Hey guys, I am about to order a new custom barrel in 7mm WSM for my long action M70. I want to get it throated long for berger 195gr. I am not sure how to tell the manufacturer what I want. Is that enough? Will they want a specific throat dimension? I have never ordered anything outside of SAAMI spec. I appreciate any help.
7mm WSM long throating
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Varmint Hunter
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The best way is to send a loaded round before the rifle gets chambered/throated.
FWIW - you may want to consider a 7-300WSM or a 7SAUM. Either of these will solve the (no) brass problem that has plagued the 7WSM for a decade. I shot the 7WSM for MANY years and really liked the cartridge but when it was time to rebarrel, I went with a 7PRC and easily found high quality brass for it.
FWIW - you may want to consider a 7-300WSM or a 7SAUM. Either of these will solve the (no) brass problem that has plagued the 7WSM for a decade. I shot the 7WSM for MANY years and really liked the cartridge but when it was time to rebarrel, I went with a 7PRC and easily found high quality brass for it.
I have tons of brass I scored from a small gun shop. I have a SAUM already and I don't get quite the speed I am looking for. I like to shoot obscure cartridges. Thanks for the info.
Varmint Hunter
Well-Known Member
Sounds like you're in good shape. Enjoy your 7WSM, one of the most underrated cartridges of our time. I went through two custom match barrels before I finally made the switch.
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Justice1327
Well-Known Member
Travis at TS Customs has a 7WSM set up for the 195's.
crashlanding
Well-Known Member
7wsm = 1 fine cartridge
I called mcgowans and they told me to send in 3 dummy cartridges. I would love to know what already works for someone though.
Looking back over a decade at the Accurate Shooter website, Dave Kiff was recommending .19 freebore for the 180 Berger VLD's available at the time. I have not seen any specs for the 195. The WSM series was designed to fit in a 2.86" action, but since you will be using a long action, COAL can be whatever you want, which is why McGowans asked for dummy cartridges. My guess is that your COAL will be over 3".
It is useful to ask if they will use a custom reamer or a SAAMI reamer followed by a throating tool. A custom reamer would be better. The freebore of of a precision 7mm cartridge (like the 7mm PRC) is normally something like .2846". The SAAMI chamber is a forcing-cone-only design (1.5° per side), but it starts at .287" dia (+ .002 tolerance), which is considered pretty sloppy today. In other words, if they start with a SAAMI reamer, the bullet will go through the sloppy section before it can get to the tighter added freebore.
Here is a thread that goes over some of the confusing aspects of the SAAMI 7mm WSM chamber design. Even though the SAAMI WSM chamber is technically a "no freebore design", it starts off at .287", so there is a significant distance before the tapered forcing cone reaches the lands:
https://www.longrangehunting.com/threads/does-anyone-have-a-7-wsm-reamer.200416/
It is useful to ask if they will use a custom reamer or a SAAMI reamer followed by a throating tool. A custom reamer would be better. The freebore of of a precision 7mm cartridge (like the 7mm PRC) is normally something like .2846". The SAAMI chamber is a forcing-cone-only design (1.5° per side), but it starts at .287" dia (+ .002 tolerance), which is considered pretty sloppy today. In other words, if they start with a SAAMI reamer, the bullet will go through the sloppy section before it can get to the tighter added freebore.
Here is a thread that goes over some of the confusing aspects of the SAAMI 7mm WSM chamber design. Even though the SAAMI WSM chamber is technically a "no freebore design", it starts off at .287", so there is a significant distance before the tapered forcing cone reaches the lands:
https://www.longrangehunting.com/threads/does-anyone-have-a-7-wsm-reamer.200416/
Love my wsm. I loaded some 195s to 2.98"mag limited…throat was at 3.07" in my SAAMI throated rifle. Was able to get just shy of 2800fps out of a 22" barrel. Guessing a bit longer you may close in on 2900 (where my 175s settled). Sweet round for long range shooting for sure.
MagnumManiac
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Make a dummy round with the heal of the bullet at the neck/shoulder juncture and have it throated accordingly with +.010" on that measurement. Simple.
I went through this, couldn't find anything in 7mm I could get brass for, so I went with 7STW, NEVER looked back, same when I built my 270 Weatherby…
Cheers.
I went through this, couldn't find anything in 7mm I could get brass for, so I went with 7STW, NEVER looked back, same when I built my 270 Weatherby…
Cheers.
As tahoe1305 just noted, a SAAMI chambered 7mm WSM can have an OAL over 3". Working backwards from his and Berger's numbers of a "nose length" of .874", the rifling on his SAAMI started about .096" from the front of a 2.1" case. Some modern high-BC bullets add length to the ogive rather than to the full diameter shank, so they don't necessarily need a long freebore.
In a recent thread, a gunsmith added freebore length when it was not needed because he incorrectly thought that the "long, high BC" bullets needed it. As it turned out, the shooter was using a Berger bullet and most of the added length was in the ogive. Some of his shorter bullets would fall out of the case before encountering the lands.
In a recent thread, a gunsmith added freebore length when it was not needed because he incorrectly thought that the "long, high BC" bullets needed it. As it turned out, the shooter was using a Berger bullet and most of the added length was in the ogive. Some of his shorter bullets would fall out of the case before encountering the lands.
I believe I am just going to send a few dummy rounds of the largest bullets I may use and tell them make sure they fit. If not adjust accordingly. I did a 7 SAUM on a 700 action I opened up to allow up to 2.95" last year. Got a standard chamber. I have shot up to 180 ELD-M at 2.95" with no issues. I don't have any 195 bergers but it appeared my 180s ELDs could go all the way to 3.10".
The advantage of a custom "match style" reamer would be that the support of the .2845" .2846" dia freebore would start sooner. Even if the start of the lands would be in the same spot, the bullet would be held in aligment better. For some reason, Winchester stuck with the older "forcing cone-only" style chamber long after other companies switched to "match style". One of the main arguments for Remington's SAUM cartridges was the generally more accurate chamber.
I know that you mean a "Dummy Round" with where you want the bullet in the case for the CBTO. Not a Loaded cartridge. BUT some may take you suggestion literally????
You can also have a SAAMI cut chamber and if you feel that you can work on the chamber or have you GS get a "Uni Throater" to extend the throat to your bullet.
