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Yes, I realize that most loading manuals use longer than normal barrels for their tests, but even when I'm using the same length barrel, I almost always am below the velocity stated in the manual for any given load. The latest example is in my new .270 Win for which I am loading 58.5 grains of of H4831sc under 140-grain Accubonds. Book says I should be at 3050 fps with a 24-inch barrel. However, with my 22 inch barreled M-77, Mark II, I average about 2900 fps. 150 fps for 2 inches seems like a lot of lost velocity. Now, I'm using an electronic scale that I use check weights on pretty regularly, so my powder volume should be correct. The only other thing I wonder about is whether my Shooting Chrony is measuring low. If it is, then it is consistantly low, because all my loads are pretty close (10-20 fps). BTW this load is VERY accurate, and I seriously doubt any animal I shoot will notice the lost velocity (certainly the nine-pointer I shot last Saturday didn't notice when it bang-flopped). The only time I might miss velocity is in extra-long-range shooting when calculating bullet trajectory. Any ideas? | ||
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FWIW...quickload estimates your load will do 2878 and is operating at 55k pressure. YOu could probably bump up to 59.6 grains which should give you about 2960 and about 60k pressure. That little bit is pretty meaningless but you are really a victim of a manual that is too optimistic.....your gun is "on the money" according to this forecast. | |||
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It's that damned Nosler manual. It gives me penis envy ever time I load it's recipes! | |||
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The load tests are done under ideal temperature humidity and (lack of) wind conditions using a solidly locked in position barrel. The lab where the loads are tested also has a blast screen in front of the chronograph. Care is also taken to eliminate most it not all light entering the sensor fields from the sides. Believe it or not I have actually witnessed loads chronographed at or above the claimed velocities listed in the Sierra manual for the .30-06 and a couple other rounds using the data supplied. It was unusual, but it can happen. If the enemy is in range, so are you. - Infantry manual | |||
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Your components are not the same as Nosler used. There are variations in the powder, primers, case capacity, bullet jacket and core hardness. The chamber of your rifle is not the same and is likely a bit larger then the labs. The bore of your rifle probably isn`t as tight nor is the angle of the leade, nor throat the same. Temps in the lab are controled, as is humidity. The chrony as noted is set up different, and velocity is adjusted to the muzzle where you likely took a reading at some distance and called it good. ------------------------------------ The trouble with the Internet is that it's replacing masturbation as a leisure activity. ~Patrick Murray "Why shouldn`t truth be stranger then fiction? Fiction after all has to make sense." (Samual Clemens) "Saepe errans, numquam dubitans --Frequently in error, never in doubt". | |||
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one other thing is that the slow burning powders in large cases will loose more velocity than average. the slow burning stuff uses a longer barrel to completely burn | |||
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I have a bunch of 30-06 and 308 rifles. Performing load testing and getting the rifles zero'd I have built up a large data base of velocity data. So I have a good idea of what should be a safe upper limit for a load. And I have one 03A3 that has a slow barrel. Cross checking data proved it. However whenever you have a one of a kind rifle, until you start having blown primers, leaking primers, or a sticky bolt lift, you really don't know how far you are from a maximum load. And whether the velocities you get over the screen are maximum, close to maximum. So, use your judgement. If you really want to find a maximum load, keep adding powder till you blow a primer. Record the velocity and stay away from it in subsequent load development. | |||
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Yep, A chronograph sucks! One thing I have learned is that all firearms are diff. You can load identical ammo in two rifles of like manuf. & still get 100fps diff. Precise size of chamber & bbl., smoothness of the bore, plus normal deviations from shot to shot, plus we are not using the exact lots of components, all play into the ultimate vel. readings. I have gotten close to the Nosler manual w/ some loads & not even on the same page w/ others. Just note it & move on. It's just is what it is.  LIFE IS NOT A SPECTATOR'S SPORT! | |||
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I too find that the Nosler manual is often unrealistic. I prefer to use the Speer to begin dialing in a new load. All you need to do is compare a few manuals and youll see that there are considerable variations. I replaced a barrel on an 06 a few years ago and gained an average of 200 fs. Lots of variables, but like I said, from the collection of manuals Ive gathered I find the Speer to be the most consistant and realistic reguarding stated velocities. | |||
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Interesting conversation. Chronys can raise eyebrows at times. For example I have two 30-30 marlins. I've chrony'd the same ammo through both of them. One of them has a 336SC w/20" barrel and the other a 30TK w/18.5" barrel. The shorter rifle consistently get higher velocity with all ammo. What I have learned from it is that the TK has a very tight chamber, and I had to back off loads that are safe in the SC. In my other rifles I have found velocity is about what manuals predict they should be. They are neat tools but don't get hung up on some unrealistic goals. | |||
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According to the Barnes Manual #4 44.5 gr. of IMR-4350 should deliver 3124 FPS from a 24" barrel.257 Robt. with the 100 gr. TSX. My ex-son-in-law and I both have Winchester M70 Featherweights chambered to the .257 Robt. using that 44.5 gr./IMR-4350 load, his rifle delivers 3050 FPS and my rifle 2851 FPS, both guns tested over the same chronograph on the same day. I loaded all the ammo for the test with the powder and primers all from the same respective lots. Brass for both rifles was Winchester as were the primers. I can see the 74 FPS loss due to his 22" barrel but I'm at a loss to explain why my rifle is 273 FPS slower than the Barnes gun. That's a pretty radical difference. The only thing I can think of is my gun is installing drag chutes on the bullets as they exit the barrel.  Paul B. | |||
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I suspect the biggest single reason we get lower speeds from both factory ammo and our handloads than what is predicted is that our mass produced and factory cut chambers and bores are sloppier. With a given charge, a larger diameter chamber/bore will obviously obtain lower pressures than a smaller one. Test gun barrels are, usually, specifically ordered and chambered for the tests and they are tight. | |||
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If you look at Nosler data for the 270 you will see they use a Shilen 24" long barrel for their testing. If you could build a rifle using the same barrel/length/twist etc you might come close or exceed the published data. The load for my Hart barrel 270 came out of the Hodgdon #26 manual 150gr bullet 58gr/H-4831 @ 3015fps which is a max load same load in my rifle gets 3077fps. About 25 years ago I had a real good load for a factory 270 using 130 gr bullets took alot of deer with that load then I got a chronograph found out my load was appr 200fps slower than published data almost wished I didn't get that chronograph. It was a good learning experience for me in that I work up my loads then check velocity. Well good luck. VFW | |||
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I doubt that Nosler is outright LYING about the velocities they say they got. Those figures are indeed valid for the gun they were using, and the other conditions present on the day the loads were tested. In the days before chronographs that we could all afford, we thought we were getting the published velocities, and were happy as clams. Now, we chronograph our loads in our guns, and when they don't come up to book levels, we become frustrated, and say nasty things about the guys who wrote the reloading manuals. "Bitte, trinks du nicht das Wasser. Dahin haben die Kuhen gesheissen." | |||
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Yeah! We even get to think that a bullet striking a deer at 1900 fps will bounce off! Regards 303Guy | |||
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Hummm, Nosler says I should get 3005fps with the load I'm using, and I'm only getting 2997. IOW the problem is YOUR chamber/barrel, NOT the data they reported. | |||
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The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Guns, Politics, Gunsmithing & Reloading Reloading Book vs. Actual velocities for a given load?
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