Off-season project - 7mm Rem Mag

[perma]

Here’s what I got:

Lands - 4.010”
Max length - 3.990”
Mag length - 3.736”
SAAMI max - 3.560”
Nosler recommended - 3.550”

What I can tell you so far is that groups were bad at 3.549”-3.550”, even with different powder charges. Nosler said 85g was the most accurate they tested and that was at 3.550”. I do want to keep my cartridges in the mag just so that I don’t have to hand feed them in the event a second/third shot is needed. I have another few rounds at 3.550” with new steel rings, so if that does not work and I can group factory ammo, I’ll make a new set at mag length and go from there.

Might go shoot them tonight so stay tuned.

 

[Sheltowee]

Experiment with one variable at a time. Do your ladder test at book-specified COAL. Find a load that shoots accurately but, more importantly, gives you a good ES and SD (SD removes the human error variable in accuracy). You should find a powder node that gives you pretty good consistency. Then, start playing with seating depth. You might look at my .257 Ackley thread to see how I work through the process. Change any component (brass mfg, powder, primer, projectile) and start back over at the ladder test.

I’ve always had mixed luck using the jammed bullet method to find distance to lands. Much better results using the Hornady COAL gauge. You’ll need to buy a modified case for each cartridge you load, though.

Hornady Lock-N-Load Overall Length Ga Bolt Action

The Hornady Lock-N-Load Overall Length Gauge is one of the best kept secrets to accurate reloading. This tool allows reloaders to quickly and easily...

www.midwayusa.com

 

[BackofBeyond]

Nosler said 85g was the most accurate they tested and that was at 3.550”.

So here’s the deal - that was with Nosler’s test barrel, with Nosler’s test barrel chamber, with Nosler brass, and Nosler’s lot of primers and powder.

To echo @Sheltowee, do a ladder of 10 rounds with your powder/primer/projectiles at mag length. Preferably shoot them at 300 + yards (distance makes the differences easier to find,) and find a node (group of 3 shots that group close to in another despite the different powder charges.) Take the charge weights from the node and make yourself some 5 round test groups, and shoot those for best group. If you find a group you can accept, that’s your load.

You likely won’t find a huge difference in accuracy doing seating depth testing, especially on something as overbore as a 7 RM.

Also, read this thread:

Load Development in a Time of Scarcity

Kind of like “Love in the Time of Cholera” but totally different. I’m about to start load development on my .300 PRC, and the scarcity of components has me a little spooked. The last time I did a full work-up any and all components we’re easy off the shelf items. I’ve got 100 brand new ADG...

www.hunttalk.com

I got some great advice in load development a while ago, that should help you along as well.

 

[mtmuley]

Feed it a 168 HHT. mtmuley

 

[perma]

Feed it a 168 HHT. mtmuley

My gun does fit the twist rate spec….

 

[perma]

So here’s the deal - that was with Nosler’s test barrel, with Nosler’s test barrel chamber, with Nosler brass, and Nosler’s lot of primers and powder.

To echo @Sheltowee, do a ladder of 10 rounds with your powder/primer/projectiles at mag length. Preferably shoot them at 300 + yards (distance makes the differences easier to find,) and find a node (group of 3 shots that group close to in another despite the different powder charges.) Take the charge weights from the node and make yourself some 5 round test groups, and shoot those for best group. If you find a group you can accept, that’s your load.

You likely won’t find a huge difference in accuracy doing seating depth testing, especially on something as overbore as a 7 RM.

Also, read this thread:

Load Development in a Time of Scarcity

Kind of like “Love in the Time of Cholera” but totally different. I’m about to start load development on my .300 PRC, and the scarcity of components has me a little spooked. The last time I did a full work-up any and all components we’re easy off the shelf items. I’ve got 100 brand new ADG...

www.hunttalk.com

I got some great advice in load development a while ago, that should help you along as well.

Now that’s a good thread.

 

[perma]

Decided to take a nap today instead….

I also loaded up 86.5g and 87g loads. Something funky is up with my die set though, seating consistency is within 0.003”, not sure why. Gonna clean it and see what happens. Ordered some new bushings too because these OE Lee ones are cheap and they move too damn much. Annoys the hell out of me.

These are compressed loads so we’ll see what they do.

 

[Alpine01]

Decided to take a nap today instead….

I also loaded up 86.5g and 87g loads. Something funky is up with my die set though, seating consistency is within 0.003”, not sure why. Gonna clean it and see what happens. Ordered some new bushings too because these OE Lee ones are cheap and they move too damn much. Annoys the hell out of me.

These are compressed loads so we’ll see what they do.

For some very informative reloading videos, check out Sam Millard (https://panhandleprecision.com/). He hasn't done anything new that I can find but I found his reloading videos very helpful.

 

[perma]

Weatherby’s are bratty guns. But I think I got it figured out.

To start, need to go back to the 7 mag. That gun does not like Hornady anything. I had 3 stuck cases after they were shot. It likes cheap boring soft point Remingtons, no heavier than 150g is my guess. I like heavier bullets so I’ll see how I can make this work with reloading.

The Mark V on the other hand does not like whatever they factory ammo is. However, I think I found the sweet spot.

87g



86.5g

 

[Alpine01]

Weatherby’s are bratty guns. But I think I got it figured out.

To start, need to go back to the 7 mag. That gun does not like Hornady anything. I had 3 stuck cases after they were shot. It likes cheap boring soft point Remingtons, no heavier than 150g is my guess. I like heavier bullets so I’ll see how I can make this work with reloading.

The Mark V on the other hand does not like whatever they factory ammo is. However, I think I found the sweet spot.

87g

View attachment 316049

86.5g

View attachment 316050

Does look like it is tightening up for you. You can play around the 87 load by a few tenths. Curious what a 87.5 might yield.

