.5 MOA Is The Best I Can Expect?

I might see part of the trouble, krieger wants you to cut off that 1in of the muzzle, if that barrel was chambered, threaded and crowned without cutting off one inch, Maybe. ed
 
alinwa said:
Yo Tim,

Here's the thing wit' da' neck..... The neck slaps out to seal against the chamber walls BEFORE THE BULLET MOVES. The bullet tail is then slammed against whichever random side it hits and is forced into the lands under 500-600lb of pressure. The purpose of a "tight neck" is so that the case neck itself acts as a guiding means, a bushing as it were, to keep the bullet aligned as it's hammered into the lands.....

Therefore it follows that anything you do to increase neck clearance simply translates into increased in-bore yaw. The initial alignment is meaningless.

(IMO :))

At least this is what the experts tell me and my anecdotal backyard experimentation has borne it out. Two winters ago when it friggin' SNOWED forevermore and cold I fired some bullets into snowbanks and recovered a percentage of them in the spring, the results were inconclusive... but results on target have never led me to believe that turning already oversized necks offers any gain.

I'm well aware of all the folks who claim gains, I'm only sharing my opinion.

The matches at Tri-County take place on Saturday, we generally arrive about 7:00AM and wrap up by three.

It'll be a week or three before I'm shooting here, work and Memorial Weekend and all..... I'm having to shoot outside now, my indoor range is temporarily decommissioned ..... and you've seen the weather of late! I've been looking for a three day sun window in Longview since Dec! I've got a job to fix....

Anyway, I'll give you a call one of these days.

al
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. The neck slaps out to seal against the chamber walls BEFORE THE BULLET MOVES.
Well i guess neck tension is out of the picture, glad you cleared that up. ed
 
Al,
Are you really telling us that neck tension doesn't matter? What about uniformity of neck tension? It would seem that if it has no effect that uniformity wouldn't matter...and I should add IMO it seems to. Also, in my experience, it is a factor in tuning, and some pretty fair shooters that I know choose not to ignore it.
Boyd
 
Hi guys, mostly a lurker here but the neck tension thing doesn't seem to make sense.

Here's my take on it, not scientifically proven or anything. I'm just kind of thinking it through.

It takes gas pressure to expand the neck, and if the neck is against the bullet then no gas can be there to force expansion. So it seems to me that the neck has to expand out in sort of a wave from the bullet/neck intersection somewhere around the shoulder up to the end of the neck. Now this would be a fairly fast wave, but it isn't instantaneous.

If the tension isn't consistent around the bullet, one side will get ahead of the other and want to push the bullet to the other side of the neck. This would cause accuracy problems.

At some point during this wave progression, the pressure on the bullet is going to be more than what the remaining neck against the bullet can hold, and so the bullet should start moving. The dynamics here are nearly impossible to predict. I guess a person could calculate the acceleration 60K psi would have on the projectile and get an idea of what might happen. Without any real test data to go by, its hard to say how far the wave has to go before the bullet breaks free.

Just my $.02 worth.

Steve
 
Steve,

Sometimes the neck expanding business is hard to understand. In very simple terms Alinwa is correct. At least in regards to the results.

The way I think about it is the primer is hit with the firing pin and this starts a very fast rise in pressure inside the case. The bullet moves forward even before the primer flame is burnt. The bullet hits the lands and then it stops.

Pressure in the case is climbing upward at a very very fast rate. This expands the neck. If the neck OD has slop in the chamber then the bullet is left unsupported.

The pressure rises so fast it is like the bullet gets hit on the butt with a sledge hammer. As the bullet is larger in cross section area than the barrel it is a very hard press fit into the barrel. When the hammer hits the bullet swells out with a budge and then is extruded into the bore. Any slop between the bullet and the case adds to issues that increase the group size on the target.

This year I have been working with a few new 25 BR barrels. Until I got my dies and brass correct I had groups that were 3/4" or so.

Once I got the dies and brass correct with tight necks the groups went down to 1/4" and better. Same barrels, same bullets same powder but fitted brass with tight necks.

Aliawn descriptions may not be perfect but he is right on with the results on the targets.
 
Hey Guys,
I have not be able to post in a while.
I have a Bald Eagle rest bolted to a piece of .50 inch steel plate, with a heavy bag for the rear. The setup is good and solid.
I have no experience with the wind and I am trying to learn. I need more trigger time.
The stock I have is the flat bottom. I will put a new trigger in when I can.
I meet up with alinwa over the weekend and learned allot about my reloading techniques for one.
Good guy, nice family and I am very appreciative for his time.
Thanks Al.
I am going to change a couple of things with my reloading techniques and see what I can do. I also feel a few rounds are harder than others when seating the bullet. I am going to set them aside this time and see what that does.
Thanks for all your post on this. I will let you guys know how and when I get this gun shooting better.

