Hard to beat the 7mm-08ai?

[Highvoltage1]

I had a 7-08ai built last year. Used a 24” proof barrel with Mesa precision altitude CF stock. Topped with Zeiss 4-16x44 V4 it’s 8.2lbs. I’m loving it. Currently using 140gr absolute hammers at 2946 FPS and 168 Berger VLDs at 2705FPS.

What twist and what powder on those 168s?

 

[longbarrel]

Ackley Improved cartridges are trendy but back to back tests vs. standard have repeatedly showed that most of the gains are from running higher pressures, not the slight increase in case volume.
Increasing the powder charge from using a bigger case does help velocity of course, but a longer barrel helps too. Rather than seeking a magic velocity increase from the case, I would blend case size with barrel length, In Hatcher's Notebook, early tests on the ,30-06 using the less capable powders of the time, still good velocity gains were had going all the way to 29".
Asking a guy who insists that short barrels are far more handy, what does his cousin Bubba use in the woods? The reply is his 30" full choke with punkin' balls. So much for short. After all, bull elk RUN through those thick woods somehow, despite having huge antlers.
I have used rifles with barrel lengths from 18" to 29" and appreciate the performance increases from the longer barrels without increasing the powder charge.

 

[Northpark]

What twist and what powder on those 168s?

I use Staball 6.5 over a Fed210m in Nosler brass. I have an 8 twist barrel.

 

[HeavyForCaliber]

"Good for short barrels" can mean different things. To my thinking it means burning almost all of the powder before the bullet exits, avoiding excessive blast, recoil, and flash. Like the bore/stroke ratio in an engine, cases which are fatter and shorter have faster flame travel and can use faster powders for a given pressure and powder volume. This is good for short barrels where the bullet leaves quickly, so it is hard to beat the 7mm-08 at 18" without getting fatter. E.g. going from 7mm-08 to 280 (longer version of the same case) increases velocity, but not efficiently. On the other hand the 284W is fatter than the 7mm-08 but also longer, and 18" looks a little short to use the extra powder well. There are some great 7mm bullets that will work down to 1800 fps, so 7mm-08 AI is a nice balance at 18" and keeps you in a short action.

I got QuickLoad to simulate some of these tradeoffs, the output is below for a 18" barrel. 20" favors the larger cartridges and slower powders. QL is conservative but helps with comparisons. I couldn't attach the files so I just put the Hodgdon powders. Pmuzz relates to pressure at the muzzle (blast). From my testing, 10kpsi is my threshold between "normal/quiet" and "loud". Prop.Burnt % relates to flash if you care.

