6x47 lapua education

[david12601]

never too late thanks for some good info

 

[6ShotsOr5?]

There is a bit of information about necking down from 6.5 x 47 on the forum 6.5 x 47 page, https://www.accurateshooter.com/cartridge-guides/65x47/

 

[Idaho-45]

Well, I, too, am a bit late here, too. I just noticed this thread, so bear with me. Several years back, now, I had a 6x47L built. Every place I read said run your 6.5x47L brass through the Forster FL die, & you're ready. I tried a few, & didn't like the results. So, my process now is to run virgin 6.5L through a Redding 6x47L Body die first, then through the 6x47L Forster FL die. I'm very happy with the results now!!!! I didn't even know Petersen made 6x47 brass, Ha Ha, guess I'm out of touch !!!!!!!!

 

[SecondsCount]

It's been about 8 years since I formed brass for my 6X47 but I do remember that the Forster 6X47 dies I bought were .001 too tight in the neck and I could barely get the bullets to seat without leaving a ring in them. Maybe they have changed since then because I am reading a lot on here that have had success. I ended up turning down the brass .001 before forming and have not had an issue since.

I'm super happy with the caliber though, and have built two rifles for it.

 

[Ranger188]

Forsters are tight from the factory, but you can have them custom honed to any size you want.

 

[david12601]

I necked down 65 rounds using the readding body then the forester full length Die and then used a wilson neck mandrel die......still waiting on barrel .......my smith is busy doing a bunch of bbls for the northeast palma team.......I also bought some once fired brass but about 35 cases look to be neck turned and trimmed and trimmed a little short the others just once fired.... What should the trim length be on once fired....the ones just once fired are 1.855 the ones neck turned and trimmed are 1.798 in length are they too short??

 

[Kracken McGraw]

I necked down 65 rounds using the readding body then the forester full length Die and then used a wilson neck mandrel die......still waiting on barrel .......my smith is busy doing a bunch of bbls for the northeast palma team.......I also bought some once fired brass but about 35 cases look to be neck turned and trimmed and trimmed a little short the others just once fired.... What should the trim length be on once fired....the ones just once fired are 1.855 the ones neck turned and trimmed are 1.798 in length are they too short??

Books show 1.840 trim length and 1.850 max.

 

[david12601]

So should I get rid of the short ones

 

[Kracken McGraw]

So should I get rid of the short ones

I’m not qualified to answer, but 40 thousandth sounds excessive.

 

[dstoenner]

When you neck down a cartridge the length shortens. The neck thickness also grows. Just math and physics.

David

 

[Old Navy]

My 6mm CM barrel arrived before the Lapua brass. I didn't want to wait so I necked down and neck turned some 6.5 CM. I used them for breaking in and now for fowlers. They have been shot several times now and ten I just measured are within .003" of my once fired 6mm CM.

 

[xswanted]

You may want to do some measuring with a loaded round that will tight. mine is .271 and with starting with a 6.5x 47 Lapua cases, I had to turn a lot off to get .003 clearance ...... jim

Same here.

When I necked Lapua brass down to 6x47 I had to neck turn. The gun would not shoot consistently without turned necks. Tension was all over the place.

 

[xswanted]

When you neck down a cartridge the length shortens. The neck thickness also grows. Just math and physics.

David

It seems to me it gets longer doesn’t it?

Fireformomg I’ve alway found cases to get shorter but necking down usually they get longer. Thicker is right from my experience.

 

[dstoenner]

It seems to me it gets longer doesn’t it?

Fireformomg I’ve alway found cases to get shorter but necking down usually they get longer. Thicker is right from my experience.

Here is my analysis to why I believe they grow shorter when necking down. That is what I saw when going from 308 to 260 Remington for the first time. So I sat down and drew out what was going on and mathematically what I saw was what came out of the calculations.

Here is what I found out. Basically you are turning the part of neck wall into the hypotenuse of a small right angle triangle as an extenstion of the shoulder. The base of the triangle is the difference in the starting diameter less the finishing diameter divided by 2. In this case we are taking a 6.5mm to a 6mm which is .264-.243=.021 divided by 2 is 0.0105. The hypotenuse is that base leg of 0.0105 divided by the cosine of the shoulder angle (30 degrees in this case) 0.0105/0.8660 = 0.0121. The side of the triangle that is the extension of the inside neck ( the point where the new shoulder neck junction moved to) is the 0.0105 x the tangent of 30 degrees which is .0060. The difference between the hypotonuse and the new neck junction is 0.0105 - 0.0060 = 0.0041. That is how much shorter the case is.

The neck is bending to make the hypotenuse which is always longer than any other side of a triangle. If you are necking up the calculations are still valid just that the hypotenuse is being added to the neck from the shoulder so the case grows in length.

It has taken about 4 firings of my necked down 6.5X47L to 6X47L to get to where I actually sarted trimming the neck. These are cases that had never been fired.

HTH

David

 

[david12601]

So the bartlein barrel is here and already assembled finished mounted a sightron big sky 36 x so like I said in the beginning of this post....I bought some brass from a guy on here 100 PCs about half have been neck turned and trimmed very short.....they would not chamber so I used redding body die then Forster full length sizer without the expander...then a Wilson mandral to true up the neck...
. I emailed him to find out if there was a reason the brass was not sized correctly or if ther was anything specific about it but he never answered
I was going to load up some berger 105 and sierra 107 and 110 nosler 107 headed to the range tomorrow

 

[Kracken McGraw]

So the bartlein barrel is here and already assembled finished mounted a sightron big sky 36 x so like I said in the beginning of this post....I bought some brass from a guy on here 100 PCs about half have been neck turned and trimmed very short.....they would not chamber so I used redding body die then Forster full length sizer without the expander...then a Wilson mandral to true up the neck...
. I emailed him to find out if there was a reason the brass was not sized correctly or if ther was anything specific about it but he never answered
I was going to load up some berger 105 and sierra 107 and 110 nosler 107 headed to the range tomorrow

I just loaded up a new batch from Lapua 6.5x47. Not that this will do you any good but it might be a reference. They grew in length just a little in the forming down process, trimmed them to a equal length of 1.8435. Loaded neck with 107 SMK was .2695 measured with a set of digital calipers.

 

[david12601]

Thanks good info

 

[david12601]

No range time too windy

 

[david12601]

Range today ........sight in new to me sightron big sky 36 x scope fired 50 rounds cleaned a dozen times I really like how the brass formed nice and crispm used 103 grain bullets with a heavy dose of 760 just to blow out the brass....ordered 2 boxers of brass today off of another site.....its a shame that the guy I bought this brass from trimmed it way too short going to use it for critters

 

[Lefty Trigger]

When I first started doing 6 creedmoor from 6.5 brass I just stepped down with a couple of bushings so it was not such a harsh jump.