C'mon guys help me with this powder puzzle!?

I was trying to develop a 7MM Mag load and could not get accuracy under an inch, A friend of mine dug up some factory ammo from a 7 Mag he had and gave them to me. I was going to use them for foulers but turns out they almost consistently touch when grouped at 100 yards. These are Federal premium 160 Gr partitions. I weighed some loaded rounds from the box and they had as much as 10 Gr varience in weight. Yet they still group excellent and velocity is 2975 out of my 26" Barrel. I pulled one of the bullets and found 69.5 Gr of something, they are small cylinders that measure .040x.085 almost every time. I checked my inventory and the closest thing, almost exactly to it IMR4350, but the manual lists max @ 60GR??. What is this mystery powder??? If I can't find the brand, god help me Im GONNA USE FACTORY AMMO!!

<333-OKH>

posted

Most likely you are not going to find that powder. The big ammo makers often buy production lots of powder with specified burning rates that are not the cannister powders sold for reloading. They simply specify the characteristics the powder should have and a recipe is mixed that will provide that result. Might look like 4350, might be produced in the machines that make 4350, but it ain't 4350! Or any other cannister powder. The variations on burning rate controlled by the mix of ingredients and application of deterrent coating is quite large and what is in the factory case today may not be what is in there tomorrow even though the end result is the same. Actually watching the process is fascinating, all the steps that are required to change cellulose into gunpowder, many of which can be deadly. And double base is real cool, ever been in the presence of gallons of Nitroglycerin? Don't sneeze! Good luck with your loads.

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If Elmer didn't say it, it probably ain't true.
Michael

posted

http://recipes.alliantpowder.com/rg.taf?_function=centerfire&step=2&bulletID=389&cartridgeID=1068&caliber=7mm&cartridgedescr=Rem%2E%20Mag%2E&bulletdescr=Nosler%20160%20Partition

Maybe Alliant RL-25 is what you are looking for. Here is a link to Alliants online data with 160gr partition in 7mmRemMag.

Good Luck! MM

<David>

posted

I haven't tried 160 gr Partitions yet, but I have used 140 and 150 gr Partitions in my 7mm Rem Mag. So far the best powder in my rifle with both of these weights is IMR7828. Good velocity and good groups. It is very easy to get close to 3200 fps with the 140s and 3100 with the 150s. If this trend holds true, it should be very easy to get 2950 to 3000 fps with 160 gr. bullets.

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David Sipe

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They should both be changed regularly, and for the same reason

Pecos41

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333 is exactly right. The ammo makers quite often don't use the same powders available to the public. Guessing at what it is can be risky.

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A well placed bullet is worth 1,000 ft/lbs of energy.

Posts: 19677 | Location: New Mexico | Registered: 23 May 2002

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posted

The powder has to be in spec with the 7MM Rem Mag, and would be worked up. I just want to avoid buying 10 different powders and launching 200 parti$ion$.I would not just substitute a powder and cringe my face as I pulled the trigger. I would first tie a string to the trigger and stand behind a tree...Hmmm? Ha Ha.

Mike375

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heider,

Something else you may wish to try is your own die settings.

Quite often shooters dies simply do not full length size enough and this can result in factory ammo shooting better.

Ideally, full lenght sizing should result in around .003" of headspace or alternatively you should neck size only.

Also, it is very common for cases sized for a few thou headspace to shoot best withthe bullet back off the rifling and for neck sizing to shoot best with the bullet just off the rifling.

You could pull some bullets from the faactory ammo, then use 160 paritions with your own powder in those factory cases and also seated to the same depth as the Federal ammo.

Mike

Posts: 7206 | Location: Sydney, Australia | Registered: 22 May 2002

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Nutoy

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heider, the reason I started reloading for rifles was because of my 7mm Rem Mag. I tried just about every factory ammo available and was just about ready to sell it for scrap iron.
Now, after a trigger job and a muzzle break installed it's the best shooting hunting rifle in the locker.
It absolutly loves Sierra 140gr SPT's over 64.5grs. of Reloder 22 @ 3190fps. Just today it shot 3 - 5 shoot bug hole groups @ 100yds with 3 different shooters, 2 - .5" ragged holes @ 200yds and 1 - 1.5" group at 300yds with a .5" flyer.
It does almost as well with Sierra 150 grainers. I've tried heavier bullets but havn't seemed to find the right combo yet.
Keep trying and you'll find the "majic" load.
Good luck, *Nut*

Posts: 268 | Location: God's Country, East Tex. USA | Registered: 08 February 2002

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posted

Commercial ammo loaders almost never use powders we can get our hands on. If you load your own, just make sure you weigh the powder charges and bullets and make sure you have enough crimp but not too much, just make sure everything is consistant.

posted

Gunpowder does not affect accuracy that much. The big things are loose sights and guard screws and bullets.

Get some Sierra bullets, 4831 powder and full length size the cases with good loading techniques.

<.>

posted

First off, what's with the format for this post?

Technically, "headspace" is the depth that the whole round sits in the chamber of the firearm. It has nothing whatever to do with the distance of the bullet off the lands -- not directly any way.

Distance off the lands is refered to as "seating depth." It's pretty crucial to serious accuracy. There are several ways to figure seating depth. Sinclair offers some gauges, but it's possible to make your own.

Powder has little to do with accuracy.

The real sources of accuracy are getting uniform loads. Brass should all match. It helps to weigh the cases and sort into batches. That way you get uniform case capacity.

Even the best bullets vary in weight. Sort these by weight too.

Some speculation amongst bench shooters that volume plays a more important role in loading powder than does weight. They throw a volume charge and load -- without weighing. I'm still weighing each charge. My chrono tells me that this careful weighing is a waste of time.

Varmint Als discusses reloading at length. I could post all his tips, but it's easier to just post a link:

http://www.cctrap.com/~varmint/arelo.htm

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posted

heider:After reading your post I thought I knew the answer to your problem but I had to check my sorce just to make sure. The powder you're looking for is quite likely IMR 7828. My source "Propelant Profiles" 3rd edition, 1991,Wolf Publishing, page 60, re: IMR-7828 states....."It (IMR7828)was featured in the development of the 7mm Remington Magnum cartridge unveiled in 1962.....". It also goes on to say a little on further down the page that..."There is no way the handloader can distinguish IMR-7828 from IMR-4831 or IMR 4350, so don't attempt it." hence the same measurements as IMR 4350. Hope this solves the problem.

posted

Have a look at Hodgdon H1000 powder.
ADI (Australian) manufacture sells direct to many muntions factories world wide.
They list 70gn max load for a 162 Gn projectile in the 7mm Rem Mag.

(most handloading books list their maximum about two grains above ADI's manual for many calibres but I strongly suggest you check this before use as this would be a near max load from this manual)

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