What makes a bullet shoot BAD!

[RonAKA]

Shot a set of groups with the 62 Grain Berger today, and nailed the velocity I was looking for - 3400. Went from a 10 jam to 20 jump. The group sizes were the best so far, but by an insignificant amount. They are still nearly 10 times the size of the best groups. I think I am going to have to accept that this bullet and this gun have irreconcilable differences. May try it again at a 40 jump just for curiosity (and to use these things up!).

I'm starting to think that this gun likes a longer bullet bearing surface as compared to a shorter one. Wonder what the length of the bearing surface has on trajectory as the bullets exit the muzzle. It would seem like a short bullet and larger bore might be a bad combination.

 

[jo191145]

Ron

I know from one of your other posts your theory that 3400fps worked for 68's that it should work for other bullets as well. I'm a big fan of Creighton Audette but theres a flaw perhaps your not seeing.
Time in the barrel MUST be measured by the base of the bullet.
Seeing as your 62's and 68's have different bearing surfaces 3400 will not work, theoretically anyway ;D

It would be interesting to see if you seated the 62 the same depth into the case as the 68, then ran it to 3400fps what the results might be.
Interesting maybe but probably not worth the effort. Like you said theres times you just need to give up.
That being said I run an Audette if I just change primers. I have seen huge differences in nodes doing so.
That does defy Audettes theories. I'm not smart enough to know why. I just roll with the data as presented and more often than not it works. Thats all I ask. I would suggest you bury them 62's .150 in the case and run a full Audette again. Let em run wherever they want. Might work, might not.

FWIW I run the 68's at 3550 with X-Term. Just found a HOT node at 3690 for the 69's. Definately will not be using the Fed 205's if I decide to explore that further. It is as they say, HOT ;D

 

[BoydAllen]

If you would like to know if your bullets are the problem, send them to me and I will test them with one of my barrels for my Viper actioned, 10.5# 6PPC. I have every confidence that, under favorable conditions, groups in the twos will be the result, possibly bettter, with my tuning and shooting skills being the limiting factors. Contrary to some reports in this thread, I have found Berger bullets to be as easy to tune as any others. Because of their availability, I recently recommended that a friend choose them (68 gr. BR) as a good starting point for his new 6 PPC. He is a record holding rimfire Benchrest shooter, with a high level of shooting skill , and speaks fluent windflag. Under good conditions, he has shot many teen groups with those 68s. Being a curious fellow, he has tried several other brands of bullets, even though I remind him that they are all made with the same jackets. I have not heard that any of them have been more accurate than the Bergers. Send the bullets, I will work up a load. It may not be a good load in your rifle, but we can at least rule out the bullets.

 

[bozo699]

(Quote)Contrary to some reports in this thread, I have found Berger bullets to be as easy to tune as any others.

BoydAllen,
I have made the statement they are harder for me to tune than serria or lapua's
I don't disslike them though I know if you get them to shoot they shoot!! anyway what is your method from say start to finnish. You build a new gun where do you start with your load work up using bergers,lets just say it is a 6br for arguments sake. I would seriously like to know as I have plenty of bergers in just about all calibers and would like to use them.
Wayne.

 

[mikecr]

RonAKA, did you load develop seperately for each bullet tested? Why were all bullets jammed?
Try finding the best seating first, and with enough neck holding the bullets.

 

[BoydAllen]

First of all I evaluate the ogive shape, and pick a starting seating depth based on experienced on what has worked well with that general shape. For single radius ogives, around 7, I like to start with rifling marks that are about one third as long as they are wide.

All of my load development is done loading at the range (important), over wind flags, on a day when the wind is fairly light and not too difficult.

My first task is to do a pressure series, with a powder that has the prospect of having a full case at peak usable pressure, based on bolt lift.

I FL size every time I load a case, with a die that does not move the case much, adjusted for a shoulder bump of .001, on the cases that I happen to be using that day. I fire a set of cases in strict rotation, so that they will continue to have the same number of firings and sizings. Sets will require different die settings depending on their degree of work hardening.

For a case the size of a PPC or BR, I use charge increments of .3 grain, starting well below my desired velocity level ( based on loading manuals and some guessing) I shoot the series, one shot per load, onto one target, at a single aiming point, paying close attention to the flags, and noting how the shots cluster, or don't, as pressure rises, until I get a shot that feels a little too tight as I lift the bolt.

If the powder seems to have potential, I will pick a load that showed little change in POI as the charge was changed (middle of that range) and retest, with a fast two shot group. I feel that the fewer the number of shots, the greater chance of their being able to be shot in the same condition. With my bench rifle, I can fire a second shot within five seconds, or less, of the first. It the two shot group looks good, and conditions are reasonable, I will try a group with three and then five.

