Neck Turning Winchester brass (7wsm)

[jcann]

I’m shooting a 7wsm with a neck chamber of 0.320”. I have measured all my unfired brass neck wall thickness and have determined in order to get consistent neck wall thickness I need to turn the necks to a wall thickness of 0.0125”.

My question is, is the neck chamber too loose (0.320”) for this dimension (2 x 0.0125”) + 0.284” = 0.309”? I had planned on trying one of the three Redding neck bushings of 0.306”, 0.307” or 0.308”.

Any guidance would greatly be appreciated.

 

[40X Guy]

Depending on the intended usage of your rifle, if wanting to hunt with it, your neck clearance of .011 (.0055 per side) while loose will work. If wanting to use for target shooting then you are definately too loose to go after any serious accuracy. I assume your chamber/rifle is stock as from the factory? You may want to invest in a case neck tool and after running your brass thru an expander die, use the case neck tool to cull out any cases that have inconsistent neck wall thickness. Keep the ones that have .002 or under and just clean them up 50-75% with your neck turning tool. .011 neck clearance is a lot. Best to shoot for a tighter neck clearance. I see Norma makes .300WSM brass and another option is to take that brass and neck it down to 7MM and then run them thru an expander. Should be a couple thou thicker.

Frank

 

[XTR]

I think most will agree that's a bit loose in the neck. I don't shoot a WSM, but in 308s WIN has thinner walls than most others, most notably Lapua.

Not sure what other options you have for brass, and before you get too wrapped around it take it out and shoot it. Unless you're shooting BR you may find that you are plenty accurate for your purposes. If you're target shooting then barrels are a consumable, in a WSM you're not going to get more than about 2000 +/- rounds out of it anyway so order one now and get it chambered the way you want it.

 

[jcann]

Frank,

The rifle is a GA Precision. George uses a reamer with a 0.320 neck. I want to use it as a long range hunting rifle.

I've been in the reloading room and have decided to turn (clean up) the necks to 0.0145".

(2 x 0.0145) + 0.284 = 0.313"
With a 0.320 neck chamber will this be much better? Also would you buy bushings at 0.310, 0.311, and 0.312 to get started?

 

[dennisinaz]

You have discovered the biggest problem with the 7 WSM. The only way I found around the bad W-W brass was to buy Norma 300 WSM and fire-form it. If I were to do a serious accuracy 7 short magnum, it would be a 7x300 WSM to take advantage of the much better quality 300 brass out there without having to fire-form.

 

[TonyR]

+1 on dennisinaz comments. It is very easy to make a 7/270 WSM from 270 WSM brass with one pass of an expander mandrel then turn the neckss to whatever. Or you can neck down 300 WSM brass and end up in the same place because the 270 and 300 WSM case bodies are the same dimensions. I made my dies by cutting 0.040 inches off the bottom of a Forster 7mmWSM FL resizer and Ultra micrometer seater. I am using a 0.310 loaded neck with a 0.314 inch chamber neck.

 

[40X Guy]

Frank,

The rifle is a GA Precision. George uses a reamer with a 0.320 neck. I want to use it as a long range hunting rifle.

I've been in the reloading room and have decided to turn (clean up) the necks to 0.0145".

(2 x 0.0145) + 0.284 = 0.313"
With a 0.320 neck chamber will this be much better? Also would you buy bushings at 0.310, 0.311, and 0.312 to get started?

Some good advice here, but if you are stuck with the Winnie brass, then your plan of cleaning up the necks to a loaded round measurement of .313 is sound. Buy the .310 and .311 bushings, the .312 will not be enough neck tension. You may even want to buy a .309.

Frank

 

[Jeffvn]

.320 is very roomy. If you are stuck with that chamber and are taking it down to .313 or below in size, I suspect you'll be better off sizing your necks in two stages. I never managed to size over 0.005 without having some induced concentricity issues (even from my REdding competition dies). I have sized up to 0.009 in a two stage process 0.005 and then 0.004 with no issues at all.

I don't think Winny brass is all that bad for the price (at least when I got mine) and have used it in my 7WSM for over 5 years ago. I bought a ton of it at one time and am slowly working my way through it. As we speak I am now down to my last 500 cases sitting in the garage ready to be prepped.

Jeffvn

 

[Dirtball]

I have also been shooting the 7WSM for a few years and have used Winchester brass with out a problem.
My advice to you since you said you were going to use the rifle for hunting, is with a .320 neck I would NOT turn the necks.
Even if you just "clean them up" a little you are going to be between .313 and .314 which will work the brass 6 to 7 thou every time you fire and resize, and as was stated this could give you concentricity issues that would negate any accuracy benefit from turning the necks in the first place.
Even if you don't turn the necks you are still going to have to anneal every couple of firings or the necks could harden and start slitting.

