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Thread: load exchange

  1. #1
    Boolit Master nueces5's Avatar
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    load exchange

    I was looking into developing a load for my Mauser 765, and I did the best thing I can do, which is take a known load and go from there.
    I load with 314299 size to 309, 42.5 grains of win 760. That gives me a speed on my cz 550 308win of approximately 2350 fps.
    Now I wanted to do the same with the 7.65 x54, and I started to see the amount of water grains that both brass have. 56 for the 308 and 58 for the 765.
    Do you think there will be any difference in behavior? I think there should be less pressure.

  2. #2
    Boolit Master
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    You're going to get a lot of varied opinions on this. The 308 case is essentially a very slightly shortened 7.65 case. Pressure should be a little lower. Is your 7.65 a 1909 Model or 1891 Model? I don't know what the pressure limitations are on the 1891 but I have read that they have a lower pressure limit.
    Hick: Iron sights!

  3. #3
    Boolit Master
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    I shoot a sporterized Mauser 98 in 7.65 Argentine Mauser. It has a 1908 Brazilian receiver with a 1909 Argentine stepped military barrel. So far the most accurate load that I've experienced with it is 24.0 grains of Shooters World Buffalo (same as 5744 powder), using the Lyman #311284 bullet. I take the as cast bullet and powder coat it to bump up the diameter, then size it to .3125" Powder coated and gas checked this bullet is around 215 grains. I seat the bullet so that the bottom of the gas check is even with the case shoulder. At 50 yards it has always made just one raged hole. I haven't shot it at paper targets at 100 yards, but it has struck everything that I've shot at at that distance, and hit right where I was aiming. In my rifle the 311284 is even more accurate than the 311299 (which is no slouch). The ballistic coefficient isn't as good as the 311299 so there will be more bullet drop at long range, but if the accuracy is better, then that would be a good trade.

    I consider the 308 and the 7.65x53 to be two completely separate cartridges, and load them accordingly. They may have similar cast bullet performance, but things like barrel throat configuration, the difference in case shoulder diameter and angle, the twist rate, and the difference in bullet seating depth, plus other things, means that I make loads for them individually and don't share the same load between the two.

  4. #4
    Boolit Grand Master


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    You will have lower pressures in the 7.65 with the 308W load all other things beside the load being relatively the same. This is because of the increased volume of the 7.65 and also the difference in the expansion ration of the .308 vs .312 groove dimaters.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  5. #5
    Boolit Buddy

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    Lyman already did the work for 200 grain cast lead in 7.65x53. Why not just get the book and use the Lyman start data and work from there?

  6. #6
    Boolit Master nueces5's Avatar
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    Thank you all for the answers, it was more or less what I thought.
    In the third edition, which is the one I have, the win 760/h414 load does not appear for my 7.65
    I have no idea if it comes in new editions.

  7. #7
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    Texas by God's Avatar
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    The 7.65 is the first smokeless Mauser cartridge and they got it right- as I’m finally finding out with a nice 1891 sporter that I got last year.
    My rifle is 34 years older than its brass!


    Sent from my iPhone using Tapatalk

  8. #8
    Boolit Buddy

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    Quote Originally Posted by nueces5 View Post
    Thank you all for the answers, it was more or less what I thought.
    In the third edition, which is the one I have, the win 760/h414 load does not appear for my 7.65
    I have no idea if it comes in new editions.
    Sorry, I did't realize you wanted to stick with 760/H414. Lyman 4th Edition doesn't list them either.

  9. #9
    Boolit Grand Master


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    Quote Originally Posted by Texas by God View Post
    The 7.65 is the first smokeless Mauser cartridge and they got it right- as I’m finally finding out with a nice 1891 sporter that I got last year.
    My rifle is 34 years older than its brass!


    Sent from my iPhone using Tapatalk
    I really like the M91 Argentine, especially for shooting cast bullets. I have 4 of them; an all original M91 rifle, along with 3 that were "sportered" and then sold. Two of them are still 7.65s [an excellent cartridge for sure!] and one which had a pretty bad barrel I rebarreled to 35 Remington. The M91 with it's single stack mag will feed any bullet nose configuration w/o the problems, especially with WFN cast bullets feeding from the left side of a staggered magazine.

    This is my M91 "truck rifle". For S&Gs I have shot the 314299 using the leaf rear sight out to 600+ yards. Lots of fun. However, it's mostly used with Jacketed, either 123 AK/SKS SPs or the Hornady .312 SPs.

    Click image for larger version. 

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    Last edited by Larry Gibson; 06-25-2024 at 12:44 PM.
    Larry Gibson

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    ― Nikola Tesla

  10. #10
    Boolit Master
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    nueces5: The folks that have responded to your post have all been singing the praises of the 7.65x53 Cartridge (and a very good cartridge it is!), but in that glowing admiration we've left a few things go unnoticed. You said that you want to shoot your 314299 cast bullet at a velocity of 2350 fps (same as your 308 load). A typical Argentine Mauser has a barrel twist rate of very close to 1 turn in 11 inches (darn that metric system!). That would be giving your bullet a spin rate of around 153,818 rpm. I'm pretty sure that Larry Gibson may be along again pretty soon to explain why that may not give you the optimal accuracy in your rifle. Velocity is important in that it decreases the rate of bullet drop, and allows less time in flight for cross winds to cause bullet drift, but ultimately shot to shot consistency is more important to accuracy than higher velocity.

