Need help with hand loading a 7mm rem mag

[HyperMOA]

Where do you guys find reliable load data; and why can it vary so wildly? We have 6 manuals and with a 160 grain projectile 4 manuals say max load with reloader 22 is 62 grains. 1 manual says 63 grains. 1 manual says 66 grains. Looking up a few online I’m seeing 65, and 65.5 grains.

We loaded to 62 grains and I felt it was starting to group but thought that we were at max load at that point. How far would you go? What do you do when manuals vary wildly with a certain powder?

[petew]

I go by the Nosler on line data, and load for the actual bullet I am loading, {always a partition}. not all bullets of same weight are listed with the same powder charge.

[Pathfinder76]

You NEED a good chronograph. Velocity, in general, gives great indication of pressure. Powder charges can vary wildly depending on case volume, powder lot numbers, projectile etc.

[elkhunter11]

The charge weights vary due to variations in chamber dimensions, powder lots, case volumes, and bullet bearing area, etc. You need to learn how to recognize pressure signs. Excessive expansion at the belt or case web is a pressure sign, flat primers are a pressure sign, and the easiest to see is excessive velocity. If the velocity is higher than the max velocity listed in manuals, the pressure is probably also greater. The problem is that the maximum velocity can also vary by 100-150 fps from manual to manual, so velocity isn't an exact measure of pressure either. If you take the average maximum velocity from several manuals, you are probably fairly safe. If the primer pockets become loose after a few firings, back off the powder charge, as either the cases are soft, or the pressure is excessive.

[waldedw]

The rule of thumb is start low and work up slow until you find a good load that doesn't show pressure, different bullets ie: monolithic bullets can cause pressure to spike in a hurry if you use the same load you use in a cup and core bullet. Also you will notice that some manuals list 55.000 psi as max and some new ones now list 63,000 or more and some don't list the pressure at all so the onis is on the loader to watch for signs and back off.

[tranq78]

Originally Posted by waldedw

The rule of thumb is start low and work up slow until you find a good load that doesn't show pressure, different bullets ie: monolithic bullets can cause pressure to spike in a hurry if you use the same load you use in a cup and core bullet. Also you will notice that some manuals list 55.000 psi as max and some new ones now list 63,000 or more and some don't list the pressure at all so the onis is on the loader to watch for signs and back off.

Can you explain why mono's can pressure spike at same loads as cup/core? I've seen this comment before but haven't seen any explanation. Is it because of longer bullet length of the all-copper?

Hornady states its all-copper GMX bullets can use the same load data as its SST line. I did test GMX projectiles with SST loads we developed for 30-06 and they work fine. We carefully tested TSX/TTSX at SST loads and they were ok, too.

We have found GMX/TSX/TTSX/LRX all like a lot of jump, something other loaders I talked to have said the same.

No additional knowledge is bad when it comes to reloading. Thanks in advance.

[DiabeticKripple]

I always load a few grains past book values. On both my rifles I didn’t see pressure signs until after the book values.

You need a chronograph. I’d chase velocity (for your given barrel length) and look for pressure signs on the way up.

[32-40win]

Originally Posted by tranq78

Can you explain why mono's can pressure spike at same loads as cup/core? I've seen this comment before but haven't seen any explanation. Is it because of longer bullet length of the all-copper?

Hornady states its all-copper GMX bullets can use the same load data as its SST line. I did test GMX projectiles with SST loads we developed for 30-06 and they work fine. We carefully tested TSX/TTSX at SST loads and they were ok, too.

We have found GMX/TSX/TTSX/LRX all like a lot of jump, something other loaders I talked to have said the same.

No additional knowledge is bad when it comes to reloading. Thanks in advance.

Where that comes from, is the original Barnes X bullet, and some of the other off breed monometals around these days, even the Nosler E tip is like that, note the warning in small print on current Nosler site data, to reduce E-tip start load by 10% from the others in the same data page.
It is all about bearing surface length and obturation and compression when fired.
X bullet didn't have anywhere for compressed length to move to, built pressure really quick compared to a lead bullet. TSX was an improvement, TTSX was the next one, they kept adding compression grooves and reducing bearing surface, seeing as any monometal for say 150gr, is about same bearing surface langth as a 160-165gr lead bullet.

[tranq78]

Originally Posted by 32-40win

Where that comes from, is the original Barnes X bullet, and some of the other off breed monometals around these days, even the Nosler E tip is like that, note the warning in small print on current Nosler site data, to reduce E-tip start load by 10% from the others in the same data page.

It is all about bearing surface length and obturation and compression when fired.

X bullet didn't have anywhere for compressed length to move to, built pressure really quick compared to a lead bullet. TSX was an improvement, TTSX was the next one, they kept adding compression grooves and reducing bearing surface, seeing as any monometal for say 150gr, is about same bearing surface langth as a 160-165gr lead bullet.

Thanks sir!

Sent from my SM-G781W using Tapatalk

[waldedw]

32 - 40 beat me to it

[aardvaark]

And I’ll throw my thoughts into the mix as well.

Each gun is an individual. You can have identical loads for two different guns and they will both shoot differently. Same thing happens with the writers of the reloading manuals, what works well in their test rifle works differently in another. And as you will see here, the thoughts and opinions will vary from one experienced handloader to the next.

As was said above, if you take the average of your manuals, it will likely be pretty close to what you get out of your gun. Same with the opinions and thoughts of all of us here, read them all and try to arrive at an ‘average’ of what we all say.

You are experiencing what all handloaders go through, you are tailor-making a round that best suits that rifle (something that you cannot buy at any store), and it likely will perform differently in another identical rifle, might even be extremely differently. The manuals are only a guide (a very necessary and extremely important guide), they are not absolute, only you can determine what is best for your individual rifle.

[MOUNTAIN MICKEY]

How old--how new are your reloading manuals??? In my older than dirt Speer manuals, they suggested more powder than my newer Speer manuals. Various rifles were listed for coming to their load data suggestions. The newer manuals get their data from loads fired from test barrels for more consistency and better measuring standards. I have been shooting the same bullet /power load since 1972 in my 7 mag but did drop the powder down 2 grains after buying a newer manual about 20 years ago. This may be an example of why you are getting different loads data info from various manuals. I used to play around with different loads just to see if there was something "better" but never changed my hunting load.

[Bushrat]

Thats why manuals tell you to start low. If people would actually read their manuals instead of just looking at load recipees they would learn this and a whole lot of other things critical to safe handloading.

[HyperMOA]

So this rifle, I have had some history with it. Changed scopes, ended up bedding it and cutting the barrel channel deeper to remove pressure points. Cleaned a bit of copper fouling and just can’t make it group. Its an old Alpine Sporter made by Parker Hale. I believe it has a 1:10 twist barrel. I’d have to verify that though, its just off the top of my head.

So I have been trying to load nosler 162 grain interlocks (I think its interlocks) for this rifle. Is it possible I’m not stabilizing those 162 grain bullets and need to back it off to a 150 grain?

[Dick284]

The Speer manual had a chapter called “Why ballisticians get grey hair”
Everyone should read that!

As for 7mm REM Mag reloading, it’s one of those cartridges notorious for throwing pressure spikes while being tested, the validation of these spikes came once better pressure testing technology became available, and as a result many old “standby loads” were discovered to be unsafe because of pressure spikes.

A chronograph, and modern data is a must.