Predicted Data for Indicated Charges of the Following Powders. Matching Maximum Pressure: 52666 psi, or 363 MPa or a maximum loading ratio or filling of 115 % These calculations refer to your specified settings in QuickLOAD 'Cartridge Dimensions' window. C A U T I O N : any load listed can result in a powder charge that falls below minimum suggested loads or exceeds maximum suggested loads as presented in current handloading manuals. Understand that all of the listed powders can be unsuitable for the given combination of cartridge, bullet and gun. Actual load order can vary, depending upon lot-to-lot powder and component variations. USE ONLY FOR COMPARISON ! Cartridge : 7 mm-08 Ack. Imp. Rem. Bullet : .284, 140, Nosler Partition SP 16325 Useable Case Capaci: 51.975 grain H2O = 3.375 cm³ Cartridge O.A.L. L6: 2.800 inch = 71.12 mm Barrel Length : 18.0 inch = 457.2 mm Powder Fill/Load Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time Type % Grains Gramm fps % psi psi ms -------------------- ----------------------------------------------------------------- Hodgdon H414 96.0 48.7 3.15 2675 94.0 52667 13229 1.005 ! Near Maximum ! Hodgdon CFE223 *C 91.5 47.8 3.10 2673 97.2 52667 12946 1.005 ! Near Maximum ! Hodgdon Hybrid 100V 104.2 48.3 3.13 2661 98.7 52667 12382 1.003 ! Near Maximum ! Hodgdon H380 92.8 45.5 2.95 2628 96.6 52667 12444 1.022 ! Near Maximum ! Hodgdon H4831 SC *T 107.0 51.8 3.36 2624 88.1 52667 12661 0.997 ! Near Maximum ! Hodgdon H4831 *T 111.3 51.8 3.36 2624 88.1 52667 12661 0.997 ! Near Maximum ! Hodgdon H4350 *T 102.8 48.2 3.12 2615 93.0 52667 12301 1.006 ! Near Maximum ! Hodgdon VARGET *T 93.7 43.4 2.81 2607 97.7 52667 11884 1.008 ! Near Maximum ! Hodgdon H1000 *T 115.0 54.5 3.53 2528 84.9 47376 12562 1.044 Hodgdon Retumbo 115.0 55.4 3.59 2433 84.9 40159 12971 1.133 Hodgdon H870 115.0 56.9 3.69 2288 72.4 35149 11823 1.210 Hodgdon 50BMG 115.0 55.9 3.62 2199 60.0 35255 10057 1.212 Hodgdon US 869 115.0 58.7 3.80 2192 63.2 35048 10118 1.218 Cartridge : .284 Win. Bullet : .284, 140, Nosler Partition SP 16325 Useable Case Capaci: 57.561 grain H2O = 3.737 cm³ Cartridge O.A.L. L6: 2.800 inch = 71.12 mm Barrel Length : 18.0 inch = 457.2 mm Powder Fill/Load Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time Type % Grains Gramm fps % psi psi ms -------------------- ----------------------------------------------------------------- Hodgdon H414 93.9 52.7 3.41 2764 96.0 55840 14517 0.992 ! Near Maximum ! Hodgdon Hybrid 100V 101.7 52.2 3.38 2741 99.6 55840 13385 0.991 ! Near Maximum ! Hodgdon H4831 SC *T 105.0 56.3 3.65 2728 90.9 55840 14109 0.981 ! Near Maximum ! Hodgdon H4831 *T 109.2 56.3 3.65 2728 90.9 55840 14109 0.981 ! Near Maximum ! Hodgdon H380 91.0 49.3 3.20 2717 98.1 55840 13601 1.006 ! Near Maximum ! Hodgdon H1000 *T 115.0 60.4 3.91 2716 90.3 53967 14566 0.990 Hodgdon H4350 *T 100.8 52.3 3.39 2708 95.2 55840 13573 0.990 ! Near Maximum ! Hodgdon VARGET *T 92.1 47.3 3.06 2697 98.9 55840 12986 0.990 ! Near Maximum ! Hodgdon Retumbo 115.0 61.4 3.98 2627 91.3 45979 15180 1.072 Hodgdon H870 115.0 63.0 4.08 2484 79.5 40522 14168 1.146 Hodgdon 50BMG 115.0 62.0 4.01 2374 65.6 40208 12054 1.153 Hodgdon US 869 115.0 65.0 4.21 2372 69.4 40083 12150 1.157 Cartridge : .280 Ack Imp Bullet : .284, 140, Nosler Partition SP 16325 Useable Case Capaci: 68.081 grain H2O = 4.420 cm³ Cartridge O.A.L. L6: 3.330 inch = 84.58 mm Barrel Length : 18.0 inch = 457.2 mm Powder Fill/Load Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time Type % Grains Gramm fps % psi psi ms -------------------- ----------------------------------------------------------------- Hodgdon Retumbo 115.0 72.6 4.70 2892 97.2 56282 18780 0.974 ! Near Maximum ! Hodgdon H1000 *T 111.0 68.9 4.47 2837 93.5 56875 17314 0.963 ! Near Maximum ! Hodgdon H4831 SC *T 100.2 63.6 4.12 2797 92.8 56875 16432 0.972 ! Near Maximum ! Hodgdon H4831 *T 104.2 63.6 4.12 2797 92.8 56875 16432 0.972 ! Near Maximum ! Hodgdon Hybrid 100V 96.5 58.6 3.80 2789 99.9 56875 15245 0.986 ! Near Maximum ! Hodgdon H4350 *T 96.2 59.1 3.83 2773 96.5 56875 15700 0.978 ! Near Maximum ! Hodgdon H870 115.0 74.5 4.83 2759 87.6 50282 18248 1.035 Hodgdon US 869 115.0 76.9 4.98 2629 77.1 49018 15863 1.048 Hodgdon 50BMG 115.0 73.3 4.75 2625 72.8 48915 15753 1.047

To add another, I just read about the .358 WSSM that Indiana deer hunters were using for their regulations. The WSSM (two S's) pushes the limit of short and fat. Looks like necking the 223, 243, or 25 WSSM up to 7mm would have 5% less powder capacity than the 7mm-08 AI, but a bit higher velocity and less blast out of a 18" barrel (and less magazine capacity). 7mm-08 is a much simpler answer, but thought it was interesting.

