Difference in loads for standard and solid/monometallic bullets.

Pine Marten

Well-Known Member
Hello everyone.

I plan to start reloading shortly with FMJs for my 7mm-08, subsequently developing a stalking round. One of the bullets I'm looking at for stalking, just because I'm interested, has an unusually thick copper jacket, and the French distributor recommended that I should base loads on those for a "monometallic" bullet. I can't find any for a 150gr bullet in 7mm-08, but how do they differ generally from a standard load? I take it that the lower density means that a longer bullet is required to reach the same weight? 150gr is 150gr whatever metal you make it from so in terms of kinetic energy, it doesn't make any difference, there may be a difference in acceleration however, and therefore a possible pressure problem.

Any ideas on how I would potentially go about following this recommendation? I mean to be safe, I could just start out from the suggested starting load anyway and work my way up in increments, then I would start to see if there are any problems, but I just don't really know what the implications of having a thick-jacketed bullet are.

Thanks for any suggestions!
 
Hmmm, I shouldn't think they're that much longer given that they just have a bit more copper in the mix rather than being solids. I daresay the guy is just being justifiably cautious.
 
PM
The "problem" with mono metal bullets is the fact that they are not the same "hardness" as jacketed bullets. They require different forces applied by the propellant to engage the rifling and deform into it.
Many solid copper bullets do generate higher pressures than jacketed ones - However Barnes TSX & TTSX bullets have grooves like canelures around them to allow the metal to deform easier & keep the pressures down. The resultant lower bearing surface area also helps minimise copper fouling which can also be a "problem" with mono metal bullets.
Barnes do provide specific loading data for their bullets and in my experience it is very accurate & repeatable in my rifles.
Unless the manufacturer of the bullets you are considering can supply loading data specific to their products I would stay well clear - You can't assume that by starting at a starting load for "normal" ie jacketed bullets you will be safe. ---- You wouldn't want to burst that pretty stutzen would you?

Ian
 
I know nothing really about reloading but if it has a thick jacket does that mean it won't expend as readily in thin skinned and smaller animals (like roe for eg)?
 
I know nothing really about reloading but if it has a thick jacket does that mean it won't expend as readily in thin skinned and smaller animals (like roe for eg)?

No, it's more that there's a point about halfway or two-thirds along the jacket where there's a marked taper in its thickness, so that the front end expands and the back end stays in one piece. Same as most other expanding bullets.
 
PM
The "problem" with mono metal bullets is the fact that they are not the same "hardness" as jacketed bullets. They require different forces applied by the propellant to engage the rifling and deform into it.
Many solid copper bullets do generate higher pressures than jacketed ones - However Barnes TSX & TTSX bullets have grooves like canelures around them to allow the metal to deform easier & keep the pressures down. The resultant lower bearing surface area also helps minimise copper fouling which can also be a "problem" with mono metal bullets.
Barnes do provide specific loading data for their bullets and in my experience it is very accurate & repeatable in my rifles.
Unless the manufacturer of the bullets you are considering can supply loading data specific to their products I would stay well clear - You can't assume that by starting at a starting load for "normal" ie jacketed bullets you will be safe. ---- You wouldn't want to burst that pretty stutzen would you?

Ian

Well I don't want to burst my stutzen, no, but mainly I don't want to damage myself, so rest assured that I shan't be doing anything stupid. The manufacturer loads .270 win and 7x64 which are in the same sort of class of round currently with the same bullet, but they're currently just loading ones that are big sellers in France, which is why they don't have any 7mm-08 data. And of course they don't wish to expose themselves to any trouble, understandably, so they're keeping quiet on specifics for my possible plan.
 
Very heavy jackets can increase pressures in theory as it takes more effort to get the bullet to engrave fully in the rifling. This has the same effect on the charge burn as a heavier bullet as increased resistance has the same effect as enhanced inertia caused by weight.

In practice, I doubt if it makes much difference if it's only the jacket unless it really IS thick. Over the years I've only ever found one bullet that made a real difference to pressures when using a reasonable starting load for the weight. They were some recovered prewar US M1 173gn FMJBT bullets from old .30-06 ball ammo. Corresponding years later with the American .30-06 guru German Salazar confirmed these bullet were notoriously hard and needed a large drop in charge weights. That may well have been due to the hardness of the lead-antimony alloy used for the core as much as or more than jacket thickness. FWIW, all Norma bullets used to have mild steel jackets a generation back with a copper wash, and this is still common with East European military type bullets for the 7.62X39 and X54R. They never needed a charge reduction, or much of one, and steel is a lot harder than copper. (A lot of East European milspec bullets have steel cores too - seems they'd produce impossible pressures, but they don't!)

