Thinking about changing up my 7mag...

desertcj

Handloader
Sep 27, 2010
880
142
Well, my 7mm rem mag is already pretty deadly but I'm thinking about tuning it specifically for long range stuff by screwing on a new varmint weight barrel and getting a new stock for it. If anyone feels like running some QL data for me, that would be great. 28" barrel, 180gr Eld-M, 3.500" oal. H1000 is what I mostly have and prefer. Wondering if 3000fps is within reach? I may prefer a 26" barrel as I want to put a brake on this to help spot my own shots. What do you think?
 
Hmm with a long range scope on top in even a decent synthetic stock your looking at close to 12lb and not sure I would want to lug the extra weight around of a varmint weight barrel. A heavy sporter is bad enough in 24". My M70 7mmRem in a laminated stock with 26" sporter barrel is all I want to lug around and the Ruger 338Wm with the heavy magnum contour is all I want also. And then you throw a bi-pod on it and the sling.
But to each his own.
 
It's just my thinking that I would not screw with what is working now especially if you are happy how that rifle is presently performing. There is an old saying.......... "the enemy of good is better".............

I'd consider a new one designed specifically for long range stuff! :>)
 
desertcj":l4ztbrdy said:
Well, my 7mm rem mag is already pretty deadly but I'm thinking about tuning it specifically for long range stuff by screwing on a new varmint weight barrel and getting a new stock for it. If anyone feels like running some QL data for me, that would be great. 28" barrel, 180gr Eld-M, 3.500" oal. H1000 is what I mostly have and prefer. Wondering if 3000fps is within reach? I may prefer a 26" barrel as I want to put a brake on this to help spot my own shots. What do you think?

I'll be glad to try to help you with that, but my new version does not show the 180 ELD-M, would you give me some data / measurements according to the chart, if you have the bullets, then I can try to get a new file added to the list to pull some data for you. Unless someone else has the data already.


wtDe7kp.jpg
 
This is coming from my recent trip to Wyoming. The wind was unbelievable! I had many shot opportunities at 450-700 yards. I was able to connect 3 for 3 on my 12" steel at 550yds with my .243, I'm just thinking this has got to be more better. Unfortunately, I don't have any 180gr Eld-M bullets in hand to measure. I guess that's not going to work...lol.
 
Hodgdon is suggesting 69.5gr max of H1000 with a 180gr Berger vld but they have oal at only 3.290". I don't know where the rifling on this barrel is at as I've only fed it factory ammo, but my magazine will allow up to 3.500". That would suggest to me that there could perhaps be substantially more case capacity available depending on the throating in the barrel. Hodgdon lists 2884fps from a 24" barrel at 60,000psi for what it's worth. 60,000psi seems pretty weak for a belted magnum?
 
The ELD-X 175 grain is what I have, but the BC is .689 and the ELD-M 180 BC is almost .796
I sent you the data with the 175 grain ELDX to get a rough idea with the 28 inch barrel.

Cartridge : 7 mm Rem. Mag.(SAAMI)
Bullet : .284, 175, Hornady ELD-X 2841
Useable Case Capaci: 69.647 grain H2O = 4.522 cm³
Cartridge O.A.L. L6: 3.290 inch = 83.57 mm
Barrel Length : 28.0 inch = 711.2 mm
Powder : Hodgdon Retumbo

Code:
Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   88    56.80   2420    2277   29323   9411     96.1    1.842
-18.0   90    58.22   2486    2401   31420   9669     97.3    1.792
-16.0   92    59.64   2551    2528   33677   9902     98.2    1.742
-14.0   95    61.06   2615    2658   36110  10107     98.9    1.693
-12.0   97    62.48   2680    2791   38737  10282     99.5    1.642
-10.0   99    63.90   2744    2926   41572  10425     99.8    1.587
-08.0  101    65.32   2808    3063   44639  10535    100.0    1.535
-06.0  103    66.74   2871    3202   47957  10619    100.0    1.485
-04.0  106    68.16   2933    3342   51557  10698    100.0    1.436
-02.0  108    69.58   2994    3484   55462  10773    100.0    1.390  ! Near Maximum !
+00.0  110    71.00   3055    3627   59710  10844    100.0    1.345  ! Near Maximum !
+02.0  112    72.42   3116    3772   64337  10911    100.0    1.302  !DANGEROUS LOAD-DO NOT USE!
+04.0  114    73.84   3176    3919   69385  10973    100.0    1.260  !DANGEROUS LOAD-DO NOT USE!
+06.0  117    75.26   3236    4068   74905  11030    100.0    1.220  !DANGEROUS LOAD-DO NOT USE!
+08.0  119    76.68   3295    4219   80955  11082    100.0    1.181  !DANGEROUS LOAD-DO NOT USE!
+10.0  121    78.10   3355    4373   87602  11129    100.0    1.143  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba    110    71.00   3177    3921   74696  10378    100.0    1.237  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    110    71.00   2864    3188   47372  11381     99.0    1.488
 
Cartridge : 7 mm Rem. Mag.(SAAMI)
Bullet : .284, 175, Hornady ELD-X 2841
Useable Case Capaci: 73.005 grain H2O = 4.740 cm³
Cartridge O.A.L. L6: 3.500 inch = 88.90 mm
Barrel Length : 28.0 inch = 711.2 mm
Powder : Hodgdon H1000

Code:
Predicted data by increasing and decreasing the given charge,
incremented in steps of 2.0% of nominal charge.
CAUTION: Figures exceed maximum and minimum recommended loads !

