Tight Throat?

[NVHunter92]

So I'm having a bit of an issue and hopefully you guys can provide some help. I have a new Christenson Arms in 7mm rem mag. I am using nosler brass and 162gr hornady ELD-X's. I had trouble finding my distance to lands using the hornady oal gauge as I was getting a number well below saami max (2.619" w/ comparator). So I used Jim Wheelers stripped bolt method and a fired case with light neck tension to "jam" the bullet into the lands and both methods were very close to each other and gave me a distance to lands of 2.737" using a comparator. During my fireforming process I had the bullets seated to a depth of 2.685" using a bullet comparator and everything worked well. I even stripped the bolt and ran the unfired rounds through the chamber and they fit with no resistance. After fireforming I neck sized my brass and seated the bullets to the same depth and went shooting. I also cleaned the gun very well. The problem is that when running the bolt forward I can feel resistance as the bullet enters the throat and the bolt is stiff to lock down. When I would try to unchamber the unfired round the bolt would lift with some resistance but I had to bang on it to get it to move rearward and there is scuffing on one side of my bullet near the case mouth (see picture). The rounds shot well and showed no pressure signs and the fired cases ejected like normal. I got home and took the firing pin and ejectors out of my bolt and ran one of the now twice fired cases into the chamber and the bolt closed with little to no resistance so I think my cases are sized properly. I saved one of the problem unfired rounds and started incrementally seating the bullet deeper but was still getting scuff marks even down to a length with comparator of 2.610". It didn't matter how the case was oriented, the scuff mark was always in the same place. I bumped the shoulder back using a Redding body die and same issue. I tried seating the bullet with a rcbs gold metal match die to a depth of 2.685"...same issue. I'm really scratching my head on this one. The rounds worked well on their first firing but not on the second but the cases chamber easily.

 

[Dusty Stevens]

Looks like a mass production shop chamber problem. Id want to see that with a borescope then get a new barrel. That is if your ammo loading isnt that far off which doesnt sound like the case (except looking at that wrinkle on your neck)
Did you get the barrel throated for such a big bullet or did they put their normal 140gr throat in there?

 

[STS]

You said it didn't matter which way the case was rotated and the scuff was always in the same place. That would suggest that the neck wall thickness may be the culprit. Do you have a concentricity gauge?

 

[rsbhunter]

That definitely looks to be chamber related , in light of the different seating depths, and the same results. If the mark stayed at the same size, width and length, as the bullet seating depth was adjusted, it would appear mechanical. I would contact Christenson arms and request a return label and have them inspect it. At worst, it will cost shipping, but myself, it would drive me crazy second guessing that it is something i was doing wrong. As i've gotten older, the fun of banging my head against a brick wall trying to figure out something has lost alot of it's appeal.....just my thoughts...rsbhunter

 

[LA50SHOOTER]

View attachment 1035885 So I'm having a bit of an issue and hopefully you guys can provide some help. I have a new Christenson Arms in 7mm rem mag. I am using nosler brass and 162gr hornady ELD-X's. I had trouble finding my distance to lands using the hornady oal gauge as I was getting a number well below saami max (2.619" w/ comparator). So I used Jim Wheelers stripped bolt method and a fired case with light neck tension to "jam" the bullet into the lands and both methods were very close to each other and gave me a distance to lands of 2.737" using a comparator. During my fireforming process I had the bullets seated to a depth of 2.685" using a bullet comparator and everything worked well. I even stripped the bolt and ran the unfired rounds through the chamber and they fit with no resistance. After fireforming I neck sized my brass and seated the bullets to the same depth and went shooting. I also cleaned the gun very well. The problem is that when running the bolt forward I can feel resistance as the bullet enters the throat and the bolt is stiff to lock down. When I would try to unchamber the unfired round the bolt would lift with some resistance but I had to bang on it to get it to move rearward and there is scuffing on one side of my bullet near the case mouth (see picture). The rounds shot well and showed no pressure signs and the fired cases ejected like normal. I got home and took the firing pin and ejectors out of my bolt and ran one of the now twice fired cases into the chamber and the bolt closed with little to no resistance so I think my cases are sized properly. I saved one of the problem unfired rounds and started incrementally seating the bullet deeper but was still getting scuff marks even down to a length with comparator of 2.610". It didn't matter how the case was oriented, the scuff mark was always in the same place. I bumped the shoulder back using a Redding body die and same issue. I tried seating the bullet with a rcbs gold metal match die to a depth of 2.685"...same issue. I'm really scratching my head on this one. The rounds worked well on their first firing but not on the second but the cases chamber easily.

