7mm Rem Mag question

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revylou

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After owning thhis gun for many years I had a chance to Chrono some of my hand loads I"m using 62 gr 4831 with 160NP bullets only producing MV avg over 10 shots of 2725fps I grabbed some 175gr Win factory loads from a friend and they were up at MV avg 2853 kinda what I expected. is the published handload data that soft to protect people? I'm going to slowly up the anti with the powder until I can achieve close to 3000fps We also tried another Rifle with virtually the same results.

Anyone have and comments or pointers

Thanx Lou..
 
Some years ago I had a 26" bbl'd 7mm RemMag and couldn't come close to published velocities with any sane handloads I built and chronied. Even the factory loads were way below what they should be. My buddies 7mmMag was dead on to what the loads were supposed to be. And yup, I sold that particular rifle.
 
That 62 grains of H4831 sounds soft to me.
Most 7mm Mags I have owned would readily digest 65/66 grains of that
powder behind the 160 Partition, for close to 3000 fps.
Regards, Eagleye.
 
Sorry i should have specified i used IMR 4831 and tried Loads with RL22 as well
The factory loads were bang on advertized velocicty
 
I use 72gr of retumbo with 162sst for 3000fps. Imr 7828 gets me there as well. Didn't get there with h4831.

Since you seem to be concerned about speed I would also recommend you chrono your imr load in -10c or whatever temp it is when you hunt. I have chronographed several loads in different calibers with imr powder (280 rem with 150 btips for example lost 140 fps between summer and hunting temp). So if you are going to lose a bunch of fps anyways going from summer to hunting temps, why not go to a hodgdon extreme powder for example that doesn't fluctuate much at all between +25 and -10.
 
7mm Rem Mags velocity varies wildly. Some can't keep up with a healthy 30-06 and the next guy claims STW speeds. For whats its worth, my findings tend to make the ole '06 look good.

The last Speer manual has some interesting comments on the Rem Mag. Normally they work up their loads in a pressure barrel, then fire in house rifles for a "real world" velocity to publish. They specifically state that they don't do this for the Rem, since they don't have a clue what it will do. Makes you wonder.
 
:dancingbanana:Played around today I upped the IMR 4831 4 grains with not much gain in MV
still didn't come close to touching 3K . The RL22 on the other hand worked really well with the increased charge and shot superb I ended up with 70gr RL22 could cover the 4 shot goup with a quarter very pleased.

Thanx for everyones input.

Lou..
 
If you are using 70 grains of RL22 behind the 160 NP, then you have a generous chamber, a slightly oversize bore, or both.
In about 5 - 7mm mags I have owned, I have not been able to exceed 67 grains of RL 22behind the 160P safely.

However, I have a friend who manages to use 69 grains with good results, so there is obviously quite a bit of variance in this chambering.

My favorite, a 700 Classic, would give 3050 with 66 grains of Norma MRP, and shot sub-moa.
It also shot very well with the 150P and 65 grains of IMR 4831.

Regards, Eagleye.
 
Powder?

revylou said:
:dancingbanana:Played around today I upped the IMR 4831 4 grains with not much gain in MV
still didn't come close to touching 3K . The RL22 on the other hand worked really well with the increased charge and shot superb I ended up with 70gr RL22 could cover the 4 shot goup with a quarter very pleased.

Thanx for everyones input.

Lou..
Click to expand...

70 gr of R-22 is quite a heavy load under a 160 gr bullet. It might be safe if you approached it carefully in small steps. I would judge a load by accuracy rather than velocity. I think you got things reversed. 70 gr of H4831 is a good normal load, 70 gr of R-22 is too much, in my experience. I would try Retumbo.
 
I started up from 65 grains one at a time no pressure signs noted i had another experienced guy check them out as well I'm sure the old gun is wore out it's an old mauser 3000 back to the range today for more punishment.I have to say i was very surprised at the lack of MV gain with the IMR4831.
 
I was pretty careful goin up one grain at a time no pressure signs evident that i could see perhaps the old gun is wore out its an old mauser 3000. What really surprised me was that the 4831 didnt show much gain in MV when I incremented the loads. I should have had a chrony years ago. I will also check my scale I did with the big wieght supplied but I'll compare with the digital one.
 
Ugh! The 160 grain speer boat tail shot aussume but the 160 grain noslers sucked the big one not sure what to try next? Velocity was all consitent avg 10 shots around 3030fps maybe I'll try backing down a grain???
 
I found IMR 7828 to give the best numbers in the 7 RM above all others by about a 100 fps and excellent accuracy. I have loaded the 7 RM to 3160 fps with a 160 NP and IMR 7828 in a 24" barrel. Not saying all rifles will do it but mine did without issue.
 
Yup the 7 mag is a funny duck when it comes to velocity, as someone just mentioned try a slower burning powder like retumbo, or reloader 25 , those two powders give me the highest velocities with 150-160 pills, but I still don't get book velocity. Try H1000 as well
 
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