7mm-08 Ackley Improved..

[holstil]

I think it's worth it.
Less pressure, some more speed if you want it and it shoots factory 7-08 ammo great.

Maybe not if your thinking of changing what you have,,,,,cost a chamber job. Heck, just get another gun.

Glad I have a lathe.

 

[Zero333]

I've ran palma in 7mm-08ai in sub freezing temps with no ignition problems running varget or 4451.

What primers ???

I've had 3 duds with cci's in very cold temps ( -15 to -25 f ). But Federal primers never failed me in the same cold temps. I've shot tens of thousands of cci primers in sub freezing temps, so 3 duds is hardly any, but enough to make me avoid them for hunting loads.
I've never had a dud in above freezing temps.

My theory is the very cold temp somehow slows down the firing pin fall enough to cause a dud when using cci primers because they have harder cups than federal primers.
This is my theory based on zero evidence.

 

[NortexDM]

What primers ???

I've had 3 duds with cci's in very cold temps ( -15 to -25 f ). But Federal primers never failed me in the same cold temps. I've shot tens of thousands of cci primers in sub freezing temps, so 3 duds is hardly any, but enough to make me avoid them for hunting loads.
I've never had a dud in above freezing temps.

My theory is the very cold temp somehow slows down the firing pin fall enough to cause a dud when using cci primers because they have harder cups than federal primers.
This is my theory based on zero evidence.

Cci regular (I forget the number) and br4 but keep in mind my sub freezing isn't below zero like yours.

 

[flatlander]

I ordered 100pcs of Peterson 308 Palma SRP brass from Grafs yesterday - won't have the correct headstamp for use in the 7mm-08 Imp, but I won't have to neck it up & then back down for it either. Will be interesting to see how ES/Sd numbers with this stuff compare to that of the WW7-08 brass I've been using in this rifle. I have plenty of CCI 450, R7-1/2, Fed 205, and both Tula & Wolf SRM primers to test with the Peterson brass.

 

[Laurie]

Will be interesting to see how ES/Sd numbers with this stuff compare to that of the WW7-08 brass I've been using in this rifle. I have plenty of CCI 450, R7-1/2, Fed 205, and both Tula & Wolf SRM primers to test with the Peterson brass.

I for one would like to hear if you do see an improvement in ES/SD with the Palma brass in the AI. In a 'straight 7-08' in long-throat F-Class form, I've seen no noticeable improvement with Viht N160 with reformed Lapua Palma brass over Winchester, but with annealing every few firings I expect these cases to last a long, long time. A couple of hundred cases should easily see a barrel out. With the MVs I run with the 160gn Sierra TMK, QL suggests Pmax runs between 60,000 and 61,000 psi so I'd not expect much life out of Winchester brass. I have them too, but keep them for a mild short-range load. I also have some old thin-walled 160gn weight Norma 308 Win brass that I've necked down to give the extra capacity for slower burning powder (Viht N165) and the 175gn SMK.

Even though modest the extra capacity of the AI form would be well worthwhile with this combination as the 'straight' version sees the desired loads too heavily compressed and COAL consistency affected even in the roomier Winchester brass. (I'll try the reformed high-cap Norma 308s and N560 + N565 later this year to see if I can get the desired MVs without an over-high fill-ratio.)

 

[65BR]

Good info, thanks.

 

[RustyPin]

I for one would like to hear if you do see an improvement in ES/SD with the Palma brass in the AI. In a 'straight 7-08' in long-throat F-Class form, I've seen no noticeable improvement with Viht N160 with reformed Lapua Palma brass over Winchester, but with annealing every few firings I expect these cases to last a long, long time. A couple of hundred cases should easily see a barrel out. With the MVs I run with the 160gn Sierra TMK, QL suggests Pmax runs between 60,000 and 61,000 psi so I'd not expect much life out of Winchester brass. I have them too, but keep them for a mild short-range load. I also have some old thin-walled 160gn weight Norma 308 Win brass that I've necked down to give the extra capacity for slower burning powder (Viht N165) and the 175gn SMK.

