Is this an example of poor runout in my new setup? (T3 .260)

[Sierra.sqz]

Hey guys,

I've just gotten a new setup as follows: Tikka T3 Varmint in .260 Rem. once fired Lapua brass, Hornady SST 129 grain projectiles.

My reloading gear consists of an old Lee single stage press and new basic RCBS neck die and seating die. I have tested the max OAL of the cartridge to be 73.5mm (2.893in) and the max OAL of the magazine to be 71.5mm (2.814in). Even when I load to 71.5mm I am having to force the bolt forwards to chamber the round. Upon ejection I noticed that each bullet has a scrape mark on one portion of it. No matter how many times I load/extract the round or which way it is oriented in the chamber, the mark is always in the same spot on the bullet. There are no other marks, I am familiar what marks are left on a bullet when it is chambered into the lands and they are not present.

The problem I am having is illustrated in the attached pictures. You can hopefully see the scuff marks on the bullets all facing the camera. The bullet on the left has barely got a visible mark and out of the 5 it was the only one to chamber and eject easily. These bullets are seated at 71.5mm, well into the neck of the case and far deeper than I want.

I haven't used these RCBS dies before and I notice that they are different. I have previously loaded .308 using Lee RGB cheapies and I haven't had the same issues. My 308 would shoot 1/2 minute with these Lee RGB loaded ammo. The RCBS dies are designed not to float like the Lee dies with the o-ring do.

I am concerned that these new RCBS dies have created runout, possibly also to some wear or misalignment in my press. I'm no expert so I thought I'd ask on here. I have searched the posts relating to runout and haven't found anything like this before.

I don't have a concentricity gauge.

Edit - It doesn't matter how the round it orientated when it gets chambered, the mark can come out facing up, sideways or towards the bottom in relation to the action. So that tells me that it isn't something to do with the chamber/throat. Also I can spin the round before chambering it a second time and it still comes out with the mark in the same place on the bullet but with the mark facing a different direction.

- Also I have put the o-ring lock nut onto my RCBS die and I have also taken the locking nut off the top. The whole thing is free to have some movement, which I assume would help everything line up. It sill does the same thing, no change.

I have loaded 20 rounds this afternoon and only 1 has no marks at all. Most of them require force to close the bolt and requires a firm hit on the bold handle to extract them.

Could it be the RCBS neck die causing these problems? It was torqued down to the press quite tight, but I didn't have any issues with the de-primer pin not aligning with the flash hole.

 

[Sniper338]

I dont think that is run out.. run out is brass flowing... You can use the lee die o ring nuts on rcbs dies, Ive done it, have some set up that way.

I've had something like that happen before too, but on the brass neck, I chalked it up to be excessive ejector pressure where when the round is being unloaded the ejector is pushing/pulling the round to the side really hard against the chamber/action housing and it left rub marks like that on my brass... I dont have a straight answer though.

 

[Sierra.sqz]

It's not just a scuff mark on the bullet jacket, the pictures don't really show it very well but it's a significant force that is being applied to close the bolt and to bash it open again.

 

[justinp61]

Have you tried feeding one into the chamber then closing the bolt?

 

[nmkid]

I don't have an answer but, I'm pretty sure it's not the lands, (as you noted). If it was the lands I think the mark would be smaller and more than one. I have in the past gotten marks like that from ejecting the round. What I used to do was...As I ejected the round I would press down on the case, (as soon as I would see the case) and try to keep it from, "dragging" in the action. Hope that makes sense.

 

[jonbearman]

The gun was unfired when you received it? I was thinking you have one heck of a carbon ring or some other debris stuck in the neck area like hard carbon. I had a friend who had a remmy 700 in .270 and it had so much carbon from 35 years of not maintaining the thing you could barely chamber a round. We cleaned it by removing the barrel and there was rust and heavy carbon built up. He couldn't shoot better than 3-4 inches at 100 yds. When I got through with the extensive cleaning that darn thing shot under an inch with ease.

 

[Sierra.sqz]

I'm going to get some unfired and unsized new Lapua brass and load some rounds. That way I will be able to eliminate the factor of my sizing die causing issues. If the brass is straight to begin with and if my seating die is 'floating' so to speak, everything should line up. I still believe that something isn't 'straight' and I'm leaning towards it being a result of my neck sizing die. I just don't know what or how.

I am aware of what scratching looks like on the brass and projectiles from being chambered/extracted and this is different. The marks that I have on my bullets are not from that. As I said, even though I am a long way from the lands, I am still having to force the bolt forward to get it to chamber. There is some part of the throat that is coming into contact with a small part of the bullet. I can show that it doesn't matter which way the bullet is facing, or how many times I chamber it, it will still have the mark in the same place. That tells me it is not a problem with the gun, but rather the shape of the round.

The gun was brand new from the factory when I got it and so far it's had 100 rounds through it, two batches of 50. The first 50 were no problems, using brand new brass and the bullets seated .002 out. It wasn't until I ran the 50 fired cases through my RCBS neck and seating dies and that the second batch were difficult to chamber. I shot them all anyway and got no pressure signs even past book max loads.

 

['Freak]

Hard to tell from here but zoomed in 1000%, it’s lookin’ on my box like a die possibly made contact with the case neck/shoulder junction, as if the die needs to be backed out the press a fraction of a turn.

 

[simplerider]

Unfired virgin brass fired fine and you only neck sized and are having hard chambering issues. Sounds to me like you need to bump the shoulder back. Measure the shoulder on an unfired case and a fired case and I'm willing to bet you are having some growth there. Try a full length sizer and see if that helps. The marks on the bullets looks like your chamber was cut off center. If this is a factory gun like you say, this could be the culprit and has happened before. Sometimes they slip through quality control. I would recommend taking it to a gunsmith and have the chamber cast or see if he will scope it to see if all is cut right.

Just my thoughts, hope it helps.

 

[loinhunter]

I had the same problem. 5 rounds , same location no matter how the round was oriented. I rolled the rounds and noticed a visual wobble at the bullet tip. Out of round. Might be the neck. I'll know when they are re-stuffed . If problem persists, it's the neck of the cartridge, if not the 5 rounds were seated askew. 260 rem also.

 

[Ggmac]

I had the same problem. 5 rounds , same location no matter how the round was oriented. I rolled the rounds and noticed a visual wobble at the bullet tip. Out of round. Might be the neck. I'll know when they are re-stuffed . If problem persists, it's the neck of the cartridge, if not the 5 rounds were seated askew. 260 rem also.

4 yr old POST

 

[loinhunter]

I know . But figuring that if I found it with this problem it might help .