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Forum Index > Rifles general discussion > 2016 - 300 win mag load development

2016 - 300 win mag load development

07 Jun 2016
@ 09:06 pm (GMT)

Mike Kush

After bedding I'm beginning to re-read the reloading book, and proceed with load development.

I've been looking around for my rifle pressure rating, but havn't found anything. Anyone know what it is, or where to find the info?

Here's what I'm planning on using.

Rifle - Remington Sendero (~25" barrel due to warranty re-chambering)
Cartridge - 300 win mag

Bullet - Hornady 208grain Amax
Brass - Winchester
Primer - Federal215 (Large magnum)
Powder - Hodgdon H1000

Lee Breach Lock Challenger Kit

This pic is comparing before and after bedding the rifle, factory ammo.
The quarter is placed beside a 4 shot group.


Replies

1
07 Jun 2016
@ 11:34 pm (GMT)

Thomas Kitchen

Re: 2016 - 300 win mag load development
Hi Mike.
You'll struggle to find pressure date it will be rated to higher then saami specs but that probably all you'll find.
If your not very confident read the reloading book taking note on the chapter about reading pressure.
Start at start load in your manual and work up as per Nathans instructions.
Look for an accuracy spot with nice tight groups there should be one within reloading data and one above max.
I can not give you a margin above max that is normally safe so work up slowly and once you find a accurate load stop there.
If your not confident stay within load data for now the amax will work well so you'll got a decent amount of range for the time being.
08 Jun 2016
@ 12:29 am (GMT)

Warwick Marflitt

Re: 2016 - 300 win mag load development
Well done Mike. You just need to get the 4 holes touching in the middle of that red circle on the paper? Great advice Thomas gave to follow the books.
08 Jun 2016
@ 12:49 am (GMT)

Mike Neeson

Re: 2016 - 300 win mag load development
Excellent effort Mike

Here's what a little extra pressure can look like. I failed to properly maintain my case length causing the pressure to spike. Note how flat the primer is and at about the 6 O'clock it has flowed over and around something on the bolt face.. ejector maybe?

08 Jun 2016
@ 12:57 am (GMT)

Mike Neeson

Re: 2016 - 300 win mag load development
09 Jun 2016
@ 05:24 am (GMT)

Nathan Foster

Re: 2016 - 300 win mag load development
Hi Mike, looks like a vast improvemment. Well done.

If you can get access to a chrony, look for sweet spots between 2800 and 2900fps while watching for pressures as per the reloading book.

At a guess (because that's all I can do), I would say yours will hit its sweet spot right around 2850fps with the 208gr, seated 10 thou off the lands.

You have some good components on hand and nothing that will give a serious and unexpected spike unless a major mistake is made in your approach.

The above photo is a good indicator of max pressures. Try to stop before reaching this point. Mike was only able to go this high because he is Australian which makes him bullet proof.

09 Jun 2016
@ 11:15 am (GMT)

Warwick Marflitt

Re: 2016 - 300 win mag load development
20 Jun 2016
@ 05:26 am (GMT)

Mike Kush

Re: 2016 - 300 win mag load development
Quote:
Well done Mike. You just need to get the 4 holes touching in the middle of that red circle on the paper? Great advice Thomas gave to follow the books.


Rather than going through the trouble of trying to figure out which way to click one of the 4 nobs on my scope, I thought I'd just make sure to have the wind always going from right to left :)


Thx guys
20 Jun 2016
@ 01:58 pm (GMT)

Mike Neeson

Re: 2016 - 300 win mag load development
Just an end note... Mike you can be Mike1 and I'll be Miketoo... I had to do a double read a few times. Just to set the record straight, my bullet proofness springs from me being a Kiwi... Who happens to live is Australia. I could be tempted to say that I found Nathan's comment deeply insulting but I will refrain for fear of further insulting my dear Australian friends. Go the All Blacks! And anyone who's playing England!
26 Jun 2016
@ 06:36 am (GMT)

Mike Kush

Re: 2016 - 300 win mag load development
A quick powder question:

Hodgdon has a 6 grain spread between their max and min charges.

Hodgdon Data
COAL 86.87mm-3.420"
Starting load 71.7gr 2650fps
Max load 78gr 2869fps


Working at .5 grain increments, that would have me taking 13 three shot groups totalling 39 shots. That's a lot more than the examples given. Is there a safe approach to limiting that shot total?
Thx
26 Jun 2016
@ 04:19 pm (GMT)

Paul Leverman

Re: 2016 - 300 win mag load development
Hi Mike - I was going to give you my procedure for determining maximum pressure for your rifle, but after re-reading it about a dozen times, I just couldn't post it. There was no safe way to explain it. Follow Nathan's and Miketoo's advice and all will be good.
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