Large groups-runout issues

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Gun Man Dan

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Minuteman
Aug 10, 2024
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1
Ohio
#1
I’m having some issues with my groups being over MOA with a match grade stainless steel barrel. I’m chasing runout to be less than 5 thousands. First question, what gauge do you use to check concentricity of the case without a bullet? I have the Hornady concentricity gauge and it doesn’t measure only the case. I’m looking at the Sinclair gauge.

Thanks in advance.
 
#2
Gun Man Dan said:
I’m having some issues with my groups being over MOA with a match grade stainless steel barrel. I’m chasing runout to be less than 5 thousands. First question, what gauge do you use to check concentricity of the case without a bullet? I have the Hornady concentricity gauge and it doesn’t measure only the case. I’m looking at the Sinclair gauge.

Thanks in advance.
Click to expand...
I have Sinclair that I use to spot check my cases without the bullet and also use it on occasion to check bullet runout (TIR).

More about your rig??? (e.g. what caliber?, who's SS barrel?, Barrel contour?, bullets you're using?, brand of cases you're using?)

When I've had .005" TRI, it tends to make a very small difference, if at all. I have strong doubts that your TIR is at the heart of your MOA problem.
 
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#3
I have only done a couple of studies on runout but in both of them it trended (loosely-- I am not confident to say it is meaningful one way or the other) that more runout shot tighter dispersion. Obviously this is one of those things that can be influenced greatly with chamber/ammo fit.
 
#4
straightshooter1 said:
I have Sinclair that I use to spot check my cases without the bullet and also use it on occasion to check bullet runout (TIR).

More about your rig??? (e.g. what caliber?, who's SS barrel?, Barrel contour?, bullets you're using?, brand of cases you're using?)

When I've had .005" TRI, it tends to make a very small difference, if at all. I have strong doubts that your TIR is at the heart of your MOA problem.
Click to expand...
I have a Bergara with a 24” Shilen stainless barrel 1/8 twist 6.5 creedmoor. I shoot Hornady brass with 140 gr eld match bullets. 39.5 H4350 and a mix of cci and federal primers. I use Redding type S bushing die 289 without button and use a Sinclair expander mandrel to push out the next to get my bullet tension. I have a Hornady match micrometer bullet seater die.

I’m not sure where to go next. It’s driving me to the point I just want to sell everything. The new barrel wasn’t cheap and shooting more than MOA is really depressing. It shot better with the old barrel.
 
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#5
Double check your barrel twist rate to ensure it's actually 1:8 twist. If it's slower than 1:825 (Shilen does make a .264 barrel blank in 1:9 twist and that may have been mistakenly used instead of a .264 1:8 twist blank), you're in the marginal stability territory for the 1.380" bullet length of the .264 140gr ELDM (Berger Twist Rate Stability Calculator) unless you increase to >2850 fps.

If the actual twist rate is slower than advertised, return for replacement or use shorter bullets.
 
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#6
Evintos said:
Double check your barrel twist rate to ensure it's actually 1:8 twist. If it's slower than 1:825 (example 1:9 or 1:8.5), you're in the marginal stability territory for the 1.380" bullet length of the .264 140gr ELDM (Berger Twist Rate Stability Calculator) unless you increase to >2850 fps.

If the actual twist rate is slower than advertised, return for replacement or use shorter bullets.
Click to expand...
It’s definitely 1:8 twist. That’s good info to know though. Should I be using different bullets with 1:8 twist?
 
#7
Gun Man Dan said:
It’s definitely 1:8 twist. That’s good info to know though. Should I be using different bullets with 1:8 twist?
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In terms of bullet stability, the 1:8 will be just fine with the 140gr ELD-M. The next thing I would do is buy a box of 140gr Berger Hybrids and see if the that barrel/bullet combo shoots and if it does, you'll know it was just your lot/batch of ELD-Ms that weren't performing.
 
#8
Evintos said:
In terms of bullet stability, the 1:8 will be just fine with the 140gr ELD-M. The next thing I would do is buy a box of 140gr Berger Hybrids and see if the that barrel/bullet combo shoots and if it does, you'll know it was just your lot/batch of ELD-Ms that weren't performing.
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I did shoot some of those. I got some good 3 shot groups here and there but several off the wall flyers. That’s why I thought it must be my reloads that suck.
 
#9
If you are mixing primers that could be part of the problem. Are you able to measure velocity to give us an idea of what you're getting with 39.5 gr of H4350? You may need to increase the powder charge.

Have you tried a box of factory loaded Hornady match with the 140 gr ELD-M bullet?
 
