Shot gun cartridge crimp issue

[Silvius]

I am trying to build a tungsten shot load. I have finally got all the fiddly little bits and pieces needed for the recipe and put a cartridge together. The crimp is a bit low I think.

I suspected that this would be the case. The recipe uses a wad designed for a 2 3/4 inch 12 gauge cartridge in a 3 inch cartridge with a 1/8 felt overshot wad. I never could figure out where the other 1/8 was going to come from. If the recipe had not been from a respected authority on Tugsten shot, I would have thought it a bit odd. The cartridge actually rattles less or the same as any of the shop bought ones I have but there is a 3 mill hole in the middle of the crimp. The hole is not a functional problem because there is an over shot felt wad but I am new to tungsten and not having everything looking right makes me cautious.

So, what to do? shoot it as is, try crimping differently or add another 1/8 felt? Any thoughts would be gratefully received. The load has a pressure rating of 6300 psi if that helps, so I can't imagine another overshot felt would take it to dangerous pressures. But what do people think?

 

[Mr. Gain]

Sorry if this is stating the obvious, but have you tried contacting the source for the load, explaining your concerns, and asking their advice?

 

[stalkerboydy]

I am trying to build a tungsten shot load. I have finally got all the fiddly little bits and pieces needed for the recipe and put a cartridge together. The crimp is a bit low I think.

I suspected that this would be the case. The recipe uses a wad designed for a 2 3/4 inch 12 gauge cartridge in a 3 inch cartridge with a 1/8 felt overshot wad. I never could figure out where the other 1/8 was going to come from. If the recipe had not been from a respected authority on Tugsten shot, I would have thought it a bit odd. The cartridge actually rattles less or the same as any of the shop bought ones I have but there is a 3 mill hole in the middle of the crimp. The hole is not a functional problem because there is an over shot felt wad but I am new to tungsten and not having everything looking right makes me cautious.

So, what to do? shoot it as is, try crimping differently or add another 1/8 felt? Any thoughts would be gratefully received. The load has a pressure rating of 6300 psi if that helps, so I can't imagine another overshot felt would take it to dangerous pressures. But what do people think?

Post some pics if you can but sounds like you need a plastic disc ( can't spell the proper name some like abortur ) under your wad to lift the wad to right height . Just checked it's a plastic Gas Seal you put on top of the powder the the wad or you can use a 3" wad and put felt or cork fillers in to the wad before the shot

 

[Silvius]

I might have to do that. I am a bit embarrased to though as he gave me the load for free several months ago and he normally only gives data when people buy TSS from him. I just don't like to hassle someone who did me a favour.

 

[levigsp]

why another over shot, infact why over shot to start with? standard practice with tungston is this. case exact chamber length, powder, steel shot wad as long a column Hight as possible but as small a cup as possible. filler wads inside shotcup, mylar wrap, shot then crimp. or shot over shot card and roll.

 

[Silvius]

Here is a picture. Thanks for the advice.

 

[stalkerboydy]

I might have to do that. I am a bit embarrased to though as he gave me the load for free several months ago and he normally only gives data when people buy TSS from him. I just don't like to hassle someone who did me a favour.

Adjusted my original reply and the add I've reloaded thousands of various gauge cartridges

 

[bullet chucker]

How does your cartridge compare with a factory made one,? just seen your piccy' looks a bit deep that crimp, I think, may be wrong of course?

BC.

 

[Silvius]

I think the overshot felt is so that one can have a 3 inch case for a 3 inch chamber. Most wads for 3 inch cartridges are going to need a lot of packing as they are going to be for medium to large steel loads. The little 24 gram steel wad already has mylar and 3 packers to make the tungsten fit.

The crimp looks a bit deep to me when compared to factory ones. I am wondering how to raise it without messing up the recipe.

 

[Liveonce]

Here is a picture. Thanks for the advice.

Eight point crimp, normally associated with American carts as we favour the six point crimp.
The crimp has fallen into the case, so you need a higher height shot cup, I assume you are using a plastic wad? As Tungsten shot. Crimp is not formed properly either as still old threepenny shape around the edge, what press are you loading with?

 

[Silvius]

Its an american one -Lee loadall.

