7mm??? Build

[frequent misser]

How about a 7-300 Norma. 300 Norma brass is now available. I think that just a little more capacity than the rum. Pretty simple neck down and way better brass than the rum.

 

[geargrinder]

How about a 7-300 Norma. 300 Norma brass is now available. I think that just a little more capacity than the rum. Pretty simple neck down and way better brass than the rum.

It takes the big Lapua/Weatherby sized bolt face that many actions can't comfortably handle.

 

[mrultramag]

you sound like you want to build a 7 rum so might as well do it. you might find out what gunsmiths have worked alot with the 7 rum and see if there are any different configurations of throating it that can help extend the life of the throat. I'm not sure what options are available other than the factory style leade (freebore throat). I'm not talking about shortening the free bore but rather the angle of the leade and whatnot... something that may ease the erosion by the hot gases. Also might look into powder options and see if there is credibility that ball powders are easier on throats than coarse stick powders... US869?? Just some thoughts.. BTW I dont shoot long range but my 7 rum has approx 700 rds down the tube and still shoots well as far as groups at 100 from the bench.

 

[brentc]

Please explain.

Most long range rigs are set up as overbore hot rods. Efficiency is not the goal. Heavy bullets at maximum velocity is.

I obviously see things differently. I wouldn't even come close to saying most lrh rigs are overbore hot rods, many are but that's because people think that the "hotrod" is the only way to get out there. Let's take a look at your Edge, or even a Lapua. They are most definitely considered long range rifles capable of delivering massive amounts of energy at great distances but they are by no means a "hotrod" at 2850 fps with the heaviest bullets. You only need to drive the bullet fast enough to capitalize on the ballistic benefits of the bullet you intend to shoot. It's not about how fast we get to the target.

As far as the RUM goes, especially the 7mm RUM, Grit said it perfectly. Tuneability has a lot of merit when it comes to committing a match grade barrel to something you waste half the barrel life on trying to find consistency.

OP, please define your requirements. Why are you opposed to a belt and what are you trying to achieve? How much practical effectiveness do you actually think you will achieve by using 20 extra grains of powder to squeeze out an extra 50 fps over a 7mm/300? There are obviously differing opinions on what the maximum practicality is for a 7mm. If you are going for 1000 yards, which is about the maximum effective range for a 7mm of any type in a hunting situation, any of the 7mm Mags will work. If you need to extend further for hunting, you may as well make the jump to a big 338.

 

[fmajor]

I obviously see things differently. I wouldn't even come close to saying most lrh rigs are overbore hot rods, many are but that's because people think that the "hotrod" is the only way to get out there. Let's take a look at your Edge, or even a Lapua. They are most definitely considered long range rifles capable of delivering massive amounts of energy at great distances but they are by no means a "hotrod" at 2850 fps with the heaviest bullets. You only need to drive the bullet fast enough to capitalize on the ballistic benefits of the bullet you intend to shoot. It's not about how fast we get to the target.

As far as the RUM goes, especially the 7mm RUM, Grit said it perfectly. Tuneability has a lot of merit when it comes to committing a match grade barrel to something you waste half the barrel life on trying to find consistency.

OP, please define your requirements. Why are you opposed to a belt and what are you trying to achieve? How much practical effectiveness do you actually think you will achieve by using 20 extra grains of powder to squeeze out an extra 50 fps over a 7mm/300? There are obviously differing opinions on what the maximum practicality is for a 7mm. If you are going for 1000 yards, which is about the maximum effective range for a 7mm of any type in a hunting situation, any of the 7mm Mags will work. If you need to extend further for hunting, you may as well make the jump to a big 338.

^ That is well said.

 

[geargrinder]

You're right. Our opinions on long range chamberings are different.

Kirby's style of chambering is what I consider adequate for long range hunting.

 

[fmajor]

You're right. Our opinions on long range chamberings are different.

Kirby's style of chambering is what I consider adequate for long range hunting.

Hey grinder i like your Edge! That's a nice looking rig there. What's the stock? I'd guess Manners, but not certain.... She's looker for sure and i'd guess a shooter too!

I wonder if Kirby would advocate for a "both/and" approach given his "Allen Xpress Wildcat's" and "Allen Magnum Wildcats" line-ups?

I sure wish he or Shawn or some of our other notable gunsmiths would chime in (though i see grit has already).