    Second thing: You should go online and download Gordon's Reloading Tool. It is a free download, and is a reloading program with lots of cartridge, bullet, and powder combinations. There are lots of videos on youtube on both how to download the program, and also how to use it. GRT is very useful, and I think you'll find it a really good program for developing your loads. (one thing that I've seen on my version of GRT is that the program tries to keep the cartridge OAL within SAAMI specs., which means that when I want to load a bullet that's long and heavy for caliber: in example the RCBS 30-180-FN into the 7.62x39 cartridge, the program shows the bullet seated way too deep for what I intended. Always double check the seating depth on the program, and you can easily edit that and other features.)

  11. #11
    Boolit Master nueces5's Avatar
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    I should do my homework and read a little about boolit stabilization!
    But for God's sake! never heard of Gordon's Reloading Tool! I'm looking for it and downloading it
    I love the cartridge (7.65) since it was the first one I had, it is a shame that it does not share the possibility of using fmj .30, which are easier to obtain.
    I used the charge to do long range, so I sacrificed a little precision in the 308 to reach 600 meters easier, unfortunately the precision was not enough.
    It happens to me when you talk about yards, ounces and miles!! I have to go convert!
    Thank you very much for the advice!

  12. #12
    Boolit Master
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    One thing to take into consideration is that the 46th Lyman Reloading Handbook lists the ballistic coefficient of the #311299 bullet at .377 at 1800 fps, and increasing to .390 as the speed drops to 1400 fps. The profile of the 314299 is nearly identical to the 311299. Even if Lyman's numbers are a bit high, they still indicate that you're already shooting one of the best bullets for your long range application.

  13. #13
    Boolit Grand Master


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    Quote Originally Posted by nueces5 View Post
    I should do my homework and read a little about boolit stabilization!.........
    While the centrifugal force of RPM can and does spin some bullets apart spinning bullets apart has nothing to do with the RPM threshold which occurs at a much lower RPM than is required to spin the bullet apart or even upset/stretch the bullet. The RPM Threshold also does not adversely affect the bullets stability in flight. If stable, the bullet will continue to fly point forwad even though it may have grossly exceeded the RPM Threshold.

    The RPM threshold occurs at a point when;

    The bullet is unbalanced or becomes unbalanced due to uneven obturation in the bore or canting in the bore with ill fitting bullets during acceleration. The unbalanced bullet is forced to conform while in the barrel and its center of mass is revolving around its geometric center. When the bullet is free of the barrel's constraint, it will move in the direction that its mass center had at the point of release. After exiting the muzzle, the geometric center will begin to revolve about the center of mass and it will depart at an angle to the bore (line of departure). At 54,000 RPM to 250,000 RPM, depending on velocity and twist, the centrifugal force acting upon any imbalance in the bullet can be tremendous. It will result in an outward or radial acceleration from the intended flight path (line of departure) and will try to get the bullet to rotate in a constantly growing helix.

    "Try to" are the key words here as there are things we do (slower burning powders, harder alloys, better designed bullets, perfect fit, etc.) that we do to push the RPM threshold upward. Conversely, using a faster powder, softer alloy, no GC, etc) lowers the RPM threshold. When the bullet goes beyond the RPM threshold it does not lose "stability”. It still is flying point forward. Its flight path simply becomes a larger expanding helical one. This is why when the RPM threshold is exceeded the groups expansion as range increases is non linear.

    With cast bullets the RPM threshold will be exceeded long before the centrifugal force is enough to "spin the bullets apart". Exceeding the RPM threshold becomes apparent by the decrease in accuracy as velocity increases and the non linear expansion of group size as range increases

    Thus, if the RPM threshold (normally in the area of 120 - 140,000 RPM....where is dependent on numerous factors) is crossed accuracy suffers, particularly in a linear expansion of the group size as the range increases. However, as previously discussed in numerous other threads on the topic the RPM threshold can be moved up or down by varying several factors. I have thoroughly demonstrated this numerous times using a 10" twist .308W rifle, with 3 different bullet designs suitable for the purpose using #2 alloy and using slow burning powders. Pushing those bullets to 2200 - 2300 fps at 45 - 48,000 psi) at 167 - 178,000 RPM they have held 2 moa accuracy (just about the accuracy level the rifle is capable of) or less to 500 yards.

    BTW; my M1909 and three M91s all with original military barrels have 10" twists.
    Larry Gibson

    “Deficient observation is merely a form of ignorance and responsible for the many morbid notions and foolish ideas prevailing.”
    ― Nikola Tesla

  14. #14
    Boolit Master nueces5's Avatar
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    thanks 405 and larry, I will reread all this to better adjust boolit and speed
    The precision of 2 moas is all I have achieved in this time, if you think that in Argentina a box of hornady costs 120 dollars, approximately, 2 moas is not that much for the old 1909!
    and while we test, we have a lot of fun!

  15. #15
    Boolit Master
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    I have also pushed the limits on the .30cal and experience mirrors Larry's. I did a detailed test at 500yd with a 10 twist .308W and watched the vapor trails of the bullets. As the velocity neared 2400fps I could see the helical path of the bullets. Group went from near MOA to very large (missing the 4ft tgt board).

    My best accuracy with that rifle remains at just under 2000fps. And with some bullets you can still get decent groups at 500 and 600yd.

  16. #16
    Boolit Grand Master popper's Avatar
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    3.5% diff in case volume so seating depth/load fill will actually determine pressure. I.e., empty case space. I pushed cast in 308W to 2400 fps and did barely MOA @ 200. Not that hard to do.
    Whatever!

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check