Dilemma

[Kodiak99317]

I'm currently using fitted necks,bullet inserted into a fired case JUST goes in and when you pull it out again it makes the poop sound) and I'm getting .3" groups at both 100 and 200 yds with 105 Lapua bullets around 3000 fps. This is on my FClass 1000 yd rifle.

My necks currently measure .0127" and I'm thinking my ES MAY decrease if I neck turn again down to .0123" and give the case/bullet a little more room.

Current ES is around 25 fps now and with a 20 thou jump off the lands I can get the ES down to around 18 fps.

What are your thoughts or experiences with Fitted vs turned,with room to spare) cases? Has anyone gone this route,fitted) and then re-turned, what happened to your groups and ES after re-turning?

 

[Kodiak99317]

I have only tested at 100 & 200 yds since the LR range,300-1200yds) is 1.5 hrs out and probably under 2-3 feet of wet heavy snow right now. The road to the 100/200 test range, a mile north of me, is even closed as of last night, washing out from spring runoff. I do plan on shooting them at the true LR range once things dry up some.

I thought it over some more and figured, laying in the dirt/prairie/mud is no place for fitted necks,re-measured and I figure I had .0004 to .0005" clearance before, just enough for the bullet to let go I think), so I re-turn 36 of my 96 necks to allow for 0.0018" clearance and I'll see what it does for things and I still have 60 of the fitted cases just in case. Hopefully she still performs well or better [once my powder arrives by dogsled,just kidding) ] and I'll do the other 60 cases too. Had to do something with both ranges out of order

 

[Forum Boss]

I think that was a good call. Just remember with thinner-walled cases you'll need more neck tension. If you reduced the loaded diameter .0013", you may have to go with a .002" smaller bushing. The thin necks don't grip at hard.

With no-turn factory cases, I've seen .001" tension work fine. Not so with thinner necks.

 

[AlNyhus]

Keith, here's my thoughts on fitted necks: :nono:

For those unfamiliar with the term 'fitted neck', it doesn't mean a minimal clearance neck. a 'fitted neck' in BR terms generally means that you have under .0005, half a thou.) total clearance between the neck and the chamber.

I've messed with them and have never found them to be of any benefit at all. Matter of fact Keith, my 30BR showed improvements when the neck clearance was opened up past .002 total.

Look at it from this standpoint: When we resize the case body so it fits back into the chamber, the clearance between the case and the chamber will probably be great enough to allow a 'fitted neck' to contact the chamber neck at some point.

As to whether it will help your ES/SD numbers..heck, I don't know. Being a slack jawwed, Stone Age 100-300 yd. BR shooter, I don't use the chono much. I dust it off occasionally to check velocities. As long as the ES numbers aren't any more than 20 or so, I'm content. I'm usually surprised that the ES/SD numbers are as low as they are...which brings me to another point:

When a chronograph has a 1% error margin,eg: 30 fps @ 3,000 fps), how can you trust these low 'single digit' ES numbers that people get all excited about? Or am I missing something obvious?

Let us know how your neck experiment works out, okay? Take care and good shootin'. -Al

 

[Kodiak99317]

Thanks Al,

I agree, stats are nice but the real proof is on the target, plus with a 1 foot spacing on a Shooting Chrony, how accurate is it really?? Maybe + or - 72 fps!

I'm going to borrow a Oehler Model 35 Proof at the end of April and re-test some of my findings in May if I have time.

Planning on going out again on the weekend,powder has come in, dogs are tired) and test ...
1) new powder lot
2) re-turned vs fitted using known load
3) new load,reduced a hair) with a jump and 250M primers
4) re-visit a fire form load that was slow,2650 fps) but shoot in the 1's - maybe my best 300 to 600 yds load and why not, less powder and more barrel life, hate to over look it.

I will let you know how your neck experiment works out.

Take care and good shootin' to you too Al.

kds