.337" 30-06 chamber

[Steve Donlon]

Is there any benefit to having a .337" chamber instead of a .340" 30-06 chamber. The reason I ask is I have a rifle with a .337" chamber and my bullets loaded in Lapua brass measure .337". They will not even chamber in this rifle. If there is a reason to have this tight of chamber? It must have some benefit for non- lapua brass other than working it less. Or is that the only good thing about a tight chamber? I do notice the brass has no carbon on the necks or anywhere else. Would this be more accurate having a tight chamber?

 

[243winxb]

https://saami.org/technical-information/cartridge-chamber-drawings/ The .337" would require outside neck turning. A tight neck chamber would not work the brass aa much when sizing with a bushing die or custom die.

Should help accuracy? Depends on what it will be used for.

 

[ireload2]

Try using WW brass or try making brass from .270 brass.
You can test the thinner necks and see what if there is any impact on accuracy.

 

[Steve Donlon]

The reason I ask is Hornady and Nosler brass fit fine but I would have to turn the necks to shoot Lapua brass in this rifle with no benefit. It's just a heavy barrel target rifle no competition intended. I have never had a 30-06 with a .337" chamber and know it must be better in some way or why offer it. Why use a .337" chamber to begin with? It seems they would just make them all .340". So just looking for some answers Thanks for any input. Sorry 243winxb and Ireload2 for not wording it better. If the bores are the same why not the chambers? I understand the different free bores for different bullets but not different chamber necks.

 

[johnfred1965]

What do the Hornady and Nosler brass measure with your bullet in place? It isn't just a question of if it will fit in the chamber, but if it will cleanly let go of the bullet when fired. I would say for that caliber in a target rifle, 3 to 4 thousandths clearance would be good. Not only is this an accuracy issue, but if the chamber is too tight for your cartridges, pressures will spike dangerously.

If you purchased this rifle secondhand, the original owner's intent was probably to neck turn his brass to a uniform diameter for a cosistent, close, but not tight, fit.

 

[243winxb]

If the bores are the same why not the chambers?

The tight neck may help center the round in the chamber. I have no tight necks.

In a 243 factory chamber, i found sizing 1/2 of the neck with a bushing helps accuracy. It centers the round in the chamber, after a few firings.
If i size almost to the shoulder, accuracy is not as good on target.

 

[Steve Donlon]

What do the Hornady and Nosler brass measure with your bullet in place? It isn't just a question of if it will fit in the chamber, but if it will cleanly let go of the bullet when fired. I would say for that caliber in a target rifle, 3 to 4 thousandths clearance would be good. Not only is this an accuracy issue, but if the chamber is too tight for your cartridges, pressures will spike dangerously.

If you purchased this rifle secondhand, the original owner's intent was probably to neck turn his brass to a uniform diameter for a cosistent, close, but not tight, fit.

I have .333' - .332.5" clearance on loaded ammo. I guess every thing is good. Thanks for the input. I was told it was a .340" chamber so I was sort of taken aback when I realized it was .337".

 

[Bart B.]

The tight neck may help center the round in the chamber.

This happens only when the case and chamber neck are exactly the same diameter. Not a good situation.

Once one learns how rimless bottleneck cases fit the chamber when the primer fires, they'll know a straight 270 Win cartridge will have its neck perfectly positioned dead center in the larger 30-06 chamber neck if it was then fired. Same with a 25-06 cartridge.

It's called the "Dixie Cup syndrome."

 

[Ggmac]

I would suggest some in depth reading and find a mentor to help in your quest for accuracy in both reloading and shooting .
What type of rifle and who's barrel is on it ? If it's over 10 yrs old and in the states I'm pretty sure it would have been made for commercial brass and possible competition.

 

[Steve Donlon]

I would suggest some in depth reading and find a mentor to help in your quest for accuracy in both reloading and shooting .
What type of rifle and who's barrel is on it ? If it's over 10 yrs old and in the states I'm pretty sure it would have been made for commercial brass and possible competition.

It's new with a 30" straight taper Pac-Nor 3 groove barrel and Manners T4FA stock with a Serengeti Chamber that said on the box it was a .340 neck but was not. It took over a year to build due to unforeseen events. It was PTG where the reamer came from and now that the rifle is together I don't want to recut the chamber if the .337" neck will be okay. My Remington 700 Long Range 30-06 will accept Lupua brass so I'm not worried where to use that brass. I was not ready for a .337" neck but as long as my other brass will work I will see how it goes before recutting the chamber. It seems that with a .340" neck, I would need to always use Lapua brass for the best accuracy. So maybe the .337" neck will be a good thing. Thanks for all the comments.

