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Old June 28, 2015, 07:41 AM   #1
g-stanger
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7mm Rem Mag Powder Question

7mm Browning A Bolt, 24in barrel, Leupold Optics

First Post here..I have never had to post before because of the handy "search" button.. genius! I usually find what I am looking for but...

Here is my question. Simple, but yet I will make it longer than it has to be.

My Load
Sierra 175gr BTSP
Nosler Brass, trimmed ect..
75 grains US-869
CCI LR Primers
O.A.L 3.290 exact

From the informatio I have read on here it seems like everyone is using about 60-65 grains of powder, none of which is the US-869.
For this load is this a good ammoud of powder? 75 grains? I was thinking maybe the US-869 is a "weaker" powder compared to others and maybe thats why I am in need of more.

On the Nosler website it shows the load data for the 175grain Partitions using a startig load of 74 grains. Maybe I am over looking this or thinking too hard as this is my first rifle load which is a little different than the thousand of .45 pistol cartidges I have made with Dad. I guess it does not hurt to ask or double check if this 75grains of US869 is too much?
Thanks! and keep ip the good work TFL!
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Old June 28, 2015, 08:06 AM   #2
F. Guffey
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http://www.hodgdon.com/rifle.html

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Old June 28, 2015, 08:12 AM   #3
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^^^^^

Don't ever guess at a powder charge. Use a manual or powder manufactures website. If it's not listed, then it's probably not a good powder to use.

Personally, I like 7828 for anything over 150gr in my 7mm Rem Mag. Anything under that, I use IMR 4350.
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Old June 28, 2015, 08:15 AM   #4
F. Guffey
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Quote:
From the informatio I have read on here it seems like everyone is using about 60-65 grains of powder, none of which is the US-869.
I have no ideal what information goes into and out of a reloader mind, when loading 60 to 65 grains of powder a reloader will get more rounds per pound of powder when compared to 75 grains of powder. Then there is that other thing, I am convinced there is a narrow window of options. If I want to load 65 grains I have to select a powder that has a spread that includes 65 grains between maximum load and minimum load, something like starting and maximum.

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Old June 28, 2015, 12:59 PM   #5
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Can you spot the counterfeit part?

I have (3) BAR belted magnum rifles; 1969, 1980, and 1990.
The gas regulator is a plug nut with a hole in it.
I have made one from scratch from a piece of steel on the lathe and mill, but I would recommend just buying one with a small hole and drilling it out.

From my notes:
a) 7mm Mag is .066" hole
b) 300 Mag is .077" hole [p/n B3176146]
c) 338 Mag is .059" hole
d) My home made is .078" hole
e) recoil buffer [p/n B3176065]


A #48 drill is 0.0760"
A #47 drill is 0.0785"
A #46 drill is 0.0810"
A #45 drill is 0.0820"


The bigger the regulator hole, the hotter the load the rifle is tuned for.
The smaller the regulator hole, the wimpier the load the rifle is tuned for.

If you have a small gas hole, keep the load down to the point where the brass is not ejecting too far and the bolt is not slamming the receiver too hard.

I have been buying from these guys
http://www.midwestgunworks.com/page/...ar-rifle-parts
But there are parts from Browning, Brownells, and Midway as well.

I love the 7mmRemMag. I have shot two mule bucks and buck antelope with the cartridge in the last two years.
The cartridge is SAAMI registered at 3.29" 61 kpsi.
I am running 3.34" ~75 kpsi quickload, so I am half way to a 7mmSTW

The Hodgdon site shows 77.0 gr US-869 56,200 PSI.
Why would they show such a wimpy load as max?
My guess is that the case is full.
And ball powder does not compress enough to talk about.
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Old June 28, 2015, 02:17 PM   #6
g-stanger
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wow Clark! Now there is something I did not know. I try and learn something everyday. Now you have me curious to what my gun is tuned for. I will do some digging.

Seems with the Hodgdon website is what my load came from. I just had trouble finding which load table I based my load on and now I have it.

I am making this round for an elk hunt I am going on in September. If I cant get close enough with the old Mathews, then the last 2 days will be with the 7mm.

I am heading out to the farm over the 4th and will report back as to how she did, what can be improved or what should be changed.

Thanks again! Shoot straight!
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Old June 28, 2015, 02:37 PM   #7
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Using a Magnum Rifle Primer would be a good idea. IMO. 250 Mag†
Magnum primer for large-capacity cases and/or ball propellants. http://www.cci-ammunition.com/produc...ers.aspx?id=29

Last edited by 243winxb; June 28, 2015 at 03:19 PM. Reason: 250 Mag†
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Old June 28, 2015, 02:46 PM   #8
g-stanger
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they say for use with magnum rifles right on the box so I am good there unless there is an actual "magnum only" primer, but I believe these will work fine, range time will tell all.
.
I cant wait to see how this new load shoots. They are a little pricey to get started but the experience is everything.
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Old July 1, 2015, 11:37 AM   #9
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Quote:
Can you spot the counterfeit part?
I'm gonna guess the one on the right is the part you made, Clark. It seems to be not quite finished.
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Old July 1, 2015, 11:51 AM   #10
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That would be my guess, too.
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Old July 2, 2015, 06:18 PM   #11
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Don't know powder you are using but you are welcome to print this for reference.
Attached Images
File Type: jpg image.jpg (192.8 KB, 18 views)
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Old July 3, 2015, 11:47 AM   #12
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A-Bolt/ 869

CLARK; g-stanger: Look CLOSELY at each others' posts.... TWO DIFFERENT GUNS... UNLESS.....I'm missing something.

