Novice 7mm-08 Hunting Load Development Perspective (long)

[Commo]

Executive Summary:

Experts: I’ve got a few questions on how to proceed with hunting load development at the bottom of this post.

Newbies: You might want to read the whole thing to get an idea on how one man has gotten started/addicted to this pursuit.

Cheers. Commo
_________________________________

Thanks to all the experienced shooters and handloaders who contribute to the Accurate Shooter forums — I’ve learned a lot reading through the various topics for the past few months as I get my handloading act together for my new Sako Finnlight 7mm-08 hunting rifle.

I’m blown away by how you all are able to shoot these long distances — I’ve only shot at 100 yard ranges and have killed a half-dozen Adirondack deer at ranges up to 125 yards with an older Browning A-Bolt 270 loaded with 150 grain Federal Premium/Nosler Partition rounds.

The whole concept of shooting 300-1000 yards (and farther!!!) was unknown to me.

Til now, because I kept my hunting rifle in New York for convenience, I wasn’t shooting it much during the off season. (I’m in Michigan.)

Now retired I can spend more time to be a better marksman and hunter.

Reloading is also new to me so I’ve been loading a few different 140 grain bullets from Nosler (Ballistic Tip, AccuBond and Partition), Hornady (InterBond) and Berger (VLD Hunting bullet) to get a feel for the techniques required for safe and repeatable loading. Buying powder locally (Detroit metro area) has been hit and miss: I’ve got I4350, I4895, I4831 and Varget at this point.

I am devouring the corresponding books by the bullet manufacturers, along with a number of other books on the topic, including ‘Metallic Cartridge Handloading’ by Mic McPherson.

My workbench is accumulating lots of fun equipment — Redding Big Boss II, Master Hunter dies, #5 Powder Trickler, Mitutoyo digital caliper, RCBS 750-grain electronic scale, Sinclair primer seating tool, Lyman vibratory cleaner, Redding decapping die, Hornady bullet puller die, Sinclair expander die and ‘oversize’ expansion mandrel, plus lots of little hand tools for case mouth deburring and chamfering and primer pocket cleanup.

Recently I added the Hornady OAL tool with bullet and case comparators, so I’m delving now into the mysteries of COAL, BtoOG, etc.

Also, I bought the set of Redding Competition Shellholders that will allow me to ‘control headspace’ with my FL die.

While I have had good luck so far with Nosler brass, recently I popped for 100 Lapua 7mm-08 cases and going forward will concentrate on those for my deer hunting loads.

So with all this input I’m getting a bit overwhelmed.

Questions which have arisen lately:

1. If I’m willing to go beyond the recommended SAAMI COAL, I have some space available to get closer to the lands as my Sako seems to have a pretty long throat.

For example a Nosler AccuBond 140 grain dummy round measures 2.377” BtoOG reliably to the lands with the Hornady OAL tool. Measuring the dummy round’s COAL it becomes 2.952”

SAAMI Recommended COAL is 2.800”. Because I want my rifle to feed reliably from the magazine I certainly can’t go that long. My magazine max is 2.960”. For safety (per Mic McPherson) I need to subtract 0.035” to give my rounds enough clearance in the magazine.

Taking out that .035” means my max COAL for the 140 grain AccuBond would be 2.925”.

So my main quandary at the moment is what to do with the ~.125” I have to play with in this round.

Looks like the closest I can safely get this particular bullet to the lands is .027” and that’s using up all of the available .125”.

Have I allowed enough safety margin when I subtract .035” from the max magazine cartridge length?

Is there some formula to seek a sweet spot in that spacing, similar to the VLD testing detailed in the Berger manual?

Most importantly, what is the logic here that could guide me rather than just seating bullets at random distances from the lands?

Ranges in Michigan are just starting to open up. I have my eye on a place up north where I can at least shoot at 200 yards, so I will be able to load and test more often when Spring finally shows up..

Thanks for reading this far!

Commo

 

[Sheldon N]

Short answer to a long question....

It is good to seat out farther because it creates more space inside your case. More space in the case = less pressure = ability to put more powder in the case = more velocity at the same pressure (better ballistics) or same velocity at lower pressure (longer brass life, longer barrel life).

If the closest you can get to the lands is ~30 thou off, and that might still cause interference, I would lean towards choosing a length that doesn't risk getting hung up in the magazine and feeds reliably and then just focus on selecting a good powder charge.

 

[Commo]

Short answer to a long question....