Tim
 
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Thanks Tim :) I had a good time, and DUDE they played some good music on your way home eh!!

LOL



BTW, I didn't actually look but weren't you doing under 1/2moa? And that over a gully with no flags?



al
 
Yeah that is correct Al. I was shooting some tight groups with one flyer in each one that through it all off. The first one was me an I knew it soon as I pulled the trigger. The second one not so much. I feel good about the gun though. I am going to work on my loads and get some more trigger time in.

Second on the music, it was a nice drive home.

Thanks again,

Tim
 
alinwa said:
I can't agree with Jackie on this one.....:)

I'm tight....

I growed up poor......

And I was building other people's guns long before I could build my own, in other words I had the DREAMS long before I had the wherewithal.....


The gist of all this is, I built guns partway, and then more partway, and evermore most partway before I ever went all the way. In My Opinion it is perfectly normal for a custom barrel in a varmint chambering on an UN-trued-blued-N-tattoo'd rifle to shoot only 1/2moa in a long-range setup.

You can "cheat" a 6BR 14 twist into some perty easy and cheap groups (altho never good enough to win in the categories it's designed for...) but trying to build the accurate allaround rifle on a budget is an exercise in futility. I had 7 "accurate guns" in my possession and a whole DRAWER full of excuses before I finally broke down and ordered a full-blown 6PPC Bench Rest Rifle, I needed the baseline!

I was at a point where I didn't know if I sucked? or my flags weren't working?? or I needed more work on my loads???

Getting a real BR gun was like turning the light on.

It was like the Dawning Of A New Day.

It was WONDERFUL!!!

All's of a sudden I DIDN'T SUCK!!

I could SEE the wind and it's effect...

And all my other "accurate rifles" were shown to be what they were...... poor man's varmint guns........

I still HAVE several of these rifles. I constantly tinker and fuss with them and try to find tricks.... I use them to test ideas. But in my opinion an accurate rifle is A SYSTEM, and part of the system is the action.

And a bad action can lock a rifle into not winning, ever.

And a factory action is by definition a bad action. Not to say that finding a straightenable factory action and making it right won't work! I've got a Rem700 that was worked over by Borden that absolutely shoots lights out.

But contrary to many other posters here, I HAVE NOT had good luck just throwing a barrel on factory actions.

And, after buying the PPC, a few years later I again started chasing the Holey Long Range Grail....... and started the whole accuracy process all over again.

Long Range Stuff is HARD. A 6PPC 14 twist will shoot bugholes automatically, a 6mm T'underBoomer in an 8 twist will not. And a the 22-6mm is even worse, a horrible cartridge to make shoot. I could right now build one from scratch that would shoot 1/4-3/8 moa....guaranteed. I would shoot for 1/4moa and settle for 3/8....... but it WOULD cost 2500 bucks. Minimum. And then another 350 bucks in dies to keep it shooting. And it might dump on you at 7-800 rds, definitely by 1500.......

And within three barrels I'd expect to find my 1/4" gun... but that's a TON of money and work spent on a cartridge poorly suited to accuracy. And I could blow it away with a 6X47L....

Of course these numbers are guesses, SWAG's but guesses.

For cheap I'm ALL about the 6BR. And there are solid reasons for this.

Tim, I'm 10 miles down the road..... if you ever want to shoot over flags or actually drop some groups with a tuned accurate rifle call me at 360 904 6941.

seriously

And, if you're ever ready to take the plunge you've got a guy named Del Bishop 20min north of you who's a Real Deal Benchrest Competitor and Bullet Maker Deluxe.... and he's always got Good Stuff to sell..

And right across the river, 5 mi away by boat :) is Eric Stanton, a real hotrod shooter too, always seems to have a winning gun and a Bartlein barrel or two close to hand.... both these guys though specialize in short range BR. But the current NBRSA World Champeeen of 600yd is within an hour of you too... You really need to come down with us to Tigard and watch or even shoot the 600. I'll set you up with a 6BR that'll let you actually compete if you want. It's a clunker but it'll get you in the door.

In the end, you shoot a good gun, once, and then just SELL everything else to pay for it, and ye'r all SET!! :D


al
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Accuracy is a sort of a weakest link thing. In your case, you are probably missing some of the links. I do not say this to be condescending. Heck, I have spent many happy hours at the range in similar pursuit. Take Al up on his offer, then go to a Benchrest match or two. You have some great talent around you. They are all good folks. You will learn a lot, and have a good time.

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