2 - 6 PPC questions

308sako

308sako

New member
First: Should the fired case accept a bullet without resistance in a turned case fitted neck barrel.

Next; Help me get rid of .25 MOA of vertical... please!
 
The neck after firing will be a tiny bit larger in diameter and therfore a bullet would or could fit snuggly! However you need to neck size your cases with a bushing type die, you can decide on how tight you want the bullet to be held by varying the dimension of the bushing in the die. I currently use a .257 if I want more tension I go down to .256 or less tension .258.

As for your .25 of vertical there can be a couple of reasons 1. your front rest bag is to hard this induces vertical. 2 Increase or decrease your powder charge, sometimes a few tenths up or down in charge will make the vertical dissapear. 3 Bench Manners, sometimes gun handling can and will induce vertical. I hope this helps you a bit, there may be other problems but you have a few starting points that may cure the problem. Oh and I hope you have a set of flags that your shooting over because wind coming at you can induce vertical, also mirage. If your shooting at desert sportsman the range is a tricky one cause theres usually wind and this time of year usually pretty good wind gusts.
 
New cases that are turned for minimal clearance will often require a bit of pressure to seat a bullet. This too will pass. If it doesn't, take another look at your neck clearance.

"Fitted neck" used to mean that the cases chambered with zero neck clearance. The case neck is turned such that the bullet is seated (with fingers) to the extent of the turned portion and the resulting neck diameter equals the chamber dimension.

Is that how you are set up?
 
When neck sizing, ensure that it is accomplished with a Full Length sizing die with a cavity for a bushing. A carbide bushing is best. You're looking for consistency with the 6PPC, and it will deliver, if the entire case conforms to its designed dimensions. Full Length size each time you reload.

One great source with very reasonably priced dies: http://harrellsprec.com/index.php?crn=207&rn=384&action=show_detail There are others.

My source for carbide bushings: Bud Mundy, Director, Mississippi Valley Region, NBRSA, 636-797-5786 or 641-425-3397. Cost:$30 each, but they eliminate the task of lubing necks.
 
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Vertical can come from the front bag and from too little neck tension...after checking your front bag try smaller bushings by .oo1" increments to find where the vertical deminishes...as a last resort move your seating depth from jam to jump...moving about .005" at a time...sometimes they will group well with a lot of jump...I have a 6BR (zero freebore 14 twist) that shoots best (66 grain Barts) with a .015" jump...

Food for thought...

Eddie in Texas
 
Thanks for the responses; Yes I do shoot at Desert Sportsman's, and the wind like everywhere else is a B**** at times.

The loaded round is .2623" and the fired neck appears as .2634" Guess it is not a fitted neck, but a custom chamber with a .264 neck indicated. I do F/L bushing die re-size my cases and am currently using a .258 bushing. There is definite bullet pull present.

I really do appreciate the bench technique advise, and think that has a lot to do with my poor shooting. I will try to vary the forearm position as well as the butt's.
 
308sako said:
The loaded round is .2623" and the fired neck appears as .2634" Guess it is not a fitted neck, but a custom chamber with a .264 neck indicated. I do F/L bushing die re-size my cases and am currently using a .258 bushing. There is definite bullet pull present.
Click to expand...

With a .2640" neck chamber and a loaded round of .2623", total clearance is .0017" [1.7/1000 thds] or .00085" [8.5/10,000 thds] per side. So far so good.

It's hard to believe bullet pull is present if the numbers above are correct. Something appears out of kilter. Here's why.

If you have a loaded round OD of .2623" and used a .2580" bushing, you've applied .0043" [4.3/1000 thds] of tension to the bullet with the case. Plenty of tension, so much so, that it could not be moved or pulled by hand.

I have the traditional .2620" neck. My loaded round OD is .2600" I use a .257 bushing. I'm applying .003" [3/1000 thds] of tension and need a bullet puller to extract the bullet.
 
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Abintx, I agree that I have plenty of bullet pull! Before loading the cases the necks show .2595 after sizing with the .2590 bushing, I sometimes have tried the .258" bushing. I assume springback is what gives the extra .0005". It is after the case is fired that the bullets don't re-enter the necks... but I agree that these dimensions should be good. Some of the groups I am firing are getting 3 rounds into the low one's... and then "flyers" usually to the vertical. Looks like some shooter error for the most part. I will be working on that.

Thank you.
 
Do you have a very strong ejector spring that dents the necks? With almost two thousands clearance, the bullets should slip into the neck on fired unized brass!

//Peter
 
Sako HART barreled 6 PPC .264 neck, Leupold 36X D series small dot. Factory match trigger. Sako .220 Russian brass from the 1980's and Fed 205M primers. Currently using AR Comp as propellant and loving it!

Well, by paying extreme attention to the bag placement and tracking... and all the best I could do, considering I forgot my wind flags (Duh!) the rifle's 2 best groups were in the low 2's, and the best clusters within the groups were as low as the 0's for 3 rounds and mid teens for most... If only I could shoot now.

Thanks for the inspiration to focus.
 
308sako,
are you using the sako stock?
i shoot alot with the std 461/579 stocks and they are not easy to use on the bags like a BR stock is, being the butt is sloping very different to the line of flight, unlike a BR stock where they are more parallel, also the fore end is rounded on the edges, so they rotate some what.
if you are using this style of stock, make sure the cheekpiece is clear of the ears and try a little more forward pressure when firing, being the opposite to free recoiling
i have little experience with BR shooting, but i think it is a technique that suits your setup, you are chasing
best of luck
JB
 
JRB, Yes I am using the Sako wooden stock, while it has been glass bedded years ago. I also use a device called the HART accuracy asset. It is a plate which simulates the flat BR style forend commonly used to "prevent" canting. The rifle appears to do best when I don't touch it, so free recoil will be my method. Thanks for the response.

D
 
Look at the carbon ring around the outside of the neck after your round is fired. If the carbon ring is a straight line around the circumference of the neck, your neck isn't turned thin enough. If the carbon ring dips down, them you have enough clearance.
 
Mike
In your opinion sir, do you think you can have to much clearance? say .005. will that extra clearance effect accuracy? Just curious? I know you will be working the brass more when sizing, but i just wonder if accuracy would suffer? Lee
 
Too much clearance might not hurt anything, but I doubt if it helps anything. The necks wouldn't last as long as they would split over time. That was one of the things I noticed when I started shooting benchrest was that the brass lasted so much longer than factory rifles.
 
Now that carbon ring look see has definite possibilities. Seems to me the carbon has only been going half way down the necks, to about where the bullet base was before motion... But with that thin a neck and the pressures, isn't that to be expected?
 
In a well tuned 6PPC the carbon on the case neck will typically look like a sine wave going around the neck, with several peaks and valleys. It will not be perfect, but that is the general shape. A comment on the accuracy asset...the one problem that I see with these is that the slimmer stocks that they are designed for are usually too springy to do their best work when they are supported that far forward on the forend. It may be that some advantage can be had by rigging something up that allows you to support the rifle farther back from the forend tip. Supporting the rifle that far forward could contribute to vertical.
 
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