It is good to seat out farther because it creates more space inside your case. More space in the case = less pressure = ability to put more powder in the case = more velocity at the same pressure (better ballistics) or same velocity at lower pressure (longer brass life, longer barrel life).

If the closest you can get to the lands is ~30 thou off, and that might still cause interference, I would lean towards choosing a length that doesn't risk getting hung up in the magazine and feeds reliably and then just focus on selecting a good powder charge.

Sheldon, thanks, that makes a lot of sense..I hadn't really considered the added space inside the case. I would generally look for accuracy/case longevity over pure velocity from added powder.

Commo

 

[Sheldon N]

Agree that accuracy trumps everything. What you may find is that the node (velocity) where your barrel is most accurate happens at a lower case pressure when you seat the bullet out farther. So you get both the accuracy and the longevity benefit of the extra case capacity.

 

[Commo]

Agree that accuracy trumps everything. What you may find is that the node (velocity) where your barrel is most accurate happens at a lower case pressure when you seat the bullet out farther. So you get both the accuracy and the longevity benefit of the extra case capacity.

I love this stuff!!

 

[Brians356]

If you insist on always chambering from the magazine, you may never realize the accuracy (or energy) potential of that rifle and cartridge. But you can still find a relative sweet spot in bullet jump (seating depth) that is well within the magazine length, you just need to experiment starting with a given COAL (e.g. your 2.925" to the bullet tip) but using the Hornady gage, determine the cartridge length to bullet ogive.

Then take some promising load you develop (tweaking powder charge) at that "to ogive" length, and start trying slightly deeper seating depths, in, say, .003" increments, shooting 3-shot groups, to see if there is a marked reduction in group size at some seating depth (always referring to ogive length, not OAL.) Fine tune around both sides that promising seating depth, in smaller increments. Now you've found a powder load and seating depth combination which shoots small groups but still fits in the magazine.

You might also try loading for accuracy outside the magazine, loading singly through the ejection port. Then you can seat much closer to the lands (say, .020" bullet jump) and start trying jumps on both sides of that. You may shoot such tiny groups that you'll be tempted to go deer hunting with your "single shot" rifle!

Here's a popular thread some of us refer to for load development with due emphasis on seating depth tuning (updated instructions in bold font):

http://forum.accurateshooter.com/threads/long-range-load-development-at-100-yards.3814361/

 

[Commo]

Brian, thanks, I will do as you suggest -- already made it through the first 16 pages of the Erik Cortina thread -- very informative!

I'm going to load a set of dummy rounds at my magazine-safe 2.925 and run them in and out of the rifle chamber to make sure that's my longest possible round (and that it ejects.) Then I'll start loading some rounds to test incrementally from there on down.

And I take your point about working base-to-ogive and have that firmly in mind. I found the COALs I mentioned by measuring the COALs of rounds that I'd first measured to ogive, to study the fit-in-magazine question.

I've heard of some hunters who insert their first (longer) round above the magazine so that the first shot is their most accurate shot -- and I'm not against trying some longer rounds to see what this Sako can do as a single shot!

Commo

 

[Brians356]

I've heard of some hunters who insert their first (longer) round above the magazine so that the first shot is their most accurate shot

In a hunting rifle such as yours, on medium to large game, I doubt you can get so much more accuracy loading longer than the magazine that it will be worth making a special 1st round.

Bear in mind that the wind is a huge factor in competition and long range hunting, especially for varmints, but when developing hunting loads and looking for vertical on targets such as in that thread I pointed to, try not to let any wind distract you, and concentrate on holding vertical as steady as possible on the bags while testing groups. If you have some crosswind but can hold vertical and squeeze a group spread out a bit horizontally, but with very little vertical spread, that's what I look for.

 

[broncman]

My son killed his first dear with a Sako A7 in 7-08. Sako rifles have no issue with accuracy at mag length! He wanted the 7-08 for reduced recoil and then promptly wanted the 162 grain bullet because it was the most accurate out to 300 yards. Also had the most recoil....

Find a decent bullet you want to take game with and have fun loading up. A nice accurate hunting rifle does lead to wanting laser accurate single shot benchrest with all the bells and whistles rifle!

Load up mag length and go hunting! I assure you the Sako is up to the task! If you want to polish up your skills, load some lightweight bullets and go Crow hunting. A crow out to 150 yards walking on the ground is a formidable target!

