Need a second opinion
- Thread starter Goose25
- Start date
If it is not causing any kind of accuracy problem I would not worry about it. My guess would be that it is either an artifact of the collet die, or some machining in your chamber. Have you checked the inside diameter of a fired case with a bullet. Normally a fired case will let a bullet slip down the neck with slight resistance. If the donut is on the inside you will feel it, or even not be able to slide the bullet further. I use a Forster bushing die with Lapua brass, and I get a bit of a donut on the inside right at the shoulder. Not sure of the exact cause either. But, I do not worry about it, because I never seat bullets back far enough to get to the shoulder area. In fact I only neck size 2/3 of the neck, and leave the back 1/3 unsized. I feel that helps center the cartridge in the neck. Not sure that is possible with a Lee collet die or not. May be worth a try.
Did you get the carbide mandrel with the donut cutting flutes??? Most chamber reamers have a radius cut at the neck shoulder junction for whatever reason I don't know, brass can bend. Reamer makers think its necessary, but it just screws up the junction between the shoulder and the neck. I think I can see something, but I've seen worse.
NormB
NormB
Do the neck turning after firing and before sizing the brass, then who cares about the overall length? The important length will be the base-to-shoulder (datum) length.
Though you might actually want to think about reaming the necks to remove the 'donut' material.
Though you might actually want to think about reaming the necks to remove the 'donut' material.
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Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
The collet neck die should keep the donut from intruding into the case neck. Just put a bullet into the fired case and it should slide freely in and out. This is one of the big positives when using this form of neck sizing.
The dreaded donut that concerns us is brass flow INSIDE the neck. This screws up bullet seating and when pushed to the outside, can increase case neck thickness enough that it stops the bullet from being released - huge pressure spike and a wild shot.
You don't need to have all your brass trimmed the same length to neck turn. The neck turner doesn't index off anything on the front of the case. As was said, the case is fireformed to your chamber and the real index is the case shoulder.
All that is needed is run the neck turner back on the case so that it cuts this bulge flush with the neck. Touching a bit of the shoulder doesn't hurt either. You are getting rid of the high spot/bulge.
If you are getting a lot of brass flow into the case neck, they will now not be even in thickness. Measure several cases at 90deg spots and if more then 1 thou off, you can skim the entire neck as part of this process.
I am surprised to see this much brass flow in 1 firing. maybe there is something a bit loose in the chamber but it will not affect overall accuracy. Maybe you have soft brass?. Just something you have to maintain in your case prep.
I always neck turn AFTER sizing. You want that mandrel to be snug fit in the neck otherwise, you will cut a wavy neck - thick and thin. besides the mandrels are for a sized neck diameter and will be super loose in a fired neck.
Eventually, the cases will grow enough that you need to trim. Trim length is no biggie and will not affect your accuracy one bit. The only reason to trim is to keep the necks from being too long and jamming into the leade of the chamber.
In my 223s, I run them pretty hard and trimming happens after 3 to 4 firings. I have now mechanised the process with a Forster 3 in 1 cutter and a second trimmer to handle the outside neck turning duties. All powered by an electric screwdriver.
What a time and hand saver....
I will skim the necks each time I trim. Looks like you will have to for this rig as well.
Part of running a shallow neck case and some elevated pressures.
Jerry
The dreaded donut that concerns us is brass flow INSIDE the neck. This screws up bullet seating and when pushed to the outside, can increase case neck thickness enough that it stops the bullet from being released - huge pressure spike and a wild shot.
You don't need to have all your brass trimmed the same length to neck turn. The neck turner doesn't index off anything on the front of the case. As was said, the case is fireformed to your chamber and the real index is the case shoulder.
All that is needed is run the neck turner back on the case so that it cuts this bulge flush with the neck. Touching a bit of the shoulder doesn't hurt either. You are getting rid of the high spot/bulge.
If you are getting a lot of brass flow into the case neck, they will now not be even in thickness. Measure several cases at 90deg spots and if more then 1 thou off, you can skim the entire neck as part of this process.
I am surprised to see this much brass flow in 1 firing. maybe there is something a bit loose in the chamber but it will not affect overall accuracy. Maybe you have soft brass?. Just something you have to maintain in your case prep.
I always neck turn AFTER sizing. You want that mandrel to be snug fit in the neck otherwise, you will cut a wavy neck - thick and thin. besides the mandrels are for a sized neck diameter and will be super loose in a fired neck.
Eventually, the cases will grow enough that you need to trim. Trim length is no biggie and will not affect your accuracy one bit. The only reason to trim is to keep the necks from being too long and jamming into the leade of the chamber.
