I'm not precise yet

[KDX]

I also posted this in the reloading forum. I'm doing some load development and am not where I would like to be, but like everything it's a work in progress. 5 shot group @ 97 yards as per my range finder. 17 Remington Fireball. Half this size would make me happy.

 

[c3pppo]

another 10,000 rounds and you'll be just fine...

 

[firemachine69]

KDX:


At that range with my .308, I'm still having troubles consistently hitting the oval "Tim Hortons" on our patriotic drink.


You're doing just fine.

 

[Budweiser360]

Looks good, you should be able to tune that vertical out and it should be no problem to shrink it further...

 

[Jayph]

I am sure you have checked this but I had a rifle that would walk like that once and it was because there was one tiny preasure point on the barrel where it touched the stock. Have you checked to make sure it's floated?

 

[KDX]

There's no problem with the floating of the barrel. Normally what causes the vertical stringing? I shot this group the day before with 19.8gr of powder vs the 19.9gr in the first pic.

 

[sako6br]

Normally what causes the vertical stringing?

The bullet not exiting the muzzle at an ideal time in the harmonic cycle of the barrel.
Adjusting the powder charge is the easiest way to change the timing.

 

[jeff270]

I would pay a lot of attention to how the gun is sitting on the bags and on your breathing ,especially if your gun is sporter weight.

 

[Budweiser360]

If you have no pressure signs at 19.9 try 20-20.1 or you can lower it to 19.7 or 19.6 and see what takes place.

 

[Mystic Precision]

If the bedding, optics/mounts, rests, bench, etc are all good, I would keep adding 0.1gr and you will start to see the groups shrink, and flatten. Then they will rapidly expand and you will start to see pressure signs.

Also, keep in mind the accuracy potential of the rifle and bullet. If this is a factory rifle, I would be thrilled with consistent 1/2 min accuracy. Even more excited if using your average hunting bullet.

Match bullets like Berger will offer more accuracy BUT the barrel may not.

If things continue to improve, you will likely find your load around 20.1gr. When you do, test a bit above and see how much more it takes to cause the groups to grow to what they are now.

If it takes 0.1gr, then you have to keep an eye on ambient temp changes and adjust for that. Likely lower your loads as you get warmer, increase your load as you get cooler.

Just like keeping a musical instrument in tune.

Jerry

 

[GSoD]

Could your barrel be heating up between shots?

 

[firemachine69]

I was thinking, what type of powder are you using?


And if it's a factory sporter barrel, you're doing pretty frikken' amazing!

 

[KDX]

I'm using Benchmark powder which is supposed to be one of the ones made that doesn't vary much with temp changes. I would say the barrel had warmed up a bit as those were shots 11-15 that I put through it with no real time between groups. It is a sporter barrel also. The rifle is a Model 38 Classic made by Cooper.
edit to add...I had the action out of the stock and called Cooper and there is a specific torque that should be used on the action screws and I will be doing that later today.

 

[Mystic Precision]

The Hodgdon Extreme powders are very temp stable COMPARED to other brands.

However, they will change slightly over a large temp spread. I figure 15C is worth a tweak. Now you may not see any changes when shooting varmints or plinking at rocks but if you shoot paper, the groups will expand as if you were using a load that was a schnick above or below ideal.

Also, your barrel steel will react differently at 30C ambient vs 0C. That can change its tune and what is the ideal load.

Why I believe in testing under the conditions the rifle will be used.

Look forward to your testing results. If not done yet, bedding will likely help the rifle be more consistent.

Jerry