My 7WSM is an F-Class match rifle and I turn necks to .0125 and weight sort, etc., but my chamber has a .311 neck.

Good Luck
Dave

 

[LCazador]

Jeffvn , you got it all wrong . He has a finished neck after cleanup of .313 , his chamber is .320 so he just has to bring the neck tension down three or four thousands . It's pretty obvious you have a no turn chamber , and if you clean up and wind up with a dfference of .007 that's pretty good tolerance for a hunting rifle . If it's a custom barrel , it should do quite well with that clearance of .007 , remember that is .0035 on either side of that chamber . If it doesn't shoot than there are other factors to be considered .
A neck bushing .003 or .004 under your finished diameter of .313" would be best . If it's a repeater , a firm neck tension of .004 is advisable because of recoil . I have a 338 RUM with Kreiger barrel and that is the neck tension I've been using for some time , 3 inch groups at 600 yards with the big fog cutters in this fine rifle .

 

[dennisinaz]

I have been a big believer in .004 or so sizing of necks for hunting rounds but recently, I have discovered that you can't do that with thin jacketed Berger bullets. Remember, they are hollow at the spot where the seating stem hits them. Too much resistance and the seating depth becomes very erratic. I had to drop way back on my neck tension to less than .002 in bushing undersize!

I am going to learn to shoot with a lot less neck tension.

 

[jcann]

Thanks everyone,

I can see this project is going to be somewhat trial and error on my part. All of you have given some good advice to ponder over. I have shot 7mm for over 30 years now and this is my first custom built rifle. I should have it in March and although I have reloaded for my other rifles (not to this extent of technicality) I truly desire to get all the accuracy this custom rifle will give.

Starting work up load will probably be 65 grains of H1000 behind a180gr Berger VLD.

The rifle has a 26” Bartlein 1-8.7 twist. I probably should have specified a tighter neck but to be honest I didn’t think about it and to some extent assumed it would be. That’s my bad. I’m positive once I get it I’ll be able to work up some fine hunting loads.

This web site has been a good source of information and I really appreciate all of the input from this forum. Stay tuned, hopefully I’ll have good reports in the future.

jcann

 

[Larryh128]

I have a 284 with a .320 neck that really isn't an issue. I would probably cut a tighter neck next time but it's been accurate. Loaded rounds mic at .313 after being skim cut. As stated earlier, anneal often. I have gotten into annealing after every loading & brass just lasts a very long time.

 

[AWLEAPHART]

My 284 Win. loaded round is .312 (Lapua brass) with my rifle chamber being .320 and have shot 1" and 1 1/2" groups many times at 500 yards. For fun we shoot 16 oz water bottle filled with water. I did had my rifle throat chambered really long and load bullets one at a time.
I was also worried about having so much clearnce at first but it seams to be paying off.
Anthony

 

[Jeffvn]

Jcann

I can't and don't fault your decision to opt for as uniform a neck tension and bullet release as possbile. I do that with all my rifles. But none of my rifles (except one - discussed below) are running a standard size chamber. All of my rifles run 0.004 thou clearance over the loaded rounds or less; most run 0.003 total clearance. As an aside, I own all my reamers, so that I can strictly control the size of my chambers and the number of chambers that each reamer has cut.

Given the decision you have made, I see no reason to stop your desired progress. I would neck down in two or possibly even 3 stages with no more than 0.005 in any one stage, depending upon the final numbers of your loaded rounds. Were I in your shoes, I would be annealing every other firing to keep the neck tension under control.

Depending upon how hard you run your 7WSM, you may well burn that barrell out in a year or two (mine do not last any longer than 2 years), and then you can decide what to do on the next one. Barrels are consumables, so I look long term, not just at the decision immediately in front of me.

My tactical 7WSM (a Terry Cross, KMW built in 2004; the ONLY Rifle I do not control the reamer) has a much looser chamber than my snug chambered rifles. It is now running its 3rd barrel (true story - I love this rifle and its my go-to rifle for hammering steel and my back up for running the Mile+ in the desert). I use "cleaned" brass (0.0145) neck on it. I sized it in two stages (until I got a custom sizing dies from Neil Jones). I anneal that brass every other firing; it shoots like a beast and I recently used it to set a personal record relay in a local 600 F-Class match. The KMW continues to be one of my best shooting rifles - if that makes you feel better....

This is indentical to a post made on a different site

Jeffvn

 

[newgun]

Jcann,

Dont worry about the chamber too much if you can make up some loads that are even close your g.a.p. rifle will make you very happy. I am a BIG fan of their work. They didn't cut it that way by accsident as Im sure you well know.

 

[jcann]

Newgun

I've shot two different GAP rifles, one in 243 and a 338LM. What can I say, both were impressive. George and his crew do great work

 

[newgun]

I got my 260 back in october and it is still kind of unreal to me. It is just soo easy to shoot it well
I hope you like yours too or love it as I do mine