Cartridge : 7mm-.25 WSSM Bullet : .284, 140, Nosler Partition SP 16325 Useable Case Capaci: 49.500 grain H2O = 3.214 cm³ Cartridge O.A.L. L6: 2.520 inch = 64.00 mm Barrel Length : 18.0 inch = 457.2 mm Powder Fill/Load Ratio Charge Charge Vel. Prop.Burnt P max P muzz B_Time Type % Grains Gramm fps % psi psi ms -------------------- ----------------------------------------------------------------- Hodgdon H414 99.3 47.9 3.10 2715 94.6 55840 12844 0.984 ! Near Maximum ! Hodgdon CFE223 *C 94.7 47.1 3.05 2712 97.7 55840 12559 0.984 ! Near Maximum ! Hodgdon Hybrid 100V 107.6 47.5 3.08 2698 99.0 55840 11954 0.982 ! Near Maximum ! Hodgdon H4895 91.1 41.6 2.69 2666 99.1 55840 11770 0.999 ! Near Maximum ! Hodgdon H380 96.0 44.8 2.90 2665 97.0 55840 12072 1.001 ! Near Maximum ! Hodgdon H4831 *T 114.6 50.8 3.29 2656 88.6 55840 12261 0.978 ! Near Maximum ! Hodgdon H4831 SC *T 110.1 50.8 3.29 2656 88.6 55840 12261 0.978 ! Near Maximum ! Hodgdon H4350 *T 106.2 47.4 3.07 2651 93.6 55840 11942 0.986 ! Near Maximum ! Hodgdon VARGET *T 97.0 42.8 2.77 2643 98.1 55840 11537 0.989 ! Near Maximum ! Hodgdon H1000 *T 115.0 51.9 3.36 2461 83.0 45150 11619 1.078 Hodgdon Retumbo 115.0 52.8 3.42 2365 82.6 38210 11949 1.170 Hodgdon H870 115.0 54.2 3.51 2220 70.1 33376 10826 1.246 Hodgdon 50BMG 115.0 53.3 3.45 2138 58.2 33592 9222 1.248 Hodgdon US 869 115.0 55.9 3.62 2130 61.3 33362 9268 1.254

 

[Newtosavage]

For a non-magnum rifle with an 18-20" barrel is the 7mm-08ai one of the best options for an elk/deer rifle? The 7-08 is one of those that does really well out of a short barrel. Going to an ai gives us a little more, not much, but if we want to squeeze everything we can out of a short rifle maybe worth it? Build it on a medium or long action and you could load it long with 160's.

Based on my 2x experience tinkering with the .284 Win, I would say yes. That it would be damn hard to beat a 7mm-08 ai in terms of efficiency for that platform.

My .284's are handling heavier bullets better than my 7mm-08, but from 140's down, there really isn't enough difference between my .284 and my 7mm-08 to justify the added powder and recoil.

So I will have both, and I will use my .284 for bigger critters, probably loaded with 145 LRX's or 160 Accubonds. And my 7mm-08 will get all the "deer duties" with 120-140 grainers.

 

[Newtosavage]

I thought about that one too but dont know anything about its performance. Does it do well with a shorter barrel?

I'm shooting mine in a 21" barrel. It started out at 22" and I chopped an inch off. Not willing to chop it to 20". I'll use my 7mm-08 @ 20" but I want the added weight and velocity on the .284.

 

[Newtosavage]

Maybe someone that has one will chime in. If I remember right a few years ago I had a Savage LWH and I was getting 2900+ with factory Federal 140gr ammo out of a 20" barrel using a Caldwell crono.

2900 with 140's is zippy, but not unheard of. 2850 is pretty standard with 140's from my 20" barrels, using a variety of bullets and powder.

 

[theleo91386]

Personally I wouldn't mess with a 7mm-08ai unless I was just bored or had a 7mm-08 that's throat was just toast. Yeah, you'll gain a little bit of capacity by getting the steeper shoulder, but the rounds that benefit the most by going to an AI version have a decent amount of body taper removed as well.

Anything with more powder capacity will still give more velocity out of a shorter barrel, it's just not as pronounced as when a longer barrel is used.

 

[Prairiekid]

Google the 7 SAW from West Texas Ordinance. Run 308 brass through the sizing die and load. Essentially a 7-08 ai you don’t have to fire form.

The 7 SAW uses a non magnum bolt face?

 

[CApighunter]

The 7 SAW uses a non magnum bolt face?

Correct, just as a 308 is a non magnum bolt face.

 

[AkRyan]

Not without fire forming it correct? Anyone make a factory 7-08ai brass?

How often do you load ammo and go hunt without testing it first??? Or do you only buy boxed ammo??

 

[xsn10s]

I have 2 280ai's. This one is for my wife, as mentioned. Trying to keep it short and light on recoil.

I bought a Howa Superlite in 7-08. One thing to note when you start going for a lighter rifle you'll gain more recoil. With that said I don't find my 162gr ELDM loads excessive in the Superlite. An AI will add to the recoil, as I'm sure you already know.

 

[wyosam]

I bought a Howa Superlite in 7-08. One thing to note when you start going for a lighter rifle you'll gain more recoil. With that said I don't find my 162gr ELDM loads excessive in the Superlite. An AI will add to the recoil, as I'm sure you already know.

