Neck down 308 Win to 260 Rem

[globalflyer]

Hello to you all.

Let me start by saying that I have been an active forum visitor over the years but this is the first time I actually registered. I consider my reloading experience as average since I have been at it for over 15 years loading different caliber. The question I have is more informal and for my own personal knowledge.

I bought a Savage LRP in 260 REM. I started loading for it already and these are my components.

Lapua 260 REM brass
H4350 Start 39.0g /End 42.0gr
Hornady 140gr Amax seated 2.790 inches
Federal 210 match primers

Now as to my questions. I know this topic has been hashed over and over the years but I could not find the answer I was looking for.

I have many boxes of once fired 308 Winchester brass that were given to me by a friend. Again, I will be using my Lapua for my reloading and this question is just for personal knowledge. If the Lapua brass gets hard to get in Canada or if perhaps the 260 REM goes out of style I want to be prepared. So yesterday, having to much time on my hands, I screwed in my RCBS full length die and applied Redding sizing wax outside and inside the necks of the 308 win brass. I resized a few cases in one pass without any apparent problems. Using my Hornady headspace gauge I compared headspace on the 308 win brass before and after the resize to make sure the shoulders were not pushed back.

Win 308 brass fired once in firends savage action. Datum line indicating 1.625 inches

Win 308 brass resized in the 260 die: Datum line indicating 1.627 inches

Lapua virgin brass. Datum line indicating 1.627 inches



Now I keep reading that the issues with necking down 308 win brass to 260 rem is the fact that part of the 308 neck becomes shoulder in the 260. The necks get thicker and need to be turned down as to allow enough clearance for neck expansion and bullet release without pressure going through the roof. So I measured virgin Lapua brass seated with the 140gr Amax using a standard caliper. The necks at the top measure on average .294 to .295 inches. As for the 308 Win brass that was resized to 260, the necks measure on average .291 to .292 inches.

260 Lapua case next to a 308 Win case resized to 260


So finally my questions are. Finally lol

1- Do I need to neck turn my brass? if I do, where?
2- If this resized brass chambers in my gun without any difficulty, would it be considered safe to shoot using starting loads and working my way up?

Please feel free to enlighten me. Like I said earlier, this is my first time necking down cases and I'm doing this to tinker around and learn more about necking down cases.

Regards,

Globalflyer

 

[427Cobra]

First off, offically welcome to The Hide!

1 No you don't NEED to turn the necks, I do turn the necks on my Win 243-708 brass that I reform into 260Rem, I do this for consistency.
2 Safe YES, but IMHO 308 brass is too short, min 260 trim length is 2.025, 308 is 2.005, .020 too short is just going to burn your chamber up faster.

 

[Sutherlandsd]

I have a lot more luck going from .243 to .260 than .308 to .260 (not to mention that I shoot .308 also so my .308 brass is allocated already lol).

 

[mdharris68]

I would like to know if it is possible to size my 308 down to 243, and if so what are the necessary steps and what additional equipment would I need? And is it a good way to go or a waste of time?

 

[blackriflecollector]

Nobody can tell you definitively for your rifle if you need to turn necks on reformed brass. You have to figure it out for yourself and it sounds like you're doing your due diligence. Without knowing the specifications of your particular chamber, it's hard to say for sure that you're OK, but it sounds like you'll be fine.

I believe the SAAMI neck diameter is .298, however there are some match chambers that have a tighter neck. One thing I've seen recommended is to use a sharpie to cover the neck of a reloaded round and see if it's getting rubbed off around the neck. If it is, you're neck is probably too tight for the reformed brass and it will need to be turned down a bit. My LC .308 reformed brass with a seated bullet mics at .298 and I get rub marks with the sharpie test. I use a K&M neck turning tool to turn them down by .004 which gets me an interference free fit in my chamber.

 

[ollie]

The loaded rounds for mine didnt chamber as the necks were to thick.

 

[former naval person]

Varies with the brass...measure a fired .260 neck and measure a reformed .308/.260 neck with a bullet seated. If the loaded case measures the same or greater than the fired .260, you'll need to turn the necks for clearance. Same with the .308 to .243.

 

[globalflyer]

I wish to thank everyone for such prompt responses. It just proves once again that this forum is one of the best on the subject!

