7mm-08 and monometals - GMX, TSX, etc

Suther

Suther

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Just bought a 7mm-08. I haven't decided on what I am going to use in it yet (haven't even gotten it in the mail yet) but the only 7mm pill on my shelf is the 139gr GMX. Anyone else using this bullet in the 7mm-08? What sort of velocities can you get with it? I've seen some threads lately of some very impressive 7mm-08 loads, but those were with traditional copper and lead bullets not monometals. I've also heard that monometal bullets in the 7mm-08 show pressure signs at lower velocities than their traditionally constructed brethren. Hornady has two Superformance loads, and the GMX load is slower than the SST load from the same line (2910 vs 2950 fps).

So, what sort of velocity are you getting in 7mm-08 with monometal bullets?
 
billbmcleod said:
I think if it is coming out of the pipe at 2900 fps that is more than enough unless you like to push the limits. But that is just me and my 7-08 Rem 700.
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2900fps sounds on the high side from what I've seen for ~140gr monometals in the 7mm-08. What powder are you using?

That would be plenty of speed if I can get there though.
 
Ten years ago (in preparation for a goat hunt) I developed a good load for a Kimber 84M in 7-08 using the 140 grain Barnes TSX.

Average velocity with H414 was 2,815 fps with five-shot groups averaging 1-1/4" (with the first three in 5/8") at 100 yards off sandbags.

Previous experience with that bullet in the 7x57 was excellent on African plains game (including kudu) and bull elk back home.
 
120gr TSX, Varget, 43.0 gr, 100 jump, group.301, velocity 3074 22" factory savage barrel. This will get the job done on anything that walks in our neck of the woods under 200 yards IMO.

I tried the 139 GMX, 40.5gr was best, but tried up to 42.0gr varget and ran into too much pressure there and abandoned it. The 120s were just performing much better so stuck with them.

Elky....
 
Suther, I've been using the 139 GMX for a Mod 7 Remington, fitted with a 22 in take off Rem factory bbl.

I use 46.6 grains of W748, over a CCI 250 primer, in a Lapua case. CAUTION THIS LOAD IS OVER MAX IN MOST MANUALS.

This load does cause primers to flatten, with a slightly rounded edge in my rifle, which has very tight chamber specs. I have to use small base dies to reload for it.

Velocity is around 2800+fps.

I went with this load because it was the most accurate of all that I tried, MOA- out to 350 yards

In my rifle, this bullet fouls enough that it starts to lose acceptable accuracy after 25 or less rounds, groups open up to 1.5 MOA.

A young friend has a Tikka T3, that he uses the same exact recipe in. Like most T3s, jacket fouling isn't an issue.

Right out to 350 yards, these bullets expand reliably on Moose, going through ribs on each side of the lungs, leaving a one inch exit hole.

I wasn't at the kill site to see the hole in the hide, apparently the bullet just carried on.
 
bearhunter said:
Suther, I've been using the 139 GMX for a Mod 7 Remington, fitted with a 22 in take off Rem factory bbl.

I use 46.6 grains of W748, over a CCI 250 primer, in a Lapua case. CAUTION THIS LOAD IS OVER MAX IN MOST MANUALS.

This load does cause primers to flatten, with a slightly rounded edge in my rifle, which has very tight chamber specs. I have to use small base dies to reload for it.

Velocity is around 2800+fps.

I went with this load because it was the most accurate of all that I tried, MOA- out to 350 yards

In my rifle, this bullet fouls enough that it starts to lose acceptable accuracy after 25 or less rounds, groups open up to 1.5 MOA.

A young friend has a Tikka T3, that he uses the same exact recipe in. Like most T3s, jacket fouling isn't an issue.

Right out to 350 yards, these bullets expand reliably on Moose, going through ribs on each side of the lungs, leaving a one inch exit hole.

I wasn't at the kill site to see the hole in the hide, apparently the bullet just carried on.
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Good to hear, as I've got a moose hunt coming up in September and thats exactly what I'll be loading this rifle for!

I use 130gr Interbonds in my 270win, and I bought a box of 139gr GMX's to spit at ludicrous speed from a 7mm Rem Mag but I sold that rifle to buy myself a left-handed hunting rifle (which is what the 7mm08 is). So now I have this box of bullets, and if I'm feeding my family going lead-free certainly wont hurt things, I just wanted to see what sort of velocity other people are getting because I've read that they tend to show pressure signs earlier than lead bullets in this particular cartridge for whatever reason.
 
Suther said:
Good to hear, as I've got a moose hunt coming up in September and thats exactly what I'll be loading this rifle for!

I use 130gr Interbonds in my 270win, and I bought a box of 139gr GMX's to spit at ludicrous speed from a 7mm Rem Mag but I sold that rifle to buy myself a left-handed hunting rifle (which is what the 7mm08 is). So now I have this box of bullets, and if I'm feeding my family going lead-free certainly wont hurt things, I just wanted to see what sort of velocity other people are getting because I've read that they tend to show pressure signs earlier than lead bullets in this particular cartridge for whatever reason.
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The original Barnes monometal "X Bullet" had a reputation for pressure issues because of the relative hardness of the metal (compared to lead or cup and core bullets) and the amount of bearing surface the bullets had.
The later TSX and TTSX bullets were made with what look like "driving bands" built into the the bullet. It's apparently a good solution as it is also used in the Hornady GMX bullet.

