300NMI 245 Berger Loads

[RustyB]

I recently acquired a 300 Norma Mag Improved and was looking for some load data on the 245 Berger EOL. Any info is greatly appreciated.

 

[ISS]

Mine is almost finished, at least the metalwork (FCH) portion. We will proof five rounds with the Sierra 240's and reload those five cases as dummy rounds so it can go to Tom Meredith for final fit and then to Bc'z for clear coat.

Rumors abound that a good place to start is 88gr of N570 or about that much Retumbo.

 

[shoot4fun]

Reloading Data Center – Hodgdon Reloading Data Center

hodgdonreloading.com

Retumbo is a favorite of mine for the big stuff. I would suggest you take Hodgdon's data for the 245EOL in 300NM and work up from there.
It seems there are a couple different version of the improved but either Ryan's or @Alex Wheeler (what I have) version is 35˚ and accuracy is pretty dang amazing.
If your experience with the 300NMI is as good as mine has been you won't stop smiling.

 

[FeMan]

Retumbo is a good place to start. One of mine is a 30-inch Bartlein and likes the 245s jumped about 0.075" with 88.2 grains of Retumbo. Itll shoot 0.4 moa 5-shot groups reliably. The other is a 32" Brux and doesn't shoot Retumbo as well but its best load is 245s jammed about 0.015" with 85.5 grains of (0.75 moa 5-shot groups) .

I am in the middle of load workups with N568 and N570. The 32" Brux loves a very heavy dose of N568 at a Jam of 0.010". So far it is shooting this under 0.2 moa at 3100 fps. I plan to do a 900 yard powder ladder with both rifles and N568 and N570 next week. That should tell me more. I'll fine tune seating depth and then neck tension after that and be ready for ELR season.

 

[ISS]

thanks, I hope to be sitting there next to you watching as you proof my 300NMI.

Rich

 

[4xforfun]

Question on the Retumbo thing....I read a few posts like you, but they were 10 or more years old, and there were concerns about DANGEROUS PSI spikes at COLD temps. Is that still a thing. I steered away from my 8 pounder of Retumbo and went with RL33 for my 1st tests.

Not a 300 NM, but a 300 rum with HEAVY bullets.

Tod

 

[FeMan]

I have shot my 300 NMI Retumbo loads in temps down into the teens with no issues. Brian Litz told me a few years ago that in his testing, Retumbo was the most temp insensitive powder he had ever tested, to the point he called it virtually temperature immune.

I have read that claim about issues in severe cold temps about N570 but never heard that about Retumbo.

 

[RyeGuy]

Retumbo is a good place to start. One of mine is a 30-inch Bartlein and likes the 245s jumped about 0.075" with 88.2 grains of Retumbo. Itll shoot 0.4 moa 5-shot groups reliably. The other is a 32" Brux and doesn't shoot Retumbo as well but its best load is 245s jammed about 0.015" with 85.5 grains of (0.75 moa 5-shot groups) .

I am in the middle of load workups with N568 and N570. The 32" Brux loves a very heavy dose of N568 at a Jam of 0.010". So far it is shooting this under 0.2 moa at 3100 fps. I plan to do a 900 yard powder ladder with both rifles and N568 and N570 next week. That should tell me more. I'll fine tune seating depth and then neck tension after that and be ready for ELR season.

Would you mind posting those results when you do that test? Also steps you took? I’d like to re-test my 338NM @ distance following a fellow large caliber load dev

 

[FeMan]

Would you mind posting those results when you do that test? Also steps you took? I’d like to re-test my 338NM @ distance following a fellow large caliber load dev

Can do but I have the flu right now. I may have lost my weather window......

 

[FeMan]

Would you mind posting those results when you do that test? Also steps you took? I’d like to re-test my 338NM @ distance following a fellow large caliber load dev

I finally finished my load development. Primers are CCI 250s and cases are Lapua.

The rifle was super happy between 88.6 and 89.4 grains of N570 with only 0.11 moa vertical between the three loads. It was wonky below that and then jumped up over 1 moa at 89.8. I usually do this at 900 yards or even at 1400 yards but those ranges weren't available. The ladder below was shot at 657 yards which is all I could get access to in the timeframe I had.



So I loaded up 89.0 and did a seating depth test. For seating, I loaded up four rounds at each depth and started from 0.005" jump and moved out in increments of 0.003". I also shot a few random jam loads. The best two are shown below. 2.849" is a jam of about 0.012" and 2.811 is a jump of about 0.026". Neither is stellar. The jam load was tempting with three in one hole but the fourth flyer bothered me and seemed to repeat. For now, I decided to go with the jump load at 2.811" at 0.35 moa. I have found groups that have a round shape are more repeatable than those with a one-hole and a flyer. When I have time, I will test different bushings at 900 yards before settling on a final load.






I shot the bottom one last night at 900 and it held 0.1 mils vertical on steel in some pretty spicy winds.

 

[Ranger188]

You are pushing those 245g right along.

 

[FeMan]

You are pushing those 245g right along.

For sure. Its a 32" bbl. This is up there close but not quite max in my rifle. I got to slightly over 3200 before I actually saw signs of pressure. I was well over max by then I am certain but the case hid it well.

