Neck Tension vs Accuracy

[Joe Salt]

Jim sure glad I don't have your problems! I just go tighter with the neck tension a thou, then play with seating depth. Was it you that told me you didn't lube the inside of your necks. Can't remember? But it seems to me if you are looking for a tighter jam, you should be getting it without lube. I think that even though I'm lubing the necks and I change bushings, I am still changing things whether it still feels the same when I seat the bullet. But I do see a difference when I shoot them, whether good or bad. Am I coming across right.

joe Salt

 

[johara1]

With the short range benchrest bullets that I have tried, which include one or more that contact the rifling with an 9R ogive segment, I have never had a problem with getting a continuous circle (To clarify, I always get rifling marks by themselves.). The only examples that I know of where this happened were friends that did not know that they had some hard carbon built up in their chambers' throats. You may have mentioned it in another post, but since I can't remember, do you have a bore scope, or know someone with one, so that you can take a look at your chamber's throat? Also, what Spencer bullet are you shooting, and what is the ogive number? Do you know your chamber's freebore diameter and leade angle? Something strange is going on here. Do you get the circle with other bullets, or just that one?

Boyd, this has been going on for 12 barrels, new or old same story. Free bore .135 Free bore diameter is .2438 1.5 degree leade This is the only bullet i think it is a 15 r. It's a VLD anyway. 105H don't do it 104 bib's don't it either. It started with the first shot 2 years ago and i can't figure it out ………. jim

 

[johara1]

Jim sure glad I don't have your problems! I just go tighter with the neck tension a thou, then play with seating depth. Was it you that told me you didn't lube the inside of your necks. Can't remember? But it seems to me if you are looking for a tighter jam, you should be getting it without lube. I think that even though I'm lubing the necks and I change bushings, I am still changing things whether it still feels the same when I seat the bullet. But I do see a difference when I shoot them, whether good or bad. Am I coming across right.

joe Salt

Joe, I went up to .004 neck tension and the same old story, once the pressure ring goes through the neck, it is the only thing that is holding. It's like putting an expander down the neck. Did you talk to Matt lately ? …….. jim

 

[jlow]

Johara1 – if your Neck external diameter is 0.265 and your neck thickness is 0.0102, then your neck internal diameter is 0.265-(2x0.0102) = 0.2446. If the bullet at the pressure ring diameter is 0.2437 is it in fact 0.0009” too small to contact the inside of the neck and certainly the bullet diameter at 0.2432 is way too small to contact the neck as it is 0.0014” too small. This is why there is no grip. If you size the neck down 0.001”, it will still be too big as due to spring back, it is not going to be 0.264” but something bigger. You will likely have to size down with a bushing that is at least 0.002” smaller i.e. 0.253” to get any grip and yea, the pressure ring would work like an expander but only a 0.0005” one so I am surprise that you are not getting any grip going up to 0.004” neck tension. The only thing I can think of is your brass is work harden and even when you go up to 0.004” neck tension, the neck is in fact not going down to anything close to 0.261.

The easiest way to figure this out is to measure the actual external diameter of the neck after you size it down with the 0.261 bushing. If it is still in the 0.254” area, you have your answer.

 

[johara1]

Jlow, .2437 + .0102 =.0102 = .2641 a loaded round clearance of .0019 in a .266 neck. The neck is sized with a .262 bushing 2432+ .0204= .2636, so i see .0016 grip ahead of the pressure ring if it had enough spring back. I sized down with a .260 bushing and it made no difference…….. jim

 

[jlow]

So Jim, when you size with a .262 bushing, you should as you said have a 0.0016” grip. With a .260 bushing you should have .0036 grip but you are saying it made no difference. My assumption is that the bullet still have no grip after the pressure ring has gone past.

My question to you is after you size your neck with the .262 and .260 bushing what exactly was the neck external diameter of the case if you checked it with a pair of calipers or micrometer? Have you done this?

 

[Alex Wheeler]

Jim,
I am shooting a very similar set-up. My bullets have a .0005" pressure ring. I use .0035"-.004" nt. I have no problems with bullets moving, I used to jam this load no problem. I get 37-38 lb seating force. The pressure ring stays in the sized part of the neck.

 

[Joe Salt]

Jim no I didn't talk to matt, think he is too tired from working to pick up the phone and dial! So did you try a different seating depth after that didn't work but with the same bushing.

Joe Salt

 

[jlow]

I think he is not jamming as he said “Joe, I went up to .004 neck tension and the same old story, once the pressure ring goes through the neck, it is the only thing that is holding. It's like putting an expander down the neck.” My guess is his brass is heavily work hardened and so despite the theoretical neck tension, he is not getting the .004 reduction in neck diameter.

 

[johara1]

jlow, The neck measures what is marked on the bushing except the .261 bushing and .2615……….

Alex, what is your shank size? my problem is how it grabs the bullet 360 degrees and the lack of neck tension after the pressure ring goes through it will not spring back enough to grip it ahead of the pressure ring. a ,260 bushing is .004 neck tension and it still will not hold it from pulling the bullet on dummy round .010 in ……… jim

 

[johara1]

Jim no I didn't talk to matt, think he is too tired from working to pick up the phone and dial! So did you try a different seating depth after that didn't work but with the same bushing.