How many rounds have you fired through the barrel ?
I encountered a similar issue with a 338 caliber new barrel & it was caused by a defect in the throating part of the reamer.
I contacted my gunsmith & he told me that in 80-100 rounds the throat should be opened up enough to where I don't have this condition.
I still have to see, but in the event that it doesn't I purchased a throating reamer, mandrel & "T"-handle so if I have to re-cut the throat I'm able to do so.

 

[NVHunter92]

Looks like a mass production shop chamber problem. Id want to see that with a borescope then get a new barrel. That is if your ammo loading isnt that far off which doesnt sound like the case (except looking at that wrinkle on your neck)
Did you get the barrel throated for such a big bullet or did they put their normal 140gr throat in there?

It is their mesa long range rifle, I have no idea what they throated it for.

 

[NVHunter92]

How many rounds have you fired through the barrel ?
I encountered a similar issue with a 338 caliber new barrel & it was caused by a defect in the throating part of the reamer.
I contacted my gunsmith & he told me that in 80-100 rounds the throat should be opened up enough to where I don't have this condition.
I still have to see, but in the event that it doesn't I purchased a throating reamer, mandrel & "T"-handle so if I have to re-cut the throat I'm able to do so.

I had 50 rounds through it before the issue arose. The first 50 were nosler cases out of the box and all shot with no issues. It wasn't till I had them fireformed and neck sized that the issue started.

 

[NVHunter92]

That definitely looks to be chamber related , in light of the different seating depths, and the same results. If the mark stayed at the same size, width and length, as the bullet seating depth was adjusted, it would appear mechanical. I would contact Christenson arms and request a return label and have them inspect it. At worst, it will cost shipping, but myself, it would drive me crazy second guessing that it is something i was doing wrong. As i've gotten older, the fun of banging my head against a brick wall trying to figure out something has lost alot of it's appeal.....just my thoughts...rsbhunter

I spoke with Christenson about it when I was getting a max coal much shorter than saami max and they basically told me the rifle has to be fine and I need to shoot factory ammo through it as any reloads basically void the warranty. So I suspect that if I sent it to them they would simply shoot a factory round through it and call it good and send it back. Like I said my original cases from nosler all shot those bullets at that depth fine, it was t until after fireforming and neck sizing that the issues arose.

 

[3Ackleys]

try full length resizing, bumping your shoulder back 1 to 2 thous.

 

[Dusty Stevens]

Neck sizing is always an issue but i dont think thats your problem here except with that wrinkled neck which is a whole different issue. Do you have the tools to check your runout? It appears maybe your die wrinkling that neck like that has pushed the bullet over to the side and it rubs. You need to check runout and borescope that chamber

 

[NVHunter92]

try full length resizing, bumping your shoulder back 1 to 2 thous.

I used a Redding body die to resize the body of the case and it bumped the shoulder back 2 thous. Didn't fix it

 

[nmkid]

As big as that smear appears to be, if the bullet was hitting the lands shouldn't we be able to see the lands marks?

 

[nmkid]

I had 50 rounds through it before the issue arose. The first 50 were nosler cases out of the box and all shot with no issues. It wasn't till I had them fireformed and neck sized that the issue started.

So why not try FL sizing and see what happens?

 

[rsbhunter]

I'm with nmkid, fl sizing might be the answer. I have a 6.5x284 Krieger bbl on a Savage that if i dont fl size and push the shoulder back, feels like i'm trying to push the bullet into the rifling as well as forcing the junction of the body/ neck junction into the chamber on fired and neck sized cases....although i never had the bullet marks...I was under the impression that if not seated into the rifling, the bullet should be suspended in the chamber/ throat area ( although only by a tiny bit) . If i am mistaken, please correct me, as i am still learning, and so willing to....Also, the marks are there if the extractor/ejector are installed or not?

 

[a1712]

Blowing the pic up look at the edge of the case neck right above the buckle in the neck, looks to be jamming into the chamber end, or that's the worse champfer I've ever seen cut on a case. Brian.

 

[geraldgee]

I want to be sure I understand. You fired 50 rounds of factory ammo without issue. It wasn’t until you attempted to cycle the ammo you reloaded that the problem surfaced.