In my 223s, I run them pretty hard and trimming happens after 3 to 4 firings. I have now mechanised the process with a Forster 3 in 1 cutter and a second trimmer to handle the outside neck turning duties. All powered by an electric screwdriver.
What a time and hand saver....
I will skim the necks each time I trim. Looks like you will have to for this rig as well.
Part of running a shallow neck case and some elevated pressures.
Jerry
That is not a Donut you have pictured there. A donut will not be visible (usually) by looking at the case. You can check for a donut by dropping a bullet into a fired case and see if it gets caught in the neck or falls right into the case. (Should fall into the case)
I ordered the carbide pilots with the donut cutter but a properly turned neck is sized down then expanded to proper dimension which pushes the donut to the outside of the case and is then turned off with the neck cutter.
Looks to me like there is a lip where the neck meets the shoulder in your chamber.
Get a borescope (or find someone who has one) and look at that point in the chamber.
I ordered the carbide pilots with the donut cutter but a properly turned neck is sized down then expanded to proper dimension which pushes the donut to the outside of the case and is then turned off with the neck cutter.
Looks to me like there is a lip where the neck meets the shoulder in your chamber.
Get a borescope (or find someone who has one) and look at that point in the chamber.
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Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
The Lee collet dies pushes the donut to the outside and it becomes visible.
Because of the mandrel/style of sizing, extra brass flow cannot intrude into the case neck.
Jerry
Because of the mandrel/style of sizing, extra brass flow cannot intrude into the case neck.
Jerry
That's not a donut, a donut is what I get when I neck up brass from say 6mm to .30 cal., it can be removed by turning or firing if it still fits, either way, it's gone after firing never to return. Your's look like a prob. with either the brass or your die....IMHO
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
I have to ask. Do you have a tight neck chamber? If so/not what dimensions and what did you cut the neck too?
"If those markings are a result of rough machining in my chamber, wouldn't they appear after the 1st firing? why would they be more visible after 4 firings?"
You brass do stress after every fire, and if you don't prep and prepare your brass every time you do-reload it will tent to be very tight, as result will damage you chamber. Don't do any more reloading for now, you should pick up a reloading book and start reading.
You brass do stress after every fire, and if you don't prep and prepare your brass every time you do-reload it will tent to be very tight, as result will damage you chamber. Don't do any more reloading for now, you should pick up a reloading book and start reading.
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
Ask the gunsmith to see the reamer or the dimensions if not sure.
You don't want a highly polished chamber, but one machined properly by a sharp, no burrs or nicks reamer. You want the brass to grip the chamber when fired, not slide backwards into the bolt. Besides, extra polishing will change the chamber dimensions.
I'm still curious if your turning the necks too thin with a standard chamber reamer. Is it a tight fit neck?
You don't want a highly polished chamber, but one machined properly by a sharp, no burrs or nicks reamer. You want the brass to grip the chamber when fired, not slide backwards into the bolt. Besides, extra polishing will change the chamber dimensions.
I'm still curious if your turning the necks too thin with a standard chamber reamer. Is it a tight fit neck?
lejarretnoir
CGN Ultra frequent flyer
- Location
- 162km from Connaught
I'm thinking two separate reamers were used [as suggested] or a .243 reamer then neck/throater possibly.
The second part didn't quite clear up the neck/shoulder junction properly.
Why do you need to use the body die to bump shoulders of new virgin brass? It should easily go into standard chambers as it usually comes from the factory small based sized. I've never heard of that unless the chamber was undersized.
Also, did you talk to the original gunsmith about this and have him look at it? Might save you some pain and money.
The second part didn't quite clear up the neck/shoulder junction properly.
Why do you need to use the body die to bump shoulders of new virgin brass? It should easily go into standard chambers as it usually comes from the factory small based sized. I've never heard of that unless the chamber was undersized.
Also, did you talk to the original gunsmith about this and have him look at it? Might save you some pain and money.
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johnny boy
Regular
- Location
- Northern Alberta
I had a very simalar issue as you with a rifle that was a custom build from the ground up from a reputable smith. I had the same markings on the should but also when I full sized in my body die there were multiple rings arounf the body of the case all the way down. Long story short, rifle went back and they cut down the barrel and re reamed. They ended up replacing the barrel and using a new reamer to fix it.
Personally I would plug up the barrel just past the chamber and do a lead cast of the chamber. You can also buy a product for this purpose, whose trade names escapes me.
Carefully knock it out with a dowel and inspect with eyes and calipers. Go from there.
Carefully knock it out with a dowel and inspect with eyes and calipers. Go from there.
