Rifle tune

[Bill Norris]

Whatever way you do it, it's just a number to start from. Do whatever floats your boat.

Yea just a relative number to start from.

 

[Straightshooter1]

So i bought a used rifle that already had a great load developed for it, i had the same components but of course different lots of the bullet (Berger 80.5) and powder H4350. My first 30 or so loaded rounds with my components the rifle shot extremely well but that finished off the 100ct box of bullets and as well as the powder. New lot of components once again but It’s not shooting good at all. This lot of bullets is just touching the lands where as the others was not so I’m sure that has a bearing on it. What should I do now ? Load below and above the charge weight as well as the seating depth ? I have the original cbto length it shot well with at 2.078 but my comparator and his wouldn’t be same or the lot of bullets. If I had or knew his distance from the lands that would have been a big help Thanks

Yeah, if you know the distance from the lands he was using for that rifle you could figure out the seating depth using your particular comparator.

Hmmm??? So you didn't take any measurements and record them for the old components? If so. . . too bad! Though you have the "original CBTO", there can be a significant difference from on lot to another. . . as you have apparently found out (the hard way). If that original CBTO measurement was with your own comparator, I would think you could find the difference between the original and new and then compensate the seating depth by that difference??? That's were I'd start. Though there can be some difference also with the other components where knowing the original velocities can help you make some adjustments to get back to a load that's shooting well.

 

[ELR LVR]

Whatever way you do it, it's just a number to start from. Do whatever floats your boat.

Thats true, its just a number to start from
But I also like to monitor throat erosion, so theres that
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then the number of people that ACTUALLY,,,,,like to know where they're touching the lands
so they can accurately begin ...starting backed off the lands

 

[Homerange]

The same way I tell bullet is touching the lands
1. Open and remove Bolt
2. Drop a bare bullet into chamber, (keep trying until it goes in pointy end first)
3. Lighty tap bullet into lands against the base with the cleaning rod inserted through chamber end to ensure bullet is securely in place and not loosely in place.
Now to mark /measure
4. I insert cleaning rod from the muzzle until it just stops on the tip of the bullet, slowly and lightly so you don't dislodge the bullet you just lightly tapped into place
(must have blunt tip or attachment on end of cleaning rod to bottom out on meplat)
then Using thin tape I mark the cleaning rod at the very end of the muzzle for a reference, do this very accurately by moving head side to side and line tape up perfectly with the muzzle end.
5. Now with rod marked and still inserted through the muzzle, Tap bullet out of rifling
6. Insert and close bolt
7. Re-Insert cleaning rod through the muzzle until it bottoms out on the boltface
8. Mark this location with tape
9. Measure the distance between the right side of each piece of tape and this gives you
OAL of that particular bullet "just touching the lands"
Now go seat a bullet into a case with this OAL using the bullet you just used
Comparator can now be used to measure Ogive Seating depth

This is my ZERO Point, of just touching the lands,

By using this method...You know exactly the bullet has just stopped at the rifling, and where,,,and
There is no need to "Smoke" a bullet < mark up a Bullet, (Dykem a bullet because this method is exact.
ALSO---!!! if you do this at the beginning of a new barrel and save the dummy round you just made.....
.....You can monitor accurately your throat erosion of the rifling over time by repeating steps 1 -9
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Seating a bullet into the case by using the bolt will give false/different readings depending upon case neck tension vs lands resistance and is not an accurate way of measuring jam.
As well the rifling can grab the bullet and slightly pull it back out of the case to any degree.
(anyone who has opened their bolt and dumped powder into the chamber and magazine knows this!
I am SERIOUS!, I have heard this happens to people!!!)
Neither is measuring the amount of rifling engraved on a bullet an accurate way of measuring Jam,
,since the ogive can match the contour of the lead angle
(IE: A contact patch of the rifling on the bullet can show .040" engraving when actually it has just began to touch because the two surfaces are virtually parallel to one another)
Tilt both your hands at a 45 deg angle to the left and then move your right hand until it just touches your left...
Do you have 6 inches of forced hand engagent or did they just touch?

Yup, real easy but I swap steps 4&7 and use 2x drill depth gauges that can be clamped onto your cleaning rod.
Mic the difference and you have your max COAL ....providing they fit in your mag.....

 

[ELR LVR]

Yup, real easy but I swap steps 4&7 and use 2x drill depth gauges that can be clamped onto your cleaning rod.
Mic the difference and you have your max COAL ....providing they fit in your mag.....

Yes, if you swap steps 4 & 7 you dont run the risk of inserting the first piece of tape into the barrel and disturbing it when measuring against your bolt face secondly.
So I agree with you there, measure bolt face first to prevent that is likely better
, then insert bullet and measure
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Drill depth gauge, extend after measuring boltface
etc
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good point Sir.

 

[DLT]

Yeah, if you know the distance from the lands he was using for that rifle you could figure out the seating depth using your particular comparator.

Hmmm??? So you didn't take any measurements and record them for the old components?

