Rechambering vs new chambering reamers

[dennisinaz]

Is there a different reamer for opening up an existing chamber to a new cartridge as opposed to starting with an unchambered barrel? Reason I ask is a friend has had trouble with a 7mm STW and ordered a reamer which said on it 'for opeing up 7mm Remington Manum' If it is not just a standard 7mmSTW reamer, where would it differ??

Dennis

 

[spclark]

There are 'rough-out' reamers & 'finish' reamers, so I'd have to believe there are also reamers for 'opening up a 7mm Rem Magnum.'

What exactly is the nature of your friend's trouble that he needs a reamer to overcome it?

 

[dennisinaz]

And they would be different from a finish reamer... How??

I don't have either reamer drawing in front of me but unless the 7mm RM won't clean up with an STW reamer and has to be made 'oversize' I can't envision why you would need anything other than a standard SAAMI spec'd reamer.

 

[butchlambert]

Dennis,
I'm a little confused by your post. Does your friend have a 7STW and wants to change it to 7mag? If so it won't work as the 7STW is made from an 8mag necked down and I believe it is just as large if not larger than the 7 mag. The Stw is about .350 longer.
Butch

 

[Eddie Harren]

I've never enc ountered this but it could possibly be a reamer, that is made with a longer pilot portion, to allow the pilot to enter the bore before the body of the reamer contacts the 7 Mag. chamber.

 

[dennisinaz]

No, he has a 7mm rem mag that he wants rechambered to 7mm STW. He has a 7mm STW now with a Lilja barrel. It won't shoot for nothing. Apparently he called Lilja who told him that he needs a special reamer just for opening up 7mm Rem Mag. Dan told him that he has heard of problems if you don't use this special reamer.

I asked my friend if it had a longer pilot portion. He said he didn't know,I wondered this too but thought that it would be a double-edged sword as it would put the pilot way beyond the throat and possibly exacerbate any straightness issues that already existed.

He told me now, that he has has called Dave Kiff who told him that he has to use a bigger reamer that will completely clean up the Remington chamber. I guess if I am understanding this right, that he will now have a very generous chamber rather than a nice tight one??

Anyone ever made this rechamber? Frankly, I think most of his trouble is the action and the fact that he is using a 7 twist, 3-groove that blows all his bullets up.

Dennis

 

[canuck]

I shoot a 1/10 twist in one stw that stabilizes the 168 berger quite nicely,consistantly under 2 inch groups, or better) at 500 yards and the odd 1 3/4 at 750. Why would you even need a 1/7 twist in an stw? Just a guess but I would think with the powder charge of the stw it would chew the bullets up pretty good in a 1/7 twist even if it was a 180 grain bullet.

 

[dennisinaz]

Because apparently, that is the only twist Lilja makes a 3-groove 7mm barrel in. I agree with you completely. I believe Berger even says a 9 twist will work on their 180s- the bullet he wants to use. He ordered a 8 or 9 twist barrel to try again. I was just very puzzled by this notion that you must use a different reamer for a rechamber than for a virgin chamber job.