Cartridge for 18" barrel?

[ImBillT]

On the 3rd reloading with no issues with brass.




No. 3050 fps with a 140 grain TTSX out of a 22" barrel with 7x57 AI. I could probably go up to 3100 without any pressure signs, but accuracy is excellent at 3050. Getting 2650 with 250 grain round nose Hornady's with the 35. 2400 FPS with 250 & 286's in the 9.3. Both the 35 & 9.3 are stout in recoil.

3rd total, or 3rd after the shoulders were fully formed?

Norma brass will start getting tight and showing ejector marks before Federal or S&B primers start getting flat, so you may or may not have as much room to increase that load as you think.

You’re 100fps behind a standard 280Rem using, Nosler datawith your current load, so I would highly doubt that you could knock at the door of a .280AI.

@VikingsGuy
7-08 looses 21fps/“ so load data suggests that if you stay within pressure specs you might just barely eek out 2500fps. Pushing pressure in Lapua brass or using coated bullets could help get you there. A 7x57 or 7-08AI could both give you just enough to hit 2500fps without being hard on brass and without having to find the exact perfect powder. Neither is a substantial improvement(in terms of velocity) over a standard 7-08.

280Rem should lose about 27fps/“ so using load data says you’ll top out around 2650fps. That’s a substantial improvement over a 7-08. A 7x57AI would get close, but likely not equal if pressures were equal.

A 280AI loses about 29fps/“ so that would give you 2750fps, 2800fps with the top powder using Nosler data.

All of the above are assuming an 18” barrel, staying within book max, and using a 168gr bullet.

 

[brocksw]

vikingsguy I'd pick 2 or 3 bullets you have mind (sorry if you've discussed them already). Then run their BCs through a calculator and see what kind of speed you need to comfortably shoot them at your desired distance. That should give you your answer as to what cartridge you want to go with. If you're looking at 140-150 monos with bullets that don't have fantasic BCs, you might end up going with a bigger cartridge than I've seen listed in this thread. Allow yourself some wiggle room so if your bullet drops end up coming up short of advertised BC you'll still have plenty of speed.

With my 140-150 monos I hold to the same minimum 2000 fps rule. Some of the hammer bullets won't get you to 4 or 500 yards before dropping below 2k fps. Run your numbers.

 

[ImBillT]

vikingsguy I'd pick 2 or 3 bullets you have mind (sorry if you've discussed them already). Then run their BCs through a calculator and see what kind of speed you need to comfortably shoot them at your desired distance. That should give you your answer as to what cartridge you want to go with. If you're looking at 140-150 monos with bullets that don't have fantasic BCs, you might end up going with a bigger cartridge than I've seen listed in this thread. Allow yourself some wiggle room so if your bullet drops end up coming up short of advertised BC you'll still have plenty of speed.

With my 140-150 monos I hold to the same minimum 2000 fps rule. Some of the hammer bullets won't get you to 4 or 500 yards before dropping below 2k fps. Run your numbers.

He needs 2500fps at the muzzle to get a 168gr 7mm with a high BC to 450yds above 2000fps at sea level and 58 degrees. He will also need a bullet heavier than 150gr to meet his energy requirement unless he increases velocity substantially(2750 will meet his 450yd
velocity requirement, but it would take 2900fps at the muzzle to meet his 450yd energy requirement) Hence the suggestion that he use a 168gr or heavier bullet and that a standard 7-08 was on the ragged edge of his requirements. Reducing his range to 400yds, or going with something just a hair bigger than a 7-08 will make meeting his energy and velocity requirements easier.

A standard 7-08 should actually meet his requirement if his bullet has enough BC, but he will be limited to only a few powders and will be near max pressure, and thus potentially hard on brass. With a 280AI his requirements can be met even with 150gr bullets, with most powders, and without pushing things too hard.

 

[brocksw]

He needs 2500fps at the muzzle to get a 168gr 7mm with a high BC to 450yds above 2000fps at sea level and 68 degrees. He will also need a bullet heavier than 150gr to meet his energy requirement unless he increases velocity substantially. Hence the suggestion that a standard 7-08 was on the ragged edge of his requirements. Reducing his range to 400yds, or going with something just a hair bigger will make meeting his energy and velocity requirements easier.

