Any 7-08 Benchrest guns?
- Thread starter Terry
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rickiesrevenge
Silver $$ Contributor
There was a guy who shot the 7mm-08AI at the Memphis BR matches. I don't remember who it was. Neat looking case.
I think for hunting, the 7-08 has always had its following, and is still a popular cartridge. It's when we start looking at it as a LR round for 162gr & heavier bullets that it falls a little short. No way to load 168s or heavier to AICS magazine length without seating them way deep into the case, so you probably won't see any of the tactical guys using it. In a single-shot prone or BR rifle, it could be throated deeply enough so 180s could be seated out, but a straight 284 will easily out-perform it, so why bother? Still, I know a couple of old HP shooters who still feel it was the best bolt match rifle cartridge they ever shot in XC matches.
I had PTG grind a 7-08 Imp 30* reamer for me a few years ago, with only .0015" less body taper than the regular 7-08 so I could use it in an AR10. The reamer moves the shoulder .068" forward, so there's a slight increase in case capacity. So far, I've chambered one 25" Krieger DPMS-contoured AR10 bbl with this reamer. Got a little impatient and grabbed a 1-10tw bbl I found on Krieger's inventory list. It shoots S130MKs really well out to 600yds, but I've yet to get acceptable accuracy out of S168MKs. Always wondered if a 1-9tw bbl would've done a better job with 168s, but Berger's twist rate calculator shows 1-10 as optimal for their 168 classic hunter, which is a longer bullet than the S168MK. If it weren't for the round's shortcomings with heavier bullets in a repeater as stated above, I'd have tried the Imp 30* reamer in a bolt rifle bbl, just to see how it'd compare to the velocities I've gotten with it out of the AR10.
I had PTG grind a 7-08 Imp 30* reamer for me a few years ago, with only .0015" less body taper than the regular 7-08 so I could use it in an AR10. The reamer moves the shoulder .068" forward, so there's a slight increase in case capacity. So far, I've chambered one 25" Krieger DPMS-contoured AR10 bbl with this reamer. Got a little impatient and grabbed a 1-10tw bbl I found on Krieger's inventory list. It shoots S130MKs really well out to 600yds, but I've yet to get acceptable accuracy out of S168MKs. Always wondered if a 1-9tw bbl would've done a better job with 168s, but Berger's twist rate calculator shows 1-10 as optimal for their 168 classic hunter, which is a longer bullet than the S168MK. If it weren't for the round's shortcomings with heavier bullets in a repeater as stated above, I'd have tried the Imp 30* reamer in a bolt rifle bbl, just to see how it'd compare to the velocities I've gotten with it out of the AR10.
Back in 1999, had an AMT single shot Benchrest action glued into a McMillan Benchrest stock. Barreled it with a 26" 1:12 HV 7mm barrel chambered in 7mm-08 AI, 40*. The rifle weighs right at 14 pounds with scope.
Took it to Montana for long range prairie dog shooting. That rifle, shooting 120 grn. Nosler Ballistic Tips, made multiple kills out to 1100 yds. In fact, one dog was scrambling back to the hole after being hit at a little over 1000 yds. was shot a second time to stop the progress to the hole. All within 30 seconds from the first shot.
A healthy dose of 4064 propelled the Ballistic Tips.
Good shooting.
Took it to Montana for long range prairie dog shooting. That rifle, shooting 120 grn. Nosler Ballistic Tips, made multiple kills out to 1100 yds. In fact, one dog was scrambling back to the hole after being hit at a little over 1000 yds. was shot a second time to stop the progress to the hole. All within 30 seconds from the first shot.
A healthy dose of 4064 propelled the Ballistic Tips.
Good shooting.
XTR
F-TR obssessed shooting junkie
I think the 7-08 is a great hunting round, and if you have a 7-08 and some kind if magnum (in my case a 7RM) then you don't need anything in between because you've got all the bases covered.
In target shooting the I see the 7-08 lost in the same tweener zone that I put the 284 in for a hunting rifle.
It's not a 308 so it can't run in classes reserved for those, it's a short action but really doesn't push anything heavier than the 140s well (not saying it can't) and it can be easily out done by a 284, and in target shooting it has to weigh in with the 6.5s and the 6s. It made sense as a steel sillywet round because it could knock over steel with less recoil and more efficient bullets.
I really like the one I built to hunt with, but don't ever see me with a target version.
In target shooting the I see the 7-08 lost in the same tweener zone that I put the 284 in for a hunting rifle.
It's not a 308 so it can't run in classes reserved for those, it's a short action but really doesn't push anything heavier than the 140s well (not saying it can't) and it can be easily out done by a 284, and in target shooting it has to weigh in with the 6.5s and the 6s. It made sense as a steel sillywet round because it could knock over steel with less recoil and more efficient bullets.
