issue with Berger 105 hybrids and N150

[Deleted old_dood]

A thread on seating into, touching, or off the lands (specifically in .223) on another forum brought to my attention that three of the most commonly seen chamber reamers for service rifle cut necks to 0.2240" dia., exactly the same as that of the bullets being used.

The specific post engendered my questioning how a bullet seated off the lands could get stuck when chambered if the round were subsequently extracted without being fired. The answering post gave a chart presenting eight reamer profile dimensions. The other five had scant (0.0002") clearance up to vast (0.0030") so I'm wondering if maybe your new barrels throat is similarly 'no clearance' at 0.2430" while random Bergers may be 0.243x?

thank you very much. your post leads me to believe what I've noticed is not really a defect in the chamber, just characteristic of the reamer used. Can it be the cause of the problem though? I never had this happen to me with the original factory barrel.

 

[spclark]

Can it be the cause of the problem though?

I think it could be contributing to what you're seeing, yes. Theoretically, if your chamber features a throat that's tighter than that of your factory barrel, any variation to the plus side on bullet diameter will show higher pressures.

Since the 6XC was introduced over a decade ago there have been several iterations on specs for reamers with that cartridge designation on them. David Tubb developed and named the cartridge, I think working with Hugh Henriksen for reamer design & production.

Without having accurate chamber casts made from both chambers, and maybe reamer prints to compare them to, just how your two chambers differ from one another is gonna be tricky to nail down.

 

[Deleted old_dood]

Can it be the cause of the problem though?

I think it could be contributing to what you're seeing, yes. Theoretically, if your chamber features a throat that's tighter than that of your factory barrel, any variation to the plus side on bullet diameter will show higher pressures.

Since the 6XC was introduced over a decade ago there have been several iterations on specs for reamers with that cartridge designation on them. David Tubb developed and named the cartridge, I think working with Hugh Henriksen for reamer design & production.

Without having accurate chamber casts made from both chambers, and maybe reamer prints to compare them to, just how your two chambers differ from one another is gonna be tricky to nail down.

I just mic'd a sampling of the three different 105's I have. every one of the Bergers measured .2434 or ,2435. The Hornady's slightly less but still above .243. Every one of the Noslers measured exactly .243. I'll try out similar loads with the Noslers next time. I do plan on calling Criterion tomorrow to see what they think.

 

[spclark]

Let us know what you learn from them!

I have a bunch of Berger 105 VLDS & Hybrids, some Nosler's too but I'm out of town thru next weekend so mic'ing mine'll have to wait, as will casting my one remaining 6XC chamber.

Had Lapua's but sold 'em a couple years back; rumor is they're consistent but measure less in dia. than other brands.

 

[Old Navy]

Not with Norma 150 but with Varget, I had severe carbon fouling built up. It took lots of C4 Carbon cleaner and Isso bore paste to get the barrel back to working at a reasonable pressure.

+1 but mine was with #15. Later! Frank

 

[Deleted old_dood]

Let us know what you learn from them!

I have a bunch of Berger 105 VLDS & Hybrids, some Nosler's too but I'm out of town thru next weekend so mic'ing mine'll have to wait, as will casting my one remaining 6XC chamber.

Had Lapua's but sold 'em a couple years back; rumor is they're consistent but measure less in dia. than other brands.

the rep from Criterion contacted me on Savage Shooters because I posted about my problem there too. He told me to contact Jim Briggs at Northland who I bought the barrel from. I asked about the throat diameter and he said it was .2437 so I set my mic to that and every bullet easily passed through, nothing like what I'm feeling when measuring OAL. He told me to contact the owner of Criterion who, after discussion, said I should send the barrel in for a chamber cast. I'll let you know what transpires.

 

[Deleted old_dood]

Re: issue with Berger 105 hybrids and N150 - still having problems

well. I got my barrel back from Criterion about a month ago. They informed me there was nothing wrong with the chamber. As per their usual practice with a returned barrel, they re-lapped and re-crowned it. I still have the same problem shooting 105's and N150 at what would be considered less than a maximum load, 29.6 g. the problem is intermittant over pressure signs manifesting in very heavy bolt lift, perhaps one out of between 5 and 10. Yesterday at the range I had 10 loaded with N150 and had the symptom with 3. I loaded 12 with 29g IMR 4895 and had it happen with a few of those too. All of these were with a .024" jump.

The rest of the day I shot 25 88g Berger FB, 30.1g Varget, one hole groups at 200 with no issues whatsoever. I also shot a seating depth test of about 60 90g Berger BT target, 30.1 g Varget. Again, no issues.

I intend to shoot the rest of the 105's/N150 I have at near minimum loads.

 

[Terry]

Temperature change?

 

[Deleted old_dood]

Temperature change?

no, all of this transpired since April/May. Our summer here in NY has not been hot at all. For a while I thought it might be an issue with the lot of N150 I have. But then, how to explain the same thing with the 4895? The charge of IMR 4895 was close to the maximum but under it.

 

[dmoran]

Couple things:

1 - how much of the 105-Hybrids is in the case? And what is the free-bore?
Could be a load density issue.

2 - how much are you resizing the brass? Describe the dies and method your using...
Could be a resizing issue.

