Home Forums Hunting & Shooting Ask The Gunwriters 7mm-08 - 120gr. vs. 140gr. re-visited

you guys just need the biggest 7 rem makes 7rum thats the only 7mm thet make grin

Calvin, I'd say you had a slow tube, Ed Matunas had a big write up on 270 vs 30-06 years back, tested many 'slow - factory rifles' in 270 that did not come close to published speeds.

I figure a bbl can vary +/- 100 fps at this range of speed, though probably like a bell curve, MOST will fall closer than half that range. That said, nothing wrong with an accurate 7SAUM - little more on the shoulder and ears...but also on the other end!

Bobin, sounds like you were adding powder to that 7RM to compensate for throat erosion, given you are ready to bbl your 270! LOL. Seriously, as you know each rifle can vary, bore and chamber dimensions, twist, groove diameter/depth, etc.

Oh, on the 130s, no need to change what you have when it works...as you say..it becomes duplication. And since when was that fun - burning more powder and bullets to get to the same endpoint! Ha.

I hear you, this gack is enough to make a fellow go in circles.

Barrel wasn't slow with the 120s though. Must be one of those selectively slow barrels that Remington is kicking out.

I shot my 708 yesterday with 110gr TTSX out of a 22" tube at 3300+fps with safe pressure. Flame suit on....

I see ralfie is still whining like a chick.

"You're gonna shoot your eye out."

That is my experience, also.

Never really tried to push the 140 BT's, but I got the 139 Interlock's to ~2930 with no problem out of a 22" tube with my Stevens 200 with a book max of Varget.

I'm more interested in getting the 120 to shoot how I want, so I never messed with the 139/140's any more. I almost cracked 3300 on accident with the 120 BT and RS Big Game by shooting on a way too hot day. Got a sticky bolt and stretched primer pocket for that little error in judgement.

Needless to say that won't be happening again. I'll wait for some cooler weather before working anything else up.

65BR: That 7 mag was brand new; a Krieger #2 with longish throat....

The following are comments made by a casual shooter/handloader.not a lab ballistician (me) so take it FWIW

I think the posts by aalf and Calvin are indicative of what we see lots of times with velocity variations in different barrels.

Aalf is running a slick, smooth,custom Rock,no doubt hand lapped and the stainless machines smooth. The action is trued,distributing pressure forces equally,and likely longer than Calvin's 22" factory Remington(I assume from the post),which did not receive as much TLC....leade dimensions and internal dimensions of barrel likely differ, angle of throat,number of grooves,groove and bore diameter....

Point is, many variables,some small,conspire to make dramatic differences in the delivered velocity..

..yes, it takes pressure to move a bullet,but sometimes we see pressure signs and sluggish velocity(Calvin's rifle)...sometimes we see another 100 fps,yet signs of pressure are absent and case life good (aalf's rifle).

In other words, a whole host of little things add up to increase(or decrease) resistance to the bullet as it passes down the bore,and we see these discrepancies in velocity numbers...

We are seeing the same things back here with two Mashburn barrels, both Krieger #2 CM,24",4 land,both chambers cut with the same reamer ....I owned them both.They look like peas in a pod, yet one consistently requires 1.5-2 gr more powder to deliver the same velocity as the other,this across the board with the same components...might add they were even chambered trued up ,and installed by the same smith,same reamer, throating etc.

As one example, one takes 79.5 Retumbo with 160 AB for 3250 fps; the other(mine) gave 3330 with 78 grains....

Examples of this abound...with the 7/08, my experience parallels Calvins....I have come to expect about 2800-2850 with a 140 gr bullet from a 22" tube....less from the 20" barrels I have also had....

Bumping into a lot of this sort of thing over the years is what has led me to adopt a general rule that if I want a certain velocity level in a rifle, I pick a cartridge that I know going in, will deliver it without exception..and without regard to the little things that make one barrel show more, or less, velocity, than another.

..hence my reference to "get a 280"(or 284,7mmSaum, etc)was not to depracate the 7/08;but rather is a reflection of my own experience that powder capacity frequently offsets some of the small differences that can show up in Calvin's rifle(say), but not in aalf's.....

STA's results are impressive with the 110 TTSX:far higher than I would have expected.My own view is that the chosen load is not really proved "safe" with new brass(which is more resilient than brass fired a few times) until the very same brass is reloaded 4-5 times showing no primer pocket expansion and tight primer seating ,as aalf has already done with his loads...at that point it seems more likely to be OK.

