Handload Vertical Stringing Help

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dedrevil

New member
So I ran up my first load of some of the 135gr 6.5 Creedmoor A-tip.
Strang 4 rounds vertically, one flier, 1.6" group @ 100yds (ran 2 other 5 shot groups that were similar). Load data was Hornady's recommended powder charge and OAL as a starting point, case capacity seemed ideal using RL-16.

Then, I shot 4 rounds of Hornady American Gunner BTHP 140gr (literally the cheapest thing at the gun store) and it did 0.6" group with 3 touching and one flier.
I then did 5 shots on the chono with my handloads (just a Caldwell chrono):
StdDev: 60 fps
ExSpread: 119 fps
Average: 2740 fps (i was going for 2725 fps)

I have been handloading for a like 6 years but this is my first attempt at the long-range/super-accurate loads (sub-moa type). Normally do bulk or hunting loads moa-ish.

I am trying to figure out why the high spread on chrono and stringing. If the chrono is accurate I am assuming my Velocity inconsistency is what causes the stringing, but not sure why...

I am using a Hornady single-stage
micrometer seating die, with the a-tip seat, digital powder measure

135gr A-tip, hornady brass, tried superformance and RL16 (both had similar chrono results), fed 210m primers
Tolerances:
Seating had +/- 0.002" (measuring off the bullet tip, I have ordered a comparator but didnt use one)
Powder was +/- 0.1 grain

Gun is a Bergara HMR, vortex ffp 6-24x50, benchrest using front bipod and rear bag.
 

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Your 60 SD us an indiation of your consistant reloads. Try the factory loads over the chrono and you will see most likely see around 10-15 SD.
There is one major difference in the store bought and reloads: NEW UNFIRED BRASS. It's in the brass preparation.
 
That ES is too high. It isn't necessarily the direct cause of the problem, as bullet fall is very small at 100 yards, but the pressure difference generating a velocity spread that wide is enough to move the barrel time in and out of a sweet spot. For long-range, you want to try to get the velocity SD down as close to 10 fps as you can.

First, let's look at the case fill. I've seen 80% case fill cause 80 fps spread in velocity just depending on whether the powder was forward against the bullet or back against the primer when fired. This is easily detected by carefully handling every cartridge the same way and then always pointing the muzzle up or down and bumping the stock to get the powder in the same place before leveling it to fire. The is also a manipulating procedure called the "SAAMI twist" you can use, but it is mainly necessary when the gun is in a fixture or guide of some kind, like a universal test receiver, and you can't raise or lower it easily. The bumping works well with guns you can raise or lower. Raising the muzzle produces maximum pressure and velocity, making it the best safety check, but some ranges don't allow it, so check your local rules.

The second thing to concern yourself with is primer seating. Optimal seating compresses the anvil nose into the priming mix about 0.003" past the point where the anvil feet contact the bottom of the primer pocket. Naval Ordnance at Indian Head worked this out in the early 1980s. The late Creighton Audette published some on the subject near the end of his life in the early 1990s. You can buy the K&M Primer Gauge tool to repeat it perfectly, but the late Dan Hackett wrote:

"There is some debate about how deeply primers should be seated. I don’t pretend to have all the answers about this, but I have experimented with seating primers to different depths and seeing what happens on the chronograph and target paper, and so far I’ve obtained my best results seating them hard, pushing them in past the point where the anvil can be felt hitting the bottom of the pocket. Doing this, I can almost always get velocity standard deviations of less than 10 feet per second, even with magnum cartridges and long-bodied standards on the ’06 case, and I haven’t been able to accomplish that seating primers to lesser depths."

Dan Hackett
Precision Shooting Reloading Guide, Precision Shooting Inc., Pub. (R.I.P.), Manchester, CT, 1995, p. 271.​

Other factors are as expected. Make your charges as identical as you are able for your test loads. Fire two or three fouling shots to get the gun safely past first-shot differences. Hold the gun exactly the same way for each one. Let the barrel cool the same amount between shots. Use 5 minutes if you suspect a heating phenomenon, and then see what you can get.

The chronograph being off is always a possibility. The simplest test is to take a .22 rimfire rifle with an 18" or longer barrel with you to the range and bring a box of match ammunition for it. Because .22 LR ammunition burns all its lit powder inside the barrel, .22 LR Match ammunition from a barrel that long produces the velocity claimed on the box within 50 fps. If your chronograph reads it within 50 fps of the box label for ten rounds, the chronograph is most likely reading OK. Bigger guns can cause false triggering of sky screens with muzzle blast debris, so be sure to set the center of the unit at least 15 feet away from the muzzle, if you haven't already done so. If you were closer than that and going back further reduces the measured velocity spread, you have found the goblin messing with your readings.
 
Let someone else chronograph your rifle and ammo.

