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ruffcountry

7 mag velocity

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Can someone give me an estimate of velocity for the following load in a 7 rem mag with 26 in barrel .

 

 

65.4 grains of IMR 4831 in a hornady case with a win mag primer and 154 grain hornady sst.

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Probably somewhere between 2,850 - 3,000 FPS.

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according to the IMR website:

 

 

160 GR. NOS PART IMR IMR 4831 .284" 3.290" 57.0 2707 50,600 PSI 61.0 2858 58,400 PSI

 

However I think most of those were done with a 24" barrel at least that is something I have found with my 7mm RUM and we have increased the velocity quite a bit. Unfortunately the data didnt have your exact bullet but I bet the range of 2707-2858 is low because of your barrel length. Also it would appear that 61grn is max load and 57 grn is the min load.

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only way to tell anything even close is to shoot it through a chronograph. you might be able to get within a couple hundred fps by guessing, but that's it. maybe. i've been shooting my .300 a bunch the past couple weeks, tuning in a load for the new barrel and scope. i shoot well over 200 fps faster than what the manual says. i've got a real consistent load that i've decided on and it varies from 20 to 60 fps, and that is a pretty consistant load. 100 fps differen isn't real uncommon with a lot of loads in a given barrel. get a chronograph, shot 5 or 6 rounds through it. anything else is just a guess. seems to me that i'm usually considerably faster than what the books say the load should be. barrel lengths, chamber sizing, throat length, all make a difference. Lark.

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Ok guys , thanks for the input . The reason I was asking is because I usually shoot factory loads but a friend gave me some of his handloads to try and they shot pretty well ( 3 shots at 355 yds < 1 inch ) but the factory ammo was close too (about 1 1/2 inches) and about 2 1/2 inches flatter . I was hoping to compare the velocitys ofthe two . My factory ammo is hornady heavy mag 139 gr sst , it is suppossed to start at 3250 fps , course if I shot it thru a chrony it might be different , too .

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Ok guys , thanks for the input . The reason I was asking is because I usually shoot factory loads but a friend gave me some of his handloads to try and they shot pretty well ( 3 shots at 355 yds < 1 inch ) but the factory ammo was close too (about 1 1/2 inches) and about 2 1/2 inches flatter . I was hoping to compare the velocitys ofthe two . My factory ammo is hornady heavy mag 139 gr sst , it is suppossed to start at 3250 fps , course if I shot it thru a chrony it might be different , too .

 

 

Just currious, did you notice any signs of over pressure? I just took a quick look at my lyman reloading manual and it shows max load for those components is 64.0 grains, your load is well over a grain above the max. I know there are a lot of recipes that are above max that shoot well and have been tested. Not sure if you reload or not, i just wanted to point this out to you in case you don't.

 

For 64gr of IMR-4831 you should be around 2952 fps, not sure about 65.4 though, probably 3100 maybe, just a guess though...hope this helps you out.

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Just currious, did you notice any signs of over pressure? I just took a quick look at my lyman reloading manual and it shows max load for those components is 64.0 grains, your load is well over a grain above the max. I know there are a lot of recipes that are above max that shoot well and have been tested. Not sure if you reload or not, i just wanted to point this out to you in case you don't.

 

For 64gr of IMR-4831 you should be around 2952 fps, not sure about 65.4 though, probably 3100 maybe, just a guess though...hope this helps you out.

 

Thanks for the heads up . No, I didnt notice any signs of over pressure , no dents , dings, cracks, splits, shiny spots, no problem with extraction and primer didnt look any more flattened than the heavy mag . Are those the signs you speak of and are there others I should look for ? A friend loaded these for me as I'm not a reloader myself . I believe he's been using this load for years.

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