Depending on what I see, i will make small changes in charge and seating depth, one at a time. Hopefully, this results in a load that looks like the differences in POI are all about my shooting and the wind. Usually this means the ability to shoot low twos in good to average conditions and mid to high ones on rare days when they are perfect.

For your 62 grain bullets, i would use the seating depth that I mentioned, with 205s and 133.

Many times I encounter shooters who make excuses about not loading at the range, I think that this is more of an "uncomfortable with what I am not used to" problem, than a real one. For powders that do not measure reliably, (133 being right at the edge of this group, requiring good consistent technique) I have a scale wind box, that contains a scale and trickler, so that they are out of the wind when the cover (glass) is closed, and allows powder to be trickled with the cover is closed.

Some way to look at the wind is also a must. Sticks with surveyor's tape are OK if you don't have flags.

Good luck

 

[bozo699]

BoydAllen,
My reloading room and shooting range is located 50 yards from my house so I am very fortunate there,When it is really cold or hot I can shoot out of my reloading room otherwise I have outside benches. Thank you for giving me your method for load workup,I will give it a try. I may have a question or two,might have to pick your brain again. Many thanks.
Wayne.

 

[RonAKA]

RonAKA, did you load develop seperately for each bullet tested? Why were all bullets jammed?
Try finding the best seating first, and with enough neck holding the bullets.

I did a ladder for each bullet. The one for the 62 grain was brutal and almost meaningless. Early on, I did some testing with the 80 and 69 grain on seating depth and in both cases got better groups with a jam. I intend to close the loop and check the best loads with different seating depths.

And, to the other posts, perhaps just to restate again, these groups are BAD. With the other bullets this gun can easily shoot groups where all holes touch at 100 meters. With the 62 grain, it is in comparison a shotgun pattern. We are not talking a subtle variation. It is not a wind or shooter issue I'm not trying to suggest that it is a Berger bullet quality problem either. It just seems to be a strange reaction with my gun, and I'm trying to figure out what it may be, just as a self education process.

 

[jo191145]

Ron
I understand the self education part. Thats the most fun part of this hobby.
With the 62's you stated you have .050" shank in the case with .010 jam past "just touching"
Obviously your at the practical limit of the chamber. Jamming further is just not an option.
Thats why I suggested to seat the bullet deeper into the case and try a jump. A massive one even.

Large jumps to the land require a slightly different tuning method. Powder charge comes first followed by neck tension and subsequent consistency of said neck tension. Neck tension essentially becomes the lands/ jam. Once thats squared away small seating depth variations to fine tune "time in barrel" come into play.

A previous poster "Mark" stated horizontal can be tuned by seating depths. I'm probably one of a few that agree with him. Horizontal can be tuned out. Mostly by seating depths. In your case with massive horizontal that calls for massive changes.
The old rule developed long before I started serious shooting goes like this. Vertical grouping is fixed by upping the powder charge and seating further into the lands. Horizontal is just the opposite. Take into consideration this old wives tale was developed for very fine tuning of a load.
Its not a rule carved in stone. Few are. Most times it will show improvement. Occasiionally its just the opposite.

In the end you'd be best served by using what your gun already likes. Work with that and strive for consistency. Can you shoot 50, 80, 100 rds of that load through your barrel without cleaning and maintain acceptable accuracy. Thats the next big question/hurdle. Repeatable accuracy. Very few powders can do it. Do you even need that for your specific shooting requirements or are you a barrel scrubber? Thats a big question=) Personally thats my first demand.
Toy with the other stuff when you get bored. Its all a learning expierience.

 

[bozo699]

RonAKA,
I can feel your flustrations,it has been a long thread I myself have got off topic and have missunderstood some of it, but will stick to the thread till you get it figured out. I have had same problem in the past and finnaly did the easy thing and gave up don't give up. I my self have learned a great deal from this thread,Thanks.
Wayne.

 

[RonAKA]

I know from one of your other posts your theory that 3400fps worked for 68's that it should work for other bullets as well. I'm a big fan of Creighton Audette but theres a flaw perhaps your not seeing.
Time in the barrel MUST be measured by the base of the bullet.
Seeing as your 62's and 68's have different bearing surfaces 3400 will not work, theoretically anyway

That is an interesting thought. Had not considered the effect of seating bullets to different depths on barrel time. I know that a change of 50 fps can have an effect on group sizes, so I wondered if I could calculate how much you would have to change the seating depth to give the same barrel time as a change of 50 fps. It worked out to be 0.360" to equal a velocity change of 50 fps. That is quite a lot. And working it the other way around a .036" change likely is about equal to a 5 fps change in velocity. Not sure that should have a significant effect on group sizes.

