300 mag

Hello everyone, got a ? i recently purchased a savage 110 fcp-k in 300 win mag and have reloaded about 100 rounds of differant loads and bullets and run threw it, very good accuracy, but i have noticed that the base right above the belt grows about .004-.006 is this normal? also they have a bright ring around the case just above the belt,i started re-loading them by full lenght resizing and noticed it was getting more prenounced, then i went to just neck sizing and it stayed about the same, most of these loads where about in the middle range on charges and are backed off the lands .010 so im not jaming it in the rifling,could it have a big chamber? anyone ran into this,thanks.

What you are describing is the plague of belted cartridges, and the reason why the modern magnum rounds do not have them. It varies from rifle to rifle, but worst will let you get only two or three loadings from a case. (OTOH, I knew one shooter who got dozens of loading from .458mags, but they were loaded down to hot .45-70 balistics.) The bright ring you noticed is an incipient head separation. It is not the fault of the rifle, but rather is caused by the belt preventing the case moving forward in the chamber when the primer is ignited. Normally, a rimless case moves forward, leaving the primer protruding until the pressure inside the case rises enough to push it back. The belted case is unable to do this, so the case wall stretches instead and is thinned and weakened.

The "paperclip test" is in order here. Straighten out a paperclip and with a pair of pliers make a 90* bend on one end, leaving about 1/8" sticking out. use this as a feeler on the inside of the case, If you feel a catch indicating that there is a small groove forming behind the bright ring, the case is dead. If you keep loading it, you run the risks of case failure during firing and/or having just the head of the case extracted after firing, leaving the upper body of the case stuck in your chamber. They make broken case extractors for military rifles, but I have never heard of them for magnum rifles (doesn't mean they aren't made, just that I don't remember any specifically - you might search at Brownells). It can be a real b*tch to remove a broken case - sometimes you can just push it out with a cleaning rod, but if it's really stuck you have to remove the rifle's bolt and feed a large tap into the case to get enough purchase on it to pull it out.

Basically, that means you should hunt only with new or once-fired brass to avoid problems in the field, and that you need to be very carefully inspecting your cases after each sizing. Neck sizing may give you a little better case life, but there are no guarantees - it all depends on the rifle. RCBS X dies might help, too, but I have no personal experience with them and do not know if they are made for belted cases (call or email RCBS). For dangerous game, it is standard practice to use only new cases, but I don't imagine you're going to Africa with your .300mag.

once they fit the chamber don't mash them back down again.
you can headspace a belted mag from the belt and shoulder at the same time. as you have found through the n/sizing.

Hi I have been reloading 375 H&H for many years now.This is because of where I live and the stupid regulations regarding transporting of live ammo and powders. I load to H&H original specs at 2700fps for 270 g and 2525 in 300 grain. I neck size only and up to 8 reloads have no sign of head separation. I split the heads with a fine tooth saw randomly and check the brass thickness in this area. I only recently heard about the limited recommended life of belted magnums. Is there any other precautions or areas I should be looking at. I test every batch I reload with the chrony to maintain uniformity. g

The H&H's with their tapered cases do not seem to be (from my reading) as prone to the problems as, for instance, the big Weatherby's. Case life is reportedly much better, but again, some rifles seem to be more prone to problems than others. My personal experiences have been with .300 (bolt and BLR), .338 and .458 (both in bolt actions), and of the three, the .458's seem to have the best case life and the .338's the worst. The stories about as few as two loadings from Wby cases I have heard from other shooters/loaders and read about. The H&H's (.300 & .375) both operate at relatively low pressures compared to later belted rounds, and that may be a contributing factor to longer case life - it is definitely with .458's. The "paper clip test" is the most reliable way I have found to detect real incipient head separation - sometimes those bright rings happen in F/L sizing on all kinds of cases as the case never goes completely into the die and the slightly larger web gets polished from working through the action and in and out of the chamber. But, rimless cases can and do have the same problems, usually (but not always) it indicates a little too much headspace, sometimes a roughly finished chamber. The only sure way to tell is to run the paper clip into the case and feel for the that little trough running all around the web where the bright ring shows. I have also read that there is not always a bright ring on the case when the inside indicates a weakened web, so I would be checking the cases each time before priming with the paper clip. Every time I have found a bad case, there has been a bright ring, but when I see one appearing in a batch of cases, I will check them all to be sure.

Thanks guys, i will try the paper clip, is there a case that might give a little more life? i have purchased some nosler brass but havent loaded any yet, and have been reloading remington brass. i got a bad batch of winchester brass when i started ,the cases where cracked around the bases just above the belt, right out of the pkg ,weird huh? i could snag the crack with a small knife so i took them back.

I've had occasional bad batches from all of the big makers over the years, but I really can't say I think any one brand is better or worse than any other. (Except handgun brass with the headstamp "AMERC" - worst brass made anywhere.) Sometimes one company does better or worse with a specific cartridge, but in general all make decent products. Each loader has his/her preferences. When I order new brass, I generally go with Winchester because the prices are better, but I shoot many less common rounds that they don't produce, so I then use what I can find. Most of the common chamberings that I shoot I use range brass, so whatever comes my way gets used after careful inspection.

Although the last post is over a year old, I thought I'd add my 2bobs worth. :-)
I use a Redding Bushing Die for my .300 Win Mag. Its the same pricipal as a neck sizer but there is no expander ball that drags through the case mouth to open it back up and therefore the possibillity of the neck being out of line with the bore is drastically reduced. You select a bushing roughly .001"-.003" smaller than the case neck O.D. and that is all the neck gets pushed back in. Just enough to hold the bullet tight in the case. Its a 5-way win situation.
1) The case is headspaced on the shoulder.
2) The case remains an exact chamber fit.
3) Minimal working of the brass, so much longer case life (I've had between 8-14 reloads out of some good Nosler cases).
4) There is rarely more than .001" of inconcentricity of the neck to the rest of the case therefore my bullets very seldomly run more than .002" out of line with the bore, which is a HUGE accuracy bonus.
5) You select how much of the neck you want sized, so you can still have part of the neck perfectly aligning your bullet with the bore. Thus more accuracy.
The only downside is that the one die+2 different size bushings cost me the same as a complete new die set.
But it was worth the accuracy improvement. 1.5-2MOA down to <.5MOA just by changing dies!

I have had very good results with Lee Collet dies, too, at a fraction of the cost though they are not as versatile. Bushing dies really come into their own when you have a really tight custom or match chamber. With the often oversized chambers of older rifles and especially milsurps I am very happy with the collet sizers, and they can be had custom made for obsolete or obsolescent cartridges for very reasonable prices, especially compared to the prices of standard special order dies.