Home Forums Hunting & Shooting Express Rifles and Big Bores Only 350 Rem Mag Case Splitting

Have a Remington Model 660 in 350 Rem Mag that I have owned for 15 + years that I am just now going to work up some handloads for. Have only been shooting factory Remington 200gr CoreLocks thru it so far. Have noticed cracks in the shoulders of some of the cases, maybe 2 out of evry 20. No signs of any overload or bad headspace problems. Any one experience same with Remington factory ammo?

Give us a little more info :

What powder, bullet, primer and dies are you using ?

Is the brass factory once fired ? Full length resizing the case ?

Are you crimping the case mouth at the same time as seating the bullet ?

I have the 660, Model 7 CDL and Remington Model 7 KS in 350 mag. My load is 748 60grs and max load with this powder is 62grs. No need for max load. the 60grs is accurate and still let you know that your shooting a 350 mag. Bullet choices are the speer 180gr, 220gr, Remington 200grRN cor-loc and 200grSP Hornady. My die set is RCBS. My primers are Winchester WLR. Don't even use the mag primer.

Ken

I have a Ruger M77 in .350 Rem Mag. I've had it for six years and have never experienced any case splitting in the necks or shoulders. I used to crimp and seat in the same die, but was hving problems with crumpled shoulders. I ordered a custom Lee Factory Crimp Die (they aren't available in that caliber) and it solved the problems. My cases are lasting thru several reloads without signs of splitting.

Are you seeing this with more than one lot of ammo or all the same? I have seen Remington loaded ammo do this; a certain lot of 280 ammo comes to mind for being highly prone to splitting. OTOH, I use 350 Rem Mag brass - component brass- to reform for loading a 375 wildcat based on the same case. I have always been very impressed with these cases, regardless the lot I have gotten. Reminton 7 Mauser, OTOH, has disappointed me in more than one lot I've gotten.

Perhaps you can isolate the problem by determining if this is specific to a single lot of components.

That batch of brass may be due for neck annealing. If it's old and work hardened it'll get brittle and split.

Your rifle chamber is almost certainly a bit longer than your die, so that you set back the shoulder every time you size your brass. That works the brass at the shoulder and hardens it. If you're not doing this already, you could try sizing long and then slowly lowering the die down in increments until the cartridge just chambers into your rifle. The go a skosh more for reliability in feeding and leave it set there.

That way you will be headspacing on the shoulder rather than the belt...a useless appendage anyway.

All of the cases I'm talking about are factory new loads that I,ve shot. Have not reloaded or fired any. These are factory new loads that are splitting some of the shoulders,

Ouch!

And you've checked the headspace? Can you measure whether the shoulder has moved out after firing? You need something that will slide over the neck onto the shoulder about 1/2 way down. Measure that "overall" length and compare to a unfired round.

SUspect your chamber may be a bit long and those new cartidges are headspacing on the belt only allowing the shoulder to blow out.

Is all this factory ammo coming from the same lot? That is an important question. It is unusual, but not extremely rare, for certain lots of brass, either component brass or ammo from a single lot of loaded ammo, to have splitting problems. If your factory ammo comes from several different lots: lot numbers of ammo, then you need to look elsewhere. Otherwise, I'd be looking at a brass issue to start.

Sounds like a bad lot of brass to me.

A little excess headspace won't cause this, especially with a belted case. Cases are stretched a lot more in fire-forming in Ackley chambers. And since this is factory ammo, it surely isn't caused by anything like using magnum primers (which would have no effect on the brass shoulder one way the other).

I have seen some defectively annealed brass come out of factories. Some years ago I got a batch of Remington .338 Winchester Magnum factory loads where the neck/shoulder area totally split off in about 2-3 rounds out of each box, due to faulty annealing. This was interesting as the neck and shoulder of the case typically stayed in the chamber.

Stuff sometimes happens when factories make millions or rounds of ammo a year. I would contact Remington about it; I am sure they will make it right.

Does the split look like this


like leverite said, it may be your head clearance. IOW the gap between the case shoulder and the chamber shoulder may be excessive on new brass. Not really headspace since belted cases headspace on the belt.

The case in the pic above was on a 264 win mag that had .0295" gap at the shoulder on new cases. If so then you have to worry about case head separations on cases with multiple loads.

Yes Woods, they look just like that. After going out to the loading shop, digging thru all my fired rounds...... I have shot 9 boxes of factory Remington thru the gun. Funny, the ammo I had the most problem with had price tags on it of $17.99 box, same lot, probably bought 20 years ago. And a box I bought 5 years ago, same lot, about three of them are cracked.price on that box, $28.99... been on the shelf a while? Think it's the lot that had brittle necks/shoulders. Sterting to work up some loads, using IMR 4895.. lots of differance in my loading manuals pertaining to charge amounts. working with hornady 200 gr SP, and Speer 250 gr Grand Slams. Any suggestions would be helpful. Thanks guys for all the response!!

Thanks, after checking the brass I have, new factory bought 15 years apart, same lot, same problem. Thanks for your help!

go directly to TAC powder by Ramshot. Far and away the best for 350 rem mag.

Do you have a headspace gauge? One that will give you a measurement of how far the shoulder is moving forward on the first firing? There are lots of them out there but the one I use is the Hornady

http://www.midwayusa.com/viewproduct/?productnumber=479704

that clamps onto your caliper and the insert hits the shoulder



you measure a new case and a fire formed case and that will give you the distance your shoulder is moving. I have seen as much as .040" in extreme cases (usually you get the most with belted cases) and as little as .002" on custom chambers. You can use anything with your calipers and the right size hole in it like a socket.

If you have too much then the remedy would be to take it to a gunsmith and have him set the barrel back a thread or two and reduce that gap dimension. If you don't have that large gap then Mule Deer is right and you got a bad batch of brass.

You could also try a mild load for fire forming and maybe it won't burn through. Don't know whether a fast powder or slow powder would be better.

I've never used factory ammo in my custom 350 Mag., but have had no split cases after 4 or 5 firings with the Rem. brass that I have.

If you would like to try loading a few rounds of the new brass I have to see if they crack in your rifle, I'll send you a dozen to try if you PM your address.

Sounds like age hardened brass. You may have bought the ammunition 20 years ago, after it sat on the shelf a further few (or many) years.
Cheers...
Con

Minnmarcus,

As MD said, contact Remington, they will most likely want any of the rounds you have left and will almost certainly replace them with factory fresh. I've seen trap shooters receive whole boxes of shotshells in return for one which failed to fire. (Similarly I worked for one of the major soda companies, we took any defective product very seriously - analyzing any that was left so we could correct the problem and repaying the consumer several fold for their trouble.)

If you don't return all the spent cases to Remington, I'll suggest you anneal them before trying to reload them.

Thanks for the offer, I have new WW brass to start with, I was just looking to see if any one was having the same problem with factory Remington loads

Old obscure calibers like the .350 can sit on the shelves for years before someone buys them. neck tension and crimp can cause a lot of work hardening over the years, nasty neck cracks are the result.

You might be able to save them by annealing.

Dale