7mm Rem Mag issues

I did a quick search on issues reloading the 7mm Rem mag but, didn't see any or didn't go back far enough. I am about to be the proud owner of a S&W model 1500 in 7mm. I have been doing some research on reloading the 7mm. I have seen many different opinions on whether to use a collet on the banded cartridge(s) or not. Then there is neck resizing vs overall.

Some people are saying that the cases will only last 2-3 reloadings. I hope that is not true. It might take that many to find the right load.

Jeez, what am I getting myself into.

The 7mm mag is easy to reload for. It is designed to headspace on the belt. This works, but shortens brass life, and maybe does not provide the best accuracy. Cases grow fast this way, and require constant trimming.

The way I load the 7mm mag is to keep my brass that has been fired segregated to the rifle it was fired in. Then I neck size, and push the shoulder back just enough so that the reloaded round chambers with slight resistance.

By doing so, you are now headspacing on the shoulder, which increases case life quite a bit as opposed to full length resizing and depending on the belt for headspace. That belt, by the way, does nothing to increase case strength. A collet die on the neck might or might not result in a little better accuracy?

If your cases are sized to your chamber, and you don't load book max loads, case life can be good, certainly more than 3 shots. On older cases, run a piece of bent wire down the inside of the case. If you feel a slight catch near the base, it is probably incipit case head separation, and its time to let that brass go.

Larry

Once fired, I only neck size and get a LOT more than 2-3 loadings. Then again, I never load to max for anything, I load for the most accuracy.

The neck resizing is what I am seeing. Preferred die set? I have an old Rock Chucker and am kinda leaning toward RCBS for the dies but, it looks like I would have to buy the neck resizing die separately. If I recall correctly Lee has a 4 die set reasonably priced.

IAM Rand said:

am kinda leaning toward RCBS for the dies

Lee has a 4 die set reasonably priced.

Click to expand...

I'm gonna guess you get what you pay for.

Some time back I stumbled upon a bunch of 7mm Mag brass. The guy behind us had a bunch of it, once fired, and he doesn't reload. He was asking big bucks for it, and didn't have any takers. Early in the day I nibbled but heard his price and thanked him for his time. He was leaving and asked me if I'd take it all for $20. Probably 200-300 of them. Sounded good to me so I bought them. Sure, I know I've got to full length resize them. I'm waiting for a nice snowy day when I'm really bored.

Full length resize, load, shoot in Your rifle and then neck size only. Buy good dies like Redding or RCBS, a good trimmer and measuring stick and have fun.

The Lee collet dies are actually quite good. I use a set to load for my 260ai, it will shoot 5 into sub 1/2 moa all day.
As noted, you do NOT want to full length size for best accuracy & brass life. Neck sizing only may be an issue in a hunting rig, so you can partial FL size using std dies. Just size the case enough to get the bolt to close with a little effort.

I use the LEE collet neck sizer die for loading 303British,,another caliber with a bad rep for eating up cases and head separations early on.

With it, it simply does (re)size the neck of the case and doesn't touch any other part of the case body, neck, ect.
Plus by using the multi finger collet over a specific dia pin (which also doubles as the decapper), the brass is not over worked as with a regular die by reducing it in one step then drawing it back open as the expander is pulled back thru the neck.

Simple to set up and use.

Segregate the brass for that specific rifle as already mentioned.
You may have to FL resize or nearly the first time to get once fired brass from another source to chamber.
That fire-forming first load need not be anything near a full power load to expand it to your chamber. No need stretching it when you don't have to.

You'll have brass life much like any other center fire round.

..I could never figure the need for the belt on belted magnums..

"..I could never figure the need for the belt on belted magnums.."

Neither could I. It's a British thing. If you are reloading for only one rifle, it is always good practice to neck size only after the first firing. It is the only way to get and maintain zero headspace and perfect fit in the rifle's chamber. Neck sizing dies are best, but you can use any full-length sizing dies, just adjust the die upward a few hundredths in the press so as to not run the case in all the way and thereby not moving the shoulder rearward.

It is going to be a hunting rifle 1st. Maybe look at doing some long range stuff 2nd. It will be the only 7mm in the safe. Don't want to make them jealous.

I am assuming that it would be ridiculous to even worry about putting a factory crimp on them.

I like Redding dies. Their machining is better than others in a similar price range, at least as far as aesthetics go, and I assume if they are smart enough to make a handsome product they probably also pay more attention to other dimensions, too.

You don't absolutely have to have a neck-size die to neck-size your cases. A full-length die works fine if you just back it off enough so that the shoulder of the case is not moved.

You should have no problems with any quality set of dies. Just set them to neck-size for your load development and you should get way more than three loadings. Might get yourself a Wilson adjustable headspace gage to help you keep an eye on your headspace. They are not expensive (i.e., they are "cheap" - and they do a nice job).

The British designed the belted case at the turn of the 20th century when manufacturing standards were not what we have today.

On top of this the British used cordite powder that looked like long strands of spaghetti. The cordite powder was placed in the case "BEFORE" the shoulder and neck of the case was formed.

The belt allowed the location of the shoulder of the case to be meaningless. The belt also strengthened the base of the case for hotter loadings.

Below a rimmed .303 British in a Wilson case gauge and "normally" a cartridge case should headspace on its shoulder. This new unfired Remington case would drop further into the gauge but the case rim is stopping further movement into the gauge. (this case shoulder is a 1/4 inch shorter than the chamber)



Below a animated image of a commercial .303 cartridge being fired in a British military Enfield rifle. And at maximum military headspace the case can have .016 head clearance. And normally their is .003 difference between a GO and NO-GO gauge and max headspace would be .010.