 

[XTR]

Just to note, Accubonds are very long in the nose. I have a 7-08 with a freebore setup for the 162 Amax (.160 something I think) that I can easily reach the lands with a 140 SGK in a mag length bullet but can't get close with an 140 accubond, the good news is the Accubond doesn't seem to care much. It shoots ½ MOA at 200 jumping a long way. (forget how far but long)

Accuracy first.

Try loading with 140 Sierra Game Kings, they will probably make lands at mag length easily, my rifle shoots the 140SGK and the Accubond about equally well with similar velocities for the same powder charge.

Varget is a good choice, if I4895 is like H4895 is should be OK but a tad fast, never tried I4831 but it looks way too slow, and FYI H4350 is too slow to get full use with 140s. I was running compressed loads with no pressure signs.

I found 2000MR to work really well as a hunting powder in my 7-08. I tried it for a competion powder and found it lacked the consistency for 1000 yard F class, but its pushing my 140s a little north of 2900FPS in WW brass. Could go faster but they shoot well there and its not a bullet race, the deer cant tell the difference. As above, my rifle shoots ½ MOA at 200 yards with either the 140AB or the 140 SGK. Give the SGK a try.

 

[Commo]

Brian, Bronc & XTR -- thanks so much for your comments & advice. I know lots of this is dancing around on the head of a pin as far as hunting goes and will take the conservative route when it comes to having the gun/ammo ready to shoot for November.

I suspect my hunting rounds will end up pretty close to the SAAMI 2.800 and that they'll shoot Moment of Deer very handily. Mentally I'm seeing shots from 100-200 yards in the Adirondacks and certainly what I've got already would be 'good enough' without a bunch of further development.

Up til then it'll be fun to experiment and learn about handloading, so will try XTR's advice on powders and the Sierra Game Kings, and will watch out for that horrible tendency to want a 'laser accurate single shot benchrest rifle with all the bells and whistles'!!!

Commo

 

[Commo]

XTR, in regard to your powder recommendations as to speed -- does it make a difference if my Sako has a 20.25" barrel?

And the Sierra web site shows two 140 grain Game Kings -- do you prefer the SBT (#1905) or the HPBT (#1912)? In their photos the HPBT appears to be much longer..

Thanks,
Commo

 

[Homerange]

708 was a caliber I knew little about until I picked up a cheap crappy Rem 780 and after quite limited load development had it shooting cloverleafs @100 using 120 gr SP Hornady's and ADI2208(Varget)
Plenty good enough for the Fallow herd we have not far from here I thought, they're not big deer and 130's in a 308 had been devastating on them.
Then came that phone call from 10 miles away....there's a mob of red deer in the front paddock, get around here quick. Oh shit, I've got nothing loaded for my 308 so the 708 it has to be.
One shot kill @ 180 yds and another decked @ 250.

Sure the 120's are a little light for bigger deer but their terminal performance was very satisfactory.

In recent years I've not used any of the heavier pills for any of my rifles, preferring to keep to lower recoiling loads to combat the flinching developed early in my shooting days.

Unless you need the energy or the higher BC heavier pills offer Commo, do consider lighter loads, your shoulder will thank you for it on benchrest/load development days.

 

[AckleymanII]

The family has been 7/08 freeks for a long time, we shoot Remington's. Here in SC our deer limits are generous and seasons are long. We have tried all kinds of bullets, and shot placement trumps all of course.

Since we hunt in relatively thick places, running deer make for lost deer at times, especially if the ranges get beyond 325 with less than perfect hits( we hunt out of climbing tree stands and fixed box stands in trees, trees sway with the wind).

The following load for us in our Remington's is outstanding in accuracy and killing ability(shock)

130g Speer BTSP
42.0g of IMR 4895
Rem brass
Rem 9 1/2 primer
Clover leaf groups at 3000 fps

Some bullets are worth building a gun around, and the 130g speer BTSP is one of those bullets, old tec bullet puts a lot of shock on the deer with great penetration. If you want more penetration for bear, go with the 139g Hornady Flat base, and adjust your load accordingly. These are both very accurate killing bullets for large deer, and the 139g Hornady flat base is an extremely good bullet. The 130g Speer BTSP, 139g Hornady are bullets that have not proven to be real sensitive on seating depth, but you will find a sweet spot for each.

Since you have an issue with OAL and Mag Box length already, long pointed bullets are apt to give you headaches, and I doubt if your shots are over 300 yards, so why make things hard on yourself?