If they get much less velovity and vertical spread, you're not holding the rifle the same for each shot. Big short range spread is usually caused by inconsistent vertical position of rifle contact with shoulder.

Ballistically, a 50 fps velocity spread causes less than 2/10th inch drop difference at 100 yards.
 
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Well, Wednesday I play with the powder charges and do a load development test, chrono every shot and try to find new brass.
 
Bart B. said:
Let someone else chronograph your rifle and ammo.

If they get much less velovity and vertical spread, you're not holding the rifle the same for each shot. Big short range spread is usually caused by inconsistent vertical position of rifle contact with shoulder.

Ballistically, a 50 fps velocity spread causes less than 2/10th inch drop difference at 100 yards.
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Well, I would love to have a different chrono. I don't quite trust the $60 Caldwell haha

That day with factory ammo I shot a 0.62" and a 0.74", and with the atip reloads a 0.98" and a 1.61". I'm a decent shot, but by far not the best shooter out there. However, obviously the gun and I are capable of sub-moa.

If each shot went higher or lower than the next, then its possible the 60 fps deviation would be accurate to the spread seen. Ballistic calculators say between 2/10 and 3/10 of an inch difference at 100 yards, theoretically. I averaged about 0.35" distance between each shot top to bottom, but I don't remember what order they were shot in.

Although, it does seem a good idea to either film each group or at very least memorize and mark each shot in the order fired after each group.
 
Since you posted that you shot a decent group with the factory ammo that would pretty much rule out the rifle, optics and your technique as far as I am concerned. If you are lucky it will be a simple length or powder adjustment. I never loaded for a 6.5 CM but it's baby brother the 6.0 CM, was a snap to find a load for. I did a thread here awhile back on it's initial load. I am still shooting the load I found with it. I have never even bothered to fine tune it.
 
So today before loading up a new batch I am going to try and get a comparator and bullet seat gauge thingy. One of the links posted by ya'll I read he seats 0.020 off the lands, maybe ill try that.

How do yall decide where to start on LD testing, Ive searched for a long time and cant find anything on 135gr A-tip loads.

With RL-16 hornady's book starts at 2600fps w/ 38.9gr and ends at 2850fsp w/ 42.8gr. I started at 41gr and am starting to show over-pressure signs: slightly flattened primers and light ejector stamps.
 
Well, I had an interesting trip to the range this morning, I'm still entering in all the data. However, the vertical stringing issue is gone, unfortunately, I changed too many variables to know what caused it. :D
This time I used new brass, trimmed, and a longer COL than what I used in the rounds that strung; however the stringing load (41 grains) also produced the worst groups today, albeit with no stringing.

The best group of the day was a 0.72 MOA, velocity SD was 13.45 and ES was 26. The best SD of 9.64 produced a 0.84 MOA group. Which is interesting because powder charge consistency was the same as the group that produced a 60fps SD.

So, I seated at the maximum COL listed in Hornady's manual which was still 0.100"+ of the lands. Apparently this barrel has a crazy long throat. (2.825" from Hornady, touching the lands was 2.933")

Might do a new load up using the best group of the day but seat closer to the lands. See what happens. I have read mixed reviews on how important land clearance is. Some people claim the pros seat 0.002" off and other people claim 1/3 MOA with 0.256" off the lands.
 
There are a lot of factors involving technique that come into play that could account for every thing that you have posted. People tend to want to blame their equipment when the groups disappoint because in their mind their technique is better than Tony Boyer on a good day. Something as simple as cheek weld, shoulder pressure, grip or even moving a foot forward a few inches between shots will cause a change in point of impact
 
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Daredevil,

There is no one "magic" distance off the lands. Different guns and different bullet shapes have different optimal amounts of bullet jump. The best can turn out to be anywhere from full contact with the lands to over and eighth of an inch back of them. It's just another variable you have to test.
 
hounddawg said:
There are a lot of factors involving technique that come into play that could account for every thing that you have posted. People tend to want to blame their equipment when the groups disappoint because in their mind their technique is better than Tony Boyer on a good day. Something as simple as cheek weld, shoulder pressure, grip or even moving a foot forward a few inches between shots will cause a change in point of impact
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Tony Boyer isn't two-hand holding his 2-ounce triggered 10- or 13-pound rifle against his shoulder to aim it. He positioned it on bags so it recoils exactly the same for every shot, freely without interference from human holding variables.

I don't think people believe their techniques are better than Boyer's. Most don't know exactly what Boyer's techniques are as well as the differences in rifle and ammo types. "Most" equals smallest fraction over half or greater.

Everyone won't shoot the same stuff equally precise.

A free recoiling, 3 point supported machine rest that let's rifles recoil most naturally is best for rifle accuracy testing, I don't think any are commercially available that let's rifles recoil like they do when fired hand held off ones shoulder.
 
