Savage LRP case head expansion

[aqua9945]

I have a Savage LRP repeater action that has been rechambered a few times in different calibres... I seem to be getting more than my share of brass issues with case head expansion etc. This is in loads at about maximum... Can anyone think of a reason why this action would be more prone to contributing to shortened case life than , say, a custom target action ? Just asking.

[Hotolds442]

Are you sure it's the action and not your reloading procedures that's causing all of the problems?

[aqua9945]

Fairly sure its not my reloading, the loads I am having problems with do not seem to have the same issues in other rifles. I can back off a little, but case life is still an issue. I do not think its a chambering or specific barrel issue because its happened more than once. I am suspecting its something to do with the savage bolt or possibly the action strength thats at the root of this.

[Hotolds442]

98% of the cartridge is surrounded by the barrel. I could see maybe an inferior steel used in the construction of the barrel causing issues, but remember, the barrel is surrounded by the action for a considerable portion of the cartridge length. Headspace issues could be causing your problem, as well as excessive brass working due to sloppy chambers allowing extreme case stretch, that has to be reduced at the sizing die.

[aqua9945]

Its not the barrel, I have noticed this to some degree over 2 top brand barrels (broughtons) and 3 chamberings. Now, only the case head is surrounded by the action and thats where my concern is, that the bolt head and action are not supporting the brass well enough ? Could the steel in this LRP be expanding elastically under pressure? There is no problem with the headspace now, or in the previous 2 chamberings as far as i know....

[sixonetonoffun]

Could have a smith install the barrel nutless. Eliminating the gap between the barrel and bolthead. Would just have to be reamed to fit like a remy.

But those have to be pretty hot loads to cause casehead stretch like that. If I remember its somewhere close to 70k psi to push the brass that much.

[Hotolds442]

My WSM's don't have stretch issues, and I KNOW they've seen 70k

Big fat case with small thickness action ring, you'd think that'd be a recipe for case stretching right there.

[earl39]

Could have a smith install the barrel nutless. Eliminating the gap between the barrel and bolthead. Would just have to be reamed to fit like a remy.

With or without a nut the headspace is the same.

Are you sure they are headspaced correctly? Sounds like a case of headspace set too long and leaving a extra large gap between the bolthead and barrel. That or your load for that rifle is way to hot. Remember if you are at max then just because it shows no problem in another rifle doesn't mean it should be good to go in that one.

[gotcha]

What is your procedure for sizing cases to be used in that rifle, as far as establishing case head space is concerned ? How much reduction in web diameter do you typically see when re-sizing? Is this a belted case?

[aqua9945]

OK
The barrel is installed nutless
Its a 6.5-284 and these are prone to loosening primer pockets
Loads were 46-47gr 2209(4350) and I am switching to a slower powder and backing off a little
The web is growing by a couple of thou and FL resizing does not help the primer pockets
cases eject easily
it may be a bad batch of brass i will try to source some more
its lapua 6.5-284 cases
previously the rifle was a 260AI and the brass developed a stress line 1/2" from the bottom (a ring) so the problem was not really the same

[Hotolds442]

With no indication of bullet weight over that powder charge, it's hard to estimate where your pressure is at, but loose primer pockets are a definite indication of high pressures. Totally unrelated to the case head separation you had with the 260, that was a headspace issue or a chambering issue- possibly too much protrusion. We're running Retumbo in the 6.5-284, at 59gr under a 140 VLD. Velocity hovers around 3050 on a 24" tube and there's no signs of pressure and great brass life with both Lapua and W-W yellow box brass. We went as high as 56.5 with the H4350 but the velocity just wasn't there, some 300fps slower than the Retumbo loads. You may have a bad batch of brass, or some other issue causing pressure spikes large enough to affect the web. There are a lot of things worth looking at, but I think I'd look at the brass first.

[aqua9945]

Thats 46-47gr 4350 equiv with 140 berger VLds and its too much for this batch of cases at least. Loosening up after 2 firings, i may get 4 if i am lucky, so i am going to ADI 2213SC which is equivalent to your 4831sc. Going to start at 49gr. After reading that you are using Retumbo I am wishing I had bought a slower powder again, but I will see how this goes. The one I chose is pretty common amongst 6-5/284 shooters..

[jerry shaw]

This really sounds like an issue with headspacing. When I'm running a round that will experience higher pressures I set headspace so that the bolt will BARELY close on a GO gauge. This ensures minimal brass stretching.
I'm assuming you're using a large shank receiver. I have fired lots of abusively loaded rounds through my target receivers and have yet to experience a brass problem I did not cause.

[aqua9945]

The brass is not lengthening, but the RIM is widening by 4 thou over say 4 firings, until more and more of the cases have loose primer pockets

[bsekf]

Are you talking about case head expansion or case head separation? If case head expansion, it is pressure. Back your load off a grain and see if the problem disappears. Those cases that have been expanded may be junk, especially the ones with loose primer pockets.

[Robinhood]

case head is surrounded by the action and thats where my concern is,

There is your problem. I don't have a rifle that the case head is surrounded by the action. You need a new rifle.

the loads I am having problems with do not seem to have the same issues in other rifles.

My understanding of pressure signs and the differences between different barrels of the same chambering remains the same.


What is the protrusion of a case from the breach of the barrel?

[aqua9945]

You need a new rifle.
****************

I agree, I am getting rid of the savage and buying a dedicated target action. I am also never trying a 284 family cartridge again.........

[bsekf]

The 284 has a rim that is smaller than the web. That could be the problem. I had some 22-250AI's that swelled the base of the case and I ran them through a 444 die to get them back in the gun. But they were hot and I was vaporizing about 25% of the bullets. Kind of neat......puff of black smoke at about 50 yards. They did not stretch the primer pockets, but I segregated them anyways.

Aren't all bolt actions recessed so the case sticks out of the barrel? Or are there some with some kind of a shroud? I thought break open and falling block guns are the only ones that the case is completely enclosed in the barrel.

Bill "too soon old and too late smart"

[aqua9945]

Yes I have been learning alot about this ...
The 284 family has a rebated rim and seems prone to head expansion when 'pushed'.... its a matter of degree
Yes in all chamberings the rim is not supported in order to let the extractor hook on, but the brass of the case is thickest here
Thus if the brass is going to expand a little the pressure will force it to flow out a little, that is swell, here
where i am not clear is the role of action rigidity in helping the chamber, which is mainly in the part of barrel beyond the action (ie past the thread) , from limiting the brass swelling. Brass has to spring back a little from the chamber walls after detonation to avoid sticking in the chamber, but brass is not as elastic as steel, so if the action and barrel combo expand too much .... in some calibres like ackleys the shoulder and straight cases make extraction harder than in others. But in the 284 family there is case head expansion instead.
My issue is that my friends with, say Barnard target actions , are not getting brass issues like me, and they are pushing loads more than i am.