Even though modest the extra capacity of the AI form would be well worthwhile with this combination as the 'straight' version sees the desired loads too heavily compressed and COAL consistency affected even in the roomier Winchester brass. (I'll try the reformed high-cap Norma 308s and N560 + N565 later this year to see if I can get the desired MVs without an over-high fill-ratio.)

I see Lapua offers 7mm-08 Brass, has this been around long? Does it make any difference for improved versions?

 

[Laurie]

Lapua 7-08 cases have been around for a number of years, likely 10 or more. As with all Lapua brass it's well made, consistent and pretty strong. It is large primer / 2mm flash-hole of course and has similar capacity to the company's 308 Win - marginally less thanks to the smaller diameter neck only. That about sums it up - just as the 7-08 design is a 308 Win with a 20 thou' smaller O/D and slightly longer neck, so the Lapua 7-08 case is identical to its 308 Win stablemate apart from those changes. It has less internal capacity than Remington or Winchester 7-08 brass but will (maybe) take full pressure loads better. I know from direct experience though that whilst very good quality, it is not at all difficult to overload this brass in trying to reach target MVs in 7-08, and even more so 260 Rem. I have produced a few blown primers having relied too much on QuickLOAD in the 260 and also junked many more cases after only a loading or two where the primer pockets turned out to be slack when it came to load them again. The AI improvements will likely pay off here in giving that extra bit of capacity to reach those MVs without excessive pressure killing the brass.

Reformed Lapua (or Peterson, Alpha etc) small-primer brass will take full pressures better still though. As I said in my earlier post, I'm not 'pushing' pressures into the mid 60,000s of psi, but if you take most makes of standard (large primer) case and run them at any higher pressures than factory ammunition loadings of c.57-58,000 psi MAP, then brass life will be short thanks to slack primer pockets, or more precisely case-head expansion.

The question mark then moves to ignition reliability. There are several people on this forum who maintain that when you get to 308 Win case and charge sizes, the small primer's reduced energy allied to the 1.5mm flash-hole are simply inadequately powered to obtain reliable ignition. It is said that Bryan Litz is dubious about 'Palma' brass and uses large primer Lapua in his F/TR loads. That's hearsay and I don't know if it's true, but I do know Bryan is strongly of the view that largeish ES/SD values often result from marginal ignition efficiency (ie fractional hesitations or 'hangfires' in starting charge burn), so marginal that the shooter sees and hears nothing amiss but the chronograph shows it through MV variations. 308 Win case size obviously includes necked down or up versions including 7-08, 260 Rem, and 243 Win which also use slower burning and therefore potentially harder to ignite powder grades than the parent design. All I can say is that running with 47gn + of N160 (and a bit more of N165 in some tests), ie as much as the Lapua case will physically hold, I've seen no such issues even in temperatures not much above freezing and the MagnetoSpeed, now Labradar, show acceptable ES values, same as large primer brass equivalent loads - no better, but really importantly, no worse either.

 

[Alex Wheeler]

@Northridge is a world class shooter and has been working with this cartridge

 

[Northridge]

I've been working with a 7mm-08 Ackley with large rifle primers this last fall and winter. the cases even with large rifle primer do hold up fine if being realistic to the cases practical use. like most options we talk about, it will tune well enough to be competitive depending on how you implement the platform. the biggest bummer in working with it is the lack of boutique bullet options but that will change with some effort.

Shawn Williams

 

[TZaun]

Shawn, which bullet weight are you working with and what kind of velocities are you getting?

 

[Northridge]

Shawn, which bullet weight are you working with and what kind of velocities are you getting?

I primarily have been tuning in the 180g weight class for my intended purpose. I'm shooting a 30" barrel but powders in the h4350 burn rate range I'm in the 2700fps-2730fps range with out damaging brass.

Shawn Williams

 

[best defense]

I have been trying to figure out which if any of the common 7mm bullets will work for 600 yard matches if I stick with 7-08.
I didn't really want to go to the 284 if it isn't necessary.
I know that the heavier bullets carry better at longer distance but require a faster twist to stabalize.
So if speed is not a determining factor, how well will the 7-08 do with a 30 inch barrel and a faster twist, say a 1:7 twist
We're talking 600 yards specificlly.

