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> 7 rem mag 162 a-max
7 rem mag 162 a-max
@ 04:04 pm (GMT) |
Jim MoseleyNew to your site. I have a new 7 mm rem mag, 26" Hart barrel #6 contour, 9 twist. HS Precision stock, Jewel trigger. My load is 162gr A-max, 72 grs H-1000, Fed GM215M primers, Win brass. Bullet seated .007 of the lands. Accuracy is unbelievable! Groups measure .08,.07,.05 at 100 yds. Groups at 300yds are .3's,.4's. My longest shots at 820 yds measure 2 inches to 3 inches. Everything sounds good so for, but the MV is only 2980 fps. Nothing close to the 3050 to 3100 fps. This load will be use for Whitetails in southern USA where the deer will weigh 90 to 180 pounds. What powders are you guys using to achieve the higher MV's and still have the accuracy. At 1000 yds the a-max around 800 lbs of energy.Thanks, Jim |
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@ 11:35 pm (GMT) |
Nathan FosterRe: 7 rem mag 162 a-maxHi Jim, welcome aboard, great to hear from you.Ok, first thing I want to do is convert the lb figures to kg's for Common wealth viewers. The Whitetail deer you will be hunting will be weighing 90 to 180lb which is roughly 40kg through to 80kg (Feral goat/Roe/Fallow spiker through to Fallow Buck/ Sika Stag body weights) Really, accuracy should always come first- you know that, we all know know that, its a given. If you can get more velocity, thats great but I wouldn't be wanting to let the rifle go past .3 to .4" at 100 yards. Try to stay around the .3" mark if you can. My golden rule is, back work your load/ project. Start with the game body weights you intend to hunt (which you have done) and the ranges you intend to hunt, which by the look of your post, you want reliability out at 1000 yards and like the rest of us, are always hoping and happy to exceed this range but its not an absolute necessity to have to take 1250 yard shots. Does that sound about right? One thing you need to do is forget about the energy figure as it is misleading. I'm not going to look at my ballistics charts for confirmation of this next statement as its just an example- if we compared the 7.62x39 and FMJ ammo against say the 44 Magnum when both are at a range where energy is equal, we both know which is going to get the job done while the other causes a pin hole wound and dead running game. So when we look at the Amax specifically, the retained velocity figure is the most important as this will tell us how the Amax will perform, based on the info I have put in the knowledge base regarding the Amax's ability to expand and fragment at various velocities. As a refresh, the 162gr Amax: Expands violently and readily at 1800fps, producing very diffused, fast bleeding wounds. Expands reliably at 1600fps, produces a fast bleeding wound however wound channel diameters are more proportionate to the fragmented projectile, rather than disproportionate- dispro caused by speed/water particle acceleration (disproportionate to impact velocity) and secondary missiles (bone chips at high velocity). At 1400fps, wounding tapers right off although bullet fragmentation is still reliable. Wounding is more akin to a smaller bore cartridge with controlled expanding bullet at extended range- example, the .243 with soft point low BC bullet at 400 yards. I would call 1600fps a safe limit and 1400fps an absolute limit if a measure of reliability (relatively fast killing) is to be expected. Using a standard atmospheric model, your 2980fps load gives: 1600fps at around 1050 yards 1400fps at around 1260 yards. If you lifted the MV to 3120fps, the figures would be 1600fps at around 1150 yards 1400fps at around 1350 yards. So we are looking at about an extra 100 yards of adequately wide wounding. The difference in wind drift at lets say 1300 yards would be 7.5" or if you were dialing in the wind, an extra two clicks for the slower load. Whether or not this is worth your extra time doing further load development is of course, entirely your call. Below are the very typical loads that work in our rifles and client rifles to obtain the 3120fps quoted in the Knowledge base. Federal 210 primer Win Brass 162gr Amax H4813sc (ADI2213sc) 68.5gr working up to 69.5gr. Federal 215 Mag primer Win Brass 162gr Amax H1000 (ADI2217) Working from 72 grains up to 73.5 grains in .2 grain increments. Bullet jump is .40thou (1mm) If you want to go higher with H1000 (depending on your individual barrel tolerences), as long as you can read pressure signs, this powder can be experimented with safely, without any pressure spikes. For the 3120fps sweet spot that I find common in the 7mmRM, you will be wanting to get an extra 140fps in your rifle which may well require 2.5 grains more than you are using now. But again, safety first, work up in .2 grain increments to keep the test smooth and without 'sudden' spikes. H4813cs isn't too bad either. Its a bit more responsive than H1000 so don't expect to get past 70 grains. Ok, hope that helps for a start. Nathan. |
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@ 04:54 pm (GMT) |
Jim MoseleyRe: 7 rem mag 162 a-maxThanks Nathan, I'll be testing the current round during depredation season in May, June. Does only which weigh 80 to 110 lbs. |
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