6 PPC bullet seating depth

Iv'e been reading everything I find on this site for 2 or 3 years now regarding the 6mm PPC, still seems that I have to try everything to understand what I read. Not a problem since I love shooting so much! Have read so many times about bullet seating depth and doing multiple measurements and taking the average..... over excited or what, not sure but only did one measurement and was too long,spilled powder all over the action and shut me down for the day! learned my lesson I hope . Oh well, hopefully this time the lesson will stick. Just want to thank everyone for their patience with me and others that don't have the benifit of others at their Club that shoot actual benchrest. Can't wait for the weekend to try different seating depths to see what results I get.

Rodney
 
OK, here is a plan. It works for me. I don't make any claims for it. It involves making a dummy round to create a known reference point.

1. Prep one piece of brass as normal. Do not seat a primer.
2. Strip your bolt so that you have better feel and for safety.
3. Set the seater stem long enough that you know the bullet is into the lands.
4. Seat the bullet.
5. Pull the bullet and examine it with a magnifying glass for the rifling marks.
6. Adjust the seater to seat just a tad deeper. "a tad" is relative to how short the rifling marks are getting.
7. Polish the bullet with some #0000 steel wool.
8. Repeat till the rifling marks just disappear.
9. Label the bullet with the bullet name and the number of your barrel.

From there, I use die shims to control how far into the lands I am. With my 30 Major, 30 BR, 6 PPC and 220 Beggs, I only seat with the bullet in the lands. Since I'm an idiot at times, I actually spent the money to buy a seater top and stem for every bullet barrel combination that I settle on and I mark them with an engraver.

With my new 7 Shehane I'm playing with seating with jump. Soooo, I did the above process with a seating shim already in place equal to what I've been told the maximum jump will be. In this case, 0.025". In other words, instead of my reference being where the bullet is just touching the lands and adjusting deeper, my reference is 25 thou off and adjusting for less jump.

This is pretty much what I get from reading Tony's book and throwing in a little of my personal OCD. Your Mileage May Vary.
 
An easier method maybe..

Start with the bullet seated such that you can close the bolt without trouble. That will take some time as you can't close the bolt on a round too long. Just keep nudging it in little by little until you can just barely live with the bolt closure. Seat a few bullets with this setting and shoot them. Repeat with less and less bullet length until you find what it likes. You only have one direction to go given that you can't go longer. If you have to go longer to make it shoot then start saving for another barrel cause that one is not gonna be good...takes too long to load and re-aim....no matter how well it shoots. You can't win if you can't load and shoot quickly - largely stated.
 
IMG_20140512_174201.jpgOK so I went to the club this wekend with 5 rounds loaded the same as last week, 29.2 grains of LT 32 and Berger columns set 1.760 to the ogive according to my Hornady tool.
This is the first time with this rifle that I ever experienced the first shot from cold clean barrel was .827 inches out of the center of the rest of the group!
The rest of the groups were with 28.3 grains of LT 32 as that was a load that seemed most consistant over all on my last few outings. I went .002 deeper seating with each progressive 5 shot group until I was at .020 off my maximum length by the last of 45 rounds loaded with the 28.3 grains of LT 32.
I have come to the conclusion that no matter how or what I load my groups are going to be very inconsistant until I start working on my technique, put up wind flags then rushed my shots when I figured the conditions were similar to what they were for the last shot. A couple times I took a shot... bullet not even in the group, oh yeah look at the flag and it is flying straight out from the peg!
Having said that I shot a .150, a .264, a .314, and a .352 group out of 10 groups so I think I am on the right track. The .150 group was at 1.748 to the ogive.
I have to say I don't think I have ever shot this rifle in such a switchy wind condition before. The wind was coming steady and strong from behind us and changed left to right every few seconds!

Can anyone tell me how much the wind (on average) can move a 6 mm ppc bullet at 100 yards? The majority of my groups (other than the cold clean bore shot), had a lot more horizontal than vertical.

Rodney
 
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How far on average?

