Concentricity Question

[Deputy819]

I'm gonna throw a dart at the bore after looking at those speeds and say something is loose, or you shot the second group in a tornado.....I'm assuming you shot them off the same rest? This is another interesting one.

Oh, and shot off a Protektor front owl ear bag and Protektor rear rabbit ear bag.

 

[Deputy819]

Would this mean that my rifle is operating at significantly LESS pressure (for this particular powder) than what powder manufacturers are showing for their tests?

 

[dmoon]

I'm not familiar with 4451, I load either 4831 or 100V for my 6mm. Looking at my phone ap I'm showing an average of 3260 with a 95 grain VLD. Have you re-torqued your action screws? I'm thinking they are loose or you have a reticle loose in your scope.....If not load another round and burn some more powder and see if you can duplicate anything.

 

[Deputy819]

I'm not familiar with 4451, I load either 4831 or 100V for my 6mm. Looking at my phone ap I'm showing an average of 3260 with a 95 grain VLD. Have you re-torqued your action screws? I'm thinking they are loose or you have a reticle loose in your scope.....If not load another round and burn some more powder and see if you can duplicate anything.

Gotcha! Honestly, I'm suspicious of the scope. It's a brand new Leupold, but that doesn't mean it's not defective. My Hodgdon manual lists IMR 4451 max charge of 45.9 gr at 3189 FPS with a 100 gr Speer boat tail. As you can see I'm WAY above that (with NO pressure signs) and I missed your point in your last post....just realized that. Yes, huge disparity between group sizes with everything else being the same. Those groups were shot 1 day apart and weather conditions were the same for both days. I'll even give you my SD and ES numbers. They were as follows.
First group (.679") S.D 5.86
E.S 11
Second group (4") S.D 4.73
E.S 9
Great numbers, but something is obviously wrong here.

 

[Deputy819]

I appreciate all the great feed-back, Gentlemen. I'm kind of a lone wolf here in Frankfort, Ky and NOBODY here at the Sheriffs Office where I work handloads or even shoots that much I'm sorry to say. Talk about a crime!! So, this forum is just about all I've got (besides my Smith). I'll put my new Concentricity gauge to work this week-end and do some more tests with the Sierra's and see what happens.....weather permitting of course. Stay safe guys!

 

[jreagle]

if the shooter is all good then the scope, rings, and bases would be worth another look.
personally have had mixed results with that style ring and base setup; more room for error on the install. maybe start with a different set of base and scope rings. Maybe talley 1 piece; eliminating 1 connection point or a bedded rail and precision rings. still trouble after that then try another scope in the newly installed mounts.
also would be nice to see what the smith/builder has to say....
just my 2 cents.......

 

[Dr. Vette]

I weigh and sort my brass (Hornady) and I'm currently using Lee Collet Dies for neck sizing and a Redding body die only when my brass feels difficult to chamber.

I would use the body sizing die each and every time. You need consistency. Find out the length of a fired piece of your brass at the shoulder, and bump each case back 0.002 with each loading.
Also, if not doing it, I would recommend annealing each and every time. Studies have shown it can made a notable difference.

Just some comments after reading through the thread to this point.

 

[Deputy819]

I would use the body sizing die each and every time. You need consistency. Find out the length of a fired piece of your brass at the shoulder, and bump each case back 0.002 with each loading.
Also, if not doing it, I would recommend annealing each and every time. Studies have shown it can made a notable difference.

Just some comments after reading through the thread to this point.

You're right. I actually hadn't considered body sizing every time, but that makes perfect sense concerning consistency. On the subject of annealing I have read quite a bit about it and watched videos and so forth. Just haven't worked up the nerve to try it yet. Bought a propane torch a couple weeks ago to try it....just a little apprehensive I guess.

 

[Dr. Vette]

You can Google all sorts of ways to anneal. I'm too anal retentive to play much with the torch and count it out, so after getting tired of that I bought the Bench Source. The AMP machine looks great, but it ain't cheap.

 

[MagnumManiac]

I anneal after every shot fired before the next sizing. I find this helps with consistant neck tension.
Low ES/SD numbers don't always coincide with great accuracy, barrel harmonics make a huge difference to group size regardless of how small the numbers are.
With powders that are borderline for the cartridge expansion ratio, they often show a huge ES but shoot little groups. This can ONLY be attributed to barrel harmonics matching the huge velocity swing in the oscillation of the barrel, when it is still or near to anyway.
There's more to precision loading than just looking at the numbers.

Cheers.

 

[Deputy819]

I anneal after every shot fired before the next sizing. I find this helps with consistant neck tension.
Low ES/SD numbers don't always coincide with great accuracy, barrel harmonics make a huge difference to group size regardless of how small the numbers are.
With powders that are borderline for the cartridge expansion ratio, they often show a huge ES but shoot little groups. This can ONLY be attributed to barrel harmonics matching the huge velocity swing in the oscillation of the barrel, when it is still or near to anyway.
There's more to precision loading than just looking at the numbers.

Cheers.

Interesting. Will barrel harmonics play as important of a role in a 1" diameter barrel as it does a sporter Barrel? Another thing I've noticed about this rifle (besides it's inconsistencies) is that when it does turn out good groups they tend to be at a certain velocity and about 100-120 FPS apart. Would that be indicative of a good "harmonic node" or "velocity node"? Furthermore, will low ES and SD numbers relate with that node or does that have more to do with proper powder/primer combination?

 

[Deputy819]

I would use the body sizing die each and every time. You need consistency. Find out the length of a fired piece of your brass at the shoulder, and bump each case back 0.002 with each loading.
Also, if not doing it, I would recommend annealing each and every time. Studies have shown it can made a notable difference.

Just some comments after reading through the thread to this point.

Is there any particular head-space gauge that you'd recommend? I've just been doing it by how the bolt "feels" when it closes on a sized case. One more thing...Considering my chamber was cut with a new Manson reamer is there a chance that just maybe the chamber is a tad bit "over-sized"? I've read where people consider SAAMI spec chambers "over-sized" anyway and I've wondered what kind of effect a brand-new, unused reamer would have when cutting a standard chamber. Even more "over-sized"?

 

[dmoon]

You're extreme spread will not really start showing up until you get out around 600 yards (in my experience). I've had rifles that shot bug holes at 100 yards with SD's up over 20, never seen one that would hold even 1 MOA at 1000 with that kind of inconsistency.

 

[Deputy819]

You're extreme spread will not really start showing up until you get out around 600 yards (in my experience). I've had rifles that shot bug holes at 100 yards with SD's up over 20, never seen one that would hold even 1 MOA at 1000 with that kind of inconsistency.

@ 600 yards is where I'd like to stretch this rifle to, but the inconsistencies I'm having at 200 yards is putting a halt to that....for now. Gonna look into Concentricity and, upon recommendation by Dr. Vette, cartridge headspace. My head is spinning....but I feel like I've got avenues to look into now instead of "groping around in the dark".