 

[joshb]

Your .337 neck is for turned brass. I like at least 3 thou clearance for expansion and bullet release, so I'd turn the Lapua brass to .333-.334 loaded round. Turning your brass makes it more consistent in regards to neck tension. You're shaving off areas where the brass may be thicker and making the neck one "consistent " thickness. Many competitors agree that it helps with accuracy.

 

[Ggmac]

It's new with a 30" straight taper Pac-Nor 3 groove barrel and Manners T4FA stock with a Serengeti Chamber that said on the box it was a .340 neck but was not. It took over a year to build due to unforeseen events. It was PTG where the reamer came from and now that the rifle is together I don't want to recut the chamber if the .337" neck will be okay. My Remington 700 Long Range 30-06 will accept Lupua brass so I'm not worried where to use that brass. I was not ready for a .337" neck but as long as my other brass will work I will see how it goes before recutting the chamber. It seems that with a .340" neck, I would need to always use Lapua brass for the best accuracy. So maybe the .337" neck will be a good thing. Thanks for all the comments.

Sounds like you got a nice gun . I'd neck turn the Lapua just for that gun .
What are you using to measure the neck with ? Do you still have the reamer , if so I'd measure that .
Good luck and keep us posted on the results

 

[Steve Donlon]

Sounds like you got a nice gun . I'd neck turn the Lapua just for that gun .
What are you using to measure the neck with ? Do you still have the reamer , if so I'd measure that .
Good luck and keep us posted on the results

I just measured the fired brass and it was .337" and my Remington is .340" The guy that did the work does have the reamer. It seems that if I did not turn the Lapua brass the Hornady and Nosler would fit good but for the best accuracy I need to turn Lapua brass. I guess it comes down to how accurate do I want to shoot relative to how well I can shoot. Thanks for the advice.

 

[Steve Donlon]

Your .337 neck is for turned brass. I like at least 3 thou clearance for expansion and bullet release, so I'd turn the Lapua brass to .333-.334 loaded round. Turning your brass makes it more consistent in regards to neck tension. You're shaving off areas where the brass may be thicker and making the neck one "consistent " thickness. Many competitors agree that it helps with accuracy.

That will take about .004 off my brass. From .016 to.012 that is okay to do without compromising the brass? I will try it and see what happens. Thanks for all the help.

 

[johnfred1965]

That will take about .004 off my brass. From .016 to.012 that is okay to do without compromising the brass? I will try it and see what happens. Thanks for all the help.

I don't know German Salazar, but I will drop his name as the Guru of the 30-06. He always wrote that he trimed all his brass to 12 1/2 thousandths for uniformity with everything he had. you will not comprimise the brass. I agree with Ggmac about trimming the Lapua brass for that rifle. Using Lapua as a second choice to Hornady is a bad idea. The 3B's, put your best brass in your best barrel with your best bullets! This will make your other ammo a little sloppy in the Remington LR, but I am sure you will still be happy with the results from that factory barrel.

 

[Steve Donlon]

I don't know German Salazar, but I will drop his name as the Guru of the 30-06. He always wrote that he trimed all his brass to 12 1/2 thousandths for uniformity with everything he had. you will not comprimise the brass. I agree with Ggmac about trimming the Lapua brass for that rifle. Using Lapua as a second choice to Hornady is a bad idea. The 3B's, put your best brass in your best barrel with your best bullets! This will make your other ammo a little sloppy in the Remington LR, but I am sure you will still be happy with the results from that factory barrel.

I understand, your a big help, thanks

 

[M14AMU]

I have that chamber in this rifle and I'd be embarrassed to tell you how well it shoots!!

Beanland06 by Sharps Man, on Flickr

 

[Bart B.]

I guess it comes down to how accurate do I want to shoot relative to how well I can shoot.

The shot group size on paper equals your marksmanship skills plus that of your rifle and ammo quality.

Whatever your own skills are, they'll improve faster if your rifle shoots bullets exactly where it's aimed when fired.

 

[Steve Donlon]

Looks great! Well I ordered a Sinclair Premium neck turning tool for my 30-06 Lapua brass hope to have the same problem. Not sure about weather I need to order a 40 degree cutting blade to replace the 30 degree blade it comes with. Also, after going through the mandrel, do I need to size the neck again for proper neck tension when done turning the necks?

Beanland06 by Sharps Man, on Flickr[/QUOTE]

 

[Steve Donlon]

The shot group size on paper equals your marksmanship skills plus that of your rifle and ammo quality.

Whatever your own skills are, they'll improve faster if your rifle shoots bullets exactly where it's aimed when fired.

Your right about that. It's a great deal of motivation. Thanks