Same wind at Cactus and Fairchance. Density altitude at Fairchance I am sure was much lower and moved bullet at least twice as far, just a guess but 3 inches at 100. I held on left target frame at 200. Some and I am told the better option dialed in a load of windage. I do not think an average has much value.
Trout
 
r44astro said:
Same wind at Cactus and Fairchance. Density altitude at Fairchance I am sure was much lower and moved bullet at least twice as far, just a guess but 3 inches at 100. I held on left target frame at 200. Some and I am told the better option dialed in a load of windage. I do not think an average has much value.
Trout
Click to expand...

Thanks Trout,
At least I know that some of my issues might be me not reading the wind correctly. Also my technique still needs work but can't blame the rifle!!

Rodney
 
You're wasting time, money and barrel life testing with five shot groups. Shoot three shot groups during tuning. Even then, if you shoot a good shot and the second goes way out, save the third.
 
For preliminary testing, I figure that two shots, shot as rapidly as possible, assuming the condition will hold for a few seconds, will give the best shot at the conditions being the same for both. I try to test when conditions allow this. If two look ugly, more will not fix it. Once I have narrowed things down, I shoot groups of more shots. Since I read Gene Beggs' comment about the distance between nodes for a typical 6PPC (1.2 grains), a really ugly first group, with paper between the shots can actually be pretty useful, because I figure that I am probably between nodes, and either go up or down by .6 and the next two usually look pretty good.
For seating depth, I tend to take note of the nature of the marks from the rifling. The other day this came in handy. I was working with a bullet and barrel combination that did not leave much bullet in the case necks, and after I uncharacteristically pulled a bullet trying to find jam, I decided to back off of that setting and look for the marks that usually indicate a good depth with that bullet. That worked. After I had the marks that indicated I was in the range that I wanted to be, I adjusted the powder for final tune, and was pleased with the result. Normally I seat long and chamber a round to find jam, record the die setting of that, and come out of the rifling some to give myself some protection from pulling a bullet if I have to unload a live round. I believe that one reason that I was able to get away with just using the marks is that the bullet has a double radius ogive, with a larger ogive number in the area where the rifling engraves. I have heard, and my experience agrees with the idea that these sorts of bullet shapes are more seating depth tolerant. It was Del Bishop that told me this about a bullet that he had started making at the time, one that has a 9 ogive at the back, and a 5 at the front. Berger's Column bullets have a double radius, and I think that that contributes to their success.
 
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With a 30, you can use the lands or full jam as your point of reference. Doesn't matter.

Depending on powder, etc, though, the basic recipe that works for a 6 PPC ain't a gonna work with a 30 PPC. A 30 PPC is inherently a 30, not inherently a PPC.

Look back here about what I said about a 30 BR and try it. Works in the 30 BR. Works in the 30 Major, which is a 70 thou long 30 PPC. Much like what I got about the 30 Stewart from Ralph. Will likely be a lot like what works in a straight 30 PPC.

http://benchrest.com/showthread.php...ions-with-30br&p=730206&highlight=#post730206

The problem is finding the right powder.

The node that I shoot is 2950 to just below 3000. I'm using a Shadetree, past-the-muzzle tuner on that barrel. I think it helps the node width.
 
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alinwa said:
IMO there's a lot of weather in your groups
Click to expand...

Thanks Alinwa,
I thought so when I saw how much horizontal I had. Even though I had my wind flags out I think I either misread them or didn't watch them close enough. I have a tendency to do too much visiting and not enough concentrating I think.
Rodney
 
SGJennings said:
You're wasting time, money and barrel life testing with five shot groups. Shoot three shot groups during tuning. Even then, if you shoot a good shot and the second goes way out, save the third.
Click to expand...
Hi SG,
I actually never even considered that! Always heard everyone say that 5 shots were a minimum for a group but yes....I think my feeling was that the poor shot was likely me so just keep shooting to see where the other shots landed.
Rodney
 
I took my 6 ppc to the club again this weekend, all shots Column bullets, 28.3 grains of LT32 powder.
Improved my average from .449 last week to .405 this weekend. Doing the same exercise as last week with varying bullet seating depths. The only change was to go from .257 bushing to .259 in sizer die.
I paid more attention to my wind flags today so I have less horizontal overall but now I have a new problem! Need to get used to watching for conditions and NOT rushing the next shot before conditions change so I ended up with a few fliers that I was able to call. Good news is that I now have a few seating depths that showed promise both weekends

Of course I have a few new questions! All my groups last week were slightly above point of aim and to the left, I deliberately set my point of aim away from the bull so I don't shoot out my aiming point. Today all my groups are slightly below the point of aim and still to the left. What would cause ALL groups to be lower? Wind about the same, just not as intense from behind?