Monometal bullets like the old Barnes X use lower charges than equivalent weight lead-core types. That's not a hardness issue, rather bullet length with copper much lighter than a lead-core / gilding metal jacket combination. They end up with very long shanks for the weight and the extra barrel to bullet shank friction again increases pressures due to increasing the effective bullet inertia. The move from plain shank to grooved designs as in the current Barnes models transformed their performance, substantially reduced pressures and the tendency to copper the barrel up, while allowing increased charges and velocities. The max loads in the Barnes manual for these bullets are only marginally lower than found in equivalent manuals for 'traditional' bullets.
 
Thanks Laurie!

I've discussed this with a chap in France who developed a load for these for his .243. He found that the bullets were the exact same overall length as the equivalent Nosler Partitions, that there was no real difference in accuracy or point of impact, but that velocities were a bit lower than with the NP due to the additional barrel friction (the bullet has a different profile from the BT, with a longer cylindrical part). The bullet as a higher BC though. I'm going to explore this further.
 
A few years back Norma produced some "normal" spec jacketed bullets but for some reason they suddenly changed the jacket material between batches for a different (harder, brass like) material. These bullets (both factory loaded & home loaded) shot very differently to the normal copper jacketed versions. Pressures were noticably different as was accuracy, zero & grouping. I had 243 & 308 at the time and the symptoms were there in both calibres.
--- What I'm pointing out is that jacket material & construction can have a significant influence on performance and produce different pressures.

Ian
 
If it is a thick jacket over a lead core, look at the Swift Scirrocco data.
7mm-08 150gr Scirocco:

IMR-4350 46 gr 2721 velocity
RL-19 47.5 2680
RL-15 40 2693

Barnes 0lder XBT
http://www.barnesbullets.com/copper_manual/7mm-08_Remington.pdf
------------------------------------
Powder Weight Velocity Load Velocity
(grains) (fps) (fps)
AA 2700 41.0 2392 45.0 2625
XMR 4350 40.5 2446 44.5 2688
RL 19 43.0 2505 47.0 2738
Varget 35.0 2352 39.0 2621
BL-C(2) 36.0 2316 40.0 2573
H380* 39.0 2344 43.0 2584
H414 41.0 2478 45.0 2720
H4350* 40.0 2419 44.0 2661
IMR 4831 40.5 2425 44.5 2665
IMR 4320 35.5 2328 39.5 2590
IMR 4350 39.5 2432 43.5 2678
Norma 204 40.5 2381 44.5 2616
VIT N160 41.5 2419 45.5 2652
Win 748 36.0 2319 40.0 2577
Win 760* 40.0 2433 44.0 2676




Barnes New TSX and TTSX
http://www.barnesbullets.com/images/7mm-08RemingtonWeb.pdf
------------------------------------
Bullet Weight: 150 gr Case Trim Length: 2.025" S.D. 0.266
Bullet Style: TSX BT Primer: Fed GM210M B.C. 0.408
COAL: 2.735" Barrel Length: 24"
Case: Winchester Twist Rate: 1:9.5"
Charge Velocity Charge Velocity Load
Powder (grains) (fps) (grains) (fps) Density (%)
BL-C(2) 38.5 2496 42.5 2713 87
H414 42.5 2585 45.0 2709 95




Nosler
----------------------
7mm-08 Remington — Nosler

From Jim Carmichael on tmperature:

To determine the exact velocity differences, I shot W760 in the summer heat and winter cold. Nosler’s 150-grain Partition bullets had an average muzzle velocity of 2,756 fps with 47.0 grains of W760 when I sighted in the Model 70 Featherweight during a 91-degree F day in August for my wife’s upcoming moose hunt. The same box of cartridges had an average velocity of 2,725 fps at 33 degrees F, about the temperature in late November when my wife sent one of the Partitions through the neck of a bull moose.
 
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If it is a thick jacket over a lead core, look at the Swift Scirrocco data.
7mm-08 150gr Scirocco:

IMR-4350 46 gr 2721 velocity
RL-19 47.5 2680
RL-15 40 2693

Thanks Southern! It's pretty similar to a Swift Sirocco in construction, except that there's a more pronounced "shoulder" in the jacket to promote expansion faster I suppose. RL-15 is very similar to n140, and 40gr is pretty much the maximum load that the Viht and Sierra load data gives for other 150gr bullets. So essentially, it doesn't look like in practice it's any different to load. It's just a question of whether or not the rifle likes it. Right, now to arrange for these things to be sent over from France.