Penetration is excellent with both bullets.
 
A-zone said:
The original Barnes monometal "X Bullet" had a reputation for pressure issues because of the relative hardness of the metal (compared to lead or cup and core bullets) and the amount of bearing surface the bullets had.
The later TSX and TTSX bullets were made with what look like "driving bands" built into the the bullet. It's apparently a good solution as it is also used in the Hornady GMX bullet.

Penetration is excellent with both bullets.
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Thanx for this A-zone.

I should have included your info in my response. It's one of those things I'm so familiar with, that I just assume most folks know.

I should always remember that such things aren't always obvious.
 
billbmcleod said:
What I was saying and I guess not that well is that you don't really need that 2900 fps. I run in the low 2800's.
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Thanks for the clarification.

Seems just over 2800fps is pretty much standard. I can live with that. If I need more speed I can always go down to the 120gr tsx... Or just load the 110gr TSX i have in my 270, should be able to get 3300+ fps with them! Lol
 
Suther said:
Thanks for the clarification.

Seems just over 2800fps is pretty much standard. I can live with that. If I need more speed I can always go down to the 120gr tsx... Or just load the 110gr TSX i have in my 270, should be able to get 3300+ fps with them! Lol
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I expect that a monometal 120 grain 7mm bullet would perform very well. Because copper is less dense than lead, the physical size would be similar to a conventional 140 grain jacketed bullet.

The idea that "speed influences expansion" was demonstrated for me with 350 grain TSX bullets in the .375 H&H. They expanded a little bit in soft tissue (in giraffe) but otherwise behaved more like a solid. Going with a lighter bullet (like a 270 gr TSX) probably would have produced better expansion, more like a jacketed controlled-expansion 300 grain .375" bullet.

I haven't had good accuracy with the 120gr TSX in the 7x57, although the 140 grain version has been very accurate. So, if you can get it to shoot, I'd say "try the 120 gr". It can be hard to shake the "heavier bullets penetrate better" approach.
 
I use the 120gr TTSX, would have to check my book for what powder though. I was getting 3125fps with 22" barrel and I don't believe that was a max load or had pressure signs. I haven't chrono'd it since I chopped 2" off the barrel.
 
If you want to rip on the 7-08, use a short thicker jacketed bullet like a 120 Sierra Prohunter or 120 Nosler BT. These bullets are stout, can be driven fast, are cheaper and will burn through deer sized game. These bullets have decent heavy jackets that will knock over silhouettes as well.
 
A-zone said:
I expect that a monometal 120 grain 7mm bullet would perform very well. Because copper is less dense than lead, the physical size would be similar to a conventional 140 grain jacketed bullet.

The idea that "speed influences expansion" was demonstrated for me with 350 grain TSX bullets in the .375 H&H. They expanded a little bit in soft tissue (in giraffe) but otherwise behaved more like a solid. Going with a lighter bullet (like a 270 gr TSX) probably would have produced better expansion, more like a jacketed controlled-expansion 300 grain .375" bullet.

I haven't had good accuracy with the 120gr TSX in the 7x57, although the 140 grain version has been very accurate. So, if you can get it to shoot, I'd say "try the 120 gr". It can be hard to shake the "heavier bullets penetrate better" approach.
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139GMX is whats on the shelf now (have a box left after I bought a 7mag then decided to switch to lefty guns) so thats what I'm going to start with. If I can get 2800fps and MOA I'll call that good to go! If I can't get them to shoot, then I'll start looking at other options.

After that it becomes time to develop el cheapo load! (something cheap for range fodder)
 
Suther said:
Thanks for the clarification.

Seems just over 2800fps is pretty much standard. I can live with that. If I need more speed I can always go down to the 120gr tsx... Or just load the 110gr TSX i have in my 270, should be able to get 3300+ fps with them! Lol
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I'm not saying that the 120 grn bullets won't do the job, but a 140 grn bullet will do it better, simply because the bullet will penetrate all the way through both sides on a boiler room shot, right out to 300 yds on a moose
 
bearhunter said:
I'm not saying that the 120 grn bullets won't do the job, but a 140 grn bullet will do it better, simply because the bullet will penetrate all the way through both sides on a boiler room shot, right out to 300 yds on a moose
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Oh for sure. For my moose hunt this year a 140gr at 2800+ sounds like a fantastic choice. I was meaning in general if I decide I want more velocity... Of course, if I really need more velocity thats a good excuse to buy another rifle... Just not now. I don't even have this one in my hands yet! lol
 
Suther said:
Oh for sure. For my moose hunt this year a 140gr at 2800+ sounds like a fantastic choice. I was meaning in general if I decide I want more velocity... Of course, if I really need more velocity thats a good excuse to buy another rifle... Just not now. I don't even have this one in my hands yet! lol
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I agree with that model.

I have three different range tables stuck on the right side of the butt of my Mod 7, for the trajectory of the three different bullets I load for it.

Each has the scope dial increments for POI at 200 yards. It's also on each box of loaded cartridges.

Whenever I change bullet weights, I return the scope to it's CENTER SETTING, then adjust to the setting on the appropriate panel.

It works well, both in the field and at the range. It's proven to be consistently repeatable with the Leupold variX III, 3x9x40.
 
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