Step    Fill. Charge   Vel.  Energy   Pmax   Pmuz  Prop.Burnt B_Time
 %       %    Grains   fps   ft.lbs    psi    psi      %        ms

-20.0   84    56.00   2401    2240   30288   9057     93.2    1.819
-18.0   86    57.40   2463    2358   32419   9332     94.4    1.769
-16.0   88    58.80   2526    2480   34710   9591     95.6    1.720
-14.0   90    60.20   2589    2605   37173   9833     96.6    1.673
-12.0   93    61.60   2652    2733   39824  10056     97.5    1.618
-10.0   95    63.00   2715    2864   42678  10257     98.3    1.566
-08.0   97    64.40   2778    2998   45759  10437     98.9    1.516
-06.0   99    65.80   2840    3135   49083  10592     99.4    1.468
-04.0  101    67.20   2902    3273   52679  10723     99.7    1.421  ! Near Maximum !
-02.0  103    68.60   2964    3414   56570  10827     99.9    1.376  ! Near Maximum !
+00.0  105    70.00   3026    3557   60790  10904    100.0    1.332  !DANGEROUS LOAD-DO NOT USE!
+02.0  107    71.40   3086    3702   65351  10966    100.0    1.290  !DANGEROUS LOAD-DO NOT USE!
+04.0  109    72.80   3147    3848   70358  11023    100.0    1.250  !DANGEROUS LOAD-DO NOT USE!
+06.0  111    74.20   3207    3996   75794  11076    100.0    1.211  !DANGEROUS LOAD-DO NOT USE!
+08.0  114    75.60   3267    4146   81732  11124    100.0    1.173  !DANGEROUS LOAD-DO NOT USE!
+10.0  116    77.00   3326    4299   88236  11166    100.0    1.136  !DANGEROUS LOAD-DO NOT USE!

Results caused by ± 10% powder lot-to-lot burning rate variation using nominal charge
Data for burning rate increased by 10% relative to nominal value:
+Ba    105    70.00   3148    3851   74465  10415    100.0    1.232  !DANGEROUS LOAD-DO NOT USE!
Data for burning rate decreased by 10% relative to nominal value:
-Ba    105    70.00   2839    3133   49015  11073     96.8    1.464
 
Awesome, thank you. Looks like H1000 is a little fast and Retumbo is better suited. I may give this a try in my 24" sporter barrel just for kicks before I go all in on a rifle rebuild.
 
Ever seen a Wyoming wind sock? For me a 400-700 yard shot on the windy prairie is a "spray and pray" proposition. no matter what the equipment. That said, part of the fun is "updating stuff". Let us know how you make out. CL
 
My .243 was 6" off at 200 yards with about the highest BC bullets available in 6mm! Yeah, the wind blows over there...
 
OK, I got some 180gr Eld-M bullets in my hands. Small diameter of taper-.245". Large diameter of taper-.284". Length of taper-.210". I'm not sure if it's a parameter, but as best as I can tell the bearing surface is .550" long. OAL is 1.550"
 
One of the dummy rounds I made to have my barrel throated. Other bullets on my list are the 183gr Sierra and the 175gr LRAB. I'm also thinking about keeping the barrel at 26" plus a brake....I don't want it to get so long it's rediculous to handle.
 

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Depending on you mag box length, subtract .050" off that and use that IMO. That way you'll get the most of whatever you use, and if you can keep the bullet shank right at the neck shoulder juncture the better, and have just the boat tail below the neck.
 
Those are at 3.500" which is the max my magazine will allow. I'm going to seat them down to at least 3.480". I will consider taking them down to 3.450" though.
 
You should get almost 3k or a little more. But that rifle will be a pig to lug around as stated.
 
It's ok, I have a model 70 featherweight I can carry if I'm feeling tired :grin:
 
desertcj":24wrosqc said:
Those are at 3.500" which is the max my magazine will allow. I'm going to seat them down to at least 3.480". I will consider taking them down to 3.450" though.
My only reason for using that number is the fudge room i.e. bullets are never exact and/or exactly the same. That way you'll have some wiggle room if the chamber is a little off from what was predetermined in your layout of the reamer. I do think it's better to get to the lands vs. not IMO, I've found a lot of my best accuracy comes from being really close, or at the lands even with bullets that most wouldn't think so. i.e. Barnes Bullets. I noticed the velocities were near identical when the bullets were placed right at the lands, 0.00" vs. 0.010-0.035" off until they got +0.050" or more off.

I think you're on the right track though. I was just talking to Jay Jarrett yesterday about making a long throated reamer for my 280 AI and spin on a fast twist barrel. My Remington mag box is 3.550" long and why I called out 3.500" usable space with him.

I get 2950 fps with 56.0 RL-22 and the 160 TSX FB out of my 280 AI @ 3.300" = 2.2600" CBTO Unfortunately my barrel won't stabilize any of the long 175+ grain bullets since it's a 1:10".

BTW I have #80 162 ELD-X's if you're interested or anyone else for that matter, $28.00 shipped.
 
I think you'd do great with a 26" barrel spun up to an 8 twist. With the BC of the 180 ELD, 100 FPS won't mean a ton and H1000 should get you to 2900 pretty easily in a good barrel. If you didn't mind a little extra work, a 7mm-300 or 7mm Mashburn Super would be the cats meow with the 175/180 class bullet. No issues at all running 175's in the 3050 range with my old 24" Mashburn and the new one will do better than that I believe.

But, for a no nonsense set up a plain old 7mm Rem Mag has a ton going for it and will do well with a great barrel with throating set up for your intended bullet..
 
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