7/270 wsm

[KT]

Got a couple questions for you guys.

I'm looking to build a 7/270 wsm.

I know I need a reamer for this. What dies do I need. Can I size with a 270wsm full length die and just use a larger bushing in it?

Can I seat with a 7wsm seater die?

What exactly is the difference between the 270wsm and 7wsm besides neck length. They are both 35 degree shoulders correct?

thanks
KT

 

[Nomad47]

The body of the 7mmWSM case is slightly longer (and therefore the neck is slightly shorter) so that a 7mmWSM cartridge cannot be chambered in a 270 WSM.

 

[jeepcj6]

I have a redding 270wsm fullsise die
and a wilson 7mm wsm seater works fine

 

[Kyle Schultz]

I can help with the dies.

I built a 7-300WSM. Same case body dimensions except I necked 300WSM brass down to a 7mm neck whereas you will be necking up the 270WSM brass. The dimensional differences between .270 and 7mm are pretty small. The Forster folks honed out the neck on their 270WSM Full Length Sizing die for a minimal cost. That's what I use to initially neck the 300WSM brass down to 7mm. Of course, if you start with 270WSM brass, you can skip this step and just use an expander mandrel. Same mandrel you would use to prep for turning the necks.

Same process with the seating die. Forster honed out the neck on a stock 270WSM die. Forster stenciled both the custom dies with the new chambering. Very very nice.

Resizing is a snap. I use their stock 300 WSM Neck Bushing/Shoulder Bump die with whatever bushing size I need.

I decided to start with 300WSM brass and neck down. I had problems with split necks using 6.5x284 brass I necked up to 7mm for my .284 gun. Necking down causes the neck wall to thicken slightly. Conventional wisdom would have you turn the neck walls down to 0.0125" and run a 0.313 chamber to give you 0.004 clearance on a 0.309" loaded round. Because my necks were already a little thicker, I was able to achieve uniform thickness at 0.0145". I spec'd my reamer at a 0.316" neck which gives me 0.003" clearance with 0.313" loaded rounds. My thought was that if the gun acted like it needed more clearance, I could shave a little more off the necks to open up the clearance. So far, at +/- 400 rounds, I'm pleased with my choices.

I think the 7-300WSM (7-270WSM) is a great round and I would encourage you to continue on with your project. Good luck!

 

[KT]

So far one person is using custom dies and one is using 270wsm full length and a 7wsm seater. Anyone else?

Can you guys pass the spec's on your reamers?

What kind of velocity are you guys getting with the 180's.

KT

 

[Kyle Schultz]

Sent PT&G a dummy round with a seated 180 Hyb and they set the free bore. My reamer is a 0.265" free bore. That's probably at the upper limit.

Again, my neck is 0.316". That dimension depends entirely on how you intend to prep your brass. No universal answer.

I can reach 3100+ fps with no pressure signs. However, I've found my gun groups best at a hair below 3000 fps. I think others like Erik Cortina and Tony Robertson have had success around that velocity threshold. 32" barrel.

The 7SAUM drivers love H4350 while the pure 7WSM shooters often report good luck with RL-25. None of these worked for me. I had the best results with RL-22 but do plan to test N-165 to hopefully find a backup powder that works. As you know the 270/300WSM case capacity falls in between the 7SAUM and the 7WSM. I think H4350 may burn a little fast and powders like RL-25 and H1000 may burn a little slow. That's my opinion based on my experience and your results may vary.

I tried the .284 Shehane (30" barrel) and could not reach 2900 fps before I started seeing pressure. That. along with the possibility of the Berger 195 EOL bullet, lead me to the magnum. That's why my free bore is a little longer than it might need to be if all I was ever going to shot was the 180 Hyb.

HTH.

 

[KT]

Kyle,
have you tried 4831sc and if so what were your results.

KT

 

[Kyle Schultz]

Yes. Tried H4350, 4831SC, RL-22, RL-25, N560, 7828SSC, and H1000. Eventually saw pressure signs as I stepped up ladder with all but RL-22 and N560. I do plan to test N165.

I'm not saying that RL-22 is the only powder that will work. Vince Bottomley had great success with RL-25 in his gun which is featured on this website. I just didn't want to burn up my limited barrel life exhaustively testing lots and lots of powders. Initial testing of RL-22 was promising and that's where I focused my efforts. Certainly if you already have powder on hand that falls in the H4350 to H1000 burn range, you should at least do a single shot ladder test to see what you find.

 

[Kyle Schultz]

Kyle,
have you tried 4831sc and if so what were your results.

KT

Specifically...

Planned to shoot 61.0 to 64.5 gr ladder of 4831SC. At 62.0 grs got first stiff bolt lift. 62.5 grs had very stiff bolt lift and I terminated the testing. My chronograph battery was dead so I do not have velocity info.

Caution: Start low and carefully work you way up. Stock Quickload prediction said I could load up to 64.5 grs without hitting pressure limits. Obviously many many variables involved and, at least on this day, my gun clearly told me to stop at 62.5 grs.

 

[wnroscoe]

I can help with the dies.

I built a 7-300WSM. I think the 7-300WSM (7-270WSM) is a great round and I would encourage you to continue on with your project. Good luck!

Like Kyle, I also own and have built several for clients. The 270 & 300 wsm are the same case except for neck dimensions. I've used 270 WSM necked up and 300 WSM necked down. I prefer the 300 necked down and neck turned / skimmed.

