Page 1 of 3 123 LastLast
Results 1 to 10 of 29

Thread: Difference in loads for standard and solid/monometallic bullets.

  1. #1

    Difference in loads for standard and solid/monometallic bullets.

    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!

  2. #2
    The only problem i can envisage is that you may need faster twist rate to stabilise your longer bullets.

    Ian.

  3. #3
    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.

  4. #4
    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

  5. #5
    Might Barnes 150 gr TTSX data for 7mm bullets not be a starting point? Regards JCS

  6. #6
    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)?

  7. #7
    Quote Originally Posted by palmer_mike View Post
    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.

  8. #8
    Quote Originally Posted by Yorric View Post
    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.

  9. #9
    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.

  10. #10
    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.

Similar Threads

  1. copper bullets - test loads
    By david1976 in forum Ammunition, Reloading & Ballistics
    Replies: 12
    Last Post: 24-05-2013, 15:49
  2. 243AI loads for 100grn Nosler Partition bullets
    By dogfox1 in forum Ammunition, Reloading & Ballistics
    Replies: 4
    Last Post: 26-03-2013, 14:08
  3. Changing bullets in home loads
    By N.F.W.M in forum Ammunition, Reloading & Ballistics
    Replies: 14
    Last Post: 28-06-2012, 20:06
  4. Solid Brass Bullets
    By Clive1967 in forum Ammunition, Reloading & Ballistics
    Replies: 3
    Last Post: 05-06-2012, 19:32
  5. Redding Standard vs Deluxe vs RCBS Standard vs Competition
    By maffs in forum Ammunition, Reloading & Ballistics
    Replies: 11
    Last Post: 12-05-2012, 16:59

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •