Bulged 45-70 brass after being fired from a Trapdoor

[bear166]

Howdy everyone. This may be more appropriate for the reloading section, but I reckon you folks have the most experience in this topic.

Took the Trapdoor out for the 4th of July shoot this weekend. I just have to add that this thing is as accurate a rifle as I own, maybe the best of the bunch. But I noticed that the brass was bulging around the base in exactly the same spot on every shell, and not all the way around, just a lump on one side of the base.

These were loaded with brand new Starline brass; I can't say I noticed this bulge on the first ten test loads I made up a few months ago with mixed brass, although I do remember that they had the same issue with extraction (I have yet to see a fired case extract properly, while unfired brass ejects every time). There is absolutely no issue with ballistic performance, it puts the lead exactly where it should every time, even after 20+ firings.

It's obviously an old rifle and I've heard all manner of things that can be inconsistent with these Trapdoors. Is it possible my chamber is just a little misformed? For the record, all of the cartridges were sized, expanded, loaded with 65 grains of Olde Eynsford 2F, a cardboard wad, and a 20:1 cast bullet with little to no crimp applied. EDIT: And Winchester Large Rifle primers were used, if that's useful information.

I guess what I'm asking is whether or not this is a normal occurrence, and whether or not the brass should be used again. I haven't experienced any other apparent issues with the brass such as splitting, just the bulge. Would that size out? I imagine the brass certainly won't last as long with these bulges happening, but it would be nice to get at least two uses out of each case, being as expensive as they are... I'm still pretty new to BPCR so I figured it would be worth an ask before proceeding. Thanks in advance.

 

[The Glockodile]

But I noticed that the brass was bulging around the base in exactly the same spot on every shell, and not all the way around, just a lump on one side of the base...

...Is it possible my chamber is just a little misformed?

View attachment 1009801

Probably so.

Maybe you can stretch the number of firings with lighter loads...

 

[The Glockodile]

I have no experience with your type of rifle, but in the bolt guns I use, I never have to worry even with a semicircular case head separation - the case head obturates enough to the point that it doesn't affect my groups (context: .308 Winchester).

 

[bear166]

Probably so.

Maybe you can stretch the number of firings with lighter loads...

Very good idea, I think only three of my test loads were that hot (the others were charged with 55 and 60 grains) so that could explain why I didn't notice any bulging at that time. Shame though... Gotta love that sharp thwack on the shoulder with a full powder black powder load.

 

[Jim Watson]

I would expend a couple more with the case oriented in the chamber, headstamp up, say. Look to see where the bulge occurs. It is possible for a case to lay on the bottom of an oversize chamber and always expand up.

 

[bear166]

I would expend a couple more with the case oriented in the chamber, headstamp up, say. Look to see where the bulge occurs. It is possible for a case to lay on the bottom of an oversize chamber and always expand up.

Good call, I will try this next time I take it out. That is basically my suspicion, but I'm glad to hear a few second opinions that seem to indicate that may be the case.

I'll add a second question here as it becomes more and more apparent that this is probably just going to be part of my experience... Is there any way I can get the ejector to actually eject the fired case? I always carry my Leatherman, so I'm never short of a pair of pliers... But it does get annoying having to yank every case out myself, haha. But I guess it gives me a special sort of respect for the frustrations of Custer's men!

 

[Jim Watson]

Is there any way I can get the ejector to actually eject the fired case?

Would it eject your lighter loads?

 

[bear166]

Would it eject your lighter loads?

Nope. Not a single one, although if I recall, it did eject the used brass I bought, even before sizing. Which, come to think of it, the fact that it chambered at all would seem to suggest my chamber might be a bit oversized.

 

[MEHavey]

That's not that bad a bulge.
Size it partially to where it will just reliably chamber again, and continue to march.

 

[mushka]

I only shoot lead cast bullets with gas checks in my trapdoor either 325 grns or 405 grns,. 55 grn of 3F black powder any lg rifle primer. No bulging and they extract well.
Sounds like the chamber is out of round in a place in your rifle. My brass has been loaded ten or more times over the years. Load yours up again and see what happens. Mine is like yours though, it's dead nuts accurate out to about 100 yds.

 

[bear166]

That's not that bad a bulge.
Size it partially to where it will just reliably chamber again, and continue to march.

Glad to hear it! That was my plan, just happy to hear others agree it's no big deal.

I only shoot lead cast bullets with gas checks in my trapdoor either 325 grns or 405 grns,. 55 grn of 3F black powder any lg rifle primer. No bulging and they extract well.
Sounds like the chamber is out of round in a place in your rifle. My brass has been loaded ten or more times over the years. Load yours up again and see what happens. Mine is like yours though, it's dead nuts accurate out to about 100 yds.

My bullets don't take a gas check, but I can see how that might help.