 

[POSM]

Neck Turning

Hey Man, I think this is an old post, but when I read it I thought that the outer diameter measurements being smaller than the virgin Lapua LOADED with A-Max indicated quite clearly that the necks are not going to overpressure your rounds. Unloaded measurements can fool you since the wall thickness of the brass can be a few thous thicker than they should. But since there was a bullet in there your outer diameter measurements indicate you can fire the round. You may want to weigh the cases and see how much heavier they are than the Lapua and if they are much heavier, knock down your powder a little until you can measure velocities and check for pressure signs. A higher weight would indicate a potentially lower internal case volume and this can increase pressure. Let me know how your necked down cases work.

Hello to you all.

Let me start by saying that I have been an active forum visitor over the years but this is the first time I actually registered. I consider my reloading experience as average since I have been at it for over 15 years loading different caliber. The question I have is more informal and for my own personal knowledge.

I bought a Savage LRP in 260 REM. I started loading for it already and these are my components.

Lapua 260 REM brass
H4350 Start 39.0g /End 42.0gr
Hornady 140gr Amax seated 2.790 inches
Federal 210 match primers

Now as to my questions. I know this topic has been hashed over and over the years but I could not find the answer I was looking for.

I have many boxes of once fired 308 Winchester brass that were given to me by a friend. Again, I will be using my Lapua for my reloading and this question is just for personal knowledge. If the Lapua brass gets hard to get in Canada or if perhaps the 260 REM goes out of style I want to be prepared. So yesterday, having to much time on my hands, I screwed in my RCBS full length die and applied Redding sizing wax outside and inside the necks of the 308 win brass. I resized a few cases in one pass without any apparent problems. Using my Hornady headspace gauge I compared headspace on the 308 win brass before and after the resize to make sure the shoulders were not pushed back.

Win 308 brass fired once in firends savage action. Datum line indicating 1.625 inches

Win 308 brass resized in the 260 die: Datum line indicating 1.627 inches

Lapua virgin brass. Datum line indicating 1.627 inches
View attachment 6877


Now I keep reading that the issues with necking down 308 win brass to 260 rem is the fact that part of the 308 neck becomes shoulder in the 260. The necks get thicker and need to be turned down as to allow enough clearance for neck expansion and bullet release without pressure going through the roof. So I measured virgin Lapua brass seated with the 140gr Amax using a standard caliper. The necks at the top measure on average .294 to .295 inches. As for the 308 Win brass that was resized to 260, the necks measure on average .291 to .292 inches.

260 Lapua case next to a 308 Win case resized to 260
View attachment 6878

So finally my questions are. Finally lol

1- Do I need to neck turn my brass? if I do, where?
2- If this resized brass chambers in my gun without any difficulty, would it be considered safe to shoot using starting loads and working my way up?

Please feel free to enlighten me. Like I said earlier, this is my first time necking down cases and I'm doing this to tinker around and learn more about necking down cases.

Regards,

Globalflyer

 

[JDR41]

Hey Globalflyer,

A good friend of mine is picking up his new 12 LRP 260 REM. this Friday and will be reloading for it, and since you have the same rifle what load data have you found that works the best in your rifle?

I noticed the load data you mentioned and was wondering how it worked out, and also what other brass have you used if any. Really appreciate whatever info you have that you don't mind passing on, as what he finds in his we would also pass your way.

I'm really jealous as I really wanted that same gun in the same caliber, well at least I will be able to fire his, great guns though.

Good luck with your findings and hopefully you will share.

I can be reached at [email protected]

Thanks

JDR

 

[globalflyer]

Hello JDR41,

I apologize for this late reply but here is the load I use. It's safe in my rifle and might not be in your!!! Start low and work up.

260 REM LAPUA case
FED 210M Primer
41.0Gr H4350
140Gr HORNADY AMAX
COAL: 2.790"

It's a very accurate load. 5 shots group just under 0.5" at 100 Yards. Velocity is 2850 FPS.

Regards,

Globalflyer

 

[Black max]

Hello JDR41,

I apologize for this late reply but here is the load I use. It's safe in my rifle and might not be in your!!! Start low and work up.

260 REM LAPUA case
FED 210M Primer
41.0Gr H4350
140Gr HORNADY AMAX
COAL: 2.790"

It's a very accurate load. 5 shots group just under 0.5" at 100 Yards. Velocity is 2850 FPS.

Regards,

Globalflyer

Your getting 2850 out of a 140 with 41grns of H4350? Are you sure about this?

 

[globalflyer]

Actually I was getting 2793 FPS avg today.
That's out of a 26" barrel, temp of 24C, Elevation of 1000' ASL.

I was getting 2850 FPS with 41.5 Gr if I remember correctly.

Globalflyer