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#10
Gun Man Dan said:
I have a Bergara with a 24” Shilen stainless barrel 1/8 twist 6.5 creedmoor. I shoot Hornady brass with 140 gr eld match bullets. 39.5 H4350 and a mix of cci and federal primers. I use Redding type S bushing die 289 without button and use a Sinclair expander mandrel to push out the next to get my bullet tension. I have a Hornady match micrometer bullet seater die.

I’m not sure where to go next. It’s driving me to the point I just want to sell everything. The new barrel wasn’t cheap and shooting more than MOA is really depressing. It shot better with the old barrel.
Click to expand...
Frankly, with that rig, I'd expect sub MOA results. . . like nothing over .75 MOA, especially with hand loads.

Just an FYI: bushing dies tend to produce more TIR on the necks than non-bushing dies. While .005 might be considered a lot, I wouldn't expect to see anything better than .002 - .003. IMHO

Hopefully your loading the 140 ELD's somewhat closer to the lands as secant ogives tend to do better that way.

Hornady brass is often not very consistent in their case volumes which can contribute to variances on paper. Chrono data would be helpful to see what what kind of performance your loads are doing. BTW: I assume this isn't virgin brass we're talking about???

Have you measured you CBTO to see how consistent that is? How consistent is your shoulder bumps?
 
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#11
ShtrRdy said:
If you are mixing primers that could be part of the problem. Are you able to measure velocity to give us an idea of what you're getting with 39.5 gr of H4350? You may need to increase the powder charge.

Have you tried a box of factory loaded Hornady match with the 140 gr ELD-M bullet?
Click to expand...
I’m not mixing primers throughout my lots so each grouping is either one or the other primers. I can’t get out to the range until Wednesday to try some factory ammo. That’ll shed some light on the problem for sure.

I don’t have a chronograph. Too far out of my budget currently and haven’t found a need for one. Is having one worth the price?
 
#14
You can pick up a used LabRadar for like $250 these days, after the Garmin chrono came out. If you like to do load development it can be very useful.

Do you have a friend that would loan you a chrono?

As for primers, stick with one or the other brand while you're developing a load.
 
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#15
Gun Man Dan said:
Hmmm. Do you have one you’d recommend? I read somewhere the magneto sporter is a good used choice for a budget one.
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The sporter would work just fine, though it's not as easy to pull data out of it like you can with the v3. I have a v3 and doesn't get used now that I have a Garmin. I think the Garmin is having a big impact on a lot of chrono's where you can find some good deals on used ones. . . like the LapRadar that ShtrRdy mentioned above.
 
#16
straightshooter1 said:
The sporter would work just fine, though it's not as easy to pull data out of it like you can with the v3. I have a v3 and doesn't get used now that I have a Garmin. I think the Garmin is having a big impact on a lot of chrono's where you can find some good deals on used ones. . . like the LapRadar that ShtrRdy mentioned above.
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I’m really new to load making. What would the chronograph tell me when I’m using all of the same materials. If I got different velocities, what would that mean to me?
 
#17
I use to use a Magnetospeed for many years and they work great. But you can't shoot groups with a Magnetospeed hanging on the barrel without it affecting group size. If you want to obtain group size information AND velocity measurements, you need a chrono that doesn't hang on the barrel.
 
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#18
straightshooter1 said:
Frankly, with that rig, I'd expect sub MOA results. . . like nothing over .75 MOA, especially with hand loads.

Just an FYI: bushing dies tend to produce more TIR on the necks than non-bushing dies. While .005 might be considered a lot, I wouldn't expect to see anything better than .002 - .003. IMHO

Hopefully your loading the 140 ELD's somewhat closer to the lands as secant ogives tend to do better that way.

Hornady brass is often not very consistent in their case volumes which can contribute to variances on paper. Chrono data would be helpful to see what what kind of performance your loads are doing. BTW: I assume this isn't virgin brass we're talking about???

Have you measured you CBTO to see how consistent that is? How consistent is your shoulder bumps?
Click to expand...
Shoulder bumps are consistent. The brass has been fired a few times and trimmed. I’m maxed out on OAL because of my magazine so I can’t chase the lands like I could otherwise. What do you think my next steps should be? Buy some better brass and make some more loads? I’m stumped.
 
#19
Do you have any rifles that shoot consistently better than MOA?

Is this the only load you’ve tried in this rifle?

Components are important and some rifles do not like certain components. In my experience the better the components the easier it is to find something that shoots well.

I would also suggest buying some factory hornady 140 and comparing it to your hand loads just to get a baseline.
 