Brass is Remington 300WSM
Powder of choice is H1000, 67.0 grains
Primer is CCIBR2
Bullet is 180 Berger VLD with a C.O.A.L. of 3.100"
Velocity is 2,950 fps
Reamer has a .315" Nk, .180" FB, 1.5 degree lead
Dies, FL Type S Redding 270WSM with .308" bushing
Loaded Nk .310"

Seater is a modified Wilson 7WSM shortened and slightly re-chambered but, you could use the standard 7WSM seat die with good results.

Accuracy is .2moa and better and has produced sub 2" groups at 600 yards.

Build either a 7-300WSM or the 7SAUM and don’t look back, either will hammer at distance.

"edit"
I originally provided the wrong reamer neck and bushing diameters, the above numbers are now correct

 

[Steve Blair]

Sent PT&G a dummy round with a seated 180 Hyb and they set the free bore. My reamer is a 0.265" free bore. That's probably at the upper limit.

[br]
It certainly is. Freebore for 180 Hybrids need be no longer than .200". The upcoming 195 Hybrid needs no more than .250". My 7-270 WSM reamer has a .233" freebore for 195 Hybrids. [br]
As far as necking up, I neck Norma .270 WSM brass up to .300 WSM in two steps and split an average of one neck per hundred, same as necking up Lapua 6.5-284 to 7mm for my Shehane.

 

[KT]

So what I'm hearing is that the 3050fps range is not obtainable? It sounds like most of you are running the 7's around 2950 to 2990.

I think one of the other things I'm worried about is the gun being very finicky. Have you guys had a lot of problems with this?

KT

 

[Elwood]

I use a Redding type S 270 WSM neck bushing die and a Redding 270 WSM bump die and seat with a Redding 7 WSM die.

3050 fps is more than obtainable, with the right powders, RL25, H1000 would be the speedsters choice, and of course it will also depend on your barrel.

 

[Savage99]

KT,

To make a wildcat like the 7mm/270 WSM is a waste of time and money.

I have both a 270 WSM and a 7mm WSM and with all the bullets available today they will both do the same thing.

It seems the 7mm WSM did not catch on. I like it and hope it still does.

Just shoot a 270 WSM for now. Wildcats don't impress me at all having been doing it for 60 years.

 

[Steve Blair]

KT,

To make a wildcat like the 7mm/270 WSM is a waste of time and money.

I have both a 270 WSM and a 7mm WSM and with all the bullets available today they will both do the same thing.

It seems the 7mm WSM did not catch on. I like it and hope it still does.

Just shoot a 270 WSM for now. Wildcats don't impress me at all having been doing it for 60 years.

[br]
I make both .300 WSM and 7-270 WSM brass from Norma .270 WSM for a very good reason. It is much cheaper. I bought 1000 Norma .270 WSM cases for $1060. Norma .300 WSM is $1670/1000. It easily necks up and works just as well. The 7-270 is even easier as it is one of the intermediate steps to .300. The .270 WSM has one big negative. It does not shoot Berger 7mm 180 grain Hybrids. So, whatever you want to do with your rifles is fine and I'm certain your 60 years of experience in invaluable to your pursuits. But, to make a statement like you did without knowing why someone might choose to use a given cartridge is just ignorant. [br]
At one time. the .22-250, .270 Win, .280 Rem, 7mm-'08 and .260 Rem, among many others, were all wildcats. Not many people would say those cartridges are a waste of time and money. [br]
Have a really nice day.

 

[Savage99]

Steve,

Why not just shoot a factory cartridge?

There is the 7mm WSM and there may be a SAUM version too!

Cheaper brass? After your done with a special reamer, a rifle that won't sell at all because its a wildcat no, load data.

 

[Erik Cortina]

Steve,

Why not just shoot a factory cartridge?

There is the 7mm WSM and there may be a SAUM version too!

Cheaper brass? After your done with a special reamer, a rifle that won't sell at all because its a wildcat no, load data.

I can assure you Steve will not worry about selling that rifle as all he has to do is take the barrel off and install a different one. As far as load data, to save time, let's just assume Steve knows everything! ;D

I guess Vince Bottomley really wasted his time when he built this 7mm/270 WSM since he only broke the World Record TWICE!

http://www.accurateshooter.com/guns-of-week/gunweek071/

 

[Steve Blair]

I guess Vince Bottomley really wasted his time when he built this 7mm/270 WSM since he only broke the World Record TWICE!

http://www.accurateshooter.com/guns-of-week/gunweek071/

[br]
No to mention that Gary Costello won the World Championship with a Warner-built 7-270 WSM. [br]
But, to answer the question: At the level of brass and load preparation that we perform, regardless of cartridge, the additional step to neck up, down or push the shoulder back is minor. I have ten reamers in various calibers. Even the .308 Win reamers (2) have some non-standard aspect to them. (i.e.: smaller neck diameter for turning, long freebore for heavy bullets, etc.) If you were to amend your statement by saying that there is not much justification for a wildcat hunting cartridge, you could make a pretty good argument on the basis of emergency ammo availability. When talking long range competition, there is not much "factory" about it.

 

[davist]

So far ive had six 7-270 wsm custom rifles built sold half of them to frends for exakly what i asked for them and they love them

 

[REastman]

Excepting recoil, why would a 7mm (of any variant) be preferable for F-Class over a 300 WSM?