243 Brass to 260

W

Wendyj

New member
I just picked up another Tikka 260 and thought I had some brass but found out it was my 243 brass. I've resized a few pieces of 243 to 260 by mistake a time or two but they are a tad short. Is the difference going to cause any issues if I were to use the 243 brass. Lapua is really expensive so I bought 3 boxes of Federal match ammo today to just get some brass and have some loads to do a barrel break in and zero before using good reloaded ammo.
 
Dimension-wise the .243 to .260 would seem to be a near perfect conversion. One might guess that the reformed .260 from .243 would be slightly longer rather than shorter but slightly shorter should not be of any consequence. Sounds like a good conversion if .260 brass not available. After expanding the neck to .260, bullet tightness might be a consideration since the brass on the neck may have thinned somewhat but have never heard that to be a problem. They do expand '06 cases to .35 Whelen. For conversions I have only neck sized downward rather than upwards.

You are about to become the expert on this and then you can advise others.
 
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If you want to really expand it perfectly you can load up some and expand them using the COW method.
 
I do have an extra 100 or so federal 308 cases. They have been loaded quite a lot and if I could find somewhere to do it I have around 300 to 400 rounds of 308-7 mm mag 7-08 that I would like to have annealed. I tried a few with a torch and wasn't too happy with the outcome.
 
If you are considering converting the .308s to .260, it then might be necessary to check neck diameter after bullet seating, comparing against a standard .260 round at the neck, to verify that neck diameter with bullet seated is not over sized for proper chambering. Especially so with the usually heavier Federal brass which might be thicker at the neck than others.
 
Explain the process a little. I suppose that if the parent case, probably like '06 to .35 Whelen, will chamber in the other rifle without resizing first, so much the better. I don't think a .243 case would chamber in a .260 so some resizing would first be required before applying the COW fire forming. Would the fire forming expand the neck properly without first having to run the neck over the expander button. I'm assuming that all this is done without bullet intact and can do it while watching TV, well maybe out in the garage ;).
 
Thanks guys. Don't want to do anything unsafe. I wouldn't consider resizing the 308 unless I could get it annealed. Does anyone know a company you can send brass off to to get it done or is it cheaper to just buy new brass. A guy at my gun store says that there is an add on Snipers Hide for someone that does it but it cost around $100.00 to join the forum when I go to it. I've got a lot of Hornady, Remington, Lake City, Federal and Norma brass that really is in good shape still but has had a lot of firings. Just my preference but I really like Remington brass and from what I've seen lately it's not out there. Election coming up so I've stockpiled a lot of pistol and rifle primers and powders that have worked good for me. I've only been at this for about 18 months but posts I've seen on here said primers and powder would be way harder to get than bullets. I have enough bullets for about 250 in each caliber I load. Don't know about where you all are at but here in Ga all factory ammo has raised by 20% in last 6 months. Going today and get a set of 380 dies and some bullets. Factory is outrageous here if you can find it. I picked up a 100 rounds of 357- 9mm and 380 brass about 2 weeks ago just in case. It was cheap Remington and Starline brass and it s no fun depriming all these to clean with ss pins. Lol. I'm cheap
 
Condor, here is the process:

1. If the brass will already chamber in your rifle the skip this step. If it won't (i.e. it has fireformed to a chamber that is larger than yours) you'll need to remove the expander button from your die and bump the shoulder back enough for it to chamber.
2. Prime and load with a relatively small charge of a very fast burning pistol powder. The starting weights can be found on the internet but it is kind of a trial and error process. You'll be dealing with volumes that won't generate really high pressures so its a matter of finding out what it takes to fireform the brass without wasting excess powder.
3. Fill the rest of the case with an inert fill - most people use cream of wheat and top with a wad of toilet paper.
4. Point the barrel in a safe direction and fire.

This will result in a case that is fireformed to your chamber. The neck should now also be expanded enough that it will only need neck sizing to seat the bullet.
 
243 will work fine for your purpose. Once your re-formed 243 cases are fired they will re-form to fit the 260s chamber as good as factory made.
Don't worry about seeing a little shorter Neck on this occasion. Your 260 bullets will seat to COL just fine. But such bullets will be a bit more exposed beyond there case Necks. On such occasions not having a hunting bullets cannelure ring to crimp into. You will have to re-set or slightly reduce your Seater Dies crimp to accommodate a no ring sitution.