So if I get a disc to raise the wad, how big do people suggest please and will it change the internal ballistics snough to worry?

 

[stalkerboydy]

Its an american one -Lee loadall.

So if I get a disc to raise the wad, how big do people suggest please and will it change the internal ballistics snough to worry?

I've loaded several TSS loads what load are you trying to load. By putting a gas seal under the 70 mm wad it would take up the space as if you was using a 76mm wad. Why don't you just load 70mm cases or just to through another into the mix ( this has been tried and tested ) put a 20ga wad inside the 12 GA wad or there are loads where instead of Packers use steel shot BUT you would really need to know what you are doing for those type of loads but again the work very well if done safely and correct. Unfortunately using TSS does involve a bit of trial and error to get a good crimp. To tidy you crimps up use a Gaep BN3 crimp finisher

 

[Silvius]

Thanks Stalkerboydy Its a 1 1/4 OZ load. I have a 3 inch chamber, so I am trying to get a 3 inch cartridge load even though I am using mylar as I don't want to scratch the bore.

Would it be OK to use a gas seal under the wad or would it be too big a change to the load?

Thanks

 

[LeftHandGuy]

I am a total know-nothing novice when it comes to shotshell reloading, so I have just begun a few experiments of my own.

Would it be totally stupid to simply try shooting what you have made and seeing how it patterns?

 

[Silvius]

It appeals to me a lot to try to get a better crimp by experiment and then just shoot a few at a pattern board and see.

Its just that I am not experienced in this field and I know that deep crimps can increase pressure to some extent. I am looking for reassurance as to "its OK to try, its just a bit leakier than a normal crimp if you get a pocket full of water" or any recommended small tinkering to get a better crimp -like another overshot felt or a disc at the base of the cartridge that will not effect the load enough to risk going over pressure. I don't myself know enough to know if any of these little tricks would be OK.

Thanks for all the replies guys.

 

[stalkerboydy]

Thanks Stalkerboydy Its a 1 1/4 OZ load. I have a 3 inch chamber, so I am trying to get a 3 inch cartridge load even though I am using mylar as I don't want to scratch the bore.

Would it be OK to use a gas seal under the wad or would it be too big a change to the load?

Thanks

If you are using a 70mm ( 2-3/4" ) wad in a 3" case then yes I'd try a plastic Gas seal under the wad but personally i only load 70mm cases with TSS load's . What you could try is put 1/4oz of Steel then 1oz TSS which is then a 1-1/4oz load.

 

[paul o']

try a card packer over the felt this may help with the middle collapsing ,sorry not much help but i used to only load 2-3/4 carts .

 

[Liveonce]

Most 2.3/4” cases are 69mm and 3” case are 76mm so you are some 7mm a drift if using load data for a 2.3/4” case. A poor crimp will result in poor combustion of the propellant likely causing unburnt powder, a dirty load and poor velocity, the latter may not be so important with tungsten shot given its density advantage.
If you add a 6 or 7mm plastic obturator on top of the propellant then the wad, it is unlikely to cause a pressure issue as you are already using plastic (wad) obturation anyway. It will add further to the cost of the cartridge needing both the plastic obturator and wad. Different obturator sit differently on the propellant as some are hollow some are not (also depends what is available to buy) but if 6mm turns out to be to much of a filler then try a 4mm over powder card.
As you have deviated from the load data you will have to find what works to give you a nice tight crimp.
If concerned about pressure reduce the propellant dose and work backup to maximum.

 

[Silvius]

I just tried a 3mm 20 bore cork packer on top of the felt. Perfect crimp. I can only think that a 20 bore packer is going to get pushed down a 12 bore barrel without adding resistance. Please correct me someone if I am wrong.

I also ordered 6mm stackable gas seals that should stack with the wad. So now I have both options. However tungsten is not cheap and unless someone says its a bad idea, I am tempted to go and pattern the 20 bore packer option and if it is OK, then stop there, rather than back off the charge and then work back up with the gas seals.

Please let me know if this sounds like a bad idea.

 

[caberslash]

Here is a picture. Thanks for the advice.

If you are running a break action then go ahead.

Semi's are a lot more critical on crimp.

You really need to be trying to blow up a shotgun, rifle not so much.