Interesting numbers loading 7mm mag

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Re: Interesting numbers loading 7mm mag

Post by RBHarter »

I fall back on a couple of 30-06's I've had .
To seat to the lands in one meant that a #3033 Hornady 150 SPBT was barely held in the case and the other rifle had to be within the crimp groove .
In the long one I once turned a 180 RN upside down in a sized without an expander case . The bullet crimp groove was about .05 above the mouth of the case . So to say it was long throated may be a touch under stated .

Your rifle sounds like a low mileage standard chamber .

The book would have a firearm reference in the data . Who knows what reamer might have been used . Then there's the universal reciever .

I look at my prep and find that for what I'm loading and working towards I put too much effort in to the quest .

Every rifle is a rule unto itself .
I don't know who said it first but the truth is definitely there .
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Re: Interesting numbers loading 7mm mag

Post by Ranch Dog »

If you have any other appropriate bullet for the 7mm Rem Mag, it would be easy to check out if this is caused by rifle or bullet. If it is the bullet, the other bullet will seat and load in the chamber at or very near the load data list COAL.

If it is an ogive error with the existing bullet and you are using a Hornady Comparator, call Hornady and have them load a cartridge with that bullet at their recommended COAL and then they could measure it with the Lock'n Load Comparator. The difference between the two would be the production error of the ogive. They would probably give you a new box of bullets. Heck if you would just explain this, they would probably send you a new box.
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Re: Interesting numbers loading 7mm mag

Post by horseman »

Ranch Dog wrote:If you have any other appropriate bullet for the 7mm Rem Mag, it would be easy to check out if this is caused by rifle or bullet. If it is the bullet, the other bullet will seat and load in the chamber at or very near the load data list COAL.
I made up a dummy round using a Sierra 160 HPBT to seat 20 thousandths off the lands and compared the finished OAL to the Sierra manuals OAL for this bullet (not knowing how they come up with seating depth to lands for a given cartridge) and mine came up 12 thousandths shorter. I'm confident that my method is correct in using the Hornady tools and this number for the 160 is a LOT closer than the Speer 145's. I also have some Hornady 162 interlocks I'm going to check later. As far as the rifle is concerned when I received the rifle (long story here) I'm pretty confident in saying that it hasn't been fired more than 18 times. Reason, I've known the person that owned it prior for 17 years and know he never fired it in that time, plus it came with a full box of Hornady 150gr.... plus 2 singles. So there would be little wear in the throat. No problem that I see anywhere, I'll just load accordingly and watch for pressure as I get closer to max loads using my chronograph to see where the velocity is. However, I just may set the rifle on a lead sled with plenty of sand bags and tie a string to the trigger for the first couple rounds I've loaded...... :lol:
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Re: Interesting numbers loading 7mm mag

Post by Macd »

I have read this several times. I use the L&L comparator for all my bottleneck calibres. It is a great tool but has a potential error equal to the headspace gap as the bolt does not force the shoulder of the case hard against the shoulder in the chamber like the gauge does as well as the error you mention in shoulder (See Edit) to base for the modified case versus your own sized cases. This however doesn't explain the difference you report in the published versus tested OAL. An out of spec bullet or a short lead is my best guess.

Edit: Obviously the 7mm Rem Mag. is a belted case and the potential error is to the front of the recess in the chamber for the belt. SAAMI specs for the chamber allow a tolerance here as well as in the case belt itself.
Last edited by Macd on 02 Jan 2018 14:33, edited 1 time in total.
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Re: Interesting numbers loading 7mm mag

Post by Ranch Dog »

If you would like the QuickLoad estimate, please provide:
  • The COAL (again), just want to be certain:
  • Bullet #:
  • Powder:
I'm leaving for my morning at Dogville but will get the estimated max charge to you as soon as I can.
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Re: Interesting numbers loading 7mm mag

Post by horseman »

Ranch Dog wrote:If you would like the QuickLoad estimate, please provide:
  • The COAL (again), just want to be certain:
  • Bullet #:
  • Powder:
I'm leaving for my morning at Dogville but will get the estimated max charge to you as soon as I can.




7MM Mag
COAL 3.200
Powder: H1000 (twelve rounds loaded using 70grs.) .....also have some RX25 for heavier bullets but haven't loaded anything with it yet.
Bullet: Speer 145 SPBT #1628

Completed the same steps as in OP using my 06', same methods, same tools, and came up with more what I thought I should (?) using Speer 150gr Interlocks, .020 off lands my OAL came out 3.262, .012 LONGER than Speer "as tested" OAL. This is an "older" 06', purchased by me in 1971 when I was in college. I would estimate the number of rounds through it would be in the 200 range, perhaps less.
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Re: Interesting numbers loading 7mm mag

Post by Ranch Dog »

Horseman wrote:7MM Mag
COAL 3.200
Powder: H1000 (twelve rounds loaded using 70grs.) .....also have some RX25 for heavier bullets but haven't loaded anything with it yet.
Bullet: Speer 145 SPBT #1628
Results for 70-grains of H1000
  • 102% case fill
  • 2946 FPS at 70º(24" barrel)
  • 48.5K PSI
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Re: Interesting numbers loading 7mm mag

Post by horseman »

Ranch Dog wrote:
Horseman wrote:7MM Mag
COAL 3.200
Powder: H1000 (twelve rounds loaded using 70grs.) .....also have some RX25 for heavier bullets but haven't loaded anything with it yet.
Bullet: Speer 145 SPBT #1628
Results for 70-grains of H1000
  • 102% case fill
  • 2946 FPS at 70º(24" barrel)
  • 48.5K PSI



Thanks RD. This has been on hold for a bit so my apologies for the late response. The pressure may indicate this would be a better powder with heavier bullets, however this is not a max load. Maximum per Speer with this bullet is 73.0gr which is a compressed load.
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Re: Interesting numbers loading 7mm mag

Post by Fat Albert »

I hate to be a NIT picker but what cartridge are you talking about? There is about 20 different cartridges out there that are 7mm and have Magnum in their name. I have seen the 7TCU listed as the 7mmx45Magnum.
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Re: Interesting numbers loading 7mm mag

Post by GasGuzzler »

Before yesterday the last post was in January.
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