300 Win Mag Load Development Help

[BBean70]

Just starting out reloading and trying to develop a load for my 300 WM. I have some fire formed brass from this rifle approximately 27 pcs and have picked up some once fire brass. I've got it sized and after measuring it almost every piece of the brass fire in my rifle is under SAAMiI overall brass length of 2.62" they are coming in about 2.615 roughly, so
(1) do all these need to be trimmed back to 2.61" or will they be ok for load development
(2) of the 27 pcs of brass shot in this rife they are not same brand of brass some Winchester and some Speer some of the other once fired brass (not in my rifle) is some Nosler and Barnes will using mixed brass make a huge difference in the load developmen? i will also be using a Chronograph for testing. I'm not looking for a load I can shoot F-class with mainly just as accurate a hunting round as I can get.
I will be using 180gr Nosler AB bullets with H-1000 powder using Nosler Load data
Thanks in advance

 

[lancetkenyon]

Do not mix headstamps.
Find what you have most of, and weigh them and sort to within 2-3 gr and discard the rest.

FL size what you keep, bumping shoulders back .002 from the cases fired in YOUR rifle.
Trim if within .003" of max. Might as well trim them all at this point.

 

[BBean70]

Do not mix headstamps.
Find what you have most of, and weigh them and sort to within 2-3 gr and discard the rest.

FL size what you keep, bumping shoulders back .002 from the cases fired in YOUR rifle.
Trim if within .003" of max. Might as well trim them all at this point.

So if I am understanding you correctly I should only use brass mad by the same manufacturer ie Winchester or Nosler, etc?

I have FL sized all the brass back .002 from my fired brass and I am no math wizard but if I need to trim the brass to 2.617" and I am already .002 under that at 2.615"

 

[lancetkenyon]

So if I am understanding you correctly I should only use brass mad by the same manufacturer ie Winchester or Nosler, etc?

Yes. Then weigh those brass to within 2-3 grains max.

I have FL sized all the brass back .002 from my fired brass and I am no math wizard but if I need to trim the brass to 2.617" and I am already .002 under that at 2.615"

No. I am saying if some of the brass is within .003" of max length (2.617"), go ahead and trim them all (even if some are .008" from max or 2.612") to minimum length of 2.610".

 

[Longtine88]

What lance said ^^^^^^^

 

[BBean70]

Yes. Then weigh those brass to within 2-3 grains max.

No. I am saying if some of the brass is within .003" of max length (2.617"), go ahead and trim them all (even if some are .008" from max or 2.612") to minimum length of 2.610".

Ok. We'll hell then I guess I ought to just throw it all away and start over. That just doesn't make sense to me with all the once fired brass being sold all over.

 

[lancetkenyon]

Ok. We'll hell then I guess I ought to just throw it all away and start over. That just doesn't make sense to me with all the once fired brass being sold all over.

You asked for advice on reloading. I assume you want quality handloads when you are done.
Have to start with quality brass, that means consistency.

You wouldn't go race NASCAR with 4 different brands and sizes of tires would you?

 

[Huntsman66]

So if I am understanding you correctly I should only use brass mad by the same manufacturer ie Winchester or Nosler, etc?

I have FL sized all the brass back .002 from my fired brass and I am no math wizard but if I need to trim the brass to 2.617" and I am already .002 under that at 2.615"

You are correct, always use at least the same manufacturer head stamp when working up the load. Depending on the maker if you load to a max on powder you can creat an over pressure issue, not to mention that they will probably all shoot different .

On the trimming if they are under and they fit your chamber you don't have to, but it is a good idea to have everything like in size, and consistent .

 

[Sockeye66]

Different headstamps can/will have different capacity. LTK is spot on, if the desire is to have an excellent finished round, then invest is some quality brass. Lapua would be my first choice, but Iv'e had good luck with Norma, Hornady, and Sig. Personally I use a Redding body die (with Redding shell holder set) and a Lee collet die for my 300wm. Also, belted cases commonly will bulge above the belt, so I use a Hornady case gauge when I'm done just to check, they are a great cheap investment.

