WARNING: NORMA "Whitetail" 6.5 Creedmoor 140gr. SP ammunition- Overpressure!

[squarefour]

So I had a similar problem as the OP with my 6.5CR AR10, and it turned out to be because my bullets were jammed too far into the lands, even at 2.80" COAL. For some reason AR barrels have crazy shallow throats. With 123 FMJs my COAL to lands is 2.55". Unfortunately I didn't figure this out until I got a second barrel with exactly the same throat. I have a 6.5CR Tikka barrel and the throat is visibly deeper with a borescope.

 

[Jon Bischof]

So I had a similar problem as the OP with my 6.5CR AR10, and it turned out to be because my bullets were jammed too far into the lands, even at 2.80" COAL. For some reason AR barrels have crazy shallow throats. With 123 FMJs my COAL to lands is 2.55". Unfortunately I didn't figure this out until I got a second barrel with exactly the same throat. I have a 6.5CR Tikka barrel and the throat is visibly deeper with a borescope.

So are the signs of overpressure (brass flow, etc) due to the bullet being jammed into the lands, OR, is the cartridge itself loaded to overpressure?

 

[bert2368]

If any who have the ammunition and measuring tools on hand could measure & post, it would be interesting to know?

A: Base to ogive measurement of a few of your NORMA Whitetail cartridges, including lot number(s) for reference.

B: Bolt face to engagement with rifling measurement of your rifle.

Ideally, base to ogive SHOULD be a bit shorter than bolt face to rifling! Telescoping the bullet back into an already hot load can't be helping matters if our AR throats are all too short.

I've read elsewhere that the "Hornady Black" 140gr. load/American Gunner 140gr. load were developed for AR shooters in response to similar issues caused by other 140gr. and heavier bullet Hornady match loads run in 6.5 CM ARs contacting rifling when chambered, also reports of Hornady telling people who contacted them about high pressure signs in 6.5 CM ARs NOT to use some types of their match ammo in ARs, but run the Hornady Black instead.

Also: of all the types of factory ammunition I've fired so far in my rifle, HORNADY BLACK 140 FMJ WAS THE MOST ACCURATE. Unfortunately Hornady quit making the 6.5 CM "Black" & I've fired all I had of this ammo, I can't measure & compare. Does anyone have a few rounds left to check base to ogive?

I have never ejected a chambered round of this NORMA 140gr. Whitetail ammunition from my rifle without firing it and inspected the bullet for "ring around the ogive". When I get back after this weekend, I'll be taking such measurements & trying to cycle a round through without firing & inspecting for any marks left on bullet.

 

[Jon Bischof]

Thanks, Bert. Every bit of evidence helps. Eventually, we will get enough pieces of the puzzle to find out the cause of the problem.

 

[nhhunter]

I tried a box through my tikka definitely hot as hell primers were cratered with ejector swipes and shot like ****.

 

[shinbone]

I shot six more of these Norma Whitetail rounds today, this time with my LabRadar for measuring muzzle velocity. As a reminder and per my Post #66, three of the first twelve rounds from this box of Norma ammo showed signs of over-pressure. The measured velocities of today's six shots were:

2652 fps
2662
2666
2687
2657
2694

This out of a 22" barrel.

I am new to the 6.5CM, but these velocities look normal, to me. None of these particular six rounds showed any signs of any over-pressure.

 

[bert2368]

. .

 

[UncleDano]

I shot six more of these Norma Whitetail rounds today, this time with my LabRadar for measuring muzzle velocity. As a reminder and per my Post #66 , three of the first twelve rounds from this box of Norma ammo showed signs of over-pressure. The measured velocities of today's six were:

2652 fps
2662
2666
2687
2657
2694

I am new to the 6.5CM, but these velocities look normal, to me. None of these particular six rounds showed any signs of any over-pressure.

Velocity printed on the box is 2756 fps. But we have no idea what barrel length used.

 

[UncleDano]

I have 10 boxes of this same lot number I recently purchased through the Norma website sale -
No. 20166492, 0030343-06

Looking for more conclusive testing, now.

Problem lots originally reported by OP are 0030343-02 and 0030343-04.

I have fired rounds from the LOT# 0030342-06, with only the usual slight cratering, but no real signs of over pressure like flattened primers & ejector marks. Grouped nicely!

 

[UncleDano]

So I had a similar problem as the OP with my 6.5CR AR10, and it turned out to be because my bullets were jammed too far into the lands, even at 2.80" COAL. For some reason AR barrels have crazy shallow throats. With 123 FMJs my COAL to lands is 2.55". Unfortunately I didn't figure this out until I got a second barrel with exactly the same throat. I have a 6.5CR Tikka barrel and the throat is visibly deeper with a borescope.

This is a very good point.
Those Norma's are 2.750" OAL which is within normal specs., but those SPSP (semi-pointed soft point) have a very long shallow curve or ogive. Posing a possible problem of bullet jammed into the lands on a rifle with a shorter than spec throat. Gun needed to shoot these rounds should have min. of 2.3050" case base to begin of lands"

 

[squarefour]

So are the signs of overpressure (brass flow, etc) due to the bullet being jammed into the lands, OR, is the cartridge itself loaded to overpressure?

In my case, use of anything much over start loads resulted in popped primers.

 

[bert2368]

I spoke with Jake at APF and sent pictures, measurements & a link to this thread today.

They want to send me a new high pressure BCG, apparently their rifles in 6.5CM come with these now.

Nice of them to offer this replacement within an hour of getting my information-

See screen shot below.

I got a high pressure BCG sent to me by member Darryle last weekend (THANKS!!!) will check results of using this in the meantime.

I am still working on checking the measurements of ammo, bolt face to lands & etc., will post details here when I've got it all together.

 

[Jon Bischof]

I spoke with Jake at APF and sent pictures, measurements & a link to this thread today.

They want to send me a new high pressure BCG, apparently their rifles in 6.5CM come with these now.

Nice of them to offer this replacement within an hour of getting my information-

See screen shot below.

I got a high pressure BCG sent to me by member Darryle last weekend (THANKS!!!) will check results of using this in the meantime.

I am still working on checking the measurements of ammo, bolt face to lands & etc., will post details here when I've got it all together.

View attachment 312244

That's customer service!

 

[Darryle]

That's customer service!

Actually, they had a known issue, they should have sent him a new HP bolt and a return label first, That would have been true customer service, especially after Bert spent $1500 for the rifle.