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Everyone won't shoot the same stuff equally precise.
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Bingo ! That was the point of the Boyer reference. Also the environment changes from range day to range day and it won't be cloudy, calm and 65 F

Take the same ammo, same gear, go to the same range and have the same guy pulling the trigger and one week get multiple sub MOA centered 10 shot groups at 800 and the next week he can be off center by a full MOA and shoot a 1.5 MOA group.
 
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hounddawg said:
Take the same ammo, same gear, go to the same range and have the same guy pulling the trigger and one week get multiple sub MOA centered 10 shot groups at 800 and the next week he can be off center by a full MOA and shoot a 1.5 MOA group.
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As soon as a shot missed call limits, I'd be adjusting the sight.

Letting all those full MOA off center shots not being corrected for is poor marksmanship behavior.
 
As soon as a shot missed call limits, I'd be adjusting the sight.

Letting all those off call shots not being corrected for is poor marksmanship behavior.
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hard to correct for what you cannot see.

My spotting scope is not powerful enough to allow me to correct on the fly at anything beyond 300 and my range does not have pits with spotters. Like most of us when practicing I have to shoot, wait for cold range, examine the target, get back, wait for hot range, adjust and shoot them rinse and repeat.

That's ok though, daddy had a target camera coming on the UPS truck
 
I Handload and shoot 6.5 Creedmoor, my rifle is a Custom Turk Mauser, 24",1:8" twisted #2 contour sporter.
It likes the Starline Large primer brass and it shoots 5 different bullets and powder combos well.
Well means to me under moa, and about the same point of impact on a target at 100 yds.
When I have any test or loads that I vertically string, I go back to fundamentals and shoot it again to make sure it in fact was me or it didn't like the combo. Sometimes it's usually a trigger and shouldering foul up on my part.
If you can get it, try RL 26. I can't get it here so I'm using rl23, Rl19 for 140's and IMR 4451 for 120 range weight bullets and h4350 for 130 grn Berger's where it has put 9 rounds in a dime at 100 yds, when I don't get in the way.
 
So, I was reading a post where someone was having trouble handloading with their bergare in 6.5C (they were loading lighter bullets too). So I decided to try something, I chose the powder charge with the best group from the ladder test and seated 3 rounds at 0.033" off the lands, and 3 rounds at 0.053" off. (i only had 6 bullets of the ATM left at the time).
the 0.030 off shot 0.75 moa and the 0.050" off shot 1.48 moa, so then I started thinking maybe its not just longer seating depth, maybe it likes a longer heavier bullet too. Soo I had some factory loads I tried.
Hornady Match 147gr ELD-M and Hornady Superformance 129gr SST

The 147's beat out the 129's every way. 147's have an average group size of 0.55 moa with a max/min of 0.63/0.46 moa. 129's averaged 1.62 moa with a max/min od 2.22/0.94 moa.

Im either going to try to handload some 147 eldms or some of the 153 ATM (just depends on what the store has) and will report back.

Also, when good ol' hounddawg blames it on my shooting ability, again lol, Monday I shot these consecutive groups with my home-built AR-15 chambered in 6.5 Grendel with factory ammo.
 

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Since you posted that you shot a decent group with the factory ammo that would pretty much rule out the rifle, optics and your technique as far as I am concerned
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from my post # 8

must be nice to have perfect form and perfect conditions every time you go to the range. Now go do a few 10 round groups like that and I will be impressed,
 
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dedrevil said:
So, I was reading a post where someone was having trouble handloading with their bergare in 6.5C (they were loading lighter bullets too). So I decided to try something, I chose the powder charge with the best group from the ladder test and seated 3 rounds at 0.033" off the lands, and 3 rounds at 0.053" off. (i only had 6 bullets of the ATM left at the time).
the 0.030 off shot 0.75 moa and the 0.050" off shot 1.48 moa, so then I started thinking maybe its not just longer seating depth, maybe it likes a longer heavier bullet too. Soo I had some factory loads I tried.
Hornady Match 147gr ELD-M and Hornady Superformance 129gr SST

The 147's beat out the 129's every way. 147's have an average group size of 0.55 moa with a max/min of 0.63/0.46 moa. 129's averaged 1.62 moa with a max/min od 2.22/0.94 moa.

Im either going to try to handload some 147 eldms or some of the 153 ATM (just depends on what the store has) and will report back.

Also, when good ol' hounddawg blames it on my shooting ability, again lol, Monday I shot these consecutive groups with my home-built AR-15 chambered in 6.5 Grendel with factory ammo.
Click to expand...

Looks like you are getting it figured out...Good for you.
What is your bench set-up like front rest with rear bag or a bi-pod with a rear bag?
 
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