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7mm RSAUM Reamer Questions
Posted: Fri Apr 03, 2020 12:03 pm
by DanMac
Good afternoon forum members,
Could I please get some technical advice?
I have attached the reamer print from Manson Reamers for a product which is available on the shelf.
I'm planning to purchase a reamer suitable for the 183 SMK's.
Does anyone have a reamer print or details of the dimensions they use on a chamber that works well with these projectiles?
Manson have offered to return the freebore dimension to Zero and supply me with a 7mm throating reamer to adjust the freebore length as I see fit.
I'm 100% not sure if a 0.090" free bore combined with a 1 degree lead angle is adequate for optimal projectile seating depth.
Any help is appreciated!
Cheers
Dan
Re: 7mm RSAUM Reamer Questions
Posted: Fri Apr 03, 2020 12:21 pm
by RDavies
You are right, most who are shooting these 183gn projectiles would be using from .200-.220" freebore. They are also tending to move away from the very long taper 1 degree throats as well, with 2 degrees or more being more popular
Re: 7mm RSAUM Reamer Questions
Posted: Fri Apr 03, 2020 4:22 pm
by KHGS
DanMac wrote:Good afternoon forum members,
Could I please get some technical advice?
I have attached the reamer print from Manson Reamers for a product which is available on the shelf.
I'm planning to purchase a reamer suitable for the 183 SMK's.
Does anyone have a reamer print or details of the dimensions they use on a chamber that works well with these projectiles?
Manson have offered to return the freebore dimension to Zero and supply me with a 7mm throating reamer to adjust the freebore length as I see fit.
I'm 100% not sure if a 0.090" free bore combined with a 1 degree lead angle is adequate for optimal projectile seating depth.
Any help is appreciated!
Cheers
Dan
1 degree throat angles are not desirable for secant ogive bullets. 2 degree 30 minute to 3 degree 30 minute angles are more desirable for these bullets, these angles will still work just fine with tangental ogive bullets as well.
Keith H.
Re: 7mm RSAUM Reamer Questions
Posted: Fri Apr 03, 2020 8:24 pm
by Matt P
The minimum you can get away with 183's SMK's is 0.170" with a 1.5 degree lead. The problem with the short FB is if the barrel doesn't like 183's it's too short for 180 Bergers, which really need around the 0.220" for the VLD's and around 0.200" for the Hybrid.
Matt P
Re: 7mm RSAUM Reamer Questions
Posted: Fri Apr 03, 2020 8:30 pm
by KHGS
Matt P wrote:The minimum you can get away with 183's SMK's is 0.170" with a 1.5 degree lead. The problem with the short FB is if the barrel doesn't like 183's it's too short for 180 Bergers, which really need around the 0.220" for the VLD's and around 0.200" for the Hybrid.
Matt P
I love long neck cartridges, widens one's bullet choices, even though I tend to favour lighter bullets.
Keith H.
Re: 7mm RSAUM Reamer Questions
Posted: Sat Apr 04, 2020 9:48 am
by DanMac
Matt P wrote:The minimum you can get away with 183's SMK's is 0.170" with a 1.5 degree lead. The problem with the short FB is if the barrel doesn't like 183's it's too short for 180 Bergers, which really need around the 0.220" for the VLD's and around 0.200" for the Hybrid.
Matt P
Great info! Thanks MattP!
I figured the freebore on the SAAMI reamer was a little shallow, most 7mm mag's I've touched and played with are cut .180"+ (7mm Practical, 28 Nolser etc..)
I was also wondering what user thoughts were on the .200" line being opened an extra .001" to accommodate for work hardening and preventing primary extraction "clickers"..
I'll have some time to discuss dimensions with ray Gross from Manson Precision tonight, I just didn't want to get in to a technical conversation with the chap with out some prior knowledge.
