The Firing Line Forums

Go Back   The Firing Line Forums > The Skunkworks > Handloading, Reloading, and Bullet Casting

Reply
 
Thread Tools Search this Thread
Old February 12, 2019, 10:58 PM   #1
Bearbuck
Senior Member
 
Join Date: April 1, 2006
Posts: 148
300 win mag load development

I have been trying find the load for my 300 win mag. I am shooting 180gr Accubonds with H4831sc at 3.35 " oak. Federal brass and cci mag primers.i have worked up to 75 gr. At 74 grains out of 8 shots 6 are in same place cutting holes. The other 2 shots were on right and other one left about 1 inch. On 75 gr load 3 shots clover leafed. The first shot was about 1 inch low and left and the 5th shot was about 1 inch right straight across from clover leaf. Do these shot placement suggest anything about the loads? Should I try 74.5gr ? Thanks for help
Bearbuck is offline  
Old February 13, 2019, 12:36 AM   #2
kilotanker22
Senior Member
 
Join Date: October 14, 2012
Location: North Central, PA
Posts: 1,011
It's been my experience when seeing that much horizontal dispersion. When shooting at 100 yards. When most of the group is tight. It is usually caused by a flinch or poor trigger squeeze execution. Especially with rifles that have stout recoil. I occasionally catch myself causing these shots.

Also the win mag generates a lot of heat. If it's a Sporter barrel it will start to heat up within 5 rounds.

My 270 wsm shoots lights out till it gets warm. Then it will disperse rounds left or right.
kilotanker22 is offline  
Old February 13, 2019, 07:29 AM   #3
Bearbuck
Senior Member
 
Join Date: April 1, 2006
Posts: 148
Hey guys here more info. Mutg cases are trimmed all to 2.61" It was 42 degrees out. No wind. I was shooting seated using the small lead sled but I h as ve no weight in the tray. I am actually bumping against and putting my shoulder to the back end which does cause it to float some when breathing but I try to shoot during a steadied pause. My gun does have just a sporrter barrel on it on the 74.5 gr load question wasnt sure it would make tremendous difference. Also I will say once a get couple rounds on target it makes it hard for me to be as precise because the little red dot I try enter in my crosshairs isnt there so I'm trying to find center to shoot. Because of the off shots cant determine between 74 or 75 gr. If I had to based just off targets I would chose 74gr but I need shoot them again to feel more comfortable. I enjoy the searching and loading in finding a load. It's part of the fun but I also like knowing the finished load and sometimes gets frustrating getting their. 2 edged sword I 
Bearbuck is offline  
Old February 13, 2019, 09:11 AM   #4
kilotanker22
Senior Member
 
Join Date: October 14, 2012
Location: North Central, PA
Posts: 1,011
It is definitely a little frustrating some times.

If you have any Hodgdon H-1000 available. That is an excellent powder. Both for velocity and accuracy. Should work great with those 180 grain bullets.
kilotanker22 is offline  
Old February 13, 2019, 04:05 PM   #5
sako2
Senior Member
 
Join Date: April 12, 2009
Posts: 329
Try to get the accubonds .050 off the lands.
sako2 is offline  
Old February 14, 2019, 08:19 AM   #6
std7mag
Senior Member
 
Join Date: June 23, 2013
Location: Central Taxylvania..
Posts: 2,530
Several things.
1) Ditch the Lead Sled! Only serves to create bad shooting habits. Also it's not a natural rest. Meaning how you are behind, holding, cheek weld is different.

2) it's not a precision bench rifle custom built for matches, is it? For a hunting rifle of that cartridge, i would find your groups wholly acceptable.

3) It's a public forum. Aka the standardised warning.
THESE LOADS ARE FOR MY RIFLE, AND MAY OR MAY NOT WORK IN YOURS. USE DATA AT YOUR OWN RISK.

While happy to help someone, you'll never see me post specifics on powder charge weight, or COAL.
__________________
This country was founded on two beliefs.
And I'm pretty sure pork rinds was one of them!
std7mag is offline  
Old February 14, 2019, 11:08 AM   #7
kilotanker22
Senior Member
 
Join Date: October 14, 2012
Location: North Central, PA
Posts: 1,011
Quote:
Originally Posted by std7mag View Post
Several things.
1) Ditch the Lead Sled! Only serves to create bad shooting habits. Also it's not a natural rest. Meaning how you are behind, holding, cheek weld is different.

2) it's not a precision bench rifle custom built for matches, is it? For a hunting rifle of that cartridge, i would find your groups wholly acceptable.

3) It's a public forum. Aka the standardised warning.
THESE LOADS ARE FOR MY RIFLE, AND MAY OR MAY NOT WORK IN YOURS. USE DATA AT YOUR OWN RISK.

While happy to help someone, you'll never see me post specifics on powder charge weight, or COAL.
I agree for the most part.

I also have a lead sled. I actually shoot better from a bipod and a rear bag. I find it kind of difficult to be really really steady from the lead sled. Also its kind of awkward shooting from it. Now great groups can be had from a lead sled, but Like std7mag said it certainly does promote bad habits.