Just as with performance, I wouldn’t spend a lot of time thinking about increased recoil with a 7-08ai. The difference is minimal in both cases. The chronograph might pick up the difference, but I doubt anyone’s shoulder is calibrated to pick up the difference.


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[xsn10s]

Just as with performance, I wouldn’t spend a lot of time thinking about increased recoil with a 7-08ai. The difference is minimal in both cases. The chronograph might pick up the difference, but I doubt anyone’s shoulder is calibrated to pick up the difference.


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It's up to the OP. My 20" barrel isn't close to broken in with 20 rounds through it and I'm already at 2680 fps with the 162gr ELDM's. Once it's broken in and I hot load some SRP brass i got we'll see what velocities I get. IMHO I think an AI is wasted on a shorter barrel. I have a 260 AI with a 26" barrel, but on a shorter barrel I'd just keep it a standard cartridge.

 

[wyosam]

It's up to the OP. My 20" barrel isn't close to broken in with 20 rounds through it and I'm already at 2680 fps with the 162gr ELDM's. Once it's broken in and I hot load some SRP brass i got we'll see what velocities I get. IMHO I think an AI is wasted on a shorter barrel. I have a 260 AI with a 26" barrel, but on a shorter barrel I'd just keep it a standard cartridge.

The gains don’t care how long the barrel is. The case size increase is modest at best in the 7-08ai, speed gains are almost entirely based on being able to run higher pressures without showing the classic signs of being over pressure on the brass. It is a cartridge I love, but if you’re making a bunch more velocity than a standard 7-08 with the same barrel length, rest assured you’re not dealing with a 61k psi cartridge anymore.


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[xsn10s]

That's the whole point of srp brass. Increase pressure which increases speeds. Whether it's an AI or srp with increase powder and pressure there will be an increase in recoil. In a lighter rifle the felt recoil will be more unless the rifle is braked or suppressed. I really like Ackley Improved cartridges. But in a 18-20 inch rifle I don't see the point. I'll save the added work for a longer barrel rifle. Just my opinion. YMMV.

 

[wyosam]

That's the whole point of srp brass. Increase pressure which increases speeds. Whether it's an AI or srp with increase powder and pressure there will be an increase in recoil. In a lighter rifle the felt recoil will be more unless the rifle is braked or suppressed. I really like Ackley Improved cartridges. But in a 18-20 inch rifle I don't see the point. I'll save the added work for a longer barrel rifle. Just my opinion. YMMV.

Not arguing any of that. My point was that it’s not a significant difference. Even if you rev that 162 to 2800, you’re less than 2ft/lbs increased from the top of standard 7-08 for that bullet. My 20” won’t get there without beating the crap out of brass (Peterson SRP). I can get 2750 without too much issue, but it shoots better slower. And the ballistic difference is pretty meaningless.


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[HandgunHTR]

Not arguing any of that. My point was that it’s not a significant difference. Even if you rev that 162 to 2800, you’re less than 2ft/lbs increased from the top of standard 7-08 for that bullet. My 20” won’t get there without beating the crap out of brass (Peterson SRP). I can get 2750 without too much issue, but it shoots better slower. And the ballistic difference is pretty meaningless.


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You would have to be stepping on a standard 7-08 pretty hard to even get 2750 from a 162 out of a 20" barrel. That is the upside to AI cartridges or larger chamberings in small packages. You get standard cartridge performance out of a barrel that is 4 inches shorter (i.e. you pick up an extra 80-125 fps when all things are equal).

 

[xsn10s]

Not arguing any of that. My point was that it’s not a significant difference. Even if you rev that 162 to 2800, you’re less than 2ft/lbs increased from the top of standard 7-08 for that bullet. My 20” won’t get there without beating the crap out of brass (Peterson SRP). I can get 2750 without too much issue, but it shoots better slower. And the ballistic difference is pretty meaningless.


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So I used a recoil calculator ( https://shooterscalculator.com/recoil-calculator.php ) and the recoil differences are around 2lbs. My current load is around 2680 fps with a 162gr ELDM. It's still breaking in so I'm hoping for more even though it's not bad. If I bump up the velocity to 2800 fps it does increase to 27.74 ft/lbs which it just over 2 lbs more recoil. Looking at the page's bar graph for recoil my current rifle's recoil at 5.5 lbs is about the same as a 7 lb 30-06 rifle. At 27.74 ft/lbs that comes out to a 9 lb 300 win mag. So unless I'm reading that wrong I'd say that's a significant difference. Beside the OP on post 24 stated that the rifle is for his wife and he wants to keep it light with lighter recoil. My opinion is a standard 7-08 fits the bill. but he wants to do a 7-08 AI that's fine. He could always download it if the recoil it excessive.

 

[xsn10s]

I just noticed this is an old thread lol. I'm sure the OP had already picked his wife's rifle lol.