7mm-08 bullet reccomendations.

[deadcenter]

Anyone have any recommendations for bullets for the 7mm-08?

Rifle is a stock Remington 700, 24" varmint barrel, 1 in 9.25 twist.

Mostly 100 to 600 meters but would like to try it out to as far as possible occasionally - 1000 yards?

Have read that it's quite an efficient round so was wondering about any of your personal experiences with it, load data, favorite bullets, ideal weights for twist etc.

Any help greatly appreciated.

[tisme]

I've just sold my 708 but was using Hornady ELD 162gr. They are very good at long range ( got mine out to 1663yds). The splash I got from them always seemed easier to spot than Bergers and other bullets I tried. At 1000yds it was very good.

[Chris-NZ]

If you're only stretching to 600m, any 140 class bullet should be fine. The boiler room of a 7-08 is a tad marginal for 162s. Do the numbers and take your pick. It's a forgiving cartridge for loads.

[tisme]

If you're only stretching to 600m, any 140 class bullet should be fine. The boiler room of a 7-08 is a tad marginal for 162s. Do the numbers and take your pick. It's a forgiving cartridge for loads.

Love to know how you work that out

[Chris-NZ]

What in particular?

 

I've a well-used 7-08 as closer-range hunting gun but use a .280AI for long range deer.

[Laurie]

In a factory sporter or tactical short-action rifle, 7mm-08 suffers from the '260 Rem problem' only if anything worse. That is a 2.8 inch COAL and a case that is IIRC 2.035 inch length. Subtract one from the other and you have just over three-quarters inch of bullet outside of the neck and everything else inside. With heavier, pointier 7mm bullets around 1.5 inches OAL, that means you have three-quarters of an inch of bullet shank inside the case, most of it below the neck and severely restricting usable combustion chamber capacity, also putting the bullet into a sub-optimal position.

 

The actual freebore given by the factory and single-loading if an option can mitigate these downsides to some extent, but the full answer for ballistic optimisation is a single-shot rifle built around whatever bullet one hopes to use. In sporting rifle form, 140gn has proven itself the optimal bullet weight as Chris points out. This is recognised by the factories too - according to Bob Forker's book 'Ammo and Ballistics III' there are 20 such on the market and of these there is a single 120gn loading, one each in 145 and 150gn and no less than 17 139/140gn loadings.

 

I use 7-08 for short/mid-range F-Class and have also used it in 600 and 1,000 yard benchrest comps a few times. The rifle was built to accept the 168gn Berger VLD seated optimally giving a COAL right on 3-inches. Even then, I did a lot of desktop exercises and a bit of soul searching before getting the variation and shelling out for the rifle build. Basically, 260 Rem similarly optimised (and now 6.5 Creedmoor) use 140gn bullets which have the same BCs as a good 7mm 168 - in fact the 140gn Berger 6.5 VLD and the 168gn 7mm VLD have identical BCs. So, the 7-08 has to match 260 Rem/140 MVs to be on an even footing. When I first thought that I might like the 7-08 as a competition cartridge, I mistakenly believed that this wouldn't be an issue, but no matter how I played around with combinations in QuickLOAD, it showed that in the model anyway, it would be difficult to match 260 velocities and impossible to improve on them. The long and short of it is that 2,900 fps is on in a 260 competition rifle with many 140s, but that it's not that easy to significantly exceed 2,800 fps in the seven with the 168gn class bullets. Yes, you could stuff a reformed Lapua 'Palma' small primer case with RS60 / Re17 or Viht N550/560, but my aim was to run reasonable pressures and use single-based powders.

 

As it turned out, the barrel didn't like the 168gn VLD, another problem, just leaving the 162gn AMax available at that time, the 168gn Sierra MK being a nice tolerant bullet design, but low BC in relative terms. Luckily the 160gn Sierra TMK just became available then and it has worked out very well at around 2,830 fps MV from a 31-inch barrel using Palma brass and a gnat's whisker short of a full 50gn Viht N160 in a compressed load. I have used the Sierra 175 (an excellent bullet) and the old 180gn SMK over both N160 and N165, but to get the MVs needed and consistent performance charges were so heavily compressed that COALs couldn't be kept consistent. Anyway, I have a 284 and that's what shoots the heavier bullets.

 

The plus for the 7mm-08 in the match role is that it should match sensibly loaded / pressure smaller 6.5s, produce similar precision, and not so much more recoil that you really notice it, but that barrel life will be considerably enhanced. That's why I won't use the 'hot' powders, although I will do a few tests over the coming year with some just to see what sort of velocities can be obtained.

 

It works well for me, I like it, but the fact that custom 7-08s are a real rarity on the match scene outside of the Americas and their much loved metallic silhouettes (for which it is still an ideal choice) while match lists are stuffed full of competitors toting 6.5 Creedmoors, 284s, 7mm SAUM and WSMs tells you something.

[gbal]

Love to know how you work that out

Tisme,here are some clues others (ammo manufacturers). Have worked out/SAAMI specs so comparable pressures etc:

There are 2 139 and 12 140 g commercial ammunition loadings available.,and one 150 (no 160 I know of)-sugest something?