Yep just depends on the bullet.

Keep in mind Vikingsguy, if you havent already ordered your barrel. A 170ish class bullet in copper will require a tighter twist than it will in a cup and core. So like I said, start with the bullet. Then build the rifle.

 

[ImBillT]

Yep just depends on the bullet.

Keep in mind Vikingsguy, if you havent already ordered your barrel. A 170ish class bullet in copper will require a tighter twist than it will in a cup and core. So like I said, start with the bullet. Then build the rifle.

As long as he is hunting a fair bit above sea level, a 1-8” twist will stabilize almost all 7mm bullets, including a 170gr mono. Even at sea level it would likely be accurate but give up a little BC to tip wobble.

I’m not sure there is a 7mm bullet that will not have full BC from a 1-8” twist as long you’re 3000’ or higher.

 

[winmag]

After looking at some numbers, I don't think you'll quite get there with a 7-08AI, even with Absolute Hammers. Looks like folks are getting 2995fps with the 130gr AH in 18" barrel 7-08AI, and that won't meet your energy requirement.

And solid copper projectiles >140gr are going to eat up way too much case capacity in a 7-08 to be a viable option.

You'll get there with 280AI.

 

[brocksw]

As long as he is hunting a fair bit above sea level, a 1-8” twist will stabilize almost all 7mm bullets, including a 170gr mono. Even at sea level it would likely be accurate but give up a little BC to tip wobble.

I’m not sure there is a 7mm bullet that will not have full BC from a 1-8” twist as long you’re 3000’ or higher.

I would agree, only a couple that wouldnt. A 1 in 8 should cover you for mono and heavy cup and core. Honestly, I'd see no reason to do a more common 1 in 9 or 9.5 like is found in many factory rifles.

 

[brocksw]

After looking at some numbers, I don't think you'll quite get there with a 7-08AI, even with Absolute Hammers. Looks like folks are getting 2995fps with the 130gr AH in 18" barrel 7-08AI, and that won't meet your energy requirement.

And solid copper projectiles >140gr are going to eat up way too much case capacity in a 7-08 to be a viable option.

You'll get there with 280AI.

That was kind of my suspicion as well. You'd have to have the smith add a lot of freebore in the 08 and you still might not get there.

Hammer's don't always have the greatest BC either so something to keep in mind.

280 ai would be a fine choice imo. Same with a 7 saum. Those would be the top two I'd look at it if you didnt want to go wildcat.

 

[winmag]

You'd have to have the smith add a lot of freebore in the 08 and you still might not get there.

I had a similar thought, since the Tikka mag box is generous for short action. But then you might as well just do a 280AI at that point.

 

[brocksw]

I had a similar thought, since the Tikka mag box is generous for short action. But then you might as well just do a 280AI at that point.

Right. Can always load the ackley light...real tough to safely load more than what a given cartridge/rifle wants to give you.

 

[ImBillT]

I would agree, only a couple that wouldnt. A 1 in 8 should cover you for mono and heavy cup and core. Honestly, I'd see no reason to do a more common 1 in 9 or 9.5 like is found in many factory rifles.

I bet you can’t name one that won’t have full BC at 3000’ from an 8” twist.

 

[brocksw]

I bet you can’t name one that won’t have full BC at 3000’ from an 8” twist.

Off the top of my head....Badlands precision bulldozer 2 in 160 gr

And the 180 gr cutting edge MTH

 

[ImBillT]

After looking at some numbers, I don't think you'll quite get there with a 7-08AI, even with Absolute Hammers. Looks like folks are getting 2995fps with the 130gr AH in 18" barrel 7-08AI, and that won't meet your energy requirement.

And solid copper projectiles >140gr are going to eat up way too much case capacity in a 7-08 to be a viable option.

You'll get there with 280AI.

I hadn’t really thought of the case capacity issue with monos. A 168gr mono is going to eat case capacity, and he’s going to have a tough time meeting the energy requirement with a lighter bullet from a standard 7-08.

 

[ImBillT]

Off the top of my head....Badlands precision bulldozer 2 in 160 gr

And the 180 gr cutting edge MTH

The bulldozer 2 loses 2%.

The Cutting Edge maintains full BC

 

[brocksw]

The bulldozer 2 loses 2%.