 

[Quickoz]

I used to run a 7mm08AI with Palma brass and H4350 and Varget. I had 180gr VLD running at 2770 in my first barrel. Won me an FO state champs with it. It will work, but your going to be behind the 8ball if your competing against SAUM's. It will hang with a 284 however...just. I ran 47.3gr H4350 with CCI450 and it shot remarkably well. I also ran Varget with 162gr Amax and it shot very nice at 2840fps aswell. I think the cartridge is best suited for the 160gr class bullets. A Berger 168gr VLD with Varget would be my combo if I was going to run it again.

 

[Laurie]

I think the cartridge is best suited for the 160gr class bullets. A Berger 168gr VLD with Varget would be my combo if I was going to run it again.

I'd agree with that. I had my straight 7-08 originally set up for the 168 Berger VLD, but couldn't get it to group well so moved onto the 160gn TMK as a stand-in. (... and am still using it over 1,500 rounds fired later! ) I'll have to go back to the 168 though and try Berger's ever-larger jump process to find a position it likes as I still believe this is the optimal ballistic choice for the straight case's capacity. Most impressive that you nearly got 2,800 with a 180 from the AI however.

 

[Quickoz]

Laurie,

I did get over 2820 in testing with 180VLD. But accuracy wasn't there. I think that would be asking too much for this case. I had 162gr Amax upto around 2870 I think, but again accuracy wasn't there.

If I was going to try the 180 class again, I'd run 180 Hybrids with shorter throat and they have shorter bearing surface.

 

[284winner]

While the 7-08 AI won't make 284 velocities with the same bullets, it comes as close as any non- magnum short action 7mm can. That said, I believe the 7-08 AI really shines with 160 class bullets. I also believe that the straight 7-08 does very well left as is for the under 150 class bullets. IMO, any time you can get extra performance from a non-magnum SA 7mm cartridge, do it. The .284 caliber bullets offer outstanding ballistics and keeping the bullet weight reasonable with the 7-08, it really is a great little powerhouse round. I've read many threads by quickoz pertaining to his experience with the 7-08 and 180s. He's definitely a 7-08 wizard. Hell, if it works, keep working it. I've opted for the 284 from the start for the 180s as it's less work to get performance. Hats off to quickoz for his dedication to the 7-08 with 180s, it's obviously paid off.

 

[DHuffman]

I have a Northridge built 7-08 AI

I purchased it from Shawn last summer and shot the August Championship match at Deep Creek with it as a heavy gun. It's just over the LG 17# cut off so not a true HG and will make LG with a barrel change.

I think I finished 3rd for score Sunday and 6th or 7th overall HG score for the match.

It runs the 180 hybrids around 2730 - 2740 fps easily. Other than a few nice groups here and there with another gun it was the first success I've ever had as a 1000 yard Benchrest shooter.

I shot it again at Elbow Lake early this month at 600 yards and it agged 3.8" on 4 targets and I honestly think I was a tenth or two off on the powder causing it to open up. It had been shooting steady +/- 2" at home tuning. The load I shot at Elbow Lake shot as small as 1.5" up to 2.5" at home so first trip east and half the elevation of home I was off the tune a little.

I'm using Lapua 7-08 brass, RL 16 and BR 2s and 180 hybrids.

First test on the 184s this morning. The 184s shot to the same POA with the same charge as the 180s but 10-15 fps slower. I'll tune some more and possibly shoot the 7-08 AI at the 600 yard Nationals coming up.

 

[DHuffman]

Here's a target at home with the 180s just before Elbow Lake.

I plan on making a set of SP brass, either Lapua or Alpha this winter and testing it. I'm running no where near pressure now.

I also plan on testing H4350 and IMR 4451 only because RL 16 is pretty dirty at these speeds .

 

[DHuffman]

Tried the 184s slower and out of the lands this morning.
Conditions were trashy enough I almost didn't shoot. It immediately went dead calm half hour later.
The 184s seem much happier out.