35 Whelen Case Failure

[trobin]

I worked up a load using Win 748, 225 Accubond, Hornady Brass, and CCI LR primers. Charges were: 56.2x1, 57.3x1, 58.4x1, 59.5x5, 59.9x5, 60.3x5, 60.7x5, and 61.1x5. I shot them in a ocw fashion and everything looked good until the fourth shot of the last three highest charges. Their heads started to seperate. I was able to break the head off the fourth 61.1 case with my hands. My question is why did these last three cases fail when none of the previous cases did. This brass was only fired once and there were no pressure signs. Gun is a TC Encore Hunter.

[condor bravo]

The powder charges seem OK but do any of the fired cases have that shiney ring around the case near the case head indicating the possibility of headspacing problems and weakening of the cases at that point? Possibility overly shortened cases during sizing or exceptionally long chamber.

[trobin]

Just those last 3. It progressively got worse with those.

[Jimro]

The only time I've had an 06 based case have head separation is one a rifle with excessive headspace issues.

Why it only happend on the last three? There isn't enough data available from your post to come to a root cause of the failure.

Could be that multiple lots of brass ended up in the brass you used. Could be that the you bumped the shoulder back just enough to cause headspace issues. Could be that something weird is going on with that particular powder charge such as a secondary pressure spike.

Could be a lot of things.

Jimro

[F. Guffey]

http://www.tcarms.com/firearms/inter...ore-pro-hunter

This brass was only fired once and there were no pressure signs

That was good, most omit the receiver design, Thompson/Center? We are talking about a receiver that is a break over. I have an H&R 17 cal. that has been shot into oblivion. I have shot guns that break over to open and that is it. everything else has support on the top, bottom and sides of the receiver. The break open rifles can jump almost every way but loose. I would not load the break open rifle with total disregard to my perception of a weak action and I would track stretch.

The 35 Whelen does not have a large shoulder, I am the fan of limiting case travel meaning I do not size a case with total disregard to the chamber length from the shoulder/datum to the bolt face (and we all know your rifle does not have a bolt). I have friends that built rifles and experienced case head separation on the first firing. They claimed they were fire forming I suggested they form first then fire.

F. Guffey

[trobin]

The brass was from two different lots and fired in two different guns originally. They were both Hornady Superformance factory ammo. I also had set the shoulder back farther than I wanted but I don't think it was terribly bad. The thing that gets me is it started mid way through the session on the last three charges. I would think a problem would've presented itself immediately or evenly across the board.

[trobin]

So to sum it up Mr Guffey: I need to match my case as close to identical to the chamber in regards to base/datum length?

[F. Guffey]

Trobin, I am the fan of cutting down on all that case travel. I can chamber a round, pull the trigger then measure the length of the case from the shoulder to the case head. I will not fire a round in a chamber I have not measured.

I would suggest you not load your 35 Whelen T/C with maximum loads.

F. Guffey

[Doyle]

Trobin, I think you are onto the answer. Encores aren't known for having short chambers (or shallow throats for that matter).

[F. Guffey]

I think you are onto the answer. Encores aren't known for having short chambers (or shallow throats for that matter).

Doyle, "onto the answer"? The T/C is know as a break open receiver, I believe an owner of a break over/open receiver would be onto something if they loaded on the low to mid range of a load and made an effort to determine the length of the chamber. I have decided it is impossible for a reloader to determine the length of a chamber before firing, that leaves after firing.

F. Guffey

[Doyle]

Guffey, I don't think we are saying different things. I think we are both advocating letting the actual chamber length dictate how much to resize. Right?

[Jimro]

trobin,

It could be a combination of weak action, excess headspace, and bad lot of brass. The fact that the brass was fired through two different guns before you reloaded it also adds a comfounding factor, as one of those guns could have had excess headspace which caused an internal divot to form in front of the pressure ring ensuring that the brass would fail on the next firing.

While I can't say for sure, I think the most likely cause is bad brass. I would redo the load work up with virgin brass.

Jimro

[F. Guffey]

This brass was only fired once and there were no pressure signs. Gun is a TC Encore Hunter.

as one of those guns could have had excess headspace

I have purchased thousands of once fired cases, I first measured the length of the cases from the shoulder to the head of the case. I wanted cases that were fired in trashy? old chambers. I was willing to pay .08 cents each. The firing range threw in 10 additional cases for free just in case there were rejects. Fired in another chamber has never bothered me, what I do not want is a case that is shorter than my chambers and smaller in diameter.

