Does that mean the lighter case have a larger internal capacity?
This all started when using Lith cases, the normal load I use with Fed GM and LC Match cases is too hot in the Lith cases. The groups are all over the place with a 168 smk using 41.5 H4895 in Lith cases. I am down to 39.5 H4895 and things are improving big time. Am I on the right track?
The Lith cases with a 150 HPBT and 41.5 IMR 4064 are outstanding in my rifles. I'm trying to find a load using Lith cases with 168 SMK. Thank you. art
I hate to say it but I never looked at it that way but you it looks like you are right, the lighter the case the greater the volume. If you can give me the volume info for the Lith cases (in grains of water after they are trimmed to your desired length) I could work some numbers for you using my QuickLOAD software. It wont tell you what is the most accurate but at least it will help you predict what load would be within the muzzle velocity and chamber pressure specs that you are trying to achieve. I would need to also know what bullet you want to use, the powder and charge weights you are interested in and the OAL of the cartridge and the barrel length.
I will have more information after the range trip tomorrow. I am shooting five shot groups off the bench with the M1A. So far the three best loads have been, measuring the best of four out of five shots,, have been 39.5, 40.0 and 40.5 grs of H4895 with the 168 on top. All of these have been under an inch, tomorrow I plan to bump up to 41.0 grs., I'll let you know the results, if this load is five shots under an inch there is no need on this end to mess with it any further. I didn't realize how lucky I was when getting my ammo free, the food wasn't that great but the Haircuts were free. Thanks, art
Not a problem Art, glad to be of help to someone of your caliber. I have used IMR 4895 and I like a charge weight of 41.3gr for my rifle, since H 4895 is just a tad hotter I'll bet you end up right around 40.5 - 41.0 grains.
LC NATO 08 brass
trimmed to 2.004"
sized and unprimed case weight: 175.1 gr.
weight of H2O from case.(rubber seal in primer pocket): 52.8 gr.
Federal NATO 08 brass
trimmed to 2.006"
sized and unprimed case weight: 176.6 gr.
weight of H2O from case.(same rubber seal): 52.7 gr.
GGG 04 brass
trimmed to 2.006"
sized and unprimed case weight: 178.5 gr.
weight of H2O from case.(same rubber seal): 52.5 gr.
Here's the kicker Art.
I use a Lee hand press to size my brass. I do this in part to get a feel for each manufacturers brass and to give me an idea when the brass has lost its malleability.
FC of course is the softest brass of the bunch.
LC is nice and hard.....But
GGG is even harder than the LC.
I am thinking that the slightly lower internal case volume plus the greater hardness of the brass is what is causing your loads to be hot in GGG cases.
Thank you both for adding to my limited loading knowledge base.
Clearly the ggg Lith, cases have a smaller capacity, peegee's contribution, and Rammac hit it right on the money with what he predicted the correct powder charge would be..
Today, which was a very windyTexas adventrure, the Lith cases with 40.5 and 41 grs. gave the best results. I'll settle in with that and use up some of these 168's. Several times today small animals blew across my sight picture, pure Texas BS. Thank you both again. art
I use LC-07 brass avg wgt is 176grains for a trimmed unprimed case.
168SMK loaded to 2.80 COL, with CCI#34
only 40.4g of new stock IMR 4895 yields 2560 avg fps from my M1A, measured across my Master Chrono. With no pressure signs....could probably go to 41 grs...but its not necessary for me, I need only 2550 fps, so I stopped there. I know quite well that the original Army tech manual called for 42.0g of 4895 in M852 cartridge(I'm assuming 4895 has gotten a touch warmer over the past 50 years so slightly less powder is needed to reach the original velocity)
40.1 grains yields 2500 avg fps.
as usual make sure to work up to your own max loads.
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