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Posted: 10/7/2008 8:16:24 PM EDT
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Can someone help me out with a max load? I am loading 70grn tsx using varget. My manuals tell me two different things. One says, for a 70grn jacketed bullet using varget, a max load of 24.5 grns, and the other says 26 grns. I shot up to the max load of 24.5 over the chrono this past weekend. I got velocities just above and just below 2700. I had no pressure signs whatsoever. Can anyone enlighten me of what the true max load is? FOrgot to mention its for .223 |
No, nobody can enlighten you because the max load will be different for every rifle. |
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I understand that, I am talking about a published max load. I have two manuals, one says 24.5, the other 26. I am just wanting someone to pipe in and tell me which is correct. 1.5 grns is a big difference. I working up a round for my rifle.....i want to know if i am already at the max, or should I continue towards 26 grns |
| Technically they are both right. It just depended on the components and equipment that the testers actually used. If the 24.5 gr showed no signs of excessive pressure then you shouldnt have any problem if you gradually increase from that. Since every rifle is different, some safe experimentation is required with this hobby. |
They are BOTH correct.... As stated earlier, max is different for every rifle. There were two different rifles used to obtain the max loadings in the manuals you have. To obtain the max for YOUR rifle... there is no substitute for the proper load developement. Nobody online (Or anywhere else for that matter.) can help you determine what that max load will be. Best, Swampy Garands forever __________________ 2007 NRA Missouri State 600 yard Service Rifle Champion. Score 774-29X... with an M1 Garand owner Swampworks Inc. / JLK Bullets The difference between a Hot Dog and a Weenie is a very fine line. Never underestimate the power of human stupidity.... You say that you believe in man made global warming??? AHHhhh BWA-HA-HA-hahahahah...... Sorry, I was having a "moment". See the last line above. |
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It is really too bad that there seems to be no factory ammo loaded with the 70-gr Barnes TSX bullet in .223. If there were, you could shoot that ammo thru your rifle and see what factory velocity was in your gun. Then you could load your handloads to give the same velocity as the factory ammo and know you are running at the proper pressures - which is something that I would call the "practical maximum (or working) velocity". Failing that - the second best thing is to observe what velocity the loading manuals get with their maximum loads and do not exceed that (as an average). For instance, Sierra says 26.1 will give you 2850 fps from a 20" AR with a 69-gr bullet. Hornady says 24.9 will give you 2800 fps from a 20" AR with a 68-gr bullet. Barnes data (with different powder, but in the same burning rate area) gives a maximum velocity of around 2900 fps, but with a longer 24" bbl. Keeping in mind that the all-copper TSX may react somewhat different than the, hair-lighter, cup-and-core Sierra/Hornady OTM bullets, so caution is good. I think that you could safely work up to 2800 fps without any pressure issues as a maximum for a 20" bbl. Of course if you have a 24" bolt gun, you can probably go 2850-2900 fps. You use this chronograph method in conjunction with observing other pressure signs. Make sure you shoot enough rounds to get a good average. At least 5, and 7 to 10 is better. In my personal experience, I have found the Sierra data to be a bit closer to my "real life" experimentation in .223 than the Hornady. I hope this helps you out. "Muzzle velocity for a selected load is a function of the mean effective pressure and the barrel length." - Lloyd E. Brownell, Ph.D. - Firearms Pressure Factors, Wolfe Publishing Co. "...next to real pressure equipment, a chronograph is the best guide to excessive pressure for the home handloader. There are no “magic barrels” that allow another 100 to 200 fps!" - Handloader, June 2004, “More Pressure Experiments”, John Barsness. |
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