I do have chambers that are long from the shoulder to the bolt face, when forming cases for the long chambers I use long cases. It is not easy to add .014" to the length of a case without firing it. I choose a better option, I form long cases, for example, I form 280 Remington cases to 30/06, I form and fire. The difference in length between my formed case and the chamber length is .002" from the shoulder to the case head.

F. Guffey

[Unclenick]

Originally Posted by trobin

I would think a problem would've presented itself immediately or evenly across the board.

I'm not seeing why the problem would be even across the board. You are using different peak pressures. That causes a couple of things to happen differently: One is just more brass flow. Another is that more stretch occurs in the steel, allowing a little more brass stretch. When the bullet jumps to the lands, it momentarily slows and the volume the powder is burning in nearly stops expanding, creating a pressure impulse against the breech and oppositely against the barrel through the bullet. An action that is more ridged on one side of the chamber (the hinge side) than the other will see a little extra stretching on the less rigid side, the amount of which increases with pressure. This is why Mr. Guffey was suggesting you may not want to go for maximum loads in this gun. It's hard to be sure without being there to measure things.

Finally, I wonder if you probed these cases with a bent paperclip or a dental pick looking for a thinned pressure ring before you started reloading them? Since they were Superperformance loads originally, they were probably loaded near the top and without a lot of margin. Because the powder in those loads is special and holds pressure up in the barrel longer than average, it may have flowed the brass a little more than normal and done some of this pressure ring damage firing the original load.

Finally, as already discussed, you don't want to over-resize the cases. You just want them to fit your chamber with a thousandth or two clearance to spare. Then there's little excess headspace left to require the brass to fill by stretching, so it doesn't.

[Longshot4]

I wonder what the history of the cases actually was as far as how many times fired in the other rifles. If you have different size chambers and different size dies you could be hardening the cases in the chambers and resizing in different dies causing stress on the brass causing the separation.
The 35 Walen is a heavy cartridge as bullets go. Why are you trying to make it so hot? The primers did not show any sign? The only load information I was able to find for W-748 was Nosler Max load was 61.0gr. You are pushing the envelope.

[reynolds357]

Get a nogo gague and see if it goes in the chamber and the action closes.

[trobin]

Longshot.. Nosler list 61 while Speer and Lyman list 62. Yes I know Lyman and Speer used different bullets. Also I made it hot because the data posted by Nosler showed it performed better at the top end. In actuality none of it performed well.

I'll try again with new brass and a reduced load. I'll also work the brass more carefully to fit the chamber better I believe the cases I have are stretched to fit now.

Unclenick. I probed them after firing and couldn't feel anything. The brass was given to me by the original shooters. Majority of it came out the gun it was loaded for.

[Jimro]

I would try IMR4064 instead of Win748 if you are looking for accuracy. Or H4895 or Varget.

Win748 is a great powder, especially for 308 and 223, but it is easier to get a consistent initial pressure curve with the easier to light off extruded powders.

I generally just stop load workup once I get a load that is MOA or better, so ball or stick powder doesn't matter too much to me, but for some folks extruded is the only way to go for accuracy.

Jimro

[trobin]

I was thinking about switching it up to Varget. Haven't seen 4064 and/or H4895 in a while.

[F. Guffey]

I was thinking about switching

I would suggest you change methods and techniques. Reynolds357 suggest purchasing a no go-gage. The no go-gage is .004" longer than the go-gage. The field reject gage is .005" longer than the no go-gage and .014" longer than the minimum length case from the shoulder to the head of the case.

I suggest you learn to measure the length of the case from the shoulder to the head of the case. You past up an opportunity when you acquired cases fired from another chamber. A reloader can take advantage of the incline plane/thread in the press and on the dies. You could have started sizing a case until one would chamber. to me there is nothing more mindless than full length sizing cases without a purpose. If I return a case to minimum length I am sizing cases for go-gage length chambers.

Tools, most recommend purchasing tools, the thread in the press and on the dies afford me the luxury of making tools.

F. Guffey

[trobin]

How did you ever learn so much F Guffey?