7mm WSM reduced loads still accurate?

[ScottMcc]

Hi all, first post. I have been researching ideas for building an F class rifle for about a year. Every time I think I am ready to jump, I learn something new that makes me glad I waited! Lately I am torn between the 7mm saum vs the 7mm wsm. The 7mm guide in here has me leaning toward the 7 saum for it's reduced capacity and longer barrel life. But the 7 wsm has the advantage of a little more velocity if/when it is needed. So the question is, why not reduce loads in the 7 wsm by 5-10% when max vel is not needed, like calm conditions, or 5-600 yard shooting? What effect does it have on accuracy?

scott

 

[Steve Blair]

No effect on accuracy and some reduced loads can be extremely accurate. Low ES may be another matter. My experience is that full case and pressure makes it easier to achieve low ES numbers. Just my 2¢.

 

[kennyg]

I don't know what your target velocity is, but my 7 SAUM will push the 180 hybrids over 3000fps out of a 28 inch barrel. It is fast enough for me. YMMV

 

[Kyle Schultz]

I'll endorse one other option... the 7-300WSM, which is also described on the 7mm page.

1. Case water capacity is in between 7SAUM (73.6gr) and 7WSM (81.0 gr). My cases average 79.46 gr.
2. Cases easily made by either necking down 300WSM or necking up 270WSM brass. I'm necking down Norma 300WSM brass. No fire forming required.
3. 7-300WSM necks are longer than 7WSM necks. Gives more seating depth flexibility.
4. Dies easily made by honing out necks on stock 270WSM dies. Pretty cheap option.
5. I have pushed 180 HYB up to over 3100 fps w/ H1000 but have found my most accurate load right at 3000 fps using 63.5gr RL-22.

I'm very pleased with the caliber so far. 225 rounds down the tube. Hoping for 800 before the throat goes.

 

[ScottMcc]

I have read about the 7/300 wsm, but I would rather stay with a factory round.

I figured 2900-2950 with a 180 vld would be a good goal for both 1000 yard range and decent barrel life.
But you guys are getting serious velocity with the 180s. Are you using moly coated? If both the 7 saum and 7 wsm can exceed 3000 with 180's, then 2900 would be a reduced load in both right? Barrel life is really more important to my limited budget than an extra foot or two of drop at 1000, so I guess what I am really asking is how much does backing off hurt accuracy? And how much extra life can really be gained?

 

[Steve Blair]

I'll endorse one other option... the 7-300WSM, which is also described on the 7mm page.

[br]
Some of us call this a 7-270 WSM. I gues it depends on which way you look at it. I expand .270 Norma and turn necks. My PT&G reamer is marked "7mm/270 WSM." It also helped that I got 1000 Norma .270 WSM cases for $1.06, each. It's pretty silly that .300 and 7mm WSM brass sells for so much more and is essentially the same.

 

[expiper]

Scott,,,as your know there are lots of really good 7mm's being experimented with (thanks to lots of good bullets now on the market) at this time....to answer your question to my best,,,is no...I and many others have tried slightly "reduced" loads and it seem like if the pressure is not adequate during the burn time of the powder it is erattic....now if you go wayyy down to black powder or squib loads (like the schutzen rifles) and use different (pistol-even shotgun) powders....and even cast bullets ,target quality accuracy can be achieved.....but as I see your ??? it sounds like you want to load down to 7x57 vel and still have one hole accuracy ..,,,there are lots of loads that allow you to download so that your 10yr old or g/f can shoot a deer and not bruise his/her shoulder...but typically the accuracy is minit of deer,,,not world class Palma/Benchrest worthy......IMHO....Roger

 

[ScottMcc]

OK cool. So 2900-2950 with a 180 vld is 7x57 territory? The loading books I have seen must be way conservative. The hodgdon reloading table says it takes a regular Rem 7mm mag to barely reach 2900 with a 180 berger.

 

[Steve Blair]

OK cool. So 2900-2950 with a 180 vld is 7x57 territory? The loading books I have seen must be way conservative. The hodgdon reloading table says it takes a regular Rem 7mm mag to barely reach 2900 with a 180 berger.

[br]
Reloading manuals do not consider extended freebore, seating or 32" barrels. In the case of legacy cartridges like 7X57, they must recommend loads that will be safe in old, military actions. Strong, modern actions and long barrels with long freebores can achieve excellent velocities with cartridges like: 7X57, 6.5X55, 7.5X55, etc. Be careful and work up in increments.

 

[wboggs]

sleepygator is spot on reguarding the old timers.I have a modern M70 with a 24" barrel in 6.5-55
It is easy to get 2900-3000 using 120gr bullets with modern pressures.

 

[ScottMcc]

Thanks, sleepygator. your first reply is probably all I needed. I may already be past the point of nagging, so I promise this will be the last time I bring this up.

