The First Thousand Shots

[justin amateur]

No wind, temps in the mid 60's, beautiful spring morning.

Couple of boxes of some less than stellar quality of CCI SV.
This brick has some poorly assembled cartridges with visible problems.
The worst being poorly seated bullets with bullet material crimped down onto the brass.
Didn't expect consistent results, didn't get any.

CZ 455 Varmint on the heavy bags with the new barrel, 100 yards

20 five shot groups, from 1 inch to 3.5 inches of spread.

More wear showing on those lands.
That silica is doing a number on the tooling marks.

Bore images - After 900 shots

 

[Gleedus]

unhealthy for 5 shot groups wow!

 

[justin amateur]

I purchased a case of CCI SV back in 2014, 5 cents a round including shipping.
It was all this bad. Been using it to annoy locals.
They like to claim 1/2 inch groups with CCI at 50 yards.
Being an evil old coot, I ask them to show me and even provide the free ammo.
Fun to watch the shock of seeing how bad bulk ammo can be, sink in.

 

[Matagorda308]

^^^That ain’t right!^^^

 

[justin amateur]

It ain't right? Why not? It's damn funny to watch the frustration level rise.

Also educational when I show them why they are producing all those strays.
Most never bother to look at the cartridges as they are fed into the magazines.
After seeing what happens when you purchase a batch of poorly made cartridges,
inspecting for problems before chambering, can explain why those fliers show up.

A pic of some of the problems with this batch of CCI SV

 

[Gleedus]

^^^That ain’t right!^^^

I know eh! The price of ammo these days!!!!

 

[oldfatguy]

I know eh! The price of ammo these days!!!!

When you can find any.

OFG

 

[DaveCo]

Justin amateur

Somewhere in the recesses of my fading memory, it seems I recall an analysis of what certain types of damage to the cartridge do to the accuracy.

If that was you, could you post a link? If it wasn't you, do you remember it?

Thanks (and thanks for this thread, really enjoying it)

 

[justin amateur]

