308 to 260 Conversion

[atlsniper6.5]

Good Evening Gents,

So here is my first attempt at converting some 308 Win brass to 260 Rem:

I don't think this is going to chamber...

I was using one of the Forster FL dies . Yes, I used lube (insert dirty joke).


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[atlsniper6.5]

P.S. The purpose of me showing
you this was so you could tell me where I went wrong.


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[J_Roger]

I'm no expert, but I'm pretty sure it's not supposed to look like that.

 

[BobinNC]

Having one of these helps Redding Trim Die 7mm-08 Remington

This gives you an intermediate step so your brass does not look like your picture....

 

[atlsniper6.5]

I'm no expert, but I'm pretty sure it's not supposed to look like that.

LOL


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[atlsniper6.5]

Having one of these helps Redding Trim Die 7mm-08 Remington

This gives you an intermediate step so your brass does not look like your picture....

Thank you, sir. Exactly what I was looking for.


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[buffybuster]

May want to consider annealing and neck down in a two stage process. I've done this many times and hardly loose a case. Then you may want to neck turn so even out the necks.

 

[mdmp5]

Ok, so my guess is that you tried to neck down in one step. You are essentially taking a case mouth with a fired diameter of 340+ and trying to neck down to about 295. That is way too extreme. You need to do it in stages. Personally, I would do it in 3 stages, .015 at a time.

When I size my 308 brass, I do it in 2 steps. Fired Lapua brass measures .345 or so for me. I get it down to .336 by sizing down to .341, then to .336. The smaller step down ensures a more accurate neck diameter because it is less of a radius that the case mouth folds inward.

 

[17874]

What kind of brass were you using? What kind of lube? I have done Federal, LC, and Winchester in one step and never had an issue.

 

[atlsniper6.5]

This was Winchester brass with Hornady Lock N Load Case Lube. I also lubed the expander ball. I actually tried doing it in mutiple steps, but my press seemed to stop at a certain point and not want to go any further. When I forced it the case mushroomed as you can see in the picture. I'm wondering if annealing would help, like buffybuster said. I also wonder if I need to polish the inside of the die. Anyone have any experience with this? I could spend the $30 on a 7mm die for the first step, but I would rather not.

 

[former naval person]

When you size it down it grows in length. The constriction at the mouth may mean that it contacted a lip inside the die and buckled. Check that.

 

[atlsniper6.5]

What kind of brass were you using? What kind of lube? I have done Federal, LC, and Winchester in one step and never had an issue.

What kind of die are you using?

 

[Hondo64d]

To the OP, when I was necking Winchester .284 brass down to .25-284, I had the same results as you UNTIL I used the seating die as an intermediate step. Worked like a charm after that.

John

 

[atlsniper6.5]

To the OP, when I was necking Winchester .284 brass down to .25-284, I had the same results as you UNTIL I used the seating die as an intermediate step. Worked like a charm after that.

John

I must be misunderstanding you or I'm about to learn something... How would a bullet seating die assist in necking down cases?


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[Hondo64d]

Seating dies are a slightly larger dimension than a sizing die, providing an intermediate step.

I should point out that this was with a conventional seating die, not a competition type with a floating sleeve. They might work too, but I haven't tried that so can't say with certainty.

John

 

[nso123]

Looks to be the new .260 short mag now. Like said above, use a 7-08 die as an intermediate step. I had looked at necking down .308 brass before, but decided against it after I figured out the likely need to neck turn and everything else involved. When I figured in my time it would be just as cheap to buy more expensive brass.

 

[Hondo64d]

Agreed. 7mm-08 die as an intermediate step would be fine. Might have to neck turn or not, depending on thickness of parent brass and how tight the chamber is. In a SAAMI chamber, I had no issues going from .284 Win brass to .25-284 and had no issue going from Winchester 7 mag brass to .257 Wby, but in a tighter necked chamber, might have to turn.

John

 

[atlsniper6.5]

Looks to be the new .260 short mag now. Like said above, use a 7-08 die as an intermediate step. I had looked at necking down .308 brass before, but decided against it after I figured out the likely need to neck turn and everything else involved. When I figured in my time it would be just as cheap to buy more expensive brass.

Funny you mention buying more expensive brass... I use Lapua brass normally, but I am doing this as an experiment. I want to see if I can mirror the results of my normal loads with cheaper brass (mirror as in achieve same velocity, consistency to the point where I don't have to adjust my tables). I'll keep using my Lapua brass no matter what the results are, but it would be nice to have a fall back if it ever isn't available for some reason.

 

[Petrov]

Good Evening Gents,

So here is my first attempt at converting some 308 Win brass to 260 Rem:

I don't think this is going to chamber...

I was using one of the Forster FL dies . Yes, I used lube (insert dirty joke).


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You used lube and went right in! You jammed it right in the die and when you pulled out it made a mess didnt it? Newbs!

Listen you gotta take it slow. Put on some Barry white, get your 308. die with sizing inserts, size it with normal die so she feels comfortable and familiar.
But try to spice it up, insert smallest 308 bushing you have and use a little bit of lube.
Once she is comfortable with it say something like
"Hey baby lets try 260 REM fulls size, JUST THE TIP"
Insert it into the 260 die barley doing any sizing, take it out and tell her "Hey you are doing great, you dont have to do this if you dont want to"
If she is comfortable with it try screwing down the 260 full length die to size down a bit more and using the biggest 260 rem bushing you have.
Once you do that your next step is to do screw down the full length die for complete sizing and using the bushing you want.