WILL
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Old July 5, 2015, 09:45 AM   #13
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Will-j in Clarks defense he's been awful busy lately with chambering a rifle barrel, so he might have thought BAR and not A Bolt.....
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Old July 5, 2015, 04:56 PM   #14
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I know......I'm just in a picky mooood.

WilL.
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Old July 5, 2015, 06:24 PM   #15
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A bolt, huh?
Never mind.
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Old July 12, 2015, 04:32 PM   #16
g-stanger
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Hello all!
Yes, the particular gun I am working with currently is an A Bolt.
I was a little confused with Clarks picture post but I figured you guys are the experts so I dug a little deeper and as many times as I have cleaned it I have never seen anything like that. I thought we may have gotten some wires crossed at some point, but its all good now and I appreciate the replies.

Now on to the fun stuff.

I have ony got to shoot this particular round at 100 and 200 yard increments.

@100 Yards I had no adjustment to the scope (sighted in 7 years ago with Rem Core-Lokt, props to Leupold for holding a zero for this long)

@200 yards I have about 6in drop, and was able to celebrate and entertain the kiddos with some Tannerite.

Now, all and all I am pretty happy with the performance. But there is always room for improvement. I am now wondering if I could make a flatter trajectory with aother grain of the US-869. I believe the max load for this powder is 77 grains. If I could cut the drop in half and get a 3 inch drop at 200 yards would be great but I am not sure if its possible with out going to a lighter bullet, or possibly a different powder.
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Old July 12, 2015, 05:12 PM   #17
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100yd zero/200yd 6" drop.

G-S:
Bullet drop, for all intents and purposes, is....Linear (relative to line-of-sight) in that; A 6" drop at 200yds with a 100yd zero can be adjusted very easily.
Since line-of-sight is linear, any distance considered at 100yds will be double @ 200yds, triple # 300yds etc. 1" high from zero @ 100yds =2" higher rise from the 6" drop @ 200yds(4" drop); [3" rise from whatever the poi would be at 300yds] SO....

100yd [X] +1" high (zero)=6" original drop*POI*-2"=4" POI drop @ 200yds.
100yd [X] +2" high (zero)=6" original drop*POI*-4"=2" POI drop @ 200yds.
By raising the POI @ 100yds by "X" amount(whatever amount is really irrelevant), You double that amount at 200yds; triple that amount at 300yds.....And so on. So, with your current load/100 yd zero/POI....By simply raising the POI to 2" high @ 100yds, you will alter your POI @ 200yds to only 2" low. Practically no change in hold needed, and a LOT more simple to calculate drop a little farther out, and, in any hunting situation, any hold "On Hair" out to 200-250yds means fresh meat for supper.

BTW, Bullet weight will have no bearing on the preceding tabulation, PROVIDED, the individual bullet weight/velocity/100yd zero data is maintained for the different tests.

WILL
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Last edited by Will-j; July 12, 2015 at 05:19 PM.
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Old July 12, 2015, 05:43 PM   #18
g-stanger
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Will,
That is some good advice. A 200 yard zero would be a quick to reference bullet drop and rise for game and targets out in the field and on the range.

Does anyone set a chronograph out at the target to see what the speed of the bullet is at POI?
I was looking at a couple of them on ebay but for $120 I am not sure if its worth that or not.
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Old July 12, 2015, 07:08 PM   #19
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I've read of some people doing it, but it would be wise to have an accurate-enough rifle that you'd feel comfortable with and confident in using, out to 100, to 200-300 yds. without fear of damaging your chrono/equipment.

There are some older manuals,[NOSLER's # 2&3; SPEER'S #s 10&12 come to mind] which have [in their indices] retained velocities at distances to 500-600 yds in 100 yd increments and out to 250yds in 50yd increments for bullets with specific BCs. and bullet drop/height above L-O-S at specific ranges from certain zero yardages. I have a list with % of velocity loss per each 100yd increment with different BCs, and I'll post it as soon as I can find it. It's a general list, but close enough (ballpark figures) for layman's work. Nothing is "Definitely Exact", even from manufacturer's statistics.

I'll get back with you.

WILL
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Life's too short to worry about the small stuff.......
IT'S ALL SMALL STUFF.
D@MN, I really miss my meds.
THE WINDS OF TYRANNY ARE BLOWING FROM OUR OWN CAPITOL.
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Old July 12, 2015, 07:30 PM   #20
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Awesome! I find this stuff so fascinating for some reason.

thanks so much!
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Old July 13, 2015, 03:44 AM   #21
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That's all well and good, but don't let the fascination cloud your judgment and interfere with your attention when loading. One mistake can literally [blow up in your face] If you don't remember anything else.....Always pay attention to detail...CLOSE Attention.

Good luck.

WILL.
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Life's too short to worry about the small stuff.......
IT'S ALL SMALL STUFF.
D@MN, I really miss my meds.
THE WINDS OF TYRANNY ARE BLOWING FROM OUR OWN CAPITOL.
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