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Rifles, Reloading, Optics, Equipment
Reloading
7mm Rem. Mag. load help
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<blockquote data-quote="SakoShooterSD" data-source="post: 514892" data-attributes="member: 33931"><p>I've put about 200 Barnes TTSX and MRX bullets down the 24" barrel of my 7mm Rem Mag in the past year, and been very happy with their performance. </p><p>All of my hand loads have been MUCH MUCH better than factory ammo I was shooting before. (I was getting ready to get rid of the gun, producing 2" to 3" groups, before my dad did some hand loads for me.)</p><p></p><p>As for powders, I chose IMR 4831 to begin with, because of the many good things I'd read on the internet about it with respect to the 7mm Rem Mag, and because it appears as the most accurate powder for 3 out of 5 listed bullet weights for this cartridge in the Barnes manual. It has been a very good powder in my gun. </p><p></p><p>Retumbo has worked very well, and has produced the very best group I've ever shot.</p><p>IMR 4350 has been good.</p><p>RL-22 has not been as good, though I may have just skipped over the optimum powder charge(s).</p><p>I've heard very good things about H1000, but have not tried it.</p><p></p><p>150 gr TTSX have been very good.</p><p>140 gr MRX also worked well, but I did not get to try as many loads with them.</p><p></p><p>All loads done with CCI LR250M primers, and Nosler brass . . . up until now.</p><p>(I just received 100 pieces of Norma brass, and will start load development again. Sigh.)</p><p></p><p>After having a new stock put on with glass bedding, and having the barrel cryogenically treated, my "optimal" load changed significantly.</p><p></p><p>Was:</p><p>IMR 4831 . . . around 59 grains (1/2" groups @ 100 yds)</p><p>behind a 150 gr TTSX</p><p></p><p>Now:</p><p>60.5 gr IMR 4831 </p><p>behind a 150 gr TTSX (1/2" group)</p><p>or </p><p>68.9 gr Retumbo </p><p>behind a 150 gr TTSX (0.35" group, and very consistent velocities on the chrono, averaging 2964 fps)</p><p></p><p>69.0 gr of Retumbo also worked very well</p><p>behind a 140 gr MRX . . . except for on flier (which was probably my fault): </p><p>4 rounds all touching at 100 yds (0.37" group)</p><p></p><p>Disclaimer: As always, start at the low end of your manual's recipe, and work up.</p><p>I go in 0.5 gr increments, and identify one or two good groups. Then do 0.1 gr increments around those points.</p><p></p><p>The B.C. on the 150 gr Barnes TTSX (0.450) with it's Boattail design and ballistic tip, is better than that on the 160 gr TSX FlatBase (0.392).</p><p>It is also has higher gyro stability margin. I think it is plenty big enough Elk, and has excellent terminal ballistics. </p><p>(As you probably know, BCs published by different bullet manufacturers are not all equivalent.)</p><p></p><p>One issue I saw with the Retumbo was a black powder marks on the outside</p><p>of the neck and shoulder area. I would be very interested to hear if you see anything like that in your load development. </p><p>This could possibly be from too light a powder charge (even though accuracy was very very good), too low a bullet weight, not enough neck tension or cases necks that had been work hardened too much. (Hence my new Norma brass, to see if the problem goes away.) If the new brass, or annealed necks don't fix the problem, I'll go back to IMR-4831, or try the H1000, or maybe some VIT N560 or N160.</p></blockquote><p></p>
[QUOTE="SakoShooterSD, post: 514892, member: 33931"] I've put about 200 Barnes TTSX and MRX bullets down the 24" barrel of my 7mm Rem Mag in the past year, and been very happy with their performance. All of my hand loads have been MUCH MUCH better than factory ammo I was shooting before. (I was getting ready to get rid of the gun, producing 2" to 3" groups, before my dad did some hand loads for me.) As for powders, I chose IMR 4831 to begin with, because of the many good things I'd read on the internet about it with respect to the 7mm Rem Mag, and because it appears as the most accurate powder for 3 out of 5 listed bullet weights for this cartridge in the Barnes manual. It has been a very good powder in my gun. Retumbo has worked very well, and has produced the very best group I've ever shot. IMR 4350 has been good. RL-22 has not been as good, though I may have just skipped over the optimum powder charge(s). I've heard very good things about H1000, but have not tried it. 150 gr TTSX have been very good. 140 gr MRX also worked well, but I did not get to try as many loads with them. All loads done with CCI LR250M primers, and Nosler brass . . . up until now. (I just received 100 pieces of Norma brass, and will start load development again. Sigh.) After having a new stock put on with glass bedding, and having the barrel cryogenically treated, my "optimal" load changed significantly. Was: IMR 4831 . . . around 59 grains (1/2" groups @ 100 yds) behind a 150 gr TTSX Now: 60.5 gr IMR 4831 behind a 150 gr TTSX (1/2" group) or 68.9 gr Retumbo behind a 150 gr TTSX (0.35" group, and very consistent velocities on the chrono, averaging 2964 fps) 69.0 gr of Retumbo also worked very well behind a 140 gr MRX . . . except for on flier (which was probably my fault): 4 rounds all touching at 100 yds (0.37" group) Disclaimer: As always, start at the low end of your manual's recipe, and work up. I go in 0.5 gr increments, and identify one or two good groups. Then do 0.1 gr increments around those points. The B.C. on the 150 gr Barnes TTSX (0.450) with it's Boattail design and ballistic tip, is better than that on the 160 gr TSX FlatBase (0.392). It is also has higher gyro stability margin. I think it is plenty big enough Elk, and has excellent terminal ballistics. (As you probably know, BCs published by different bullet manufacturers are not all equivalent.) One issue I saw with the Retumbo was a black powder marks on the outside of the neck and shoulder area. I would be very interested to hear if you see anything like that in your load development. This could possibly be from too light a powder charge (even though accuracy was very very good), too low a bullet weight, not enough neck tension or cases necks that had been work hardened too much. (Hence my new Norma brass, to see if the problem goes away.) If the new brass, or annealed necks don't fix the problem, I'll go back to IMR-4831, or try the H1000, or maybe some VIT N560 or N160. [/QUOTE]
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