shorten 7 mm ultra magnum
- Thread starter maddysdad
- Start date
Just take the ultra outta the name and there u go a 7MM Mag that has proven itself over and over. No need for change
The 7 MM Mag has proven itself out to 1000 yards for many years. More range time behind a 7MM Mag learning and creating an accurate dope card will prove more effective than spending time trying to develop another cartridge and exert all your time working the bugs out of it. I have several 7 MM Mags and 7MM Ultra Mags and love them all. My hammer is a custom 7MM Mag pushing 162 Amax at 2860fps ( She has a 20" fluted tube with a break installed). This gun has proven 1 shot kills out to 600 yards.
Nothing wrong with a belted magnum, IF you setup the shoulder for headspace rather than using the belt for that purpose. More brass in the boltface is a good thing. Set the headspace to about .0005 or .001 longer than virgin brass and you've stopped the incipient case separation problem dead in its tracks...
Got nothing better to do than dream of wildcats? It is quite the pastime for Winter evenings, but... aside from bragging rights, in most cases (pun intended) just not worth it.
280 Rem AI is magnum comparable. .284 Win is fine as-is. The 7mm SAUM is written up here on the site. Just easier and always will be easier to get the `06 variant brass, or make it yourself.
For all-around use, in 7mm bore, it'd be hard to do better than the .280rem AI. 5 instead of 3 in the magazine, great barrel longevity, fine gains in velocity from the improved case. A .284 in a long action could have the edge if looking to shoot long VLD bullets consistently. Nice to have all that magazine length to seat long bullets into so they don't intrude on the case body.
Then there's the 7mm-08 with even more options for you if you aren't a velocity hog... and maybe a 7mm XC or 7mm International AI. Still, nice to have a die set that don't break the bank and doesn't cost you serious barrel life just forming cases...
Have fun!
Got nothing better to do than dream of wildcats? It is quite the pastime for Winter evenings, but... aside from bragging rights, in most cases (pun intended) just not worth it.
280 Rem AI is magnum comparable. .284 Win is fine as-is. The 7mm SAUM is written up here on the site. Just easier and always will be easier to get the `06 variant brass, or make it yourself.
For all-around use, in 7mm bore, it'd be hard to do better than the .280rem AI. 5 instead of 3 in the magazine, great barrel longevity, fine gains in velocity from the improved case. A .284 in a long action could have the edge if looking to shoot long VLD bullets consistently. Nice to have all that magazine length to seat long bullets into so they don't intrude on the case body.
Then there's the 7mm-08 with even more options for you if you aren't a velocity hog... and maybe a 7mm XC or 7mm International AI. Still, nice to have a die set that don't break the bank and doesn't cost you serious barrel life just forming cases...
Have fun!
This is actually my little project for the summer. I looked at other offerings and they didn't really appeal to me. Plus, I have never created my own wildcat from scratch, so I thought it would be fun. The availability of Norma 300 RUM and 7mm Rum brass sealed the deal.
I call it the "7mm Kraken", after the Norse sea monster. Seemed appropriate since the availability of the Scandinavian brass was the motivation...
This is it between a WSM and a RUM:
It has a 0.375" long neck. It was designed to be fed from a 3.850" Accurate Mag .338 Lapua magazine with the new 195 Berger Hybrid EOL, without it going into the donut area. I used the drawings posted by Berger for reference.
I've ordered the reamers, but haven't received them yet. This is the sizing die reamer drawing:
This is the chamber reamer throated for the 195 Hybrid:
This is the reamer throated for the 180 Hybrid (since the 195 is not out yet):
I'm not clambering rifles for this, creating dies, or brass to market or sell. It's just my own little project. Feel free to order the reamers and use them. There is no license or trademark on it. But, keep in mind that I haven't tested them yet.
I call it the "7mm Kraken", after the Norse sea monster. Seemed appropriate since the availability of the Scandinavian brass was the motivation...
