chamber problem?

[liseo]

Hi guys


I just chambered a 308 Winchester Bartlein barrel for one Remington 700 friend rifle. But something strange happens. When shooting, there is a very well-defined soot mark, and I can't find an explanation for it.

The reamer used is a PTG Palma 1995, used only for the final profile, as I do the prebore. I've made several rifles with this reamer, without any problem. The owner suggested that there was a step on the neck, but I see no reason for that to happen, and no mark is visible that suggests a step, other than soot.
May a long barrel (28 inches" ) and powder in the fast side allow the case spring back in the neck and soot go between chamber wall and neck?

Any suggestion is welcome, because I am lost

Sorry for mistakes, its not my mother tongue.

 

[wwbrown]

A good use for a bore scope a close up look at the neck is probably called for. In general I think bore scopes are used for the wrong purpose, looking at the condition of the bore in an attempt to guess whether it will shoot or not.

I think bore scopes are great for evaluating cleaning schemes, quality of chamber work and checking throat condition. Using them on factory barrels before shooting them will just upset you and there is usually no way of telling whether they will shoot or not.

 

[SBLH10]

Never seen or noticed anything like it before looks & sounds more like a ammo problem /reloading problem than a chamber problem. Sizing die setup /bullet seating depth in the brass.
Chet

 

[DaveTooley]

Soot being there is not a mystery. The uniform line is something you don't see often.
You could be correct with the 28" barrel. Pressures would be falling rapidly. I would shoot it and keep an eye on it.

 

[spitfire_er]

I would question reloading/brass/ammo. I can see no step in the reflection of any of those cases which would indicate a chamber issue.

 

[gambleone]

What brand of brass? Is it new? I'd try another brand with same load & see what happens.

 

[liseo]

What brand of brass? Is it new? I'd try another brand with same load & see what happens.

Lapua brass. But this happens even with Magtech factory ammo

 

[gambleone]

I'd try a different powder then.

 

[Bc'z]

Soot being there is not a mystery. The uniform line is something you don't see often.
You could be correct with the 28" barrel. Pressures would be falling rapidly. I would shoot it and keep an eye on it.

The straight carbon ring has me wondering about neck clearance.
Thinking out loud.....
Are Palma chambers tighter?
Can a bullet drop freely into the case?
I just went through a preasure issue with a PTG match reamer used on my 06' , lapua brass was over preasure due to clearance, whereas RP shot fine.

Hi guys


I just chambered a 308 Winchester Bartlein barrel for one Remington 700 friend rifle. But something strange happens. When shooting, there is a very well-defined soot mark, and I can't find an explanation for it.

The reamer used is a PTG Palma 1995, used only for the final profile, as I do the prebore. I've made several rifles with this reamer, without any problem. The owner suggested that there was a step on the neck, but I see no reason for that to happen, and no mark is visible that suggests a step, other than soot.
May a long barrel (28 inches" ) and powder in the fast side allow the case spring back in the neck and soot go between chamber wall and neck?

Any suggestion is welcome, because I am lost

Sorry for mistakes, its not my mother tongue.

I'm relatively new to this but,
Measure neck of loaded round, and compare to fired, try dropping a bullet into fired case.
Curiosity

 

[DaveTooley]

I thought about that also

 

[liseo]

Fired case measure .343" at neck. Lapua brass with seated SMK 168 grains measure .337" in this lot

 

[Bc'z]

Fired case measure .343" at neck. Lapua brass with seated SMK 168 grains measure .337" in this lot

Puzzling, .343" fired neck is large compared to my .340" neck, you should have plenty of clearance.
Does a bullet fall freely into fired case?

 

[SBLH10]

What is the length of the free bore/Lead? Are the bullets jumping, touching or jam? Measure where the Boat Tail starts on a seated loaded round.
Chet

 

[Ggmac]

The soot line appears to be slightly different in length on the neck . This is interesting, is the base ( parallel sides of bullet ) seated at the line closest to the shoulder ? If so id think the brass expands behind the bullet before release. Thats just a wild guess .

 

[Straightshooter1]

Lapua brass. But this happens even with Magtech factory ammo

The fact that this happens with factory ammo suggests to me there's something about the chamber that's at work here. I'd start with inspection with a bore scope if nothing can be seen, then get measurements of the throat to see if it's actually cut per your reamer.

 

[liseo]

As soon I receive back the rifle, will report what I found.

Thanks to all

 

[Bc'z]

As soon I receive back the rifle, will report what I found.

Thanks to all

For shitz n grinz could you measure the flutes on neck portion of the reamer?

 

[Oleg S]

How many times this brass was fired and resized?

 

[gambleone]

If it was case neck spring back with fast powder & 28" barrel like you stated, why would you get a perfect line of soot from case mouth? Wouldn't you think the soot line wouldn't be in such a straight line? This perfect soot line makes you think of chamber neck. Brain teaser for sure.

 

[tobnpr]

^^^
Yep, borescope- or chamber cast if OP doesn't have a scope.
I really don't see how it could be. He's cut multiple, problem-free chambers with the same reamer. It's a form cutter, can't do anything but cut the same every time.