 

[Ranger188]

I find with the N568, you can't hardly put enough in the case to max it out.
Not sure if it's cause it burns cooler or it's slower than N570 (not suppose to be)
N570 is one of the better powders to get the most out of this case.

 

[Ranger188]

Are you using the EOL's or hybrids?
I see you have used one or the other in another post.

 

[ELR LVR]

I finally finished my load development. Primers are CCI 250s and cases are Lapua.

The rifle was super happy between 88.6 and 89.4 grains of N570 with only 0.11 moa vertical between the three loads. It was wonky below that and then jumped up over 1 moa at 89.8. I usually do this at 900 yards or even at 1400 yards but those ranges weren't available. The ladder below was shot at 657 yards which is all I could get access to in the timeframe I had.

View attachment 1751135

So I loaded up 89.0 and did a seating depth test. For seating, I loaded up four rounds at each depth and started from 0.005" jump and moved out in increments of 0.003". I also shot a few random jam loads. The best two are shown below. 2.849" is a jam of about 0.012" and 2.811 is a jump of about 0.026". Neither is stellar. The jam load was tempting with three in one hole but the fourth flyer bothered me and seemed to repeat. For now, I decided to go with the jump load at 2.811" at 0.35 moa. I have found groups that have a round shape are more repeatable than those with a one-hole and a flyer. When I have time, I will test different bushings at 900 yards before settling on a final load.

View attachment 1751143


View attachment 1751144

I shot the bottom one last night at 900 and it held 0.1 mils vertical on steel in some pretty spicy winds.

Agreeing with your 89.0 grns when comparing the clusters of the 1-11 shots made at 657 yds
as far as your Jump vs your Jam load
I agree in liking a more round pattern overall so thereby sticking to the Jump Load
but
I don't believe you tested jam deep enough when stopping at the tested 2.849" at .012" Jam
---
I would explore going deeper and see if that Random Damn Flyer closes in on the one hole group
I have jammed as deep as .060" when gauging strictly by Land Mark Engraving
(not with a 300 NMI, but with other cartridges and VLD's)
Powder charge may have to be adjusted to adjust for pressures
keep in mind, land engraving marks are not indicative of the actual Jam depth
If you are using that as a Gauge at all
you may have .030" land marks on the bullet but only be jammed .010"
due to the Ogive closely matching the leade angle
Ex: say if both angles are exactly the same at touch for instance
you could have .100" land marks, and that only be .002" jammed
---
In the diagram, the bullet is just about to touch the leade, but once it touches would have .100" contact surface, once into the lands .001", it would show .100" contact patch engraved
---
if the Leade Angle is less than the Ogive angle, .012" jammed may only be halfway into the Leade
Anyway, just offering some info in case this hasn't been considered.

 

[FeMan]

I don't believe you tested jam deep enough when stopping at the tested 2.849" at .012" Jam
---

My post is a very abbreviated version of my testing. I agree with you and actually tested jam as deep as 0.026". I also tested three powders. I just didnt show all this as I wasnt as organized as I could have been about it and it would be a lot of data and pics. I was sure a powder tweak would close the gap but it didnt. The jam loads just all had that flyer.

A quick summary of my testing is Retumbo and N568 would not shoot a predictable load to my liking. Things changed when I went to N570. I tested loads from 0.026" jam to 0.075" jump. I settled on the jump load above. I also did load development on my wife's 300 NMI alongside mine and hers ended up at around the same jump with a little more powder. Hers is shooting in the 0.2's but her vertical at distance isnt quite as tight. Here is a four shot group with her 300 NMI and the 245 LRHT

 

[FeMan]

Are you using the EOL's or hybrids?
I see you have used one or the other in another post.

These are LRHTs. I did load developments for two customers last year and one was shooting the EOLs in a straight Norma. The other was LRHTs in an improved. I need all the BC I can get so I went right to the Hybrids.

 

[Sgt. Brumbaugh]

Those are very spicey loads; what is your brass life like? It is pretty well known that 300 Norma, Lapua made brass is very tough- you prove that with those velocities.

What are your ES's and SD's on average. How many rounds do you leave the barrel in service for competitive use?

N570 does often seem to be the magic sauce for large case capacity cartridges.

 

[FeMan]

Those are very spicey loads; what is your brass life like? It is pretty well known that 300 Norma, Lapua made brass is very tough- you prove that with those velocities.

What are your ES's and SD's on average. How many rounds do you leave the barrel in service for competitive use?

N570 does often seem to be the magic sauce for large case capacity cartridges.

My ES is right at 20 and me SDs are between 5 and 6. Since a granule of N570 weighs about 0.8 grains, I think this is pretty decent.

As far as barrel life, I don't know. My wife's has 500 rounds on it and mine has 300. The throats have really not moved at all, but that's due to no match shooting yet. I run my high flow barrel cooler for at least a minute between each shot and let it cool longer if the barrel feels the least bit hot. I know that once I start shooting matches and shoot long strings in short periods, that will al change rapidly. I am hoping for 1,000 to 1,200 of accurate barrel life. I have four new blanks and will chamber and do load development for two soon so they are ready to swap on if one or both of these goes south before the end of the season. Based on my calcs our season will require 825 rounds more on each barrel. I really doubt my wife's will go that far but we shall see.

 

[Sgt. Brumbaugh]

Cool, good luck!
What ELR venues do you shoot?