This may not be the same as having pressure read in a lab, but it has kept me mostly out of trouble for 40+ years of handloading,so I relate it for what it's worth...

Everyone have a great day...

I've only handloaded for 4 7-08's, which isn't a vast sample but better than one rifle.

Two were Rem. 700's with 22" barrels, and two were Winchester Model 70 Compacts with 20" barrels. In both the Remingtons I could easily get 2900+ fps with published data with the 139-grain Hornady Interlock. In the pair of Model 70's, published data got 2800 or a little more with various 139-140 grain bullets.

John, you are showing great restraint here as to the notion of fast and slow barrels.

My 22" will make 2800 fps with slightly more H4350 that Hogdgon says to use.

My 20" M7 would run them about 2700 fps.

120's at warp speed with Ramshot Big Game, is intriguing, I must admit.

In most of my rifles after 5 or 6 reloads my brass starts to puke on me... The case necks start splitting.... Only had primer pocket troubles one time with a 264win. The load was hot to damn hot. Had trouble getting the books max fps out of the rifle and keeping brass longer than 3 reloads...

BobinNH, thanks for that info!

That reads like a necks getting sized too small and expanded back up issue. How much are they being sized compared to how much they need to be sized?

STA, yes sometimes those case necks take a beating....and don't last as long as the primer pockets do....

Time to anneal?


JeffO I don't think there are "fast" barrels and "slow" one's....pressure is at work in all of them...just that some puke at less velocity than others...and some might not show the same pressure signs as others...

That 3330 fps load I mentioned above, did not make that case nor rifle whimper......no blown primer, easy extraction,and the primer pocket showed a bit less resistance to a new primer......but the chronograph told me the load was out of character and over the top for what I "knew" about the cartridge....time to back it off....

Most of my dies are Redding full length. I set them up so not to get a 100% resize but to get a very light bolt crush when I close the bolt on a chambered round. Is this not right?

Some rifle/die/brass combos are neck-splitters, some aren't in my experience. Which is limited compared to some here. My 300 WM is the worst. Even if I anneal I get 4 reloads or so before I'm culling out splits.

My .358 will run 10-12 loads with .308 brass that is sized up to .358!! Go figure.

In the past I have annealed my brass and it did help. With work and spending time with the kids I don't anneal anymore just buy new and rock on....

That's controlling headspace clearance. I'm talking about how much the diameter of the neck is being reduced compared to how much it needs to be reduced.

Here's an example. I reload a bunch of 308 stuff using a variety of brass. Federal brass is thick and winds up with .338" diameter necks on the loaded rounds. WW brass is much thinner and winds up about .332" loaded.

I have a Redding FL die in my collection (currently out on loan), and with the expander ball removed sized brass comes out of it with .328" necks IIRC. Federal brass only needs to be sized down to .336" for a .002" interference fit on a bullet. So if I use this die on Federal brass the necks are getting sized down .008" more than necessary, and then brought back up that much when the expander ball comes out of the case. So the case neck is getting a bunch of unnecessary cold working, and that makes brass brittle. Brittle brass splits.

The 140 bullets I have reloaded for the 7-08 were Partitions, AB's, NBT's and Sierra GK's.

Is there something about the bearing surface of the Hornady 139 that will allow it to get in the 2980 range using a 22" tube with published data?

Got it and thanks will take a look... Most brass I shoot is Winchester.. Good INFO!

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Here is how it shakes out for you:

Muzzle -1.5 3300 2660
100 1.2 2988 2180
200 0.0 2696 1776
300 -6.0 2424 1435
400 -18.0 2169 1149
500 -37.3 1929 909

With a BC or .319, as you can see, as you lighten up on weight, the lesser BC is 'less efficient' downrange vs. higher bc bullets, which are typically heavier and have more energy downrnge. No doubt, it's flat, and probably deadly to 300-400 yds, but honestly having checked that out before, the 120 would be my pick in the Barnes for a lightweight - if by a small margin in performance. 120TTSX below w/ .373 bc.

Muzzle -1.5 3050 2479
100 1.5 2796 2083
200 0.0 2556 1741
300 -6.8 2330 1447
400 -20.1 2116 1193
500 -41.1 1912 974



Mathman - my head hurts Thanks.

Bobin, good posts.

JM - yes, bullets have varying lengths of bearing surface, take for example the RP 150 CL in 7mm, IIRC, it is a 2-diameter bullet to reduce friction. Someone might confirm that, or perhaps correct my terminology - perhaps 'dual diameter' is more appropriate. The 139 may well have a shorter bearing surface but I don't believe I have any to check.