I really like the one I built to hunt with, but don't ever see me with a target version.
smoking-brass
shoot straight....shoot often
I built a 7mm-08 for f-class open 5 years ago....I used it from 300-1000 yard competitions. It shoot well but not as effective as other chamberings like the 284.
The best load for accuracy at long range was lapua 308 palma brass necked down.... 168 gr. smk for the bullet... 47.5 grains of imr 4007 ssc...cci br-4 primers. Long throat for the use of heavier bullets. 1:9 twist barrel.
Vince
The best load for accuracy at long range was lapua 308 palma brass necked down.... 168 gr. smk for the bullet... 47.5 grains of imr 4007 ssc...cci br-4 primers. Long throat for the use of heavier bullets. 1:9 twist barrel.
Vince
flatlander said:
I have a similar fun project in the works mine is a M1a, for a barrel I will be using a heavy Obermeyer 5R 8.5ROT. I suspect that the 130/140's will shoot just fine on the short lines with good speed, but I've been eyeing the Barne's 171 with there claimed .645 bc seated out to a coal of 2.90 for the long lines.
Like most knuckle dragging ATC shooters I have gobbs of .308 brass so the plan is too use what I have and neck down my brass, new brass is threw the roof for cost. However some extra case capacity would also be great with this pill, so how does the longer case body fit in the 7mm08 sizer? Did you just back the die off so it doesn't bump the shoulder back as much? Did you have them make you a sizing die and chamber gauge or did you make your own?
Phil,
I had a RZ reamer ground on the same order as the finisher. Used Troy Newlon's sizer die blank to make a FL sizer with a neck bushing, then bought a Forster Ultra Mic seater in 7-08, and used the 7-08 Imp 30* finisher to open that seater's sleeve for the improved case. Remember, my reamer has a 30* shoulder & less body taper, so there's no way to use a regular 7-08 sizer.
I had a RZ reamer ground on the same order as the finisher. Used Troy Newlon's sizer die blank to make a FL sizer with a neck bushing, then bought a Forster Ultra Mic seater in 7-08, and used the 7-08 Imp 30* finisher to open that seater's sleeve for the improved case. Remember, my reamer has a 30* shoulder & less body taper, so there's no way to use a regular 7-08 sizer.
smoking-brass said:
That's pretty well what I'm doing currently. My number 2 308 FTR rifle has just been rebarrelled with an HV profile 1-9" Bartlein and throated for the 168gn Berger VLD at ~3.00" COAL - pick her up in two weeks from the gunsmith. The object is club level F-Open at 300-600, and we'll see what she can do.
On the face of it, a long-throated 260 Rem or 6.5mm Creedmoor shooting high BC 140s will always outperform the 7-08 if you believe QuickLOAD and the ballistics programs, but I like sevens and fancy a bit of experimentation with this number! (I have a 284 and 7mm Shehane for the serious stuff, but even these are uncompetitive these days except in very settled conditions at GB national league level.)
IMR-4007 ssc is one of the powders I have in mind - bought a lot up recently as nobody knows anything about it here in the UK and I see it has been discontinued by Hodgdon / IMR. Although I'll kick load development off with Winchester brass, necked-down 'Palma' cases are a no-brainer and will follow in due course.
As XTR says, these in-between cartridges that aren't allowed in FTR are inevitably 'losers' in serious F-Class. I'm half seriously considering asking the GB F-Class Association to look at trialling a 'Baby Open' class. Rules as F-Open but cartridges limited to those with the same case capacity as .308 Win, that is around 56gn water capacity. Club comps here are stuffed full of 6.5X47Ls, 260s, 6BRs and similar, but these people are understandably reluctant to play with the big boys when 90% of the field uses a 7mm or .30 Magnum and you need your own barrel making factory and gunsmithing business to keep the rifle shooting well.
Laurie,
I was quite enamoured with the concept of the improved 7-08 when I ordered the reamer set, but experience with the 25" bbl'd AR10 put a point on the case's lack of powder capacity. With three 284s, a 280AI, and then stepping down to a couple of similarly improved 260s, the whole idea lost it's practical appeal. If I hadn't gone so far overboard building rifles for myself the past several years, likely I'd have gone ahead with a bolt rifle in 7-08 Imp 30*, just for the experience.
But, since most of my competitive shooting centers around practical/tactical steel shooting out to 1400yds nowadays, and since I've got five very suitable rifles in 6x47, 6.5x47, and 260 Imp 30*, the fact that the 7-08's limitations when configured as a repeater using AICS magazines overrides the desire to play with yet another cartridge. I'll continue to putter around with the AR10 in 7-08 Imp 30* when time permits, but OTOH, there's a Krieger DPMS contoured 6.5mm/1-8tw blank out in the shop, along with another AR10 upper receiver & parts that's likely going to get done in 260 Imp 30* - which will probably take the place of the 7-08 Imp upper that's currently on the lower.