 

[BoydAllen]

It terms of when in the muzzle' vibration cycle the bullet clears the crown, I think that there is more going on than a slight velocity change would indicate.

 

[RonAKA]

OK, I don't give up easily, but today was it for these stubby little 62 Grain *!#*!!'s. I have no clue why, but these things just do not agree with my Savage. I seated 9 more of them at a more normal seating depth just over 0.100" into the neck. This gives me about 0.070" jump. They shot the worst set of groups ever in this gun, at nearly 2".

Interestingly in the previous load shot today, I got my second best set of groups with the other (former) problem child, the Berger 69 grain High BC Varmint. These bullets were seated so short in the neck, I'm sure you could just bend them out of the neck. Average group size was 0.250", and the velocity was not likely ideal.

Here is a graph to show how far off the mark these 62 grain bullets are. This graph represents all 3 shot, 3 group averages I have to date out of the gun. My code for the data points is the grains, B for Berger, and either V for varmint, or T for target.

I've run out of ideas...

 

[mikecr]

It isn't powder or bullets causing 2" groups. It's wrong seating depth.
If you don't believe me, find the best seating depth for the 62s, then vary the powder from one extreme to another. It will never get so bad as 2" with this, and somewhere in that powder spread you'll match or beat the others..

Only seating can cause such chaos in a gun capable of <1/2moa

 

[RonAKA]

It isn't powder or bullets causing 2" groups. It's wrong seating depth.
If you don't believe me, find the best seating depth for the 62s, then vary the powder from one extreme to another. It will never get so bad as 2" with this, and somewhere in that powder spread you'll match or beat the others..

Only seating can cause such chaos in a gun capable of <1/2moa

The green triangles in the graph above are the 62 grain loads. Going from left to right they were seated at 10 jam, 20 jump, 10 jam, 71 jump. Where would you suggest exploring? Essentially all of the sub 0.5 moa loads were a 10 jam. If I try for more jam, I suspect the bullets will fall out.

 

[mikecr]

Well I don't blame any desire to drop the 62gr bullet with this. All I could suggest is what I do;
With a mild load, vary seating 10jam 5off, then 10off to begin. Then I tweak smaller. Then I move on to primers & powder with my seating forever set on that bullet/barrel.
With one of my guns shooting 139Lapuas I run 5off even.
+/- 3thou from this is a stepping point grouping size outright triples(even with different powders/primers)!
So my combined HS/seating error MUST stay below 3thou, but thats a huge margin really.

I've never gone so large in seating adjustments as you.
So just throwin that out there.

 

[RonAKA]

OK, I will give it a try. These things are just foulers now, so nothing wasted in trying except the primers, powder, and barrel life. A regular at the range likes 0.003 jump. I have kind of avoided anything real close to the 0.000 touch the lands as any error will be a jam/jump mix. I just use the split case method of setting my cartridge seating depth, and 0.005" is probably a realistic tolerance of error. So I will try 0.005 and 0.010" off to see what that does. I don't feel very optimistic though...

I still think there is something else much more major going on. That was my reason for trying the 0.071" jump and normal seating depth in the neck. I thought the total neck depth was much more significant than the jam/jump. Turned out not to be the magic solution.

 

[6BRinNZ]

RonAKA - what are your thoughts on neck tension affecting things with this bullet?

 

[RonAKA]

RonAKA - what are your thoughts on neck tension affecting things with this bullet?

I have maintained neck tension exactly the same on all the loads since I started shooting this 6BR. It is real close to 0.001" fit, with a .267 bushing. About the only thing I have varied is the method of cleaning the neck and the lube. I have used graphite since the start but on the last set of loads I used a nylon brush to apply it, instead of the 7 1/2 lead shot and graphite mix.

 

[jo191145]

Me? Personally? As a last minute hail Mary just for ha ha's. I'd push em faster and quite a bit. JMO

Never tried H-322 in the 6BR. No idea if it can get em going faster without pressure.
Tried H-322 in the 6PPC. Shot some real tight groups. Day to day it needed constant tuning to keep those tight groups. Even more than N-133 in my expierience. Haven't used it since.

Beyond that, forget it and move on. Chamber and rifling is geared towards 68-80gns. Go with it.
In a short throated 14-12 twist I have no doubt those 62's would come alive. Perhaps its just not to be.