I would put a bipod on it with a rear bag for range work. Or an adjustable front rest and rear bag.
kilotanker22 is offline  
Old February 14, 2019, 11:14 AM   #8
kilotanker22
Senior Member
 
Join Date: October 14, 2012
Location: North Central, PA
Posts: 1,011
I will be beginning Load development for my new 300 win mag next weekend. I have owned a few 300 win mag rifles. The new one I ordered came in today.

Once I start load development, I would be happy to share and compare notes with you. Via Private message of course.
kilotanker22 is offline  
Old February 14, 2019, 11:38 AM   #9
Stats Shooter
Senior Member
 
Join Date: August 26, 2016
Location: North Dakota
Posts: 1,599
The .300wm can be difficult to load for consistently. I have loaded for several .300wm's including hunting and F-Open rifles. You can go back and look at some of my threads I started on this cartridge a while back.

First, as someone said, heavy sporter barrels in the 0.577" or below range get hot quickly. My model 70 is hot after 3 or 4 shots in a 4 or 5 minute period. This can cause some issues, depending upon how well it is bedded and different rates of metal expansion.

Second, 3.35" OAL is a long jump in a .300wm. I don't know what your chamber dimensions are, but I am betting you are probably jumping 1/8" or more. My model 70 and my Savage 110 would only allow an OAL of 3.34" to feed from the magazine so I had to use much shorter bullets like the partition to move deeper into the lands while still feeding from the magazine.

3rd: It is easy to generate a lot of runout in the .300wm due to the very short neck of the cartridge, especially when seating these longer and sleeker bullets. Having tight groups and then a flier here and there might be due to high runout on 20% or so of your loads.

Finally, Shooter fatigue is high with lightweight .300wm's. I use a trap shoulder pad AND a limb saver when I am doing load development for my hunting .300wm's and still can get the flinches. So in between groups as my barrel cools I will go shoot some .223 or .22 long rifle as well as some dry fining to maintain control, and limit my sessions to 25 or 30 rounds.

Otherwise, you might check the base to ogive and ensure you seating dept is consistent as well.
Stats Shooter is offline  
Old February 16, 2019, 02:55 PM   #10
Nick_C_S
Senior Member
 
Join Date: March 21, 2013
Location: Taxifornia
Posts: 4,869
Quote:
I will be beginning Load development for my new 300 win mag next weekend.
Heh, much the same here too. I'm lurking this post because I just started loading for 300 Win Mag. My step-daughter's boyfriend has a 300 Win Mag, and just for fun (and to have something in common with him), I bought all the dies, components, etc. to load for it. He gave me his saved brass.

Anyway, I won't hijack this post. But I have loaded five rounds - pending shooting. We'll run 'em over a chronograph. R-P brass; CCI 250 primers; Speer 180 BTSP '2052'; 69.0 grains of IMR 4831; trim length 2.610"; OAL 3.340; no crimp.
__________________
Gun control laws benefit only criminals and politicians - but then, I repeat myself.
Life Member, National Rifle Association
Nick_C_S is offline  
Old February 16, 2019, 04:12 PM   #11
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 16,003
The 1995 Precision Shooting Reloading Guide includes mention by one of its authors of a .300 WM target rifle he could never get to shoot under about 2 MOA, regardless of load tweaks and special attention. Then one day he decided to try outside-neck-turn the cases to improve concentricity of the bullet in the chamber. Bingo. Under 1 moa. He had no idea why, and, IIRC, had never seen that extra brass uniforming step matter nearly so much to any other gun. So, you just never know what you might discover.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is offline  
Old February 16, 2019, 05:40 PM   #12
Nick_C_S
Senior Member
 
Join Date: March 21, 2013
Location: Taxifornia
Posts: 4,869
Quote:
outside neck turn the cases
What is that?

Sounds like truing up the necks with some sort of lathe-type process??
__________________
Gun control laws benefit only criminals and politicians - but then, I repeat myself.
Life Member, National Rifle Association
Nick_C_S is offline  
Old February 16, 2019, 08:02 PM   #13
Unclenick
Staff
 
Join Date: March 4, 2005
Location: Ohio
Posts: 16,003
I should have hyphenated it. For about three decades now people shooting super-precision rifles have had their chambers cut with special non-SAAMI spec reamers that leave the neck portion of the chamber narrower than standard. This lets them turn their neck wall thickness down a thousandth or so with a hand tool that does what a lathe might do. It supports the neck on a close-fitting mandrel while a carefully adjusted cutter shaves the outside brass off. This lets you make the neck concentric with the bullet inside and out. The narrow-neck chamber is made with the expectation you will turn the case neck so that, with a bullet seated, it has half to one-thousandth clearance. This serves a couple of purposes. One is centering the bullet better and the other is increasing the life of the case you just went to all that extra prep trouble with by having a neck that doesn't need much resizing to bring back down to size.

In addition to the hand tool, there are lathe type turners (Hornady) and motorized tools both in the form of electric screwdriver attachments and Gracey makes one based on their power trimmer platform.
__________________
Gunsite Orange Hat Family Member
CMP Certified GSM Master Instructor
NRA Certified Rifle Instructor
NRA Benefactor Member and Golden Eagle
Unclenick is offline  
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 12:45 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2018 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.06144 seconds with 9 queries