 

[Huntsman66]

So if I am understanding you correctly I should only use brass mad by the same manufacturer ie Winchester or Nosler, etc?

I have FL sized all the brass back .002 from my fired brass and I am no math wizard but if I need to trim the brass to 2.617" and I am already .002 under that at 2.615"

Based on what you said here, if 2.617 is max… trim to 2.614 on all and then every time you fire trim back to 2.614

 

[smokey3]

Just starting out reloading and trying to develop a load for my 300 WM. I have some fire formed brass from this rifle approximately 27 pcs and have picked up some once fire brass. I've got it sized and after measuring it almost every piece of the brass fire in my rifle is under SAAMiI overall brass length of 2.62" they are coming in about 2.615 roughly, so
(1) do all these need to be trimmed back to 2.61" or will they be ok for load development
(2) of the 27 pcs of brass shot in this rife they are not same brand of brass some Winchester and some Speer some of the other once fired brass (not in my rifle) is some Nosler and Barnes will using mixed brass make a huge difference in the load developmen? i will also be using a Chronograph for testing. I'm not looking for a load I can shoot F-class with mainly just as accurate a hunting round as I can get.
I will be using 180gr Nosler AB bullets with H-1000 powder using Nosler Load data
Thanks in advance

That is my load exactly for my 300WM. I have been using Winchester brass, 180gr AB's, Fed 210 Match primers, and 79.3 grains H1000, brass was fire-formed before initial load development. Also when I used magnum primers CCI, Fed and Win, my SD & ES was erratic but settled in at about 15' ES & 8' SD with the 210 primers. The Win LRMP showed signs of pressure with everything else being the same, they seem a little hotter in my gun. 26' Kreiger 1 in 10" twist barrel giving me 3100' FPS. Holding <1/2 MOA out to a 1000 yards. I have Peterson Long Brass and only tried a few rounds and it is showing really good potential at 9' ES & 5' SD but required a few tenths less powder on new cases. Like others have said, mixed brass will not give you the results that you desire. If the Lapua brass had been available when I bought the Peterson I may have bought it instead but the long version from Peterson is pretty good I think. The Winchester brass was new but from the nineties and is ok also.

 

[dgogogomez]

OP. On a 300WM it may take 2-3 firings for the shoulder to stop growing forward. I might suggest FL sizing but not bumping the shoulder back until the brass won't fit or they all stop growing at about the same base to shoulder length. Others here might have a different method to accomplish this.

 

[Buckys]

You asked for advice on reloading. I assume you want quality handloads when you are done.
Have to start with quality brass, that means consistency.

You wouldn't go race NASCAR with 4 different brands and sizes of tires would you?

BBean70, minimizing variables increases probability of best possible quality of results.

Suggest that you offer some insight into what you are trying to achieve. May very well be best QoR is beyond the scope of this attempt.

 

[BBean70]

BBean70, minimizing variables increases probability of best possible quality of results.

Suggest that you offer some insight into what you are trying to achieve. May very well be best QoR is beyond the scope of this attempt.

I understand that using the best possible components will yield best results. I am not looking to shoot out to 1000 yards. I am trying to develop a hunting load that I can use to reach out to about 600 yards (practice) with good accuracy that I feel confident If I have to take a shot at 400 yards or hopefully less on an elk as I will be going on my first elk hunt later this year. My new rifle shoots well with factory ammo but like everything right now its hard to find. I've been wanting to start reloading for a while so I figured I would start now. I can seat powder, bullet seat depth, etc play a big role just wasn't aware brass played that big a role or I would not have bought the once fired and bought new premium brass. Not trying to cut corners just save where I can as getting into this hobby the purchases can be endless and the rabbit holes are deep