Gunsmithing 260 Lapua

wnroscoe

wnroscoe

Gunny Sergeant
Full Member
Minuteman
Jun 12, 2006
3,907
56
NW Louisiana
#1
I've received enough phone calls and emails lately that I thought I'd share the info with who ever needed it. In the past, a typical 260 reamer/chamber for us has been .295" Nk, free bore from .080" to .100" and lead angle at 1.5 degrees, minimum SAAMI from the neck shoulder juncture point south. I run Nosler brass in two 260's with the same chamber as listed above and have found it to be superior to everything except Lapua, they're same/same from what I can see.

Since Lapua came out with their 260 brass it forced me to take another look at my chambering reamers. The only change I made was to make the neck .298" to accommodate the Lapua brass. The reamer was renamed 260 Lapua to help me keep it separate from the other reamers I have. The specs are as follows;

.090" FB
.298" Nk
1.5 Degree Lead
Minimum SAAMI from the neck south

Dave at PTG or the fine folks at JGS can help you with this reamer if you'd like one. Don’t forget your go gauge either.

The above FB dimensions of .090" will allow you to shoot 130/140 Berger VLD's at 2.922" with a +.010" jam or the 139 Scenars at 2.845" with a -.005" from the L&G's. Load data has been pretty much same/same across the board from gun to gun but, change neck tension or FB and the load will change due to pressure differences. The load is as follows;

Nosler 7-08 or 260 Brass
41.5 to 42.0 grains of H4350
CCIBR2 Primers
.289"/.290" neck bushing
.002" neck tension

Bergers jammed
Scenars jumping

Hope this helps.
 
#3
Re: 260 Lapua

Roscoe

Thanks for the post

i do have a couple questions.

If you were planning on running Lapua brass and doing a 100% neck cleanup from the start. What neck dia would you run?

Also if you were going to run modifed AICS mags and 140 VLDs would you reccomend a slightly longer freebore?

Thanks for any help
 
#4
Re: 260 Lapua

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Tim K</div><div class="ubbcode-body">Those neck bushing sizes are correct? They look 0.005" small to me. </div></div>

The loaded necks on my Nosler brass is .292". That calls for a max of .289" or a min .290" bushing for .002" neck tension.

Yes, those neck bushing sizes are correct.

My chamber necks are .295", if I used a .294" or .295" bushing it wouldn't size the neck.
 
#5
Re: 260 Lapua

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: .257</div><div class="ubbcode-body">Roscoe

Thanks for the post

i do have a couple questions.

If you were planning on running Lapua brass and doing a 100% neck cleanup from the start. What neck dia would you run?

Also if you were going to run modifed AICS mags and 140 VLDs would you reccomend a slightly longer freebore?

Thanks for any help </div></div>

If I were going to turn necks, and I have/do, I'd run the .295" nk reamer. I made 260 brass out of 243 Lapua and had to turn the necks for them to chamber. 100% clean up and the loaded necks run .290", I use a .287" bushing for those but, a .288" bushing would be better.

For a straight up VLD rifle, .060" is probably better. That gives you room to chase the lands. At a FB of .080"+, you dont have the option of chasing the lands for long until you run out of magazine. For comp rifles, the 139 Scenar is the way to fly, hands down. For hunting rifles, run the VLD's and chase the lands, thats the way my 260's are set up.
 
#9
Re: 260 Lapua

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: .257</div><div class="ubbcode-body">Thank You

Just wondering,

Since you have built countless 260s, Im assuming you have had better accuracy out of the 139 vs the 140 berger??

</div></div>

Actually, the 139's hold their own quite well and I have had several 3" groups and under at 1k with them. I just reccomend them for comp rifles because from my experience, tangent ogives tend to be less finiky than secant ogives when tuning a rifle for peak accuracy and maintaining that accuracy. It's hard for some to grasp but, as little as .005" in seating depth difference can make a rifle go from an easy .2 moa rifle to a 1 moa rifle. Granted, a 1 moa rifle can hold it's own during certain matches but, loose a tune like that and it can be a deal breaker on certain stages like a know your limitations stage.

The way I see it, we spend $3,500+ on just the rifle, why not have it perform to it's absolute peak in the way of accuracy. Ammo plays just as big role if not bigger than the barrel does.