 

140g @ 2800 fps come in at around 80/30 drop /drift " at 600y And 330/92 for best at 1000y (varies a few inches with BC)

 

!50g @2650 comes in at 94/38 at 600y,and 436/126 for 1000y. Maybe MV could be a tad higher-only one load,but:

 

139@3000 (two loads)BC .486 and .392 come in at 600 with 65/26,and 73/34;and by 1000y 387/85 and 348/115

...so 200 fps more helps,but shows a bit more fps isn't all the answer for the 150,and 160 can hardly fare better on drop/drift.....

 

The data is comparative-eg hot up one,hot up the other,differnces preserve,these are controlled,comparable data

 

There is a fair bit of practical experience,as Chris implies too. 7-08 is a fine mid range cartridge,but at distance,heavier bullets are just running out of boiler house puff.

 

Just for fun,120g Nosler BT @ 3050 BC .417 come in 38/31 at 600 and 311/103 at 1000y (as usual,light bullet decreases drop,due to increased MV,but increases drift with lower BC.With distance this is an interactive trade off. ("No free lunch")

 

All that said,the classic short barrel,low MV(2300fps) 6.5 x 54 M/S cartridge with 160g bullets ( or,more comparable with 7-08,the 7x57 with heavy 175g )was a very effective game getter,but hardly a distance target number-deep penetration was the strength (and sheer clout for the 7x57) kept to short ranges.So terminal performance comes in when stalking etc rather than more distantpaper punching. Choose accordingly( and wrt the actual game size).

 

gbal

[tisme]

My 7 08 was shooting 162gr @ 2708fps. BC i was using was .307 g7, zeroed at 100yrds, drop for 1000 yrs 30.25moa, drop for 1663 was 81.25moa, it got there no problems and splash was easy to see. The transonic zone was at around 1250yds and went through it no worries, I didn't find any other bullet that did as well. I also know a couple of others with 7-08 that also shoot 162 elds by choice.

But hay maybe I just didn't try hard enough with the other bullets but when you find one thats does what you want you dont tend to try harder with ones that didn't

[gbal]

tisme,the 7mm 162 ELD match bullet does change the current playing field....with an excellent BC (.338 G7or your more conservative .307 G7)....

...I had no known comparrable pressure loads using it,nor is there (yet?) a 140 equivalent.....

 

280 Rem 160g (.522 G1) @ 2800 gives 317/85 at 1000

280Rem 160g. (.475 G1) @ 2775 gives 348/98 at 1000y showing the reduced BC/MV effect clearly

 

7Rem Mag 162 A max (BC .625 G1) @2950 gives 251/62,showing the gains from better BC/MV. (All these 200 zero)

 

Your data is 7-08 162 ELD Match (BC .307 G7) @ 2708 giving 30.25 moa at 1000 (100 zero)

 

Previous (SAAMI pressures) gave lots of 7-08 loads with 140g @ 2860 fps...alas no 160g data

 

So we 'extrapolate' 150 fps MV down/G1 BC Increase of at least .3xx and 20 g heavier...and a pressure indication...

 

.....or wait for a 140 g 7mm ELD match.......

 

But you have a load that is working for you now,as a LR target load in 7-08

 

Vorsprung durch technik. :-)

 

gbal

[Laurie]

The ELD-M's quoted BC is identical to that produced by Bryan Litz for the old AMax suggesting it's not a new design probably just the old one with the new higher melting point material in its tip.

 

The 160gn TMK appears to have a similar form and BC to the AMax / ELD, a G7 BC on or around .300 and that certainly works fine with elevation settings out to 1,000 yards, in fact appears to be understating its efficiency a bit. However, as I've not done a 'tall target' test to check scope click accuracy, that might be down to scope error. In any event, there is obviously nothing much if in fact anything at all between the two designs ballistically so choice comes out as availability, cost, and of course the old crucial factor - which your chamber / barrel prefer. In my rifle, the Sierra is definitely superior. Having weighed and BTO checked some pretty large samples from three different 160gn TMK production lots, I can say their manufactured consistency appears very good, better than most Bergers in fact.

 

I should in fact say barrels plural rather than barrel singular (both Bartleins) as I also load the 160 for my 284 for mid range matches on days forecast to be rough. A relatively mild 284 load produces another 100 fps over the 7-08, also using N160 and it's a pleasure to shoot in a 22lb F-Class piece off a bipod, no front-rest wanted or needed.

[deadcenter]

Very useful and interesting info as ever guys. Thank you.

 

I was surprised when looking at load data for the 7-08 that muzzle velocities were quite a bit down on the .308 for similar weight bullets, not what I expected, which is why I asked for experiences with 7-08.

 

All in all, answered a lot of my questions, very interesting as always. thanks again, great place of learning.

[Chris-NZ]

.. 7-08 that muzzle velocities were quite a bit down on the .308 for similar weight bullets, not what I expected,..

 

Squirting the same weight solid object down a tighter tube will always be less efficient - friction and fluid dynamics..

[deadcenter]

True, was just a bit surprised at the difference. I can shove a 190 smk down my 308 at a similar speed to the speeds given from the manuals for a 168 smk in the 08. Most loads call for slower powders too.

 

Longer bullet - larger bearing surface but...... Larger dia - larger bearing surface. Over simplified I know and I'm too lazy to do the measurements and math for the differences, it is what it is and you are correct.

 

You look into things and sometimes it raises your eyebrows. It's one of the things I love about it all. I think I like reloading almost as much as the shooting...... Almost .

 

Thanks for everyone's input.