If this is the case, I would suggest you review the steps you take to reload your ammo. Prep a piece of brass and ensure it will chamber without issue. Once you are satisfied that your cases are correctly trimmed and sized, create a dummy load with the bullet you hope to use. No powder nor primer, just a bullet. To the best of your ability and the tools you have on hand, measure/compare your dummy load to a factory round that you are sure will chamber. I am confident that if you move slowly and deliberately and with measured steps, you’ll discover the issue.

Good luck.

Gerald

 

[fredo]

Remember, if you're neck sizing via bushing without first 'truing' thickness, all you're really doing is pushing any eccentricity (high spots) to the ID. Then, when you seat a bullet, that eccentricity again is pushed back to the OD, which isn't doing much to build straight ammo...

P.S. Make sure your neck bushing is floating in the die. If the stem is snugged down hard against the bushing, it might bind it up & induce runout to your case necks...

Great advice above! Go sloooow, and measure!

 

[LCazador]

I had 50 rounds through it before the issue arose. The first 50 were nosler cases out of the box and all shot with no issues. It wasn't till I had them fireformed and neck sized that the issue started.

I've had this issue with brass before. If you have a tube or neck micrometer check the neck thickness all the way around in 4 places. You may find as I did a difference of 5 thousands on one side and the only alternative is to neck turn for a consistent neck dimension all the way around. Brass is undersized when new so yes you would have no problems until fireforming. If you use factory ammo or new brass every tim I won't doubt that you may also have a chamber dimension issue that is magnifying the problem. Good luck with it. Is this a carbon fiber barrel?

View attachment 1035885 So I'm having a bit of an issue and hopefully you guys can provide some help. I have a new Christenson Arms in 7mm rem mag. I am using nosler brass and 162gr hornady ELD-X's. I had trouble finding my distance to lands using the hornady oal gauge as I was getting a number well below saami max (2.619" w/ comparator). So I used Jim Wheelers stripped bolt method and a fired case with light neck tension to "jam" the bullet into the lands and both methods were very close to each other and gave me a distance to lands of 2.737" using a comparator. During my fireforming process I had the bullets seated to a depth of 2.685" using a bullet comparator and everything worked well. I even stripped the bolt and ran the unfired rounds through the chamber and they fit with no resistance. After fireforming I neck sized my brass and seated the bullets to the same depth and went shooting. I also cleaned the gun very well. The problem is that when running the bolt forward I can feel resistance as the bullet enters the throat and the bolt is stiff to lock down. When I would try to unchamber the unfired round the bolt would lift with some resistance but I had to bang on it to get it to move rearward and there is scuffing on one side of my bullet near the case mouth (see picture). The rounds shot well and showed no pressure signs and the fired cases ejected like normal. I got home and took the firing pin and ejectors out of my bolt and ran one of the now twice fired cases into the chamber and the bolt closed with little to no resistance so I think my cases are sized properly. I saved one of the problem unfired rounds and started incrementally seating the bullet deeper but was still getting scuff marks even down to a length with comparator of 2.610". It didn't matter how the case was oriented, the scuff mark was always in the same place. I bumped the shoulder back using a Redding body die and same issue. I tried seating the bullet with a rcbs gold metal match die to a depth of 2.685"...same issue. I'm really scratching my head on this one. The rounds worked well on their first firing but not on the second but the cases chamber easily.

I've experienced this issue before. If you have a neck micrometer or tube micrometer check the neck in four places around. I had cases that were 5 thousands thicker on one side. Neck turning the brass eliminated the problem. New brass or factory ammo is undersized to fit all chambers. That is why you didn't have the problem before fire forming. Also when this undersized brass flows forward when fire forming, as it will to fill the chamber, it will thicken the neck and shoulder area. You may also have a chamber dimension issue that is magnifying this. Neck turn and if you still have the problem try working through it with the manufacturer. Is this a carbon fiber barrel?

 

[rhovee]

I had something similar happen in my rifle. It was carbon build up in the neck throat area. When I removed the bore guide and scrubbed down the neck with a stiff brush and bore tech eliminator it came out. Sounds like you might have a carbon ring. I know I am .060 off the lands but after about 100 rounds I feel resistance while closing the bolt. Tight neck and dirty powder will do it. Did you check I fired round neck compared to your loaded ammo to see what your clearance is? I would clean the neck area very well along with where the lands start and see if it’s still there.

 

[Zero333]

If I read correctly....

It's hard to chamber and eject the cartridge ? BUT... With stripped bolt the cartridge feeds and ejects normally ?

Sounds like the ejector spring/plunger could be the problem ?