Lube is good but if you use too much it makes a mess and can get things stuck.

 

[atlsniper6.5]

You used lube and went right in! You jammed it right in the die and when you pulled out it made a mess didnt it? Newbs!

Listen you gotta take it slow. Put on some Barry white, get your 308. die with sizing inserts, size it with normal die so she feels comfortable and familiar.
But try to spice it up, insert smallest 308 bushing you have and use a little bit of lube.
Once she is comfortable with it say something like
"Hey baby lets try 260 REM fulls size, JUST THE TIP"
Insert it into the 260 die barley doing any sizing, take it out and tell her "Hey you are doing great, you dont have to do this if you dont want to"
If she is comfortable with it try screwing down the 260 full length die to size down a bit more and using the biggest 260 rem bushing you have.
Once you do that your next step is to do screw down the full length die for complete sizing and using the bushing you want.

Lube is good but if you use too much it makes a mess and can get things stuck.

I want to be like you when I grow up


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[atlsniper6.5]

Update: I was goofing around with my scrap brass again the other night and had one of those, "I wonder if..." moments. I decided to skip the quickness of the Hornady Lock n Load Spray on Case Lube and pull out the old RCBS pad set up. I ran a few 308s across the pad, lubed the inside of the mouth with a brush, ran them up in the 260 FL die, and out came a 308 case necked down to 260.

I guess the spray on stuff is fine for everyday sizing, but lacks the gooey-ness (new word?) required to neck down a case.


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[ZombieMonkey]

I love spray lube, especially the Dillon stuff, but there is a time and place for it, necking up or necking down brass is not one of them. A good lube will make life simple and easy when you get into certain sizing operations whereas a spray lube will fail. Glad you figured it out.

 

[Clark]

The 308 to 264 is a 14% jump.
Jim at James Calhoon tells me that the wild cat association says only 10% per step.

But if I first turn the 308 necks and then size with a Lee Collet neck die with the collet pryed apart far enough, I seem to get away with the 14% step to 260.

 

[Danco411]

Hey guys I thought I would toss this up here. I have been working on a reliable and consistent procedure to convert LC military brass to .260 and finally have it down where I get no losses with great results.

The key for me has been starting with fully prepped .308 brass. Resized, trimmed and clean. I think the fired brass is too large and too long to convert without excess stress. By starting with a properly sized case it goes really easy. Using good dies really helps. I tried a few with a cheap Lee die and had many more problems. With my Forster BR FL size die it's really smooth. You have to use a good lanolin based lube like Imperial or Hornady Unique. It does not need to be thick but enough to make it slippery. The spray stuff just does not work well. Lube the case and use slow and constant pressure on the handle. Once resized you need to trim again as it makes the case long again. I have been setting my die by starting with the die just touching the case holder and trying to chamber the case. I turn in just a smidge at a time until the case chambers correctly. By my Hornady OAL guage this bumps the shoulder about .002-.003 on the already sized .308 case. It is what the chamber on my rifle wants but yours may be different. I converted 500 cases this weekend without once single loss. I guess you can do the 7-08 intermediate step as a replacement for resizing in .308 first but why buy another set of dies. Most of us already have .308 dies and this works great.

One last thing. A once fired resized Lapua case holds 52.4g of water. My resized LC case held 51.2 so just a grain less. I backed my Lapua load of 43.5 of H4350 down to 42.5 for my resized LC cases.

 

[17874]

Hey guys I thought I would toss this up here. I have been working on a reliable and consistent procedure to convert LC military brass to .260 and finally have it down where I get no losses with great results.

The key for me has been starting with fully prepped .308 brass. Resized, trimmed and clean. I think the fired brass is too large and too long to convert without excess stress. By starting with a properly sized case it goes really easy. Using good dies really helps. I tried a few with a cheap Lee die and had many more problems. With my Forster BR FL size die it's really smooth. You have to use a good lanolin based lube like Imperial or Hornady Unique. It does not need to be thick but enough to make it slippery. The spray stuff just does not work well. Lube the case and use slow and constant pressure on the handle. Once resized you need to trim again as it makes the case long again. I have been setting my die by starting with the die just touching the case holder and trying to chamber the case. I turn in just a smidge at a time until the case chambers correctly. By my Hornady OAL guage this bumps the shoulder about .002-.003 on the already sized .308 case. It is what the chamber on my rifle wants but yours may be different. I converted 500 cases this weekend without once single loss. I guess you can do the 7-08 intermediate step as a replacement for resizing in .308 first but why buy another set of dies. Most of us already have .308 dies and this works great.

One last thing. A once fired resized Lapua case holds 52.4g of water. My resized LC case held 51.2 so just a grain less. I backed my Lapua load of 43.5 of H4350 down to 42.5 for my resized LC cases.

You turn your necks after that right. I have to with LC brass. I do the same process, I just use SB .308 dies with the expander ball removed prior to sizing to .260.