Since you own both a 243 & 260. I would strongly suggest you mark each calibers base with a separate indelible pen (color.) and too label each storage container as well.

One personal Rule I follow in case forming. Once I have a good supply of factory new brass. I pitch my old re-form brass into the junk box no matter their condition. They served their purpose. i.e. got me over a hump of not having any brass period.
 
That's great advice and I no longer own a 243. I thought I had given the guy all my brass and dies when I sold it but as a brass hoarder I found 20 round in my I might load again one day bin. No danger of firing into a 243 anymore. Thanks for all of everyone's help. Learning more everyday from here. Had never heard of the pistol powder and cream of wheat trick. Very handy advice in the future. I do have some hp38 and Titegroup. Seems hp38 not as hot as Titegroup. Will have to research that one some more.
 
Doyle, the process seems doable and must be fairly common. Perhaps a different sealant would be preferable to provide greater resistance but no doubt a compromise with amount of powder used. Perhaps a wax plug could be wedged into the neck and firing into a thick cardboard backstop. Is there wide splatter with the cow or is it confined?
 
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Condor, I've never done it myself (never needed to) but what I saw just made a big cloud of dust in the air. No need for a backstop - just keep it aimed somewhat upwards to keep all the stuff in the case and fire. I watched the whole thing with the idea of learning what was going on just in case I ever needed to myself. I was going to try it myself this year to make some Whelen ammo but I found somebody selling 3 boxes of factory ammo cheap. That will give me enough brass to use for a long time.
 
Well that's a bit disappointing. By trying it in the garage the cow would probably be scattered far and wide. And probably contaminate if it would vaporizer upon firing. So must be an outdoor activity. Possibly in a rural area back yard if it wouldn't attract attention. Loudness should be minimal. Best to do it at the range and hoping that other shooters won't think you are lacking a loading manual or two along with a few missing brain cells. But still a good procedure worth a try. I have plenty of '06 cases to convert to Whelens. But plenty of .260 rounds and brass so wouldn't need to convert any .243s.

Late addition:

If the case was filled to the neck with cow and then capped with something harder like solid wax to hold the whole thing together, you could then point in a specific direction and at close range the residue might be confined to a small area backstop. Can anyone comment on that?
 
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243 -> 260 ...ok, may form donut at base of inside of case throat
260 ->260 ... easy conversion
7mm-08 -> 260... often described as the best
308 -> 260... 90% yield rate with WIN and RP 0% with Lapua

The problem with 308 is the necks are often too thick. The typical 260 chamber has a 0.298" neck. We would like 0.001" clearance on loaded ammo necks = 0.297" or less.

After building a couple nice to look at 260s, I have given up, and now concentrating on the 6.5-06. I buy guns more often than I go to the range. I am not going to burn up any overbore barrels. So far I only have one tag to fill in 2016.
 
If the case was filled to the neck with cow and then capped with something harder like solid wax to hold the whole thing together, you could then point in a specific direction and at close range the residue might be confined to a small area backstop. Can anyone comment on that?
Click to expand...

Cowboy action shooters do shoot wax plugs at the target (that's how they score in quickdraw competitions) so it would need a backstop. The reason I wouldn't do that in COW fireforming is I'd be worried about creating too much pressure. That little bit of paper holding the COW in doesn't seem to do any harm with that small amount of powder. With a firmer plug, you'd be working off-grid from what loads others have found to be successful.
 
used cow and grits in my c and b revolver over 40 gr black powder comperssed. for civil war teenactments. in open area will project about 10 yds. never fire formed cases. make sure nothing is in front of you can accidentally become imbedded like minature bird shot. have seen it happen on battle field . no serious injuries but affected area had to be thorouly cleaned.
 
My dies came yesterday and I resized the 243 to 260 no issues but I think I used a little too much wax on brass and got some dimples on necks. Fired two and they popped out. Got two boxes of factory 260 also so I'm good to go if accuracy holds. Loaded up some Hornady eld 140 grain. No data for it in my Hornady manual so I used Nosler accubond load and backed off to 40 grains of h414. The eld is probably the most consistent in length I've used other than Barnes ttsx. No oal was more than 1/1000 off when seating.
 
You confirmed as I thought that the .243 to .260 would be a good and easy conversion. And I assume that bullet tightness was sufficient or better. Good project quickly accomplished. Every bit of knowledgeable information helps. You seem to acquire your equipment in a very speedy manner.
 
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