Peterson 300 win long brass

huntinfool18

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I just started working with my 300 win mag and Peterson long brass. Has anybody have any experience with this brass yet?? It seem the the neck tension is extremely inconsistent on mine. The brass looks annealed from the factory, maybe not enough?? The groups reflect this as well. I will get 3 touching and a flyer 3/4-1” out
I’m going to try Annealing again and see if that resolves the issue.
 

MagnumManiac

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I use a mandrel and run my Kimber 8400 300WM with .0015” tension with either a 180g Accubond or 200g Accubond. It doesn’t like more than this. My other 300’s run about the same except 1, it likes .004” and will shoot like crap unless it has it.
You need to experiment.

Cheers.
 

martinakl

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Try running them through a mandrel
^This is what I did with my Peterson 300 Win Mag Long brass. I also inside and outside chamfered. I had consistent seating.

For chamfering, I bought the bulk packed stuff (250 count). I'm not sure if the 50 count boxes need it or not? The 250 count just comes in a big bag.
 
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Longtine88

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I use the long brass. I don’t have any problem at all with it after running them through a mandrel. Actually they are the better of the brass I’ve used lately. I have 4 new boxes of ADG in 300 WM and I like the Peterson better. More consistent as far as necks.
 

huntinfool18

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I guess I’ve never heard of a mandrel as far as reloading goes. What is it?
I full length size, trim to length and chamfer before loading
Other then the neck tension issue, I’m very happy with the Peterson brass. I just picked up some 280 ack Peterson. Hopefully it’s just as good
 

martinakl

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Basically you size the neck from the inside out.

I use the extra long version of this die (I have the Sinclair version of the die too but it’s too short for 300 Win and it’ll “bottom out” with my presses).


Then you buy different sized mandrels based on caliber. There’s a few different offerings from a few companies. Some are just .002 under and some brands offer half sizes (like .0015 or .0025) and all that. Similar to neck bushings.

mandrel:
0A6C595E-EEA8-4A45-8E88-4CC2ECB42883.jpeg

Brass expands as the mandrel passes through the mouth.
33C5A745-FC26-440E-B526-762C292218C6.jpeg
 
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badthirtyone

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Basically you size the neck from the inside out.

I use the extra long version of this die (I have the Sinclair die too but it’s too short for 300 Win. with my presses).


Then you buy different sized mandrels based on caliber. There’s a few different offerings from a few companies. Some are just .002 under and some brands offer half sizes (like .0015 or .0025) and all that. Similar to neck bushings.
View attachment 305733View attachment 305734
Cool press, bro.

Sorry that you had to settle for the cheap model. 😁
 

johnnyk

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I recently finished load development for a buddy's Savage Elite in .300WinMag using the Peterson long brass and didn't notice any problems with it. I tried Retumbo, IMR8133 and settled on IMR4831. 71.5gn with WLRM primers yielded 2980fps (ES10/SD5.0) with the 200gn ELD-X.
Accuracy was sporadic (two touching & flyer) to start with but the numbers were good. I felt like I didn't need to adjust the seating depth any as I had it .010" off and it looked "short" to me and it fit his mag.
So I looked at the rifle. Barrel cleaned regularly throughout the process so I loosened the action screws from 65in/lbs (adjusted trigger to 2-2.5lbs) and retightened to 40in/lbs. Dramatic difference. All bullet holes touching with no flyers.
All I did for brass prep was take it from the container, deburr the flash holes and then deburr & chamfer the case mouth. I measured the ID of several cases and I can't remember the measurement but they seemed acceptable.
 

huntinfool18

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What’s an acceptable amount of run out? I’ve been reloading for years but fairly new to the the super precise tricks. I’m getting around .003 average. I just took 25 new piece of brass, measured everything as I went, all was good and all had consistent neck tension of .002 and felt the same when seating a bullet.
My rifle is all high quality components. Bighorn action, proof barrel, Mesa stock, bedded and floated. It is a new rifle so I don’t have a base line to compare to before working with the Peterson brass.
 
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