Short range agging strength of barrels

[Tim Singleton]

This may sound way out there Idk. The last several Bartlien and Krieger barrels I've had chambered for my short range 6ppc LV contour guns have been .237 bore.
I've kept all my match targets for the last two years noticed after the first two to three matches my groups tend to open up slightly bringing my aggs down. It seems to me when the barrel gets a good heat in it after the first two relays it just doesn't agg as well.
Would a 236 bore fair any better in this example. Once it gets a good heat in it and expands slightly would it possible agg better?
I had one lot of 68 BT that were just a little fatter than the prior lot and they seemed to do better that got me down this train of thought
Anyone shoot 236 bores for short range 6mm?

 

[dalewoolumjr.]

What I've found with myself and customers barrels. Bore diameter does not mean much unless it's small enough to heat up the jackets. The groove diameters do make more difference though. Ask your gunsmith to provide groove measurements for you. Remember that when you put 60,000 psi behind the bullet it fills the groove. A good barrel is a good barrel.

My records show that sometimes you need to change bullet seating depth to keep the agg going. One thing to try in practice shoot the whole day. See what you have to do to keep the rifle in tune during the whole day. You may be surprised what you have to do.

On barrels I've found Bartlien barrels have a good 200-300 shot competitive life. Kriegers go more.

Dale

 

[Jet]

Tim

How often do you clean during a match?

Rich

 

[Tim Singleton]

Tim

How often do you clean during a match?

Rich

I clean after each target. I have a bore scope and have checked my cleaning method while practicing. I'm getting it cleaned well.
It may just simply be I'm not staying in tune as well as I need to. It just seems to repeat over and over. It's not just a first thing of the morning relay thing where all is calm and cool or I would think its tuning and wind reading.
I can go start a practice at 2pm when it's already hot and windy. The first two groups are really good then after that they kinda open up a little

 

[Tim Singleton]

What I've found with myself and customers barrels. Bore diameter does not mean much unless it's small enough to heat up the jackets. The groove diameters do make more difference though. Ask your gunsmith to provide groove measurements for you. Remember that when you put 60,000 psi behind the bullet it fills the groove. A good barrel is a good barrel.

My records show that sometimes you need to change bullet seating depth to keep the agg going. One thing to try in practice shoot the whole day. See what you have to do to keep the rifle in tune during the whole day. You may be surprised what you have to do.

On barrels I've found Bartlien barrels have a good 200-300 shot competitive life. Kriegers go more.

Dale

Dale
I didn't think about the bullet filling the bore at such higH pressure. Good point
Most of my barrels are Bartlien.

Do you change seating depth during the match? What would indicate to you the need to change depth.

 

[Dusty Stevens]

Sometimes a barrel just wont agg. I just add it to the pile or itll drive you insane

 

[Tim Singleton]

During a practice session. The first two groups are pretty good usually teen groups.
I set a time for 15 mins while I clean the barrel size and load cases then fire another group shooting sighter shots as needed. But they will slightly open up after the first two. Not vertical just a little bigger. Unable to shoot another teen for the remaining 3 groups. Time in and time out matches and practice 3 different barrels. I've several small group pieces of wood and screamer patches, but they don't win matches

 

[Tim Singleton]

Sometimes a barrel just wont agg. I just add it to the pile or itll drive you insane

That the kind of feedback that is useful. As a newbie I think I'm always thinking its me. But I don't want to keep chasing my tail and wasting good bullets

 

[Dusty Stevens]

With the accuracy we require most barrels are scrap so never waste more than a few hundred shots. If theres a quirk that keeps popping up dont hesitate

 

[BartsBullets]

Tim,

It doesn't have a thing to do with your bore diameter or the bullets being a little different. It's all about keeping your barrel in tune and knowing when to change your load. What you're doing is describing a typical match.

It goes like this.

Normally you shoot groups 1 and 2 and get by with good targets. So a new shooter will go to the line with the same load for group 3 it gets a little big ( but you think you just missed a condition) and if you don't change it by 4th match it blows up. Then you adjust for the 5th match and it's a good group. However now you break for lunch and by the time you shoot your first match of the new agg the load is gone again.
This is why I carry a 50 round box of ammo that usually has three different loads in it. I'm always scanning for the tune.

As for heat in the barrel bring a cooler and soak a towel in cold water and put that in your barrel to cool it. I like to have my barrel cool to the touch before the next match.

Take a look at all the aggs from the shoot and you will typically see the same thing happening to a good deal of shooters.

Bart
Bart's Custom Bullets