 

[midwesthunter]

I obviously see things differently. I wouldn't even come close to saying most lrh rigs are overbore hot rods, many are but that's because people think that the "hotrod" is the only way to get out there. Let's take a look at your Edge, or even a Lapua. They are most definitely considered long range rifles capable of delivering massive amounts of energy at great distances but they are by no means a "hotrod" at 2850 fps with the heaviest bullets. You only need to drive the bullet fast enough to capitalize on the ballistic benefits of the bullet you intend to shoot. It's not about how fast we get to the target.

As far as the RUM goes, especially the 7mm RUM, Grit said it perfectly. Tuneability has a lot of merit when it comes to committing a match grade barrel to something you waste half the barrel life on trying to find consistency.

OP, please define your requirements. Why are you opposed to a belt and what are you trying to achieve? How much practical effectiveness do you actually think you will achieve by using 20 extra grains of powder to squeeze out an extra 50 fps over a 7mm/300? There are obviously differing opinions on what the maximum practicality is for a 7mm. If you are going for 1000 yards, which is about the maximum effective range for a 7mm of any type in a hunting situation, any of the 7mm Mags will work. If you need to extend further for hunting, you may as well make the jump to a big 338.

You have to remember I plan on shooting a 33" barrel so 50 fps difference I would say is off. Plan to shoot the new berger 195, or if wait is too long the 200 wildcat that I already have. Running the 195 at around 3200 with there est BC's it will run right with the big 338's out to 1500, with exception of energy, it will still have over 1500# at 1500 yards.

I'm still not sold on the RUM, as I have a 30" barrel as well that was thinking of doing a 7 REM Mag before I got this barrel. I was wanting to avoid the belted cases to just avoid some of the problems that can come with them.

 

[fmajor]

I gotta say i'm a big fan of the 7mm bore. It does well with long-range performance (trajectory essentially) and is easy to make hot-rod loadings for it without extreme increases in felt recoil.

However, with *all* calibers we run into the problem of powder burning out the barrel/throat when we're trying to get lazer-like trajectories. With radical increases in powder load (to achieve higher velocity), the throat can burn out so fast it can be challenging to develop the most accurate/most velocity before deterioration creates an unstable evaluation platform.

If extra barrel length helps that's great, but i believe the barrel length diminishing return is dependent on maximum powder charge - ie a 22-250 will achieve maximum powder-charge burn in a shorter barrel than say a 416 RUM.

 

[geargrinder]

Hey grinder i like your Edge! That's a nice looking rig there. What's the stock? I'd guess Manners, but not certain.... She's looker for sure and i'd guess a shooter too!

It's a Stockade Pdog/Tactical. A few years ago, when I got it, it was about the only option for left hand Savages.

 

[fmajor]

Thanks! I've seen their stocks one time before, but have never handled one. Looks like a really nice stock.

 

[midnightmalloy]

You have to remember I plan on shooting a 33" barrel so 50 fps difference I would say is off. Plan to shoot the new berger 195, or if wait is too long the 200 wildcat that I already have. Running the 195 at around 3200 with there est BC's it will run right with the big 338's out to 1500, with exception of energy, it will still have over 1500# at 1500 yards.

I'm still not sold on the RUM, as I have a 30" barrel as well that was thinking of doing a 7 REM Mag before I got this barrel. I was wanting to avoid the belted cases to just avoid some of the problems that can come with them.

Good luck waiting on the berger 195's. they said here they would be out last may. Still no one at berger can give a solid date. I lost $100 exchanging (selling then buying a new one) to just have it still not on the market.

If u want no belt and u have a mag bolt face without using a rum size case i will say again use the 7 lrm from gunwerks.

If you can use a .595 bolt face a 7/300 norma is a better choice than the rum and doesnt have the length problems of the rum.

If you are a tinkerer then make the 7mm version of elkahollics 30/375 s.i.

Other than that within your requirements im out of ideas.

 

[shawnb]

With that length of barrel, if it were me, I would chamber in the 7lrm. I love the 7rem mag but the length is askin for more powder. I say the 7lrm because its not so overboar that it will burn a barrel fast but also let you set the barrel back a couple of times if possible to still be efficient in a ~26" barrel.

Not sure if a barrel can be set back more than once but at 33" it might be depending on contour I guess.