The Cutting Edge maintains full BC

So you're saying I'm 1 for 2 on the requirements you set without even looking hard?

Cool I'll take it.

 

[VikingsGuy]

3rd total, or 3rd after the shoulders were fully formed?

Norma brass will start getting tight and showing ejector marks before Federal or S&B primers start getting flat, so you may or may not have as much room to increase that load as you think.

You’re 100fps behind a standard 280Rem using, Nosler datawith your current load, so I would highly doubt that you could knock at the door of a .280AI.

@VikingsGuy
7-08 looses 21fps/“ so load data suggests that if you stay within pressure specs you might just barely eek out 2500fps. Pushing pressure in Lapua brass or using coated bullets could help get you there. A 7x57 or 7-08AI could both give you just enough to hit 2500fps without being hard on brass and without having to find the exact perfect powder. Neither is a substantial improvement(in terms of velocity) over a standard 7-08.

280Rem should lose about 27fps/“ so using load data says you’ll top out around 2650fps. That’s a substantial improvement over a 7-08. A 7x57AI would get close, but likely not equal if pressures were equal.

A 280AI loses about 29fps/“ so that would give you 2750fps, 2800fps with the top powder using Nosler data.

All of the above are assuming an 18” barrel, staying within book max, and using a 168gr bullet.

My standard 7mm08 shooting 134 grain hammers with no pressure signs and Nosler (is that just rebranded Norma?) brass is giving me 2950 in a 22.4" barrel. If I give up 4.4" @ 21/inch that leaves me at 2850. I assume moving up to 144 grain hammers but going up to 7x57AI powder charges should keep me in the 2800's. But who knows - the devil always lies in the actual field use.

 

[VikingsGuy]

vikingsguy I'd pick 2 or 3 bullets you have mind (sorry if you've discussed them already). Then run their BCs through a calculator and see what kind of speed you need to comfortably shoot them at your desired distance. That should give you your answer as to what cartridge you want to go with. If you're looking at 140-150 monos with bullets that don't have fantasic BCs, you might end up going with a bigger cartridge than I've seen listed in this thread. Allow yourself some wiggle room so if your bullet drops end up coming up short of advertised BC you'll still have plenty of speed.

With my 140-150 monos I hold to the same minimum 2000 fps rule. Some of the hammer bullets won't get you to 4 or 500 yards before dropping below 2k fps. Run your numbers.

Yup - I mess around with JBM quite a bit. I tend to either hunt in the mountain west (so start with 3500 ft elevation as a generic starting point) and MN - which is more like 900 ft elevation - but in MN we are talking 50yd shots out of tree stand (or a "long" 150 yard shot along a tree line) with a 30-30 so any of these would handle that.

 

[VikingsGuy]

A standard 7-08 should actually meet his requirement if his bullet has enough BC, but he will be limited to only a few powders and will be near max pressure, and thus potentially hard on brass. With a 280AI his requirements can be met even with 150gr bullets, with most powders, and without pushing things too hard.

For hunting I don't put enough rounds done field per year to worry about brass life - just safety.

 

[ImBillT]

My standard 7mm08 shooting 134 grain hammers with no pressure signs and Nosler (is that just rebranded Norma?) brass is giving me 2950 in a 22.4" barrel. If I give up 4.4" @ 21/inch that leaves me at 2850. I assume moving up to 144 grain hammers but going up to 7x57AI powder charges should keep me in the 2800's. But who knows - the devil always lies in the actual field use.

Even at 2800fps you’re nowhere near your energy requirement at 450yds. You need a heavier bullet or substantially more velocity.

Nosler WAS rebranded Norma. They’ve started making their own, so it depends.

 

[VikingsGuy]

Even at 2800fps you’re nowhere near your energy requirement at 450yds. You need a heavier bullet or substantially more velocity.

Nosler WAS rebranded Norma. They’ve started making their own, so it depends.

JBM has me at 420yds 2165fps 1500ftlbs with 144gn Hammer Hunter (G2=.230) @ 2850fps and 3500ft elevation. At 450yds it gives me 2120fps and 1440ftbls - close enough for govt. work as they say. So for my purposes, it sounds like 7x57AI, 7SAUM and 280AI can get me there on paper.