Looking for some 7mm info

[shorttrac]

Who says the pressure signs weren't a true indication of excessive pressure? I observed excessive case head expansion, and my chronograph told me that I was exceeding the velocities listed in the manual, so the pressure could very likely have been excessive. Now if you choose to believe that loading to produce 80,000-90,000psi or more is safe, then by all means, keep loading to those levels, and perhaps you won't have a case rupture, or have something fatigue over time, and let go in your face. However, don't pretend that just because you haven't had a failure yet, that loading to those pressures is safe.

I don't think anyone here assumes loading to 80-90k is safe nor needed for the op to achieve his goal. What I think is being said is that is running running the same pressures as a rum or slightly more to achieve your result with reasonable case life is not dangerous. I am pretty sure the safety margin is quite large. Now I say this if you are an experienced hand loader and know what signs to look for. For me if ejector marks show up that is a sign to back off at least 5%.

I don't condone my reloading practices to newbies but pushing the "limits" a bit gave me a good amount of knowlage on what to expect and has taught me some very consistent things to look for when I know I'm pushing it to far.

 

[stubblejumper]

I don't think anyone here assumes loading to 80-90k is safe

If you cases are no longer usable after as few as three firings, as one poster stated, you are likely producing significantly more than the 60,000 to 65,000 psi that SAAMI is listing for those cartridges. To even produce the velocities that certain posters are claiming for various cartridges, you would need to be producing pressures in the 80,000+psi range.

 

[c-fbmi]

stubble..........the brass case won't take 80K psi, sorry it is not possible to load to these pressures and reuse your brass. 3-5 firings with the W-W brass that I use means I'm likely in the 72-75K psi range, this is the reusable threshold for W-W brass, according to all my calculations. With modern bolt actions these pressures are safe indefinitely. Until such time as someone comes up with a better pressure vessel than the brass case, we are all safe as long as the case contains the pressure and can be reused several times. I'm not exactly new to this stubble, and after 40 years of reloading, I think I know how to read a case and adjust loads accordingly. As far as what "certain posters are claiming" (you obviously mean me), I have photographed my Mod 35P printed tapes and the case heads for a lot of what I have "claimed here" and posted them for all to see. The primers are still intact and very few even have ejector marks, and all were reusable, so I don't know what more I can do to show that what I "claim" is fact.....

 

[Gatehouse]

Before rebarrelling or rechambering, I would just shoot the thing and see what results you get both over the chronograph and on the target at whatever distance you want to shoot to. You may find you are happy with the results and not need to go to great lengths.

 

[dfrombc]

Before rebarrelling or rechambering, I would just shoot the thing and see what results you get both over the chronograph and on the target at whatever distance you want to shoot to. You may find you are happy with the results and not need to go to great lengths.

You're right, I should shoot the thing before having it torn apart. I just feel I'm going to end up wanting to modify it anyway. If I decide to change the cartridge I'd rather not set up to reload the 7mm rem mag. Is anybody running a 22" barrel on their 7mm rem mag?
How's the performance with the heavies?

 

[1899]

You're right, I should shoot the thing before having it torn apart. I just feel I'm going to end up wanting to modify it anyway. If I decide to change the cartridge I'd rather not set up to reload the 7mm rem mag. Is anybody running a 22" barrel on their 7mm rem mag?
How's the performance with the heavies?

I have one with a 26" barrel and one with a 25" barrel and my friend has one with a 24" barrel. The 24" barrel, which is a 1:8.5 twist 5R Krieger, is faster by ~50 fps than the longer barrels.

 

[brybenn]

Simplest way to get a 180 gr to 3000 fps safely. Buy a 300 Wm


As for the brass issue I've used Remington brass that wouldn't hold a primer after 3 loads and I was using 46 grs varget under a 75 gr bullet in 2506. A very soft load but accurate. Switched to Winchester brass and up to 49.4 grs varget and can simply neck size for 7 loadings before I have to push the shoulder back. After 10 loadings the primer pocket is just starting to feel not as tight

 

[1899]

I too have had great luck with W-W brass in the 7mm RM.

 

[Boomer]

I looked around a bit to see who makes a 7mm/180 and could only come up with Berger. If you want to make a bullet as long as possible, the VLD is the way to go, whereas if you want to make a bullet as short as possible, it should be a flat base, design with parallel sides and a hemispherical nose. A flat base 7mm/180 gr big game bullet should be short enough to stabilize in a standard twist barrel, but Berger states that a minimum twist of 1:9 is required to stabilize his 7mm/180 VLD. Tikka's 1:9.5 twist for the 7 mag will probably only produce marginal stability, meaning that in other than ideal conditions the bullet will show unreasonable yaw and produce uninspiring accuracy and inconsistent terminal performance. Shooting at low altitudes, shooting in cold temperatures, shooting lighter than maximum loads, shooting from short barrels that cannot produce sufficient velocity, or shooting beyond 300 yards, will all have an effect on bullet stability to varying degrees under varying circumstances.

As I see it, you have two choices; you can either use bullets that are more appropriate to your rifle in its current form, or you can purchase a 26" pipe with a 1:8 twist, which can then be chambered for any 7mm cartridge you like. Keep in mind, that the Berger manual does not predict 3000 fps with this bullet from any of the cartridges they provide data for, with the exception of the 7.21 Lazzeroni Firebird. I shudder to think what Lazzeroni brass might cost after choking on Nosler .280 Ackley brass for $2/ea.

What you hope to gain with this level of performance over the 7 Mag's 2800 fps is unclear, as it would be unlikely that you could make use of the difference in trajectory under real conditions. Given a 200 yard zero, the difference in drop between a 7mm/180 VLD at 3000 fps or at 2800 is 1" at 300 yards. At 500 yards the difference is 6". At 700 yards the difference is 2 minutes and at 1000 yards the difference in drop is 4 MOA. The limiting factor at long range is not velocity, rather its the accuracy of your rifle and ammo combination, and the limits and consistency of the your scope adjustments.

 

[mudpro]

You can always go 7x300wsm and run it in your long action with a custom reamer so they can be seated deep. Lots of longrange guys doing it. Or a 284win on a long action with relaoder 17 will get you to 3000fps.