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Posted: 8/14/2010 7:05:50 AM EDT
| Anyone out there have loads or a source of loads for the MPC besides what JD supplies? I've tried calling IMR, sierra, aa etc with no help. Is there a computer program out there that can help? Thanks |
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Anyone out there have loads or a source of loads for the MPC besides what JD supplies? I've tried calling IMR, sierra, aa etc with no help. Is there a computer program out there that can help? Thanks You can look at the rounds Bore to Capacity ratio and get an idea of what class of powders would work in the MPC. What bullet weights are we talking about? The 6.5 MPC is at its best with IMR-4227, H-4227, AA-1680, IMR-4198, and H-4198. This means with the lighter bullets you can go as "fast" as, say W-296 and with the heavy bullets you can go as slow as, say AA-2015. |
| The 6.5 MPC is a necked up .223 with the shoulder set back. Well I'm new to wildcatting although I've been reloading for 30+ years. I'm trying to stick with 100 gr bullets, Nosler ballistic tips and sierra. I may go to the 107 gr sierra. I've asked JD of SSK if I can use the 6.5 TCU data and he told me no, it's not the samed cartrage. Can you extrapolate loads from cases that are close or the 6X45? I've got a pound of 1680 now and use varget in my .223. Seems I have a lot to learn but hey it is intersting. I appreciate all the help I can get. The rifle is an AR15 20 in. barrel. |
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I think that the MPC is at its best with the 90gr to 108gr range of bullet.
Varget is too slow for the 6.5 MPC. A 100gr 0.264" bullet has the same SD as an 85gr 0.244" bullet, roughly. That said, with the increased bore area you would choose a faster powder than what you would use in the 6x45. Take a look at the development of the .25x40 round (aka .25 Bailey) on this site. 19.5gr of AA-1680 would be a good starting point with a 100gr Nosler BT or Lapua Scenar. 2,700fps MV with a 20" barrel is not outside the realm of possibilities. |
| Thanks! I'm headed down to my reloading area now. JD shows a load of 22.4 grains of 1680 for a 107 gr. sierra. He also show a load of 22.2 to 24.2 of WC680 (which I believe is a surplus powder no longer available that is very much like 1680) with 100gr sierra, tested out of a 12" TC. Do you know of any trustworthy software out there that I can use? |
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Thanks! I'm headed down to my reloading area now. JD shows a load of 22.4 grains of 1680 for a 107 gr. sierra. He also show a load of 22.2 to 24.2 of WC680 (which I believe is a surplus powder no longer available that is very much like 1680) with 100gr sierra, tested out of a 12" TC. Do you know of any trustworthy software out there that I can use? If you program it correctly, QuickLoad is quite good. The thing is to actually use data from your measurements and not the presets in the program. W-680 is no longer made, but AA-1680 is quite similar in bulk and burn rate. 19.5gr of AA-1680 is a start load only, to get you on your way. I think that 22+gr would be getting close to max. Just my opinion though. If you use the 107gr Sierra MK and the 108gr Lapua Scenar OTM, AA-2015 and AA-2230 deserve a look, especially if you decide, for some reason, to go heavy (120gr). |
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Thanks Redfalconbill, How did you learn all this? I have powder burn charts etc. but not the knowledge to put them into practice. Guys on this site (ronaldmwilliams, 762x40mm, and others who I have forgotten) have done work with the .222/.223 case. It is not hard to figure out. ~29.0gr to 31.0gr of H2O case capacity (take 30.0gr as the middle point) w/ a 0.264" bore diameter. Area is pi R squared. To have fewer decimals, I use 13.2 instead of 0.132 as the radius. So, ((13.2 * 13.2 )* 3.145927)/30.0 = 18.25 Then, armed with this, you look for other rounds that have the same, or a very similar, bore to case capacity ratio. A 0.308" bore would need 40.8gr of H2O case capacity. A 0.338" bore would need 49.2gr of H2O case capacity. A 0.358" bore would need 55.2.gr of H2O case capacity. The .358 Winchester round has a H2O case capacity of ~57.0gr to 58.0gr. Close enough for government work! A 100gr 0.264" diameter bullet has, roughly, the same Sectional Density as a 180gr 0.358" diameter bullet. Usable powders for the .358 Winchester (with a 180gr bullet) are: IMR-4198 H-4198 AA-2015 H-335 AA-2230 AA-2460 TAC Since we are comparing bullets of a smaller diameter, that means they are longer, as a ratio of length to diameter, than the larger diameter bullets. Beacuse of this, I would extend the usable powder backwards, to include faster powders, like AA-1680. |
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Outstanding! Thanks for the lesson and info. Ya learn something every day. I use it as a measuring stick if the cartridges have similar pressures. Example, the .30 WCF (aka .30-30) has a case capacity of 44.0gr to 45.0gr of H2O, but it's working pressure is nowhere near the 55,000psi of the .223 Remington. |
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