Bottom line, fire form your 7mm magnum cases and let them headspace on their shoulder using a neck sizing die if possible.

I guess you would never know I collected Enfield rifles that fired a rimmed cartridge. And resizing rimmed and belted cases is the same for longer case life.



The problem with belted cases is "some" dies do not size the case just above the belt. And this is where the special collet die comes in that sizes the case just above the belt.

The above happens because many cases are made at SAAMI minimum diameter just above the belt. And the case walls are not as thick as they could be above the belt. These type case expand more just above the belt and some dies do not size this "bulge" above the belt.

Many reloaders will full length resize "but" only bump the shoulder back .001 or .002. And if you neck size only sooner or later you will need to full length resize and bump the shoulder back when the cases are hard to chamber.

And this is where having a Hornady cartridge case gauge and measuring the cases "fired" length before sizing is good to have.

Below a "fired" case from my AR15 in my Hornady gauge and used to set the die for .003 shoulder bump.

You have had some very good advice given to you already in this thread. I don't have a 7 Mag, but rather a 264 Win Mag. The only difference between the 2 is bullet size (6.5 mm vs 7 mm) and have quite a bit of 7 Mag brass I have necked down for my use. For sure, neck size only after initially firing the ammo in your rifle for better case life. And I've also found that annealing the case neck after several loading cycles also give much better case life. The majority of my case losses were due to neck splits from work hardened brass. If you don't know how, you can find several vid clips on YouTube about annealing the case neck. I use a propane torch and a deep socket the case head will fit in mounted on a drill for heating the case neck and then drop them into a can of water to quench them, then dry them in the oven set about 200 degrees.

I've found that the belted magnum cases are no harder to load than a regular bottleneck rifle case. I am using RCBS FL and seating dies and a Redding neck sizing die for my 264. Both are quality dies and either will do your job very well. And I just recently started reloading 30-06 and went with RCBS for the FL and seating die and then bought a separate RCBS neck die for it, mainly because the Redding die sets were much more expensive. BTW, I've been reloading 264 Mag since around 1970.

I load for several magnum cartridges and have found that sizing the brass just enough (using a full-length die) for a loaded cartridge to chamber with slight resistance will give long brass life. After five or six loadings, you will likely have to full-length resize, then go back to minimal sizing.

I have no idea what a collet die does. Sounds like something no one needs if they're doing everything right.

I have a Remington 700 Long Range in 7mm Remington Magnum, and I have been loading for it for about 2 years. I tend to full length resize every fourth reload, neck sizing for the other loadings. I am using Hornady dies.

My concern with the 7mm Magnum is barrel life. Historically, a 7mm Magnum will burn out a barrel within a thousand rounds or so, if you shoot it hot. I tend to load IMR7828 with 168gr bullets. I was told by a departed club member that 7828 is a lot easier on barrels than other traditional Magnum powders.

As a serious aside, if you have a bore scope, check the barrel of ANY magnum used rifle for throat erosion. The last thing you want to do is pay a premium for a nice rifle, then find that you need to drop another $500-800 for a new barrel!

Headspace is one of those things many shooters do not completely understand and cannot explain. In general, a bottlenecked case can have a very large headspace if the rifle has an elongated chamber, but that generally will not be dangerous. What it does is create a lot of case stretching that will very often result in head separation after one or two full-length resizings. I have personally seen cartridge cases show the dreaded "bright ring" above the case head on the first firing in a rifle with excess chamber headspace. That indicates considerable brass stretching. Some military rifles are purposely made with loose headspace so they will function with dirty or corroded ammunition, as reloading is not a consideration for the military.

On the other hand, I once had a .30-'06 rifle that had such tight headspace that the bolt had to be driven closed with the palm of my hand even with factory ammunition. However, after that first shot, the cases could be neck sized and would chamber with only slight snugness thereafter as they had been fire formed to fit the chamber perfectly. That rifle fired very tight groups for a .30-'06.

One thing you can do to help minimize barrel erosion is to space your shots out at the range and not get the barrel too hot. Shoot 3-5 shots at a moderate pace, then let your rifle cool down until it's just barely warm. When I'm shooting my bolt guns I generally will bring 2 or 3 and swap them out to let them cool down between strings. BTW, the 264 Mag is supposedly more of a barrel burner than 7 Mag.

One other consideration - use of single-base propellants (such as IMR powders) is kinder to the bore, as they burn cooler than double-base propellants. Ball powders are usually double-based. It probably makes little difference if you are not shooting a great deal.

Thanks all for the responses. I have been reloading for a while but, only 270 Win. I did just start for the 30-06 and have been having fun trying different powders, bullets, C.O.L........etc. I look forward to reloading for the 7mm.

Powders currently on hand are RL-19, IMR 4350, IMR 3031, IMR 4065, IMR 4895, and Alliant 4350. Looks like I might have to get a couple more to try. I understand not loading it hot but, isn't that kinda the appeal of the 7mm mag if not magnums in general. Hotter/faster loads to get less drop for the distance shots?

I am mainly a hunter and that is what I do my reloading for. Initially, in order to find a good load, the brass will probably be used 4-8 times depending on finding the ideal load for the rifle. After that it will probably be mainly for hunting. I have toyed with the idea of some long range shooting but, there are only a few ranges within driving distance. I am not too far away from Raton but, don't want to have to drive there all the time.

Thanks again.

One thing I forgot to ask is about the 303 British. I too have an Enfield MK4. One of the things I have seen to reload for the 303 is on new cases putting an "O" ring around the base when doing the 1st firing. My understanding of this is that it will force the head back against the bolt and the case will stretch forward and have less problems with future case stretching. Not sure if this would work for the 7mm brass.