Reloading 300WM

[woodchopper]

I have also had problems with once fired and resized brass not fitting in another rifle in my case it was a 7mmRM.

as for the 300WM I am running IMR4831, 69grns, and a 200Grn Accubond.

 

[TrevorJ]

Thanks woodchopper.

 

[Boomer]

If you are experiencing difficulty in chambering a resized belted case, and your bullet is not making hard contact with the lands, its because your die cannot resize down to the belt. Check out the Larry Willis die, this will probably solve your problem, and works with all belted cases except for those of the .378 Weatherby family. One end of the die works as a gauge to determine if you brass needs to be sized, if you drop your case in and it is stopped by the belt, all is good, if it stops short of the belt it needs resizing. The opposite end of the die does the sizing with a collet. Lubing the case is necessary, but he advises against liquid lubes, and recommends Imperial Sizing Wax.

A modern bottle neck belted case, should only headspace on the belt for the first firing, each subsequent firing should headspace on the shoulder, so bump it back just enough to ensure easy chambering, otherwise you are overworking your brass, and risk case head separation just forward of the belt.

 

[Ranger Dave]

300 Winchester Magnum
180gr SST
IMR-4831 72.0gr
3.380"

I haven't reloaded for my 300 win mag for a while. I don't shoot it much. I also use IMR4831 with 200gr Nosler Accubond with great luck. Winchester Magnum primers.

 

[TrevorJ]

Thanks Boomer, and Ranger Dave.

I am looking at picking up a Larry Willys resizing die.
Currently I am only neck sizing after the first firing (.3055 mandrel). I could get 2-3 firings before I would have to body size with a redding body die (on the last barrel), I suspect the new barrel will be similar (I don't have any brass that has been fired that much yet).

 

[DonnieM]

A very experienced gunsmith and shooter once told me, "The rifle will tell you what it likes, not the other way around". If you are after a accurate precise load, but are only shooting 1moa at best, you need a change in components. A change in powder could cause a 2moa load to shrink to 1/2moa like magic. Same with bullet selection. By the time you have this figured out, it may be time for a new barrel lol. That's just the way it is.

 

[Ranger Dave]

I've used Lee and RCBS dies for full length resizing on the 300 Win Mag and never had an issue. I have used this ammo in a friends rifle too and no troubles chambering.

 

[TrevorJ]

Thanks DonnieM.

 

[TrevorJ]

Thanks for all the responses to date, they have given me some ideas as to what to change, and what to expect from those changes.

 

[Kazman1960]

300 Winchester Magnum
180gr SST
IMR-4831 72.0gr
3.380"

I haven't reloaded for my 300 win mag for a while. I don't shoot it much. I also use IMR4831 with 200gr Nosler Accubond with great luck. Winchester Magnum primers.

That's the exact recipe I use

 

[TrevorJ]

Thanks Kazman1960.

 

[nevanevan]

Are you bottoming the body die against the shell holder? Using competition shellholders to remove slop from the press and uniform your headspace dimensions? On your multiple fired cases, have you inspected the inside of the case body for case head separation?

Its possible to get the banana effect if one side expands more than the other due to thinning case walls which might hinder chambering. I don't think the larry willis die is the answer considering your use of a redding body die.

Have you thought of using Retumbo? My 7mm rem mag loves it as do most magnums.

 

[TrevorJ]

Finally made it to the range for some more testing on these loads.

I installed a one piece steel HD base from EGW, and retorqued all fasteners with a torque wrench. The rear base was loose upon removal. Not sure how long it was like that.

Velocities from my chrony at roughly 15ft from the muzzle. 210 Berger vlds, cci mag primer, ppu brass, 15 thou jump, H1000. Rifle had copper fouling removed before this range visit.

72.7 gr 2861/2841/2849 fps (2850.3 fps avg, 8.2 SD+/- 9.3)
73 gr 2869/2871/2861 fps (2878 fps avg, 4.32 SD+/-4.9)
73.3 gr 2913/2884/2892/2888 fps (2894.3 fps avg, 11.2 SD+/-10.9)
73.6 gr 2892/2901/2905 (2899.3 fps avg, 5.4 SD+/-6.2)
73.9 gr 2907/2915/2924/2924 (2917.5 fps avg, 7.1 SD+/-6.9)

Published velocities in the Berger book:
71.5 gr 2646 fps
75.5 gr 2804 fps

Berger suggests 30fps faster per inch over 24", which would be 180fps for a 30" barrel. Which gives:
71.5 gr 2726 fps
75.5 gr 2984 fps

 

[TrevorJ]

72.7 gr load is what I have decided to load up, it's group had the least amount of vertical stringing at 200 yards.


Decided to load up a bit of a seating depth test this evening, jammed 10 thou, 40 thou off, 80 thou off, 120 thou off, and 200 thou off (3.36", which is almost the coal in the Berger manual 3.34" if memory serves).
A couple of weeks before I get to a long range practice, where I can really see if these loads are going to work.

 

[TrevorJ]

Decided to re-bed the action and the first 1" of the barrel, including the barrel nut.
As many of you pointed out, something isn't working. After verification of all the usual suspects (fastener torque on scopes/bases/action), and much load development, I removed the old bedding, and will start fresh.
I will keep updating the thread as I make changes.
Thank you to all of you who have given me suggestions, I appreciate it.
Tight groups.

 

[TrevorJ]

Finally got this load to shoot!
A new bedding job for the action, and the first inch or so of the barrel, and everything tightened up nicely.

73.6gr of H1000, 3.6065" COAL (jammed) 210gr Berger VLD, CCI250, PPU Brass.

I think the initial high pressure signs that I was seeing originally were likely caused in to me not breaking in the barrel correctly, causing me to "gum" things up resulting in a pressure spike. I think I have everything cleaned well enough, using kg12 to remove the copper.

I have also read, and been told that anemic loads are harder to tune in magnums. Any one on here find that?

 

[todbartell]

Milder pressure loads can suffer a bit due to lower load density, which can cause more erratic velocity.

 

[TrevorJ]

Thanks Todbartell.

 

[TrevorJ]

Had some more time on my hands, and decided to try another ladder.
Some success was had, no sticky bolt, although some minor cratering at the max load (77.1gr H1000), and some faint ejector marks on 1 or 2 of the brass from the hotter loads. See images.
Again same components, 210 VLD Bergers, CCI 250, COAL 3.6065" (unless otherwise noted). 200 yards, a bit of a blustery day for the last few increments for the ladder (bit of a thunderclapper rolled through).

74.0 gr H1000 Brass (top row), 74.3 gr (second row)


75.2 gr H1000 Brass (middle), 74.8 gr (above), 75.5 gr (below) Berger Max


77.1 gr H1000 Brass (last row), 76.7gr H1000










More in the next post.

 

[TrevorJ]

I apologize for the sideways images. The google machine is not co-operating with me.









I like the 75.2 gr load results, no image at the moment, (74.8 gr to 75.2 gr window seems consistent). Similar to the 73.6 gr, but with some more speed. Will shoot them over a chronograph at some point.