I think I posted this earlier. I never had any loaded rounds he loaded for the rifle. I used my bullets powder primers for maybe 30 rounds till I ran out of my bergers. I loaded them to the cbto he was using and they shot great at 100 and every yardage out to 650 I have. When I opened another box is when it started to fall off even though when seated they measured 2.076 only .002 shorter than the previous 30 or so rounds. Just wondering how most overcome a rifle that doesn’t sing like she used to after a new whatever is introduced. I know why people buy large amounts of the same lot when possible it’s just hard for me to swing it most times. I have to do a lot of buy a box here but a box there.
Oh. I asked him what fps he was getting and it was a ridiculous number 3550. I figure at best it’s running 3300. I don’t know if he thought of another rifle or it had been awhile or chrono messed up. No telling really, but I don’t blame him for any mistake.

And about the original cbto he had it was 2.078 with his comparator and I don’t think it was the same as this hornady I have even if it was I’m sure there would be a little difference between his and mine

 

[Bill Norris]

I know why people buy large amounts of the same lot when possible it’s just hard for me to swing it most times. I have to do a lot of buy a box here but a box there

Me and you both Bro.

 

[ELR LVR]

O

I think I posted this earlier. I never had any loaded rounds he loaded for the rifle. I used my bullets powder primers for maybe 30 rounds till I ran out of my bergers. I loaded them to the cbto he was using and they shot great at 100 and every yardage out to 650 I have. When I opened another box is when it started to fall off even though when seated they measured 2.076 only .002 shorter than the previous 30 or so rounds. Just wondering how most overcome a rifle that doesn’t sing like she used to after a new whatever is introduced. I know why people buy large amounts of the same lot when possible it’s just hard for me to swing it most times. I have to do a lot of buy a box here but a box there.
Oh. I asked him what fps he was getting and it was a ridiculous number 3550. I figure at best it’s running 3300. I don’t know if he thought of another rifle or it had been awhile or chrono messed up. No telling really, but I don’t blame him for any mistake.

And about the original cbto he had it was 2.078 with his comparator and I don’t think it was the same as this hornady I have even if it was I’m sure there would be a little difference between his and mine

Ok this helps more, slightly,maybe
I have heard
NEVER drop your bullets
If you drop one onto the floor, it upsets the center of gravity due to lead being soft ...repositioning itself in the jacket, etc
Set it aside if dropped
-----
Now Drop a full box of 100 from waist high and???
It is slightly possible that...
...Your new bullets were handled in the way most of our usps packages have been handled in shipping recently
Which
to me actually
Makes me wonder how any of our bullets shoot decently without checking them with a Jeunke Comparator.
you may just need a new box of bullets, but whose to say your next box didnt get thrown into the back of the USPS truck and bounced off the wall
then you need another box etc
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I know I tried a box of berger 144's at a time many people were raving about them and they were the worst 6.5 bullets I tried, Like give them away for free type bad.
(I could have had a similar deal with them being mishandled and wondered if I didnt give them enough of a second chance due to that possibility.)
Because theoretically, your rifle should still shoot relatively close.
I can post a pic of two 5 shot groups where the seat depth is .010" apart and it is noticeable but more like Shooting from .4 moa down to .25 moa.
0.002" should not make that significant of a difference in seating depth,
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Have you measured Base to Ogive etc to see if your new bullets fall in line with the old? (if so i missed it)

 

[ELR LVR]

Oh, one more Q?
Whens the last time you cleaned your barrel down to bare metal?
All the copper out for sure?
When accuracy goes, it goes noticeably quickly
it may just need to be cleaned properly.
With the speeds you say your buddy was getting, I'd be willing to also bet your barrel is copper fouled
If you try some new bullets try some Sierra Match Kings
They use Guilding metal which has 5% zinc and is not as soft as J-4's like Berger uses
So.... wont copper up the barrel as quickly, try that out for us.

 

[DLT]

Oh, one more Q?
Whens the last time you cleaned your barrel down to bare metal?
All the copper out for sure?
When accuracy goes, it goes noticeably quickly
it may just need to be cleaned properly.
With the speeds you say your buddy was getting, I'd be willing to also bet your barrel is copper fouled
If you try some new bullets try some Sierra Match Kings
They use Guilding metal which has 5% zinc and is not as soft as J-4's like Berger uses
So.... wont copper up the barrel as quickly, try that out for us.

I cleaned it for the first time this evening. After 2 bad trips to the range with a rifle that usually shoots well something is getting cleaned.

 

[ELR LVR]

I cleaned it for the first time this evening. After 2 bad trips to the range with a rifle that usually shoots well something is getting cleaned.

Good to hear,
Next time you shoot it then
if it shoots well again
Log how many rounds before accuracy falls off, then document that
then you know how many rounds to not go past without cleaning
I say 50 rnds max
Especially if your 3300 fps or above
(it may be 70 though, there are extreme ends of the spectrum within a bellcurve)
But I'll throw some bullets your way if you can hold same extreme accuracy (1/2" or below) for over 70 rounds