New .300WM Load Development

[lancetkenyon]

I am starting load development for a member here for his Savage LRH in .300WM. We had discussed this previously, and came to an agreement. We discussed brass quality and durability vs. price, bullet design & weight and intended use, and powder choices. We came up with a pretty good game plan in my opinion, so off we go. I supplied the components and gave him receipts and when I picked up his rifle, he had cash in hand.

 

I will be keeping this thread going during load development with photos, and will be keeping the member informed throughout the development too. He agreed that I can share the information here as well, so this is the start of another load development thread.

 

We all know the reason for reloading is not to save money. It is to get the components the shooter prefers to use, and to get the best accuracy out of your gun using those pieces. I already had a set of .300WM Redding dies, and of course the press, scales, trickler, shell holders, hand primer, trimmer, calipers, gauges etc. But 100 pieces of new brass, 2# of powder, 200 bullets, 200 primers, and two 50 round plastic boxes add up to $381.xx when you buy good quality. You can pay more for Lapua brass and Fed GM215M primers, or go cheap and do cheap brass and less expensive bullets too.

 

Component choices are as follows:

Nosler .300WM brass (x100)

H1000 (x2#)

CCI250 Mag primers (x200)

Berger .308 210gr. HVLD (x200)

 

 

I just picked up the rifle last night, so I haven't pulled it apart to clean and reassemble yet. It has about 80 rounds through it per the owner, and he tried $350 worth of factory ammo and was not satisfied with it. So here we go trying to make it shoot well.

 

The only thing I have done so far is brass measurements.

 

I weight sorted the brass, and was very pleased to find a total of .9 grains difference across all 100 pieces. Ranging from 216.8 to 217.7gr.

 

 

 

 

Base to shoulder datum using the .420" insert was pretty close too across 20 randomly sampled pieces.

 

 

 

And OAL average was just under recommended trim length for SAAMI specs. SAAMI OAL case length is 2.620", with a trim to length of 2.610". These averaged 2.605". So two firings before needing a trim is expected.

 

 

Case neck wall thickness was right at .015", similar to most other cases.

 

 

I recorded all the brass info in the new build notebook for reference.

 

 

I already had the .300WM dies, so good there.

 

[HNTNGUY]

I think you should start a topic labeled "load development for Mark's Sako 7mm" lol

[firstcoueswas80]

Wish you were in Tucson lance, id happily let you play with my 28 Nosler!

[lancetkenyon]

I think you should start a topic labeled "load development for Mark's Sako 7mm" lol

As soon as I am done with this one.....

[lancetkenyon]

Wish you were in Tucson lance, id happily let you play with my 28 Nosler!

That 28 Nosler BEGS for the 195 Berger Elite Hunter.

[firstcoueswas80]

Nah. Not enough gains short of like 1200 yards if I recall the numbers correctly.

[roninflag]

If you want a "real" challenge you should try my .257 wby........ the 300 wm is like a 308 ; very forgiving........ shooting out of 4 rem 700 senderos in 300wm we loaded 72.5 re -22 , wlrm, lapua brass, 210 berger .030 off. ...... .5" -.7". can't wait see the results with h-1000

[C. Cordova]

76g - .010 jump

[lancetkenyon]

I am ready to ladder test this weekend.

 

Weighed and measured 50 bullets (25 from each box of 100) to get a general feel for consistency.

 

Out of the 50, 4 were 210.1gr, and 5 were 209.9gr. The rest were all 210.0gr.

 

 

OAL ranged with a .010" difference.

 

 

But BTO was within .002" across all 50. I know these show me using the wrong insert (.264"), but I will switch to the .308" and re-photograph and record them.

 

 

I measured the magazine box length to see how much room I had to work with as well.

 

 

I checked seating depth jammed to lands. With these measurements, I know the rounds will have about a .075" jump to fit in the magazine smoothly.

 

 

 

 

Here is my starting seating depth to fit in the magazine.

 

 

Keeping a log of all the info so far, and you can see the bullet doesn't take up too much case space.

 

 

 

I seated the bullets about .010" short of max mag length to ensure smooth operation and no binding in the box.

 

 

I neck sized, tumbled and annealed all the new brass.

 

 

Primed all 100 cases with CCI 250 Mag primers

 

 

I always throw the charges with an electronic scale/powder throw to within .3gr less than target, then transfer to my RCBS 5-0-5 and trickle up to the individual kernel of powder for every single round.

 

This is the difference a single kernel of H1000 makes.

 

 

 

I built 9 sighters (w. red ring on bullet) and a ladder test of 14 rounds with different charge weights.

 

 

Here is my log book so far:

Rifle and scope info.

 

Brass info.

 

Bullet and cartridge COAL & CBTO info

 

And my ladder test charge weights. Note the difference between the Berger and Hodgdon suggested "Max". Berger max is at a slightly shorter COAL than Hodgdon. The COAL I am starting with is even a bot longer than the Hodgdon COAL.

 

And an example of how I mark the different charge weights in case the box got overturned or spilt. You can tell this is the 76.0gr. load by the symbol.

 

I will start low, and work up marking each shot and watching/feeling for signs of pressure, and stop when I hit that point.

[ctafoya]

You sure go a lot deeper in reloading than I do. Maybe time for me to start paying attention to this free education.

[lancetkenyon]

So I got out on Saturday to sight in the rifle at 200. The owner said he was getting 1.5-1.75" groups with factory ammo at 100 yards. I was pretty happy to see a simple consistently measured sight in load with good components netted me this sub 1" group at 200 yards. This looks promising.

 

 

 

I brought the fired cases home to measure the chamber dimensions of the brass to see how much they grew over virgin brass dimensions. Shoulder pushed forward .0200" upon firing.

 

 

So I resized them and bumped the shoulder back .002".

 

 

Again, I recorded all info for future reference.

 

 

Then Sunday, Taylor and I woke up early and headed to shoot a 400 yard ladder test.

 

 

Here were the results.

 

 

So I resized all the fired brass bumping the shoulder back .002", tumbled, and annealed them. Then loaded up some 5 shot groups in the higher node for group testing this coming weekend.

 

 

Concentrating on the higher node, here are the charge weights I will be working around.

 

 

All ready for the upcoming weekend.

 

[8OWHUNT247]

Tuned in.. I love a .300WM

[lancetkenyon]

I got out on Sunday and shot for some groups. Best load wound up being 76.0gr. H1000. Shot into .533" @ 100 @ 2920fps average. Other groups were all about 1", some a bit under, some a bit over.

 

 

Pretty happy with the lack of vertical dispersion. 5 shots

 

 

I got home and resized the brass bumping the shoulder back .002" and tumbled them.

 

Loaded up some more for seating depth testing this coming weekend. All measurements are CBTO. Shortest is .005" shorter than Berger's recommended COAL measurement.

2.820"

2.780"

2.740"

2.700"

2.660"

 

 

 

 

 

 

 

[208muley]

Awesome post!!! I am learning a ton!

[tomkat12]

Lance if you have second would you shoot me a message I tried to send you a pm but it appears your inbox is full. I have an invite I wanted to send you I think you will be interested in. Great thread btw