I always work up loads with bullets touching the lands in all 7mm's regardless of make, then seat to max length the mag will take and compare the two. I can't remember the last time I had to fire more than one shot on a deer, but 350 yards is a long shot where I live.

I would have a Limbsaver recoil pad put on that rifle, and recoil will feel extremely soft.

Good luck!

 

[XTR]

I've only used the 140SGK sbt.

Barrel length shouldn't make a lot if difference, mine is a 24", you'll probably be about 75-100FPS off what I can get.

I experimented with 140s and H4350 for a while and found that I couldn't get them past about 2800.

Another powder to try would be Rx15, it and 2000MR are both double based, you will get more velocity, but they are temperature sensitive, for target shooters who shoot from 73 in the first relay to 93 in the last in the middle of summer they are not good powders, but for hunting where you're shooting at 50 or below the whole time I think they work fine. Both can give very good accuracy and more velocity than their single based counterparts.

You may find that if you want to experiment with heavy bullets (160+) H4350 might be interesting, though I personally don't think the 7-08 has the boiler to push those as well as a lot of other chambereings. I like the 140 class bullets for the 7-08, IMO it is a great balance of terminal performance, ballistics and recoil.

 

[broncman]

The spire point SIerra Game Kings are an often overlooked gem! Not as fancy as plastic points or as sweet looking....but man are they accurate in everything I own!
I use RL15 because it is same charge weights as Varget which I save for competition.

I probably shoot more of the SGK bullets than any other except my Berger F Class bullets. They are a third of the price as Accubonds and more accurate than some of the hornady.

 

[Shaggy357]

Good information and good thread so far. The reloading manuals are made as a reference. Each of the authors, or group of authors, publish data based on the gun, or shooting fixture, they used on a specific day or days. The data may not be the same for your gun and the environment in which you shoot it. That is why there are different powders, different bullets, and so many different guns. Just like chocolate chip cookies, the name may be the same, but there are a lot of different chocolate chip cookies out there.

You tailor your ammo, for your gun, using the book as a reference (guide). Most likely you will have to adjust your AOL to what best fits your gun. Many guys have loads that wont fit in the magazine, but are accurate for shooting paper. Many have a little bit different load so they can have a couple extra rounds in the magazine for hunting. Some even tailor OAL so the ammo fits in their favorite ammo carrier. As long as you work up your load, for your gun, using the guide, and staying safe, you should be good to go.

I picked up a 7-08 a couple of years ago. It is one of my light, go to, whitetail guns. A little Varget and 140 grain bullets are very accurate in it. I worked up the loads, slowly, using my gun to set my dies, and work up my load. Lots of references out there, as proven by many posts above. You have to wade through the information and learn what is vital to use in your situation, with your components, to work safely in your gun.

Good luck, shoot straight, and stay safe.

Steve

 

[Commo]

All, thanks for the ongoing comments. I am digesting it all and will continue to work up loads as you suggest. It is more likely that I'll try some lighter bullets in the 120-130 grain range than go heavier.

In studying the dimensions of the various bullets I have on hand I've discovered some interesting things, leading me to study all my numbers a bit differently:

___________________________________________________
(All 140 grains, just random samples that I know can vary a bit)

..........................BtoOG..................OAL (just the bullet)

Nosler Partition----.6105----------------1.147
Hey InterBond-----.6490----------------1.284
Berger VLD---------.6495----------------1.263
Nosler BT-----------.6810----------------1.2635
Nosler AccuBond---.7055----------------1.2810
__________________________________________________

Recall that it is important to me to stay with rounds that will safely chamber from the magazine. That means I need to stay a safe margin from 2.960, which I'm calling MagMax in my notes, as I experiment with COALs greater than the SAAMI 2.800.

After measuring BtoOG to the lands with my Hornady OAL tool and then measuring the round's COAL I've found that the Berger Hunting VLD comes in at slightly less than a conservative 'MagSafe' dimension (2.910, MagMax - .050). (BtoOG is 2.2810; creates a COAL of 2.8945)

Which means I can run the entire VLD test from Berger book (p 100), which I've got loaded (Varget, 37.5 grains) and ready to try once it warms up enough to get to the range.

(24 rounds are loaded in groups of 6 off the lands at .010, .050, .090 & .130...very interested to see if a certain group stands out as the Berger book suggests will happen..)

Just more data points in the learning process! REALLY want/'need' to buy a chronograph...

Commo