As for the 142 SMK's, also a very good and easy to tune bullet. They set the standard for most.
 
#10
Re: 260 Lapua


William,

Do you recommend jamming the 140 VLD's .010" for a Tactical match rifle? I just did some testing when my groups opened up a bit and found that the change from .020" to .025 off in my rifle was huge. Seems to shoot better in the .010-.015" off range. Would you recommend going back and doing more testing with them jammed? (Assuming you back off load a little?)

John
 
#11
Re: 260 Lapua

Thanks Again Roscoe

I will give my opinion on jamming bergers.

I am a Berger fan. I use them in hunting, tactical matches, and a br rig.

I Would NEVER jam a Berger in a hunting or tactical rifle. If you do you WILL get a bullet stuck in the lands sooner or later.

I do kiss the lands on my BR rifle.

But I have great luck jumping bergers. For me .015-.025 on most rifles

By the way..... William built a 260 for my shooting partner. It shoots lights out. You will see some pics of a big bull killed in a couple weeks with that 260 if all the cards fall right.
 
#13
Re: 260 Lapua

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jrob300</div><div class="ubbcode-body">
William,

Do you recommend jamming the 140 VLD's .010" for a Tactical match rifle? I just did some testing when my groups opened up a bit and found that the change from .020" to .025 off in my rifle was huge. Seems to shoot better in the .010-.015" off range. Would you recommend going back and doing more testing with them jammed? (Assuming you back off load a little?)

John </div></div>

Negative on jamming a tactical comp/working rifle. I'd only jam a BR or hunting rifle if I knew the bullet wasn't going to stick. I've also found that .002" neck tension is fairly tight and I've only pulled a bullet once, when I was at +.030" in the lands
laugh.gif


Try the 139 Scenars at -.005" off. As far as the Bergers go, my BR rifles (6BR, 6 Dasher & 6XC) have done best from just touching to +.015" in. My newest 260, -.010" from a hard jam, that’s maybe +.010" in from just touching. Much over +.010" and you run the risk of sticking a bullet in the throat if the neck tension is too light.

I ran a test two days ago with my new 260 and the 140 Bergers. At -.010" from a hard jam the group was in the .1's, .005" shorter and the group opened to roughly .5" and .005" shorter it opened to 1". For me, -.010" from a hard jam is where I loaded ammo at, 420 yards it groups in a dot under 1" (<.250" moa)


Three shots at 612 yards, 260 with 140's jammed
zo989e.jpg



The rifle will tell you what it wants, you just have to look and listen, period

Our deer season opens in the AM and I may spill a little blood. The new 260 and 140 Bergers will get the knod, jammed in of course
wink.gif



I usually run an accuracy test at 300 yards to determine what seating depth will be the most accurate for a given rifle. <span style="color: #FF0000"><span style="text-decoration: underline"><span style="font-weight: bold">For me</span></span></span>, Scenars and SMK's work best at -.005" and Berger VLD's work best from touching to +.015". I will admit though that I've never tried the Bergers jumping +.015" or more.
 
#15
Re: 260 Lapua

Thanks for this thread. About to be snagging a reamer for .260 + Lapua brass, so this is incredibly timely.

Can anybody confirm whether I am correct in guessing that a 139 Scenar and 142 SMK will have very similar COAL if seated the same depth in relation to the L&Gs?
 
#17
Re: 260 Lapua

To the taggers of this and all threads did you know you can add the thread to your watched list by clicking on the Topic Options button at the top of the thread? You still get notified of the thread activity the same as posting in the thread without making everyone have to look at the updated thread just to see it was just a tagger. This is good info so I'm adding it to my list but don't find running around tagging everything to drive up my post count neccesary.
 
#18
Re: 260 Lapua

I had placed an order for a .260rem reamer (no specific measurements) with PTG before this thread started and they were on backorder for a few weeks. I received the reamer and went on vacation. Now checking out this thread I went measure the neck and sure enough it's right at .298". I'm thrilled since I was planning to run Lapua brass in this rifle anyway, but I called David at PTG just to make sure. He said he's grinding the standard .260rem. reamers with the .298 neck now since Lapua has come out with their brass.

So, just a heads up for those of you who are wanting a tighter (.295) neck, you may have to specify which one you want when ordering.
 
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