Joe Salt

Joe i think he's done working, He said he was going to get one barrel set back and one chambered and use the old reamer … I tried everything and nothing works with that bullet . Are you going to HJ. for the state shoot?……. jim

 

[jlow]

Jim – if your neck gives you .2615, even if your pressure ring pushes out and there is no spring back, you should still have .2610” external diameter and .2406” internal diameter, so if your shank is 0.2432, you should still have .0026” grip.

If you are not seeing any grip after the pressure ring goes through, re-measure everything, the neck external diameter, the neck thickness, and the bullet diameter. One of those numbers will tell you what is happening.

 

[BoydAllen]

+1

 

[snakepit]

Was it you that told me you didn't lube the inside of your necks. Can't remember? But it seems to me if you are looking for a tighter jam, you should be getting it without lube.
joe Salt

I am glad to see someone finally bringing up about putting lube inside the necks. I am curious about what this does in relationship to the topic that has been discussed in this thread. This is something I have been curious about. I am here to learn.

 

[savagedasher]

My chamber is .2704 my cases when fired it is.2697 at the shoulder and .267 at the front. My full length bump die sizes my brass to .2692 I then size with a bushing .130 of the neck to.2654.the boat tail end up being at the step in the neck. the loaded case is .2665 .
My cleaning method is vibrate with a 50 50 mix of walnut shell and corn cob. I use Poly Pro-Tec to help with the polishing. The inside of my necks are polished just like the out side. The bullet takes 18 to 20 oz to seat. It takes 3 to 4 lb to remove.
How I check that I drilled a hole in the bullet and screwed a eyelet in the hole and used my bow scale mounted over my press with a wire.
The fired cases still have the step in it Why and how come I don't understand I seat my bullets .020 off the lands. My ES is 4 or under. My best two targets at 600 YD was 1.652 and 1.059 .Shot with a Savage Dasher. Larry

 

[Alex Wheeler]

Jim the shank is .2434" and the ring is .2439". Are you annealing to much? I look for the flame to show a little orange as the case is leaving.

 

[BoydAllen]

I guess that I still want to know what the throat looks like with a bore scope, because the only instances that I know of this sort of complete circle contact have been because of hard carbon in the throat that went undetected, except by bore scope because the deposits did not color patches. Perhaps the bullet maker could shed some light on this. If the bullet has some unusual characteristic, he should know.

 

[johara1]

I guess that I still want to know what the throat looks like with a bore scope, because the only instances that I know of this sort of complete circle contact have been because of hard carbon in the throat that went undetected, except by bore scope because the deposits did not color patches. Perhaps the bullet maker could shed some light on this. If the bullet has some unusual characteristic, he should know.

Boyd, I DON"T have carbon issue , 12 barrels over 2 years and the same issue 4 different reamers. 4 records jumping them.
Tom Yes, doesn't change, used new BR brass never fired neck turned still pulls the bullet …… i couldn't remember it may be 13
Alex, I don't have this problem with any other bullet, even the fat Berger hybrids
jlow, The reason i mentioned that bushing was it is the only one that is not sizing to the size marked on it. I went down to the .260 bushing and it still will not hold, it makes no difference, you size one with the .260 bushing seat it deep and push the pressure ring through the sized part you can push it in with your fingers and i use no lube never did……… jim

 

[johara1]

My chamber is .2704 my cases when fired it is.2697 at the shoulder and .267 at the front. My full length bump die sizes my brass to .2692 I then size with a bushing .130 of the neck to.2654.the boat tail end up being at the step in the neck. the loaded case is .2665 .
My cleaning method is vibrate with a 50 50 mix of walnut shell and corn cob. I use Poly Pro-Tec to help with the polishing. The inside of my necks are polished just like the out side. The bullet takes 18 to 20 oz to seat. It takes 3 to 4 lb to remove.
How I check that I drilled a hole in the bullet and screwed a eyelet in the hole and used my bow scale mounted over my press with a wire.
The fired cases still have the step in it Why and how come I don't understand I seat my bullets .020 off the lands. My ES is 4 or under. My best two targets at 600 YD was 1.652 and 1.059 .Shot with a Savage Dasher. Larry

Larry, I don't have to do that i can push the bullet in with my fingers if i seat one deep enough to get the pressure ring past the sized part. Don't get me wrong it shoots good with low ES and set records jumping them but they shoot better in but they are not reliable…. jim

 

[dkhunt14]

I guess that I still want to know what the throat looks like with a bore scope, because the only instances that I know of this sort of complete circle contact have been because of hard carbon in the throat that went undetected, except by bore scope because the deposits did not color patches. Perhaps the bullet maker could shed some light on this. If the bullet has some unusual characteristic, he should know.

Boyd i see this in a Broughton 5C in a 300 WSM when the barrel is new. It goes away after a bunch of firings. When I got my first Brougton chambered it gave me fits because the marks were totally different on a bullet. You would basically get a small mark on bullet then a full circle that looked like you spun the bullet around with a knife against it. You could put the bullet deeper in the rifling and the mark wouldn't change. I was used to looking at the marks a Krieger left on the bullet. Yes I checked the seating depth before and after chambering to make sure I wasn't pushing the bullet deeper when chambering it.