Belted magnums reloading, from scratch

[Nvhunter]

Ok, I finally decided to work with the Sako 75 V 7mm STW. I have been reloading standard rifle cartridges for may years. My question, is there a different procedure for loading belted magnums (7mm STW) as compared to reloading a standard rifle cartridge (such as 30.06)?

 

[jmason]

I don't treat them any different.

 

[AJ Peacock]

The biggest error that is made when reloading belted cartridges is to resize them too much. Most of the stretching that occurs when they are shot, occurs just ahead of the belt. If you resize them too much, that stretching will make the area in front of the belt very thin (to the point of seperation).

If you push the shoulder back .001" only, you will be headspacing off the shoulder (just like your 30-06) and you won't have the issue.

So when you setup your die, don't just screw it in until it touches the shellholder, this will push the shoulder back too far and cause the problem.

Hopefully this made sense,
AJ

 

[Nvhunter]

Yes, That makes sense. I have found a resizing collet and headspace gauge that Larry Willis offers. I think those resizing tools will help acheive the correct shoulder spacing and resize of the bulge that develops just above the belt.

 

[boomtube]

Don't "over think" the belted thing. IF your chamber is too small for a normally re-sized case to chamber easily the collet sizer is a fine tool, but most are not.

If you want to spend some money, do it helpfully; get an RCBS Precision Case Mic or Hornady case length tool for your caliper and use it to properly set the case shoulders on your standard FL sizer dies.

 

[guns_and_labs]

If you want to spend some money, do it helpfully; get an RCBS Precision Case Mic or Hornady case length tool for your caliper and use it to properly set the case shoulders on your standard FL sizer dies.

How does that work? I know my chamber is such that I HAVE to FL resize, but I would rather headspace off the shoulder than the belt... so how will the case length tool help if the die is set up to headspace off the shoulder?

 

[Nvhunter]

Yup, not overthinking, just want to purchase the right gear only one time. I checked the RCBS site and do not see a die set for the 7STW. From what I have seen so far...Redding has Type S bushing dies that can be ordered with the correct size bushing for a 7STW.

Don't know how much a Mic die set would help. I keep things along the K.I.S.S. method. But if there is a significant advantage, I could consider a set of mic dies.

Here in the desert there may be a temperature change of up to 25 degrees where I reload (seasonnaly) throughout the year. Acheiving a consistent .001 measurement during production requires climate control. Heating and cooling of any equipment from Lee to RCBS will contribute to expansion and contraction. So , I don't know if a mic set would achieve its intention.

 

[Nvhunter]

Concerning the case length mic. I think thats the shoulder mic that Larry Willis has on his website. That tool should proove verification of proper shoulder set after I set the die at each reloading session.

Guns and labs, sounds like you may be reloading a belted magnum also. Have you seen this "bulging" just above the belt that will not allow chambering of a cartridge? I have read about it but have not seen that phenomenon myself? Is it an issue...or just an occasional happenstance?

 

[Innovative]

Nvhunter ......

Our Digital Headspace Gauge shows the clearance that YOUR handloads will have in YOUR particular chamber (at the shoulder). Handloads should have -.002" clearance. If not, you'll see how much (and which direction) to adjust your sizing die.

Our Belted Magnum Collet Resizing Die allows you to drop your belted case in the top and SEE if you need "extra" resizing. If your case fits - it's good to go, and there's no need for more resizing. However, if you have cases that don't fit . . . . then it's obvious that it needs a bit more resizing.​

The reson it works better than a conventional die, is that it pushes "inward" to resize the case instead of plowing the brass back towards the case head where it accumulates at the belt and actually increase case diameter. Read my website, and you'll see why these tools are becoming so popular. Thanks for the chance to explain.​

- Innovative​

WWW.LARRYWILLIS.COM

 

[guns_and_labs]

Guns and labs, sounds like you may be reloading a belted magnum also. Have you seen this "bulging" just above the belt that will not allow chambering of a cartridge? I have read about it but have not seen that phenomenon myself? Is it an issue...or just an occasional happenstance?

Yes, I reload a couple different belted magnums. I always full length resize, as the Blaser chambers require it for proper feeding. That's true even for non-belted loads, or so I'm told. I've never tested the statement, though.

I trim each time, and I always discard after the third reload. My accuracy is excellent on the .300 WinMag, but only acceptable on the .264 WinMag and the .350 RemMag, and I've been wondering if it is a headspace issue, or maybe a seating issue.

 

[Winchester 69]

The biggest error that is made when reloading belted cartridges is to resize them too much. Most of the stretching that occurs when they are shot, occurs just ahead of the belt. If you resize them too much, that stretching will make the area in front of the belt very thin (to the point of seperation).

If you push the shoulder back .001" only, you will be headspacing off the shoulder (just like your 30-06) and you won't have the issue.

So when you setup your die, don't just screw it in until it touches the shellholder, this will push the shoulder back too far and cause the problem.

Hopefully this made sense,
AJ

+1

It isn't necessary to seek out solutions to non-issues. Your main problem will be excess shoulder gap with virgin brass. If you take special precautions anywhere in your process, they should be taken here to ensure that you don't stretch the brass. You can form a false shoulder on the necks of unfired brass if necessary.

 

[Innovative]

guns_and_labs . . . . . .

- There's no need to discard your expensive cases after just 3 reloadings.

Winchester 69 . . . . . . .

- You and AJ Peacock are correct about pushing the shoulder back .001" or .002" and no more. That's why I developed the Digital Headspace Gauge. Unlike the RCBS Precision Mic, it works on vitrually ALL different calibers. However, belted cases can still develope a bulge - just nowhere near as bad. That's why our Belted Magnum Collet Resizing Die has a case width gauge to show when your cases are bulged. Even if you just neck resize, you still need to bump the shoulder (and you should know exactly how much) by measuring.

- Innovative

 

[boomtube]

"I would rather headspace off the shoulder than the belt... "

That's sorta my point. Fact is, even the factories don't actually make belted ammo to head space off the belts.
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NV, the RCBS Case Mic isn't a die, it's a case measurment device.

If you have no CALIBRATED GAGE to measure the position of your sized vs. fired case shoulders you have NO WAY of knowing how wel your sizer is actually set up. Get the Case Mic, Hornady's LnL or Larry's dial indicator rig to find that measurement.

A conventional drop-in type "case gage" only tells you if a case/cartridge is within SAAMI specs, minimum to maximum, you will still have no specific measurement and you NEED that info.

 

[woods]

I presently reload for or have reloaded for 19 different rifles in various belted magnum calibers, some very extensively, and have never had the need to resize at the pressure ring. Once I get to 6 or 7 reloads I get nervous and toss the case, not because of inability to chamber properly, but because of concern over case head separations (and yes, I do headspace on the shoulder and only push the shoulder back .001").

The Gauges boomtube mentioned will give you measurements to the datum point on the shoulder to 1/1000" and are indispensable in resizing cases.