Oh, for those who are interested, this is what I'm looking at (the 150gr spitzer/HP):
http://www.munitions-freyr.fr/index.php?id_product=89&controller=product

http://www.johannsen-jagd.de/data_de/katalog_en/seiten/seite168e.pdf
 
Hi PM
By the look of the pictures of the bullets shown on the link you gave, they have quite a long bearing surface. This could lead to high pressures and excessive copper fouling. It may be worth asking the manufacturer about that.
Also at nearly a £ per bullet plus shipping costs, I can't fully understand why you would choose this manufacturer over the top manufacturers like Nosler, Barnes, Sierra, Winchester, Hornady etc etc. Especially as they are not providing you with proper loading data for your calibre. --- All looks a bit "Gaelic" to me mon ami.

Ian
 
all the book data in the world is not going to help you as they are not based on YOUR rifle

they only give you an indication of a safe range

only one way to work out the best load is trial and error (not failure or accident!)
Highly unlikely that you will experience breach busting pressures if you use caution and start your loads as you would for any other bullet

Use your common sense and knowledge of YOUR rifle
is YOUR rifle showing pressure signs at the mid, upper-mid or upper point of any other range of charges?

A low charge for a comparable bullet weight is always going to be the best place to start and regardless of construction the data starts here to give you a benchmark
Incremental rise in charge may demonstrate pressure signs more quickly with mono metal or thicker jackets...but not to the point of introducing a new reloading methodology

Even Woodleigh "hydostatically Stabilised", Solid Brass bullets use standard load data
 
Hi PM
By the look of the pictures of the bullets shown on the link you gave, they have quite a long bearing surface. This could lead to high pressures and excessive copper fouling. It may be worth asking the manufacturer about that.
Also at nearly a £ per bullet plus shipping costs, I can't fully understand why you would choose this manufacturer over the top manufacturers like Nosler, Barnes, Sierra, Winchester, Hornady etc etc. Especially as they are not providing you with proper loading data for your calibre. --- All looks a bit "Gaelic" to me mon ami.

Ian

Thanks Ian, I will follow up with them. In fact, I already have and am waiting for a response. I'm not going to take any risks, don't worry. The cost doesn't really matter that much because I use so few actual stalking rounds, and even at £1 a bullet, that three times less than I'm paying for factory ammunition. In fact, so far, 95% of my shooting is practice at the BSRC, only I've been using stalking rounds for it which is expensive and daft. So my first task is actually to develop an FMJ load. Now as regards choosing the Degol bullets, they're rapidly gaining popularity in France and people obtain very good results with them. Not that deer and boar were failing to die before of course. But I just fancy being the first person to use them in the UK, it just caught my imagination, it makes the project more interesting. If the worst comes to the worst, there'll be rubbish and I won't use them. I will have lost £50, and I'll fall back on something more usual.
 
all the book data in the world is not going to help you as they are not based on YOUR rifle

they only give you an indication of a safe range

only one way to work out the best load is trial and error (not failure or accident!)
Highly unlikely that you will experience breach busting pressures if you use caution and start your loads as you would for any other bullet

Use your common sense and knowledge of YOUR rifle
is YOUR rifle showing pressure signs at the mid, upper-mid or upper point of any other range of charges?

A low charge for a comparable bullet weight is always going to be the best place to start and regardless of construction the data starts here to give you a benchmark
Incremental rise in charge may demonstrate pressure signs more quickly with mono metal or thicker jackets...but not to the point of introducing a new reloading methodology

Even Woodleigh "hydostatically Stabilised", Solid Brass bullets use standard load data

Thanks Bewsher, I'm going to be very cautious indeed. The manufacturer has now told me that he's going to help me out, just because I think it's tickled his curiosity, so that's reassuring.
 
Hee Hee PM --- welcome to the BSRC Eccentrics Society you just qualified with honours!- Just don't paint your stutzen stock with green scales! - That's called Klench's syndrome!
Enjoy.

Ian
 
Just don't paint your stutzen stock with green scales! - That's called Klench's syndrome!
Enjoy.

Ian

Not a chance! I've been working on the stock with a mixture of linseed oil and turpentine for over a year now and the grain is really starting to come out, darker veins appearing, a bit of patina, it's going to end up looking really lovely. Not to mention that it received a good soaking the other day and all the water just pearled off the stock like water off a duck's back.
 
I think the old Barnes data, the Nosler data, and the Scirocco data all point to 40.0 gr being tops.
To be safe, you need to use a chronograph as you work up there, and watch as you pass 2,600 fps.

But as other have said, why not just use a Barnes TTSX, which has plenty of data, costs less, and shoots well?

And why shoot a 150-gr mono bullet? N-140 would work better with 140-gr.
And a powder like RL-19 will give way more velocity with a 150-gr.

The 1:10 twist will stabilize it fine. I shoot 150 and 154 gr bullets in my 7mm-08s and my .280 Rem, which are 1:10.
 
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