I was quite enamoured with the concept of the improved 7-08 when I ordered the reamer set, but experience with the 25" bbl'd AR10 put a point on the case's lack of powder capacity. With three 284s, a 280AI, and then stepping down to a couple of similarly improved 260s, the whole idea lost it's practical appeal. If I hadn't gone so far overboard building rifles for myself the past several years, likely I'd have gone ahead with a bolt rifle in 7-08 Imp 30*, just for the experience.
But, since most of my competitive shooting centers around practical/tactical steel shooting out to 1400yds nowadays, and since I've got five very suitable rifles in 6x47, 6.5x47, and 260 Imp 30*, the fact that the 7-08's limitations when configured as a repeater using AICS magazines overrides the desire to play with yet another cartridge. I'll continue to putter around with the AR10 in 7-08 Imp 30* when time permits, but OTOH, there's a Krieger DPMS contoured 6.5mm/1-8tw blank out in the shop, along with another AR10 upper receiver & parts that's likely going to get done in 260 Imp 30* - which will probably take the place of the 7-08 Imp upper that's currently on the lower.
I did look at 7-08 Imp too, but decided the extra costs and trouble in getting any out of the ordinary dies right now made the basic form easier and cheaper.
As with the 260, I can see that anything relying on the3 2.800" or thereabouts magazine length is at a big disadvantage with these cartridges - the Creedmoor and 6.5X47L are always going to be better suited. And ... no matter which way you play around with possibilities, QuickLOAD suggests that a 260 at 3.00" COAL with 140s can produce higher MVs than a similarly configured 7-08 with 168s. Since the bullets have similar BCs, the 260 in theory at any rate always wins out so far as the external ballistics go anyway. The 7-08 has more retained energy to knock plates over, but I shoot F, so no benefits there.
I just fancy a play with the cartridge. I have a hope that it will perform better on the range than the ballistics modelling suggests. In any event, the barrel life should be considerably better than that of a 260 running at the limit. As a 7 v 6.5 test, I have an almost unused 6.5X55 chambered match barrel in store that came off this action when I had to cannibalise the rifle to get the action for an urgent FTR build two years ago. I'd only just run the barrel in and started load development with promising results with 140s and Viht N165 at around 2,900 fps.
As with the 260, I can see that anything relying on the3 2.800" or thereabouts magazine length is at a big disadvantage with these cartridges - the Creedmoor and 6.5X47L are always going to be better suited. And ... no matter which way you play around with possibilities, QuickLOAD suggests that a 260 at 3.00" COAL with 140s can produce higher MVs than a similarly configured 7-08 with 168s. Since the bullets have similar BCs, the 260 in theory at any rate always wins out so far as the external ballistics go anyway. The 7-08 has more retained energy to knock plates over, but I shoot F, so no benefits there.
I just fancy a play with the cartridge. I have a hope that it will perform better on the range than the ballistics modelling suggests. In any event, the barrel life should be considerably better than that of a 260 running at the limit. As a 7 v 6.5 test, I have an almost unused 6.5X55 chambered match barrel in store that came off this action when I had to cannibalise the rifle to get the action for an urgent FTR build two years ago. I'd only just run the barrel in and started load development with promising results with 140s and Viht N165 at around 2,900 fps.
flatlander said:
Mind explaining further sir? What kinda velocity could you get out of this set up with 168gr Bergers? And how about the 162 AMAX? Id always heard the 162 AMAX actually made the 7-08 a worthy long range contender....
Also, did you notice picking up any accuracy improvement with PALMA small primer brass vs. conventional large primer brass?
Laurie said:
Say sir, I remember a while back Mr Bailey saying the 6.5-284's held better vertical than the .284s and Shehanes currently being used (though obviously horizontal wont be quite up to snuff
) Did you also find this to be true? That the 6.5-284s held better vertical?Also, you said nowadays that even the .284 and Shehane aint competitive enough in the top tiers, what is then? The 7 SAUM, 7 WSM, and .300 WSM Im guessing?
Far as the 6.5x55, IIRC a South African was doing very well with a 6.5x55 GWI or some such not too long ago....??
No way to load 162s or 168s for magazine fed use w/o going way deep in the case - not even sure it can be done without having these bullets' ogives down into the case neck. The bbl I chambered is on an AR10, so mag fed is the only thing I was interested in. You can load S168MKs for mag feed, but I was only getting around 2400fps out of them, so don't figure the cartridge has much to offer in a gas gun.
Didn't use any Palma brass - had a supply of WW7-08 brass, so used that.
Didn't use any Palma brass - had a supply of WW7-08 brass, so used that.
I can't comment on the hotter 6.5s' L-R verticals. I do know they are very good with the sevens. To be competitive at national level, it's a 7mm WSM or to a lesser extent .300 WSM in the UK. Some have tried the SAUMs here, but few have stuck with them. Grant Taylor was beating allcomers a few seasons back with the Shehane, and not loaded right up either, but even he seems to have been forced down the short magnum route.
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