Neck thickness question
12-14-2004, 01:35 PM
#1
Guest
Posts: n/a
Neck thickness question
I started doing alot of neck turning in the past year and find alot of improvement regarding flyers. This is usually with remington brass. I did a few comparisons, and found my 5 shot group size srank from ~1.5" (with flyers)to .75" consistently at 100 yards on a few loads where I had trouble some days and no trouble others.
Just curious for you guys that have neck thickness guages. Approximately, how much will your neck thickness grow with each firing. Say you start out with .015".
What I usually see is thickness varying from 13-18mil or .005" with new remington brass for my 300RUM. I see alot less variation with Federal. I try to never cut my necks less than .014" and try to stay around .015" and if one side of the neck is less than .010, I just cull it out. I heard and found out you can end up in trouble with your FL dies when you get below .011". So I want to know how much the thickness will grow with each firing from a gun like the 300RUM.
Do any of you guys with tight custom throats end up with problems from the neck thickness growing? About how many shots?
Just curious for you guys that have neck thickness guages. Approximately, how much will your neck thickness grow with each firing. Say you start out with .015".
What I usually see is thickness varying from 13-18mil or .005" with new remington brass for my 300RUM. I see alot less variation with Federal. I try to never cut my necks less than .014" and try to stay around .015" and if one side of the neck is less than .010, I just cull it out. I heard and found out you can end up in trouble with your FL dies when you get below .011". So I want to know how much the thickness will grow with each firing from a gun like the 300RUM.
Do any of you guys with tight custom throats end up with problems from the neck thickness growing? About how many shots?
12-19-2004, 08:59 AM
#2
Join Date: Jul 2004
Posts: 91
RE: Neck thickness question
First of all, I believe you will have better luck asking your question on the Group Therapy board.
I'm assembling the components for a BR rifle, and it will have a tight necked chamber. Other than that, I can't give you a definative answer to your question, because the answer is only critically pertinant for someone shooting a tight necked chambered rifle, and at present I am not.
Still, the question begs to be asked, why are you using FL dies after going to the trouble of turning your necks? Using a FL die on brass with turned necks will shorten the case life. The thinner necked brass will not last as long as brass w/unturned necks.
Brass should be FL sized before neck turning, but not after. If you're lucky, the expander will size the neck id for a proper fit on the neck turner's mandrel. If it doesn't and you can't modify it on a lathe to do so, there is a caliber specific tool called an expandiron, that will. For the shooter with a standard necked chamber, the goal of neck turning is twofold. Remove the high or "thick" spots from the neck on the outside, and controlling neck tension. This is accomplished with a bushing neck sizer and annealing those necks. Given that everything else is done right, low velocity spreads will follow. You get no such benefit with a FL sizer. Other benefits of bushing neck sizing include lower T.I.R. induced by expander ball drag and longer case life, the less sizing involved, the less work hardening you get.
Your brass will of course tighten up after a few shots. Instead of a FL sizer, then you are better off with a "bump die", like this one from Redding. Body dies, or "bump" dies size only the body, not the neck. After putting all that labor into your cases, why screw them up in a FL die?
I'm assembling the components for a BR rifle, and it will have a tight necked chamber. Other than that, I can't give you a definative answer to your question, because the answer is only critically pertinant for someone shooting a tight necked chambered rifle, and at present I am not.
I heard and found out you can end up in trouble with your FL dies when you get below .011"
Brass should be FL sized before neck turning, but not after. If you're lucky, the expander will size the neck id for a proper fit on the neck turner's mandrel. If it doesn't and you can't modify it on a lathe to do so, there is a caliber specific tool called an expandiron, that will. For the shooter with a standard necked chamber, the goal of neck turning is twofold. Remove the high or "thick" spots from the neck on the outside, and controlling neck tension. This is accomplished with a bushing neck sizer and annealing those necks. Given that everything else is done right, low velocity spreads will follow. You get no such benefit with a FL sizer. Other benefits of bushing neck sizing include lower T.I.R. induced by expander ball drag and longer case life, the less sizing involved, the less work hardening you get.
Your brass will of course tighten up after a few shots. Instead of a FL sizer, then you are better off with a "bump die", like this one from Redding. Body dies, or "bump" dies size only the body, not the neck. After putting all that labor into your cases, why screw them up in a FL die?
12-19-2004, 04:40 PM
#3
Guest
Posts: n/a
RE: Neck thickness question
Reason I use my FL die is it is only made to knock my shoulder back .001" which is cool. Second this batch of brass I have was in such bad shape, I think its best to run it thru the FL first. After working the neck by turning, 50% or so had neck runout >.005". I have never seen a batch of brass so bad as this Remington 300RUM brass. I can't wait until someone else makes brass for it. I should have just took and fireformed and that would have straighten it out.
I have thought about getting a good bushing die, but never did. Actually when I fireform this batch this week, I guess I am going to bite the bullet and send $50 to Lee to have a collet die made for it.
Thanks for your reply. This gun does have a tight throat. When it was built I initially asked the Gunsmith to make it a custom throat with no freebore. But then talked to another guy that did this, and he had trouble getting good velocity and had to throw out the reload data from his manuals.
I will try your link. Thanks
I have thought about getting a good bushing die, but never did. Actually when I fireform this batch this week, I guess I am going to bite the bullet and send $50 to Lee to have a collet die made for it.
Thanks for your reply. This gun does have a tight throat. When it was built I initially asked the Gunsmith to make it a custom throat with no freebore. But then talked to another guy that did this, and he had trouble getting good velocity and had to throw out the reload data from his manuals.
I will try your link. Thanks
12-19-2004, 05:08 PM
#4
Join Date: Jul 2004
Posts: 91
RE: Neck thickness question
Also to consider, there are several different types of bump dies. Since your rifle is a custom, you may have access to the reamer. These dies at Borden Rifles are made with the same reamer as the rifle. They size the neck with a bushing and bump the shoulder, two birds with one stone.
Another neck sizing bump die is at Neil Jones Custom Products. For this die, you supply 3 fired cases to the die maker.
I'm sure there are many more options you can look into.
Another neck sizing bump die is at Neil Jones Custom Products. For this die, you supply 3 fired cases to the die maker.
I'm sure there are many more options you can look into.