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#21
Gun Man Dan said:
I’m really new to load making. What would the chronograph tell me when I’m using all of the same materials. If I got different velocities, what would that mean to me?
Click to expand...
That would indicate that something in your components, equipment or process is contributing greatly to variances in velocity (affects your group size dispersion).

An example that is both process and equipment related is - utilizing an RCBS Uniflow powder measure and manual bulk charge directly into the case. If you don't weight every individual charge, you could mistakenly assume that it's consistently dropping 39.5gr of H4350. You could be +/- 0.2 or even more based on how you run the handle.

Variance in velocity could also appear when you have inefficient combustion and this could be due to low powder charge weight. It could be something as simple as increasing powder charge weight to get you into a better spot. Most people that I know of are loading 41-43gr for 6.5cm, H4350 and a 140gr bullet. Common charge weight with no load development for that combo is just going with 40.5 or 41.5gr and sticking to it.
 
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#22
Gun Man Dan said:
I’m really new to load making. What would the chronograph tell me when I’m using all of the same materials. If I got different velocities, what would that mean to me?
Click to expand...
Velocity SD's can tell you just how well your loading your cartridges.

Some things that prominently effect velocity:
- Consistency of powder charges (measure down to individual gradual or like to .02 grs)
- Consistency of case volumes (quality brass tends to be most consistent)
- Consistency in seating depth (sorting bullets by BTO may be required as where the seating stem contact point can vary substantially resulting in seating depth variance, especially between lots). Too much interference also results in inconsistent seating depths.
- Consistent primer ignition. Different primers can make a difference. Seating them consistently. It helps to know the depth of your primer pockets and the thickness of the primers you're using so better know when your primer cup in actually touching the base of the primer pocket.
- Consistency in neck tension (using something form .0015" to .003" works well with bolt guns; must be tested to see what works best in the particular gun)

A decent chronograph will record your velocities and calculate you SD's. Get your SD's into the single digits and your groups should reflect in small groups (assuming nothing wrong with the rig or the shooter's mechanics).
 
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#24
Gun Man Dan said:
Shoulder bumps are consistent. The brass has been fired a few times and trimmed. I’m maxed out on OAL because of my magazine so I can’t chase the lands like I could otherwise. What do you think my next steps should be? Buy some better brass and make some more loads? I’m stumped.
Click to expand...
Fired "a few times"??? How many times? This brass was also fired in the old barrel?

Another thought that hasn't been mentioned. . .

What scope are you using?

If you haven't already, be sure to check your scope and scope mounts carefully. Be sure screws are all tightened properly, including the rail.

Do you know what trigger pull weight your trigger is at?

I do feel getting some better brass will help. But I think the brass is only part of the problem. You might try starting from scratch, like getting some Alpha brass???

I'll mention too that all barrels shoot differently. Take two barrel that are identical, or at least appear identical in every way, and they can shoot very differently. Highly competitive shooters buy many barrels at a time and test them and choose the one's that shoot the best out of the bunch.
 
#25
Gun Man Dan said:
I’m having some issues with my groups being over MOA with a match grade stainless steel barrel. I’m chasing runout to be less than 5 thousands. First question, what gauge do you use to check concentricity of the case without a bullet? I have the Hornady concentricity gauge and it doesn’t measure only the case. I’m looking at the Sinclair gauge.

Thanks in advance.
Click to expand...
I guess based on replies I’m stuck again. I’m only shooting out to 100 yards so I don’t see how a chrono is worth the money if all my components are staying the same for each grouping.
 
#26
Gun Man Dan said:
I’m not sure where to go next. It’s driving me to the point I just want to sell everything. The new barrel wasn’t cheap and shooting more than MOA is really depressing. It shot better with the old barrel.
Click to expand...
I've got a question for you that is important. You state the old barrel shot better.
How are you making that determination?
If you could shoot multiple sub moa 10 shot groups or was it a one off sub moa 10 shot group?
The reason I ask is because you might be giving yourself some unnecessary ass pain over this.
Rifles shoot within a range of group sizes every time we shoot. To add to that, each individual group is a sub-group of the combined group ES of all the groups you shoot over time. So unless you have a good many examples of the old barrel grouping sub moa on a very regular basis, your expectations may be out of alignment with what is actually going on.
I think the 1st question to answer is to determine how reliable a data set you have which is causing you to assume there is a problem.
If you haven't done enough testing then the picture you have in you mind may not be aligned with the reality of the overall situation.
When anyone asks questions like the one you asked, the assumption from all the guys who answer is that the situation described is indeed reality, & so they try to help as best they can. The problem may simply be that there was never enough testing done to make the determination that there is a problem.
 
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