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#7193424 - 12/16/12 11:01 PM 7mm rm mag questions
7mmshawn Offline
Member

Registered: 12/14/12
Posts: 35
hey guys i new here and im a bit confused . ive been reloading for about 5 years now and i have 2 7 mags ive been playing with . ive been shooting 140 gr sierra game kings and speer 145 gr boat tails mostly with imr 4350 and fed 215s . im shooting 64 grains and these loads shoot awesome , pretty much one hole at 100yds . i was looking up data last night and wonder why there is so much load data difference and speed difference from book to book . for example nosler shows 65 gr max with imr4350 and another book says 60 gr max . and the speeds will be 2930 in one book and 3280 in noslers book . so i guess my question is what is the best way to find the max load in a rifle when you run across this problem . would it be better to use a chronogragh to try and get to the speeds shown in books or what ? ive never chronoed any of these loads but as far as i can tell there is no signs of extreme pressure in either gun . the primers look good , ive loaded most of the cases 4 or 5 times already , and the bolt is easy to open . any suggestions are appreciated .

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#7193531 - 12/17/12 01:48 AM Re: 7mm rm mag questions [Re: 7mmshawn]
BobinNH Offline
Campfire Oracle

Registered: 01/28/07
Posts: 28013
Shawn: Review a bunch of data from various sources,as many as possible and note correlations between charge weights and velocities...understand that your rifles may differ from the barrels used to aquire the data you are reviewing,and often by a substantial margin.This is true of any caliber, not just the 7 Rem mag.

Get a weighted "average" on the velocities and charge weights.Start low and work up,with a chronograph.Generally the faster you are going, the more pressure you are generating with a given powder....another powder may generate the same velocities with acceptable pressures ,ie be better suited to the combination you are using than another.

Without a chronograph you are working in the dark.

Try to use no more than one or two powder/bullet combos at a time to avoid jumping all over the place...this can lead to confusion and false results and no real conclusions.

When you think you have reached max for a trouble-free hunting load,take ten cases,and use the same max charges to check primer pocket tightness for several loadings in those ten cases.If your primer pockets stay relatively tight,and are absent of high pressure signs you are likely OK.

Sometimes this will correlate to listed data,and sometimes it won't.I would not be concerned.This is common with any cartridge; not just the 7 Rem Mag although the printed data does jump around.

What I do after all the other stuff above is done, is load a batch of ammo with that load and shoot year round;summer heat and winter cold,and watch the load.

This may not be perfect but is as close as we can get without pressure equipment for our rifles.

I have loaded for 7 Rem mags well into double figures.Using these methods I have not had so much as a hiccup with the cartridge,and great field performance from it as well...I can't even remember even getting an ejector mark on a case,and certainly never a blown primer.


I know the 4350's work in the 7 Rem Mag and some savy guys on here use it.I prefer something slower myself, but your work will tell you what works in your rifle.Good luck.

Welcome to the CF. smile
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#7194050 - 12/17/12 07:01 AM Re: 7mm rm mag questions [Re: BobinNH]
Dogshooter Offline
Campfire Ranger

Registered: 02/18/01
Posts: 1569
Loc: WCR 57/WCR 114, CO
In 24" barrel, my experience leads me to the following velocity thresholds with the 7RM:

120s - 3450ish
140s - 3350ish
150s - 3200ish
160s - 3050ish
175s - 2900+

Use your book (and your coconut) to get a good starting charge..... then work up. Good luck, and welcome.
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#7196403 - 12/17/12 05:33 PM Re: 7mm rm mag questions [Re: 7mmshawn]
boomwack Offline
Campfire Regular

Registered: 12/26/11
Posts: 439
Loc: The Rockies
Welcome to the 'fire.

I also found Load data in manuals is a 'little' anemic and greatly varied for the 7mm rem mag. Chronograph some factory ammo.... most stuff will not be as stated.

Agreed with bob, no chrono your kinda in the dark. I recommend using one highly.

In the heavier weight bullets in my 7mm rem mag, my findings have been spot-on with dogshooters said velocity, but with 'rogue' charges compared to most manual. Other than limited loads with some 150 grainers, I have not done much work with 160 gr. and below.
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#7196409 - 12/17/12 05:33 PM Re: 7mm rm mag questions [Re: 7mmshawn]
jwall Online   content
Campfire Guide

Registered: 09/06/10
Posts: 4503
Loc: Southern Arkansas
7mmshawn -

Welcome to the 'Fire', and sometimes it gets HOT round here.

BobNH has given very good advice per load development.

