raises the grain, much like spraying water on a piece of unfinished wood raises the grain, resulting in rougher necks that need to be smoothed. Some people use lube (graphite, etc..) on their bullets or necks, I think that is ineffectual because it does nothing to solve the problem. I polish the brass with stainless pins in tumbler, the side benefit is that you get like new brass and very clean dies.
If you start to anneal every time, you will find that the force required to seat the bullets increases. As Catshooter put it the brass gets "grabby". I believe that heat changes things: during the annealing, the heat softens the brass but also raises the grain, much like spraying water on a piece of unfinished wood raises the grain, resulting in rougher necks that need to be smoothed. Some people use lube (graphite, etc..) on their bullets or necks, I think that is ineffectual because it does nothing to solve the problem. I polish the brass with stainless pins in tumbler, the side benefit is that you get like new brass and very clean dies.
I think bullet seating gets easier after annealing. The brass is softer and takes less force to push the bullet in. I use a Wilson seater and can feel the difference. My buddy has a gauge on his K&M arbor press and told me he lost tension after annealing. I believe when brass gets grabby is from cleaning to bare brass. I anneal and clean to bare brass with steel wool for all my match rounds. I use a graphite in the necks. I can even pull a bullet and 98 percent of the graphite remains. Matt
Joe R- The reason you are getting harder seating after Annealing is you are not using anything in the neck for lube, thats like not putting lube on the lugs of your bolt, after a while it will get hard to close or open also! And if you are using any neck tension like I use you better lube. Lets face it if you fire brass 15-20 times its got to flow somewhere. I make it a point to check my brass every firing, if something changes I fix it.
Joe Salt
Joe Salt
CatShooter
johara1 said:
I didn't invent the word "grabby", someone else did, but I liked because it aptly describes the odd feeling of freshly annealed brass cases. Kinda like a horse's nose... no texture, but lots of grab on your fingers when you run them over the annealed part. Not sticky, but it wants to keep your fingers there.
And as johara1 said, after annealing, my bullets seat like greased owl poop... and uniformly. But they have enough grab on the bullet, that they are held there and when you pull them with a collet, they have to be pulled, they do not "fall out" from dead soft metal.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.