 

[perma]

Does look like it is tightening up for you. You can play around the 87 load by a few tenths. Curious what a 87.5 might yield.

I thought of that myself, and maybe that alludes to the next question; do I keep going up or do I start lengthening the bullet seat? Truth be told, I’m happy enough to use this for bears this spring but it would be cool to get tighter groups…

 

[mtmuley]

Does look like it is tightening up for you. You can play around the 87 load by a few tenths. Curious what a 87.5 might yield.

Tenths of a grain in a big cased magnum are a waste of powder, bullets and barrel in my experience. mtmuley

 

[perma]

I could chalk up the variances to the wind, it was a bit ripe today.

 

[std7mag]

Several things jump to mind here.

1) Finding your lands, what was the Loctite used for??
Slight crimp on the neck, you can use pliers to do it, so the bullet moves with fingers is all you need.

2) Weatherby cartridge chambers have REALLY long freebore/throat!
Load to slightly less than magazine length.

3) https://sierrabullets.wordpress.com/2017/06/01/long-range-load-development-2/
This is the method i use for load development.
Note, with the powder charge ladder test, your looking for the closest vertically.

With the COAL stuck at magazine length and not off the lands, your pretty much stuck with powder charge for adjustment.

3) "3 stuck cases"
Does this mean that the bolt had hard lift? (Sign of over pressure)
Or the extractor wouldn't pull the case from the chamber?

4) Any ogive measurement is just for you.
It won't mean a thing to anyone else.

 

[perma]

Several things jump to mind here.

1) Finding your lands, what was the Loctite used for??
Slight crimp on the neck, you can use pliers to do it, so the bullet moves with fingers is all you need.

2) Weatherby cartridge chambers have REALLY long freebore/throat!
Load to slightly less than magazine length.

3) https://sierrabullets.wordpress.com/2017/06/01/long-range-load-development-2/
This is the method i use for load development.
Note, with the powder charge ladder test, your looking for the closest vertically.

With the COAL stuck at magazine length and not off the lands, your pretty much stuck with powder charge for adjustment.

3) "3 stuck cases"
Does this mean that the bolt had hard lift? (Sign of over pressure)
Or the extractor wouldn't pull the case from the chamber?

4) Any ogive measurement is just for you.
It won't mean a thing to anyone else.

I’m FUBAR-ing this thread and mixing in two different guns, so I may be confusing you.

#3 is related to the 7 mag. This is with factory ammo, and two different Hornady boxes. I’ve used federal and Remingtons and it didn’t have the issue. The case walls were scratched to hell, hard to lift the bolt and pull it out. No idea why.

#1 loctite was just something I read on the internet from UR. Quickly realized that it was a waste of time and borderline stupid because of how much scratching it did to the bolt face.

#2 I think that’s what I want to do next. Ladder test with 87g loads and go from there.

 

[std7mag]

I’m FUBAR-ing this thread and mixing in two different guns, so I may be confusing you.

#3 is related to the 7 mag. This is with factory ammo, and two different Hornady boxes. I’ve used federal and Remingtons and it didn’t have the issue. The case walls were scratched to hell, hard to lift the bolt and pull it out. No idea why.

#1 loctite was just something I read on the internet from UR. Quickly realized that it was a waste of time and borderline stupid because of how much scratching it did to the bolt face.

#2 I think that’s what I want to do next. Ladder test with 87g loads and go from there.

Hard bolt lift is a sign of over pressure. Even factory loads can do it with some rifles.
Remington had a batch of 270 Win that was dangerously high pressure!

Low powder charges, especially in magnum cartridges can produce a secondary pressure spike.
You shouldn't have to worry too much with H1000.
But watch going below 85% case fill.

Gavin on UR, and I disagree on a lot of things.
Hence why i unsubscribed from his channel on YouTube.

As for the ladder test, yes i even do 0.3gr increments in my 7mm Rem Mag & 7mm WBY Mag.
A RUM is on a whole other level!!
Instead of writing the charge weight on the cartridge, i use the plastic ammo carriers from Federal.
Holds 10 rounds nicely. Just use a sharpie and write the charge weight.
Clean off with some spray silicone and use again.

 

[std7mag]

Decided to take a nap today instead….

I also loaded up 86.5g and 87g loads. Something funky is up with my die set though, seating consistency is within 0.003”, not sure why. Gonna clean it and see what happens. Ordered some new bushings too because these OE Lee ones are cheap and they move too damn much. Annoys the hell out of me.

These are compressed loads so we’ll see what they do.

What OE, Lee bushings??

Been using Lee dies on their 4 hole turret press for over 10 years without an issue.

I have no clue as to the number of rounds I've done with it.
In the tens of thousands.
I used to do over 1,500 rounds a year just with rifle.

 

[perma]

Gavin on UR, and I disagree on a lot of things.
Hence why i unsubscribed from his channel on YouTube.

It took that one video and scenario to make me think that I shouldn’t follow his advice.

What OE, Lee bushings??

Been using Lee dies on their 4 hole turret press for over 10 years without an issue.

I have no clue as to the number of rounds I've done with it.
In the tens of thousands.
I used to do over 1,500 rounds a year just with rifle.

The original bushing on their challenger press seemed to have a lot of play, so I bought the upgraded splined ones. Feels more solid, pretty nice $17 upgrade.

 

[perma]

Which brings up the next topic. With all these friendly folks helping me out with advice and equipment, I’m going to jump in the deep end and start buying more stuff. I just bought some 7 mag dies from Redding.

As far as next step, I was in between a case prep machine or some sort of brass cleaner/media tumbler. What would you upgrade next?

 

[Idahoarcheryhunter]

Buy a wet tumbler some ss pins and you’re off to the races. I would buy that first all the case prep can be done with hand tools.