Cheers
Dan
Re: 7mm RSAUM Reamer Questions
Posted: Sat Apr 04, 2020 12:06 pm
by Gyro
DanMac wrote:Matt P wrote:The minimum you can get away with 183's SMK's is 0.170" with a 1.5 degree lead. The problem with the short FB is if the barrel doesn't like 183's it's too short for 180 Bergers, which really need around the 0.220" for the VLD's and around 0.200" for the Hybrid.
Matt P
Great info! Thanks MattP!
I figured the freebore on the SAAMI reamer was a little shallow, most 7mm mag's I've touched and played with are cut .180"+ (7mm Practical, 28 Nolser etc..)
I was also wondering what user thoughts were on the .200" line being opened an extra .001" to accommodate for work hardening and preventing primary extraction "clickers"..
I'll have some time to discuss dimensions with ray Gross from Manson Precision tonight, I just didn't want to get in to a technical conversation with the chap with out some prior knowledge.
Cheers
Dan
I wouldn't worry about opening up the chamber rear as brass just fireforms to whatever size it is. A colleague over here very recently got a 7saum reamer that was POSSIBLY smaller than spec because when he went to FLS the fired case the case rear never touched the sides of his die. Maybe the die or maybe the reamer ?
Most of these numbers are in a sense 'nominal' and need to be managed by the reloader and thier experience/awareness of what's actually going on.
Re: 7mm RSAUM Reamer Questions
Posted: Sat Apr 04, 2020 1:14 pm
by Matt P
Dan
That dia @ the 0.200 is fine and will work with off the shelf dies, my reamers are that and work very well with most batches of Norma brass and off the shelf sizing dies.
The only real change I would make to that print is to lengthen the FB and tighten the neck a little (measured some brass and work out what dia will work, but around the 0.320-321 should work without turning). Some batches of brass have had some rather large variations in the neck once necked down, for a target rifle I would highly recommend lightly turning cases just the even them up.
Now here's where it gets tricky, I'm told that the ADJ brass is quite small at the 0.200 line (as small as 0.546" where as Norma varies from 0.548-0.550) now you can get a reamer ground to suit but as Gyro said the dies don't size the base of the case. The only fix is to then have a custom FLS die made and down the rabbit hole you go !!!!
Matt P
Re: 7mm RSAUM Reamer Questions
Posted: Sat Apr 04, 2020 3:56 pm
by DanMac
Matt P wrote:Dan
That dia @ the 0.200 is fine and will work with off the shelf dies, my reamers are that and work very well with most batches of Norma brass and off the shelf sizing dies.
The only real change I would make to that print is to lengthen the FB and tighten the neck a little (measured some brass and work out what dia will work, but around the 0.320-321 should work without turning). Some batches of brass have had some rather large variations in the neck once necked down, for a target rifle I would highly recommend lightly turning cases just the even them up.
Now here's where it gets tricky, I'm told that the ADJ brass is quite small at the 0.200 line (as small as 0.546" where as Norma varies from 0.548-0.550) now you can get a reamer ground to suit but as Gyro said the dies don't size the base of the case. The only fix is to then have a custom FLS die made and down the rabbit hole you go !!!!
Matt P
Cheers for the additional info Matt P,
I have just purchased myself an IDOD turner from F-Class Products, so the neck turning won't be an issue.
I run Warner Tool FLS dies for my magnum and standard bolt face cartridge. Getting the inserts is a piece of cake, after the initial investment, custom die sleeves and tops are on par with the off the shelf dies as far as cost. I was only asking as one of my good mates said that clickers might be an issue..? I never experienced any issues with my 284Win, which I have been told was also a cartridge that formed a tight .200' line after a few firings..
At the moment I was looking to purchase a off the shelf reamer to get started and learn how the cartridge behaves before getting uber serious with it.
Manson have a couple on the shelf and ready for alteration if needed, I was thinking to get a zero FB reamer and throater to open it up to suit.
I have a production position with JGS, which is 12-14 weeks from now. As soon as my ADG brass arrives I'll have a dummy round in the post to them for a customer reamer for the ADG brass.
I appreciate the assistance gents.
Dan