I use IMR 4350, knowing I could get a little more vel using slower burning powders. I am able to get the vel/accuracy I want.

Dogshooter - is also very close on expected vels.

Good Luck
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"The 270 Winchester, Every Man's Beltless Magnum" JOC

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#7196895 - 12/17/12 07:11 PM Re: 7mm rm mag questions [Re: jwall]
7mmshawn Offline
Member

Registered: 12/14/12
Posts: 35
thanks guys for the replys . it looks like i need a chrono to take to the range . i actually have one now but its wired for 110 so i only use it for archery work . and bobinnh thanks for the info on the 7mm mags . ive tried several slower powders and did not get the results i wanted as far as accuracy in both my 7 mags . i tried h1000 , retumbo , and 7828 but it could be bullet weights that i was shooting . i also tried rl22 and it shot good on 40 to 50 degree days and i went to shoot it on a day that 88 degrees and it was blowing primers out of the case so i stopped using hercules. i have shot the 4350 on days from 12 degrees to 90 with no issues so thats the only reason ive stuck with it .

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#7196969 - 12/17/12 07:25 PM Re: 7mm rm mag questions [Re: 7mmshawn]
Dogshooter Offline
Campfire Ranger

Registered: 02/18/01
Posts: 1569
Loc: WCR 57/WCR 114, CO
My brother runs 140 TTSX at 3250 with 63.5 grains of RE17 (Tikka T3)... which is quite similar to 4350.

You could also back that RE22 load off a grain and give it a run... IME, it's hot loads that tend to get real hot when the mercury perks. A grain or grain and a half reduction could lead to little lost on the top end, with a lot more stability when it gets hot.

I've also seen good loads go bad, when it's hot out and you let one stew a little in the pipe.
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#7196989 - 12/17/12 07:31 PM Re: 7mm rm mag questions [Re: 7mmshawn]
Dogshooter Offline
Campfire Ranger

Registered: 02/18/01
Posts: 1569
Loc: WCR 57/WCR 114, CO
Originally Posted By: 7mmshawn
ive never chronoed any of these loads but as far as i can tell there is no signs of extreme pressure in either gun . the primers look good , ive loaded most of the cases 4 or 5 times already , and the bolt is easy to open . any suggestions are appreciated .


Originally Posted By: 7mmshawn

ive tried several slower powders and did not get the results i wanted as far as accuracy in both my 7 mags . i tried h1000 , retumbo , and 7828 but it could be bullet weights that i was shooting . i also tried rl22 and it shot good on 40 to 50 degree days and i went to shoot it on a day that 88 degrees and it was blowing primers out of the case so i stopped using hercules.


Didn't notice this before..... but it looks like you found your signs of pressure.

Classic example of without a chrony.... you're just guessin'. Even after you've got the chrony... it's just a informed guess.
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#7197247 - 12/17/12 08:35 PM Re: 7mm rm mag questions [Re: Dogshooter]
7mmshawn Offline
Member

Registered: 12/14/12
Posts: 35
Originally Posted By: Dogshooter
Originally Posted By: 7mmshawn
ive never chronoed any of these loads but as far as i can tell there is no signs of extreme pressure in either gun . the primers look good , ive loaded most of the cases 4 or 5 times already , and the bolt is easy to open . any suggestions are appreciated .


Originally Posted By: 7mmshawn

ive tried several slower powders and did not get the results i wanted as far as accuracy in both my 7 mags . i tried h1000 , retumbo , and 7828 but it could be bullet weights that i was shooting . i also tried rl22 and it shot good on 40 to 50 degree days and i went to shoot it on a day that 88 degrees and it was blowing primers out of the case so i stopped using hercules.


Didn't notice this before..... but it looks like you found your signs of pressure.

Classic example of without a chrony.... you're just guessin'. Even after you've got the chrony... it's just a informed guess.

yeah i did see signs of pressure with rl22 but nothing else ive shot has . retumbo and h1000 just didnt shoot under an inch so its not for me . im still getting a chrono though for kicks , ill just tell my wife its for safety measures , lol .

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#7197486 - 12/17/12 10:01 PM Re: 7mm rm mag questions [Re: 7mmshawn]
17ACKLEYBEE Offline
Campfire Kahuna

Registered: 11/04/07
Posts: 19491
Loc: A wash in the west.
Hornady Vol. II is your huckleberry!
They have loads for the 139 Gr. Interlock of 3350 to 3400 both loads will chronograph at those speeds out of a 24" barrel.


Edited by 17ACKLEYBEE (12/17/12 10:03 PM)
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