 

[Deleted old_dood]

Couple things:

1 - how much of the 105-Hybrids is in the case? And what is the free-bore?
Could be a load density issue.

2 - how much are you resizing the brass? Describe the dies and method your using...
Could be a resizing issue.

I don't have a loaded round available but I'd say between 1/8" and 3/16" of the bearing surface is in the neck. I don't know what the freebore is but since it's an aftermarket, prefit barrel, It's probably SAAMI spec for 6mmbr norma.

I use Redding type S FL die, bumping between .002 and .003, bushing selected for .002 neck tension. This is the same method I use for all loads/bullets.

the loads are definitely too hot. when I have it happen, if I try to rechamber the just fired case, I get heavy resistance.

 

[dmoran]

I don't have a loaded round available but I'd say between 1/8" and 3/16" of the bearing surface is in the neck. I don't know what the freebore is but since it's an aftermarket, prefit barrel, It's probably SAAMI spec for 6mmbr norma.

If you have the OAL wrote down in your records, you can figure out very easily:
- Measure a bullet length and subtract it from the OAL and the case/neck length.
And/or make a dummy round up from your records and compare a bullet to it for position.

 

[Deleted old_dood]

I don't have a loaded round available but I'd say between 1/8" and 3/16" of the bearing surface is in the neck. I don't know what the freebore is but since it's an aftermarket, prefit barrel, It's probably SAAMI spec for 6mmbr norma.

If you have the OAL wrote down in your records, you can figure out very easily:
- Measure a bullet length and subtract it from the OAL and the case/neck length.
And/or make a dummy round up from your records and compare a bullet to it for position.

I don't have the OAL written down. I use the Hornady comparator inserts to measure base to ogive. that's what I have recorded. I'll load a dummy round and get back to you.

 

[cocopuff]

sounds like the same issue I was haveing with my 6br....Only I was using H322 and went to H 4895 and got the same results,,But I was not getting any
marks on the brass from the bolt face.Just stiff bolt lift....And cases would not rechamber as you say...I narrowed mine down to a carbon ring..I got so I could feel it when chambering a round...I removed mine with black powder solvent and a nylon brush chucked in a drill...Took several patchs to get it all out and fianlly the patchs were cleaner.....Alot of powder are noted for this...I think if you work at it you will get it out of there...Good luck

Or you can try a small base body die and see it that works.....I did and it helped some..But the carbon was the big part..Most shooters never pay any attention to it or even think of it...Clean the barrel and thats it....

 

[Deleted old_dood]

I don't have a loaded round available but I'd say between 1/8" and 3/16" of the bearing surface is in the neck. I don't know what the freebore is but since it's an aftermarket, prefit barrel, It's probably SAAMI spec for 6mmbr norma.

If you have the OAL wrote down in your records, you can figure out very easily:
- Measure a bullet length and subtract it from the OAL and the case/neck length.
And/or make a dummy round up from your records and compare a bullet to it for position.

.351" in the neck. of that, about .200 is bearing surface.

 

[Deleted old_dood]

sounds like the same issue I was haveing with my 6br....Only I was using H322 and went to H 4895 and got the same results,,But I was not getting any
marks on the brass from the bolt face.Just stiff bolt lift....And cases would not rechamber as you say...I narrowed mine down to a carbon ring..I got so I could feel it when chambering a round...I removed mine with black powder solvent and a nylon brush chucked in a drill...Took several patchs to get it all out and fianlly the patchs were cleaner.....Alot of powder are noted for this...I think if you work at it you will get it out of there...Good luck

Or you can try a small base body die and see it that works.....I did and it helped some..But the carbon was the big part..Most shooters never pay any attention to it or even think of it...Clean the barrel and thats it....

I plan on working on that. thanks. I've got some Boretech C4 and Iosso I'll be using.

 

[dmoran]

.351" in the neck. of that, about .200 is bearing surface.

It don't really matter how much of the bullet is the neck, what matters is how much of the total bullet is in the case.
Example question: - if your bullets are 1.290" long, how much is out?
Example answer: - 0.790" is out = 0.500" In (minus the neck (.350") and you have .150" behind the junction).

 

[Deleted old_dood]

.351" in the neck. of that, about .200 is bearing surface.

It don't really matter how much of the bullet is the neck, what matters is how much of the total bullet is in the case.
Example question: - if your bullets are 1.290" long, how much is out?
Example answer: - 0.790" is out = 0.500" In (minus the neck (.350") and you have .150" behind the junction).

I misstated that. It's .351 in the case.

 

[XTR]

Any chance that you have lube on the cases, or that they are wet when fired? That will give you bolt thrust and show ejector marks with just about any load.

 

[Deleted old_dood]

Any chance that you have lube on the cases, or that they are wet when fired? That will give you bolt thrust and show ejector marks with just about any load.

No, I wipe the lube off the cases before firing. What I've done so far: wrapped a patch around a brush, saturated with Boretech C4 and spun with a drill in the throat area. Did the same thing with Iosso on the patch. Iosso on nylon brush and short stroked.

On Saturday I'll shoot some loaded with 29.6g but beforehand do a ladder test starting at the recommended minimum of 27.5.