IMG_20140517_212926.jpg
 
Your poi will ALWAYS change day-to-day.... an accurate rifle is never "sighted in."

It can't be.

#1-the rifle changes,

#2-ambient conditions change,

but most importantly you're launching through a 100yd river of moving air.

With no steering mechanism.

al
 
alinwa said:
Your poi will ALWAYS change day-to-day.... an accurate rifle is never "sighted in."

It can't be.

#1-the rifle changes,

#2-ambient conditions change,

but most importantly you're launching through a 100yd river of moving air.

With no steering mechanism.

al
Click to expand...

Thanks Al,
I was hoping that was the case, I noticed this before with my Sako but thought it was the wood stock doing it!
Rodney
 
IMG_20140519_182119.jpg

Went back to the club today with the 4 bullet lengths that produced the best results over the last couple of weekends, was able to get my average down to .3642
Average with the 2 seating depths the rifle likes is .2606
Looks like I will be shooting it "jammed" for the most part as that seems to be the most consistent with the best results overall.
Still seem to have some wind issues but only been using the flags for a few weeks now and need to get used to them.
Rodney
 
rodauto said:
I took my 6 ppc to the club again this weekend, all shots Column bullets, 28.3 grains of LT32 powder.
Improved my average from .449 last week to .405 this weekend. Doing the same exercise as last week with varying bullet seating depths. The only change was to go from .257 bushing to .259 in sizer die.
I paid more attention to my wind flags today so I have less horizontal overall but now I have a new problem! Need to get used to watching for conditions and NOT rushing the next shot before conditions change so I ended up with a few fliers that I was able to call. Good news is that I now have a few seating depths that showed promise both weekends

Of course I have a few new questions! All my groups last week were slightly above point of aim and to the left, I deliberately set my point of aim away from the bull so I don't shoot out my aiming point. Today all my groups are slightly below the point of aim and still to the left. What would cause ALL groups to be lower? Wind about the same, just not as intense from behind?

View attachment 14840
Click to expand...

One possible cause of the lower impact is the change to a larger neck bushing. Reducing the neck tension probably lowered the pressure and velocity. A chronograph would show one way or the other.
It may just be shooting better at the lower pressure not so much the grip. A .259 bushing won't give IMO enough grip to allow for much of a jam. The bullet will push back.

Make a target with 4 bulls across the top and 5 bulls down. Start with 4 powder weights across the top say
28.3 , 28.6 ,28.9 ,29.1
Go down each row of 4 bulls with varying seating depth.
Jam!!, .005 off,.010 off,.015 off,.020 off

Shoot 3 shot groups, in 60 rounds you may learn more than you have thus far.

IMO go back to the .257 bushing
 
Three points:

1. "Jam!!" could easily be misconstrued to be full jam. Going from full jam to 10 thou off would miss a bunch of good spots.

2. I've, personally, never jumped a PPC *anything* like 20 thou. I use just kissing the lands as an index and vary in and out by 3 thou. Seems like I mostly end up a bit in.

3. Other people start at full jam and work back toward kissing. Either way works. I start out just kissing because it is independent of neck tension.
 
JAM and each persons definition of it
That's the issue when we are talking about a few thousands of an inch.
When you jam with high neck tension as others have stated, is much different than with light tension.
When I jam with a .256 bushing you can measure a good mark left by the lands that maybe .025 wide.
Starting at that point backing out .020 ends up with what some call kissing the lands. Multiple ways to skin the cat
 
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