This is it between a WSM and a RUM:
It has a 0.375" long neck. It was designed to be fed from a 3.850" Accurate Mag .338 Lapua magazine with the new 195 Berger Hybrid EOL, without it going into the donut area. I used the drawings posted by Berger for reference.
I've ordered the reamers, but haven't received them yet. This is the sizing die reamer drawing:
This is the chamber reamer throated for the 195 Hybrid:
This is the reamer throated for the 180 Hybrid (since the 195 is not out yet):
I'm not clambering rifles for this, creating dies, or brass to market or sell. It's just my own little project. Feel free to order the reamers and use them. There is no license or trademark on it. But, keep in mind that I haven't tested them yet.
I did something similar taking down a 7mm saum 200 thou at the shoulder. Mark spencer of spencer tool and grind made the form die for me it works really well he is a great guy to deal with too. One thing to consider is that if you push the shoulder down on the rum case the brass thickness at the shoulder on your new brass maybe thicker than normal causing a click at top of bolt lift effect, similar to the click caused by tight case head-chamber clearance. I have to anneal after every firing to avoid this problem. Other than the fact that forming brass gets old very quick and losing brass when hunting is tragic :-\ it has worked out very well and is accurate too.
That kind of die is exactly what I have planned for knocking down the shoulder. I'll probably make several of them and just do the conversion on my progressive press, changing it in 5 steps.
you need to anneal after every 2nd step otherwise you get puckering at the shoulders -like this -at least i did. I have found that minor folds "fire out" without issue but if you don't get it right due to major ugly folds (at least in my experience) you will end up ditching 10% of your brass
Yeah, I got a similar thing when converting 270 brass into 6mm Crusader brass. It wasn't as bad when I used 30-06 brass, and reduced both the case mouth diameter and adjusted the shoulder a little bit at each step. I find it happens when you try and make too big of a change in one step. That's why I got the 300 RUM cases instead of 7mm RUM.
I've got a bunch of R.P. cases to use for figuring out the best way to convert the case. Saving the Norma stuff till I've got that hammered out.
I've got a bunch of R.P. cases to use for figuring out the best way to convert the case. Saving the Norma stuff till I've got that hammered out.
I finally got around to making my shoulder set-back die. Works pretty well.
I anneal the case and then knock down the shoulder in 5 steps using progressively smaller bushings that have a 20 degree shoulder angle. Then I anneal the case again and run it into a bushing with a 35 degree shoulder. Forms well, no puckering at all. From this point I would run it into a neck sizer to get rid of the radius at the neck-shoulder junction, then run the expansion mandrel into the mouth, trim it to the proper length and neck turn the case.
Here is the uncut case between a 7mm WSM and a 300 RUM:
I polished it up with a scuff pad to see what it would look like after tumbling. I haven't finished polishing the dies and bushings, so they leave some small scratches.
I'll eventually make a die for each bushing so that I can do the first shoulder setback on one toolhead my XL650. I'll do a second toolhead with the 35 degree shoulder die, a neck die that takes out the radius at the bottom of the neck and an expansion die.
I still haven't received my Go/No-Go gages yet, so I haven't I haven't chambered the rifle for this yet.
I anneal the case and then knock down the shoulder in 5 steps using progressively smaller bushings that have a 20 degree shoulder angle. Then I anneal the case again and run it into a bushing with a 35 degree shoulder. Forms well, no puckering at all. From this point I would run it into a neck sizer to get rid of the radius at the neck-shoulder junction, then run the expansion mandrel into the mouth, trim it to the proper length and neck turn the case.
Here is the uncut case between a 7mm WSM and a 300 RUM:
I polished it up with a scuff pad to see what it would look like after tumbling. I haven't finished polishing the dies and bushings, so they leave some small scratches.
I'll eventually make a die for each bushing so that I can do the first shoulder setback on one toolhead my XL650. I'll do a second toolhead with the 35 degree shoulder die, a neck die that takes out the radius at the bottom of the neck and an expansion die.
I still haven't received my Go/No-Go gages yet, so I haven't I haven't chambered the rifle for this yet.
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.