If I'm being honest, 100 yards with iron sights is just about stretching my abilities as a shooter, haha. I'd like to try it out to 200 one of these days just to see - bore's got a bit of pitting, but seeing how it does within 100 yards, I wonder if it might just surprise me a little.

 

[Steel Horse Rider]

The brass looks like it was fired from a Japanese Arisaka. Definitely an oversized chamber. My trapdoor doesn't swell the brass so I am sure it is not a normal event. I would say it is your choice as to whether to continue shooting it or not.

 

[bear166]

The brass looks like it was fired from a Japanese Arisaka. Definitely an oversized chamber. My trapdoor doesn't swell the brass so I am sure it is not a normal event. I would say it is your choice as to whether to continue shooting it or not.

It's less than ideal since the rifle won't extract the brass, but I'm not concerned as far as continuing to shoot the rifle goes. From my reading here and elsewhere, I don't think it is that abnormal. But I will say, I got a hell of a deal on the rifle, considering the condition of its bore and action. Guess I understand why now!

 

[dave951]

I'd have that chamber looked at by someone who knows how to work on trapdoors. It's not normal.

 

[Shortgrub]

I took a 73 Win. in trade and when I fired it, the case bulged like yours. I would probably guess both rifle had some form of factory or reloads that were excessive chamber pressures. Relined mine and never looked back. great shooter now.

 

[MEHavey]

All cases expand to fit chamber available. With revolvers it expands uniformly.
With a good rifle you'll still see the 'web ring' where the expanded/resized case is larger than the web transition
That "1-sided" anomaly however, occurs with extractor-held cases.in a loose chamber.
Nature of the beast.

Again, what I see in the pic -- IMHO* -- is not that bad at all as far as re-loading.
(especially where BP pressure profiles are involved/partial sizing is the rule)

~~~~~~~~~~~~~~~~~~
postscript: Now as for the Arisaka.... I had (still have) one whose chamber is
soooooooo bad that I wound up using 243 cases to effectively fill the void.




* YMMV or course. (and I have my lawyer's permission to say so)


.

 

[Captain*kirk]

To my eyes it looks as it the bulged area occurs right where the case walls begin to thin out from the base. I'm guessing it's a chamber issue also and you should have it looked at. If the chamber is eroded and there is a pocket it could very likely be repaired and reamed by a competent gunsmith.
You can probably feel it with your pinky.

 

[4v50 Gary]

Chambercast and then measure the cast. If the chamber is deformed, it should show up.

 

[4v50 Gary]

dbl tap

 

[243winxb]

Measure fired brass & compare to SAAMI maximum chamber. How bad is the bulge? New brass today is using SAAMI standards. I would guess no standard for the old guns?

Some modern cartridge factory ammo will show a bulge.

I was told there should be no free space in the cartridge. Bullet on powder. Guy was shooting a 45-90. He let grandson fire a shot.View attachment 1010029

 

[Captain*kirk]

Well, it appears the bulged cases are bulged enough to interfere with extraction. That in itself would be enough to have me get it to a gunsmith.

 

[bear166]

Measure fired brass & compare to SAAMI maximum chamber. How bad is the bulge? New brass today is using SAAMI standards. I would guess no standard for the old guns?

Some modern cartridge factory ammo will show a bulge.

I was told there should be no free space in the cartridge. Bullet on powder. Guy was shooting a 45-90. He let grandson fire a shot.View attachment 1010029

I'm sure there were some standards, but in my reading, inconsistencies are commonplace, whether from the more limited manufacturing equipment and techniques available at the time, or from over a century of abuse. To answer your question, the bulge shown is not something that I found to be concerning (more just annoying) but I would hazard a guess it's well outside of any standards available then or now.

Correct on the rules for the cartridge. I use a card wad between the bullet and powder, but the main thing is that there is no free space. I'm not concerned about my ammunition, although as someone else mentioned I could see where maybe in years gone someone tried loading it up with full strength factory ammo or something.

Well, it appears the bulged cases are bulged enough to interfere with extraction. That in itself would be enough to have me get it to a gunsmith.

I think you're right. I know one locally who may be able to take it on. I'm not afraid to fire it in the meantime, but I can't deny that it is frustrating. I'll have to have it corrected eventually.

 

[The Glockodile]

Can straight - walled trapdoor rifle cases be "Fireformed" and "Neck Resized" in the same way one does bolt gun bottlenecked cases?

 

[Jim Watson]

Yes. Some BPCR shooters only partly size their cases if at all. Bullets are finger seated. Sensible on the target range but not hunting or fighting.

 

[bear166]

Yes. Some BPCR shooters only partly size their cases if at all. Bullets are finger seated. Sensible on the target range but not hunting or fighting.

That's my understanding as well. I'll see what I've got when I get around to loading them back up, as it would be nice not to have to work the brass any harder considering the bulging issue. But considering how difficult it makes simply extracting the case, I'm guessing mine will probably need a pretty healthy sizing; we'll see, I'll just do it in slow increments and see what makes the rifle happy.