Measured COAL is more than manual states

[megastink]

Working up a load for the first time for my 7 Rem Mag with 175gr Nosler ABLR's. I use my Hornady OAL gauge, Hornady Modified case, and a bullet to find my lands. It's 3.419". The manual says COAL of 3.29". This is a McGowan barrel I bought used off of someone a year ago.

What should I check here? Headspace? Did I happen to buy a used barrel that's throated for longer bullets? Should I load some up to 3.419" or a few thou off and send it?

I appreciate all the help in advance!

 

[26Reload]

Sounds fishy....i would start as normal..short..then work up....

 

[sedancowboy]

I usually start at about .020 off so I would load some to 3.400 and try that. If I were doing a seating depth test I would load back in .025 increments to 3.300 and see what happens.

 

[cdherman]

Working up a load for the first time for my 7 Rem Mag with 175gr Nosler ABLR's. I use my Hornady OAL gauge, Hornady Modified case, and a bullet to find my lands. It's 3.419". The manual says COAL of 3.29". This is a McGowan barrel I bought used off of someone a year ago.

What should I check here? Headspace? Did I happen to buy a used barrel that's throated for longer bullets? Should I load some up to 3.419" or a few thou off and send it?

I appreciate all the help in advance!

Happens all the time. Probably a long throat.

2 questions:

Can you still get the rounds at say 3.400" COAL to function in the magazine?
How much of the shank of the bullet (not counting the boat tail) is in the neck of cartridge? Usually, you like to aim for around the same as the bullet diameter, so .284" of shank in the neck.

You can fudge the shank number a little, and you can use the gun as a single shot too, but I'd advise against both.

Book COAL is just a number dreamed up when the cartridge is originally taken through SAAMI. Probably the heaviest bullet anyone imagined in a 7 RM when it started was 160 grain, maybe less. But someone might have had your 7 RM barrel throated for longer heavier bullets.

Potentially, you may be in luck actually. I screwed together a 7 RM with Proof CF prefit for my Savage and was pleasantly pleased to find it had enough throat get the 195 EOL seated pretty long. They look pretty weird actually, but they function in my Savage LA

 

[Bob Wright]

Did you account for the Guage length of 1"?
My CBTO measures 2.700 on 7RM.
Make sure you re-zero calipers with guage...

 

[cajun]

Not unusual for a factory barrel. But for a custom barrel kind of unless it was throated long for say a Berger. Regardless find out what your mag box length is. That may be the limiting factor. See where your at. When you say you bought this barrel used was it checked for head space when the barrel was installed. I would assume so.

 

[med358-boise]

Book COAL is irrelevant. What is relevant (but not absolute) is bullet mfgs guidelines for distance from the lands and will it fit in the magazine.

 

[Ckleeves]

Nothing unusual about it. The book COAL is probably based off the shortest Sammi chamber they could find to make sure nobody who follows book COAL can jam a bullet.

ABLR's like to jump ime, so start at least 20 thou off and work further off to see what it likes. That COAL they give @ 112 thou off may actually be pretty decent. The book COAL is rarely if ever going to be touching in a "standard" chamber.

 

[cdherman]

Did you account for the Guage length of 1"?
My CBTO measures 2.700 on 7RM.
Make sure you re-zero calipers with guage...

He's quoting COAL and not CBTO. Would not surprise me in the ABLR bullet to have .70" long tip beyond the ogive.

 

[QuietTexan]

Very common in older calibers with newer bullets.

Seems like Nosler will list shorter-than-SAAMI COLS but never longer, so their short bullets they'll give you a good starting points but once you see the max that'll most likely be what's listed for all heavier bullets in their data.

I follow what my chamber tells me like how you measured. The times I don't usually involve very short varmint bullets that I'm more worried about keeping enough bullet in the neck to not have them pop out accidentally. If you have a half-neck length worth of bearing surface or more in the neck, should be A-Ok.

 

[bomberodevil]

Did you account for the Guage length of 1"?
My CBTO measures 2.700 on 7RM.
Make sure you re-zero calipers with guage...

That's the first thing I thought about.

 

[Bob Wright]

He's quoting COAL and not CBTO. Would not surprise me in the ABLR bullet to have .70" long tip beyond the ogive.

CBTO 3.419 at lands on his measurements. That's .719 different than my 7RM. Something is waaay off.

 

[megastink]

CBTO 3.419 at lands on his measurements. That's .719 different than my 7RM. Something is waaay off.

No sir, the measurement was base to tip. Base to ogive was around 2.770 I think. I'd have to verify.

 

[LaHunter]

Working up a load for the first time for my 7 Rem Mag with 175gr Nosler ABLR's. I use my Hornady OAL gauge, Hornady Modified case, and a bullet to find my lands. It's 3.419". The manual says COAL of 3.29". This is a McGowan barrel I bought used off of someone a year ago.

What should I check here? Headspace? Did I happen to buy a used barrel that's throated for longer bullets? Should I load some up to 3.419" or a few thou off and send it?

I appreciate all the help in advance!

Sounds like you are getting CBTO (cartridge base to igive) with COAL (cartridge over all length). CBTO is useful to the reloader for finding the land, bullet jump / jam, etc. COAL is pretty much only useful for knowing if your rounds will fit in your magazine.