how to shrink groups ?

[big5ifty]

Have you done a ladder test?

"Ladder test" means different things these days.

The original ladder test as described by Creighton Audette was to shoot one shot each of incremental increases of powder charge to the same point of aim, and see if there is a point where the shots tend to clump together.

Because that ladder test was so spectacularly useless for me, I tried to figure out why, and the best I can come up with is that the point where the shots on paper clump together is where the barrel harmonics reverse. When velocity is tracked as well, consecutive velocities may be closer together due to a +- 1 thou [ very small ] variation in seating depth between consecutive rounds. If one round is -1 thou, and the next +1 thou, those velocities will tend to be closer together because the increase in length reduces the effect of the increase in charge. The points where the shots are closer on paper, and where the velocity is closer together do not always overlap. The test clearly shows that you can change barrel harmonics with incremental change to powder charge. You can find a good load eventually this way, with a chance of shooting out the barrel before you do.

I find it more productive and less of a waste of components to find a low ES first, then manipulate group size with seating depth change. Both these tests can loosely be called ladder tests, but I prefer to avoid using the term altogether.

 

[big5ifty]

My groups are 5 shot groups and at 100 yds they are one slightly ragged hole.

This is good. It means the ammo is good, the platform is good, and the shooter is good.

Now find a better shooter than you to shoot the rifle, and compare results, before you make any changes.

 

[rebs]

Is rear screw first normal practice on a tikka?

I don't know, that is just the way I did it. I did not do a ladder test.
I will have a better shooter than me shoot my rifle and see what hapens.

 

[Beiruty]

"Ladder test" means different things these days.

The original ladder test as described by Creighton Audette was to shoot one shot each of incremental increases of powder charge to the same point of aim, and see if there is a point where the shots tend to clump together.

Because that ladder test was so spectacularly useless for me, I tried to figure out why, and the best I can come up with is that the point where the shots on paper clump together is where the barrel harmonics reverse. When velocity is tracked as well, consecutive velocities may be closer together due to a +- 1 thou [ very small ] variation in seating depth between consecutive rounds. If one round is -1 thou, and the next +1 thou, those velocities will tend to be closer together because the increase in length reduces the effect of the increase in charge. The points where the shots are closer on paper, and where the velocity is closer together do not always overlap. The test clearly shows that you can change barrel harmonics with incremental change to powder charge. You can find a good load eventually this way, with a chance of shooting out the barrel before you do.

I find it more productive and less of a waste of components to find a low ES first, then manipulate group size with seating depth change. Both these tests can loosely be called ladder tests, but I prefer to avoid using the term altogether.

When you hunt for the lowest SD, you are looking for the OFPS node, a theory I introduced in September 2018.
Here is the paper:

OFPS Theory.docx

1drv.ms

 

[Clancy]

I don't know, that is just the way I did it. I did not do a ladder test.
I will have a better shooter than me shoot my rifle and see what hapens.

Almost all actions are front first. I don’t know much about tikka but assume they are the same.

Double check that. It could make a difference.

 

[rebs]

Almost all actions are front first. I don’t know much about tikka but assume they are the same.

Double check that. It could make a difference.

ok I will check it. Thanks for the info

 

[bsekf]

Don't sell that rifle! You may look for years to find a stock factory rifle shoot like that.

However, you can have a bunch of fun trying to get a couple of thousands out of that rifle. And it shouldn't cost more than a couple of thousand dollars. I might try a lighter bullet.

 

[22BRGUY]

When you hunt for the lowest SD, you are looking for the OFPS node, a theory I introduced in September 2018.
Here is the paper:

OFPS Theory.docx

1drv.ms

EXCELLENT ARTICLE!
The way it was explained to me was that the end of the barrel oscillates/vibrates in a figure 8 pattern when a rifle is fired. The top and bottom of the figure 8 vibration being shorter in duration than the long middle of the 8-figure vibration pattern. The idea was to find two loads slightly different in weight that grouped together closely indicating that they were exiting the barrel in the long middle node of the figure 8 pattern. This would indicate a more consistent barrel harmonics advantage opportunity for the shooter.
I know that I have used this method for many years as a starting point to determine
a correct powder charge and then went on to adjust bullet seating depth and various
other load details and I've never came close to "shooting out a barrel"
Best Wishes whatever works!

 

[big5ifty]

When you hunt for the lowest SD, you are looking for the OFPS node, a theory I introduced in September 2018.
Here is the paper:

OFPS Theory.docx

1drv.ms

Interesting read, thank you.

 

[PracticalTactical]

First, as stated above, 1.5" at 300 with a factory Tikka is excellent and I'm not sure what would improve on that, but I'll throw out some ideas.

Since the 223 has such a small powder capacity, the accuracy of the powder charge is increasingly important to control muzzle velocity spreads. So I would suggest weighing charges on a proper analytical balance. Somethin that reads in 0.002 grains is ideal. Hopefully you know someone with one.

Next is think about other small contributors to velocity spreads... Neck tension is a big one.

Also despite what Cortina says... every time he opens his mouth, try using fire formed brass that is just neck sized. That will cut down on energy lost to blowing out the case to fit your chamber wall. That will reduce your velocity spreads.

 

[PracticalTactical]

I should elaborate on my comment above in reference to neck tension.

It is not neck tension that I feel is most critical. It is variation in neck tension that is most critical.

Without going off on a 50000 word explanation... One bushing will never give you consistent neck tension if you have not neck turned your brass.

If you do neck turn brass for a factory rifle, there is little gained.

The trick to controlling neck tension in your case is incrementally sizing every single case. Start with a bushing that is too large to establish any neck tension, then incrementally resize with sequentially smaller bushings until you get neck tension. Repeat that for every case.

It's best to do this by lot and brass that will hold a bullet go in one pile and brass that does not hold a bullet yet gets resized down another bushing size. If you do not have enough sizing bushings to do this then you don't have enough bushings.

If you do this you can establish very consistent neck tension despite variation in neck thickness and variation in neck hardness. Let each and every individual case tell you what size bushing it needs.

Note: dropping bushing sizes incrementally as I described here will not result in the same tension as if sizing from scratch with a particular bushing.

The last factor in neck tension is to focus on the quality of the inside neck chamfer. The best tool I have ever found for this is a cone shaped carbide burr with a 1/4" shank. Like this one https://www.amazon.ca/YUFUTOL-Tungsten-Carbide-Pointed-2Cutter/dp/B07C1KRGXR

 

[BoydAllen]

What Al said....If not, forget working on loads until you are shooting over flags, especially at that distance. For some reason everyone seems to go to their load, without considering that it could be something else entirely that is holding them back. Frankly, I think that at that distance you are doing pretty well.

 

[rebs]

I had my Tikka 23 out this morning and shot our local club 300 yd match. We shoot the IBS 300 yd hunter rifle target with 5 bullseyes and fire two shots at each on two targets for a total 20 rounds. They do this to conserve ammo. all my targets were 1 1/2 in or less. I have decided there is nothing to change on my stock T3x 223 or my load. There was a slight left to right wind.