To summarize, the 7 wsm is capable of 3100 with 180 grs. If I back off a 7wsm with 180's to 2950, it will be equivalent to a very near max load in 7 saum, but es and sd will go up. Will there be any noticable increase in barrel life over a max load in 7wsm?

thanks again, scott

 

[Steve Blair]

You should be able to extend barrel life by a few hundred rounds. It's not a huge difference but is worth pursuing.

 

[KT]

Not to high jack your thread but I have been thinking about building a 7mm variant of a magnum for F-class. The problem is that I have seen no clear winner. Everyone that has one is running something different. No one runs a straight wsm or rsaum. It's all wildcat versions.

It seems that alot of people have to bring loads for different temps for the mags to shoot well. I know at the Nat's last year a bunch of people had problems with the mags.

Mr. Biggs seems to be the most consistant with a magnum, not sure what version he is running.

So my question is: Is there a magic combo out there that someone has figured out. I hate to take the time and money to build a magnum just to figure out that it shoots when it wants too or not at all.

KT

 

[Steve Blair]

Not to high jack your thread but I have been thinking about building a 7mm variant of a magnum for F-class. The problem is that I have seen no clear winner. Everyone that has one is running something different. No one runs a straight wsm or rsaum. It's all wildcat versions.

It seems that alot of people have to bring loads for different temps for the mags to shoot well. I know at the Nat's last year a bunch of people had problems with the mags.

Mr. Biggs seems to be the most consistant with a magnum, not sure what version he is running.

So my question is: Is there a magic combo out there that someone has figured out. I hate to take the time and money to build a magnum just to figure out that it shoots when it wants too or not at all.

KT

[br]
Some folks run straight RSAUM or WSM cartridges, it's not all wildcats. I don't know what Danny is shooting but I think he's had some temp issues, too. Not at the Berger, where he shot very well. The Berger was won this year by Shiraz Balolia shooting a .300 WSM with 215 Hybrids. I was also beaten in the AZ Long Range and Palma Championships by Steve Shaw who was shooting the same combo. I have been shooting a .284 Shehane but have a new .300 WSM that I expect will do well. PT&G sent me a 7-270 WSM reamer recently but I have no barrels chambered with it. [br]
The short version is that there is no magic bullet (sorry for the pun) and every cartridge has issues that must be addressed.

 

[KT]

Steve,

How bad is the recoil on a 300WSM? I would be afraid that 180 rounds in a weekend would beat me to death.

I know there is no magic combo. I would like to know if someone has a combo that is consistant.

KT

 

[hogan]

Gonna shoot reduced loads to extend barrel life?

Why not go .7mm-08 and have the optimum result? Even a .284win is going to deliver better flexibility than any magnum. .284win will basically duplicate .280rem.

.308win has the barrel life sweet-spot working for it. Probably a .300 Savage with an AI shoulder would be even more.

Can always shoot cast boolits and there are techniques that deliver fine precision at high velocity. Can't really get the good barrel life when burning lots of powder. Burns the throat, still no alloy you can cast will wear your barrel.

Want to chase the velocity dragon once in a while? The WSM will sure do that for you. The longer I shoot, the less I care about utmost velocity. All my loads seem to work best between 2600 to 2750 fps. Then there's the recoil factor or absence of it.

7mm-08 with middling load of 4064 and 162gr Amax won't recoil noticeably at all.


Being able to make brass by necking down standard .308win cases won't hurt you any in the days to come either...

 

[Steve Blair]

Steve,

How bad is the recoil on a 300WSM? I would be afraid that 180 rounds in a weekend would beat me to death.

I know there is no magic combo. I would like to know if someone has a combo that is consistant.

KT

[br]
It is not that bad. My .300 weighs 21.75 pounds and the Shehane weight is 21, even. They are identical otherwise. The .300 has more and sharper recoil but it is not as bad as shooting a six pound .308. I shoulder the rifle more firmly and it moves a little more. I've not yet fired it in a match, so I can't speak to whether fatigue will be a factor. I'll know pretty soon. It is as accurate as the Shehane but I'm still working on ES.

 

[ScottMcc]

The US F class team recently announced they have switched to the 7 wsm. I wonder what ultimately tipped the scale toward the wsm over the 7 saum or any of the wildcats..

 

[Steve Blair]

The US F class team recently announced they have switched to the 7 wsm. I wonder what ultimately tipped the scale toward the wsm over the 7 saum or any of the wildcats..

[br]
I was not aware that they had restricted it to one cartridge. I thought that the criteria were: a 7mm magnum with velocity between 2950 and 3050. Do you have a reference to the announcement. Shiraz, the team captain, was shooting a .300 WSM at Berger.

 

[ScottMcc]

I thought I saw it here on their home page. He says they selected the '7mm magnum', but I thought he specifically said 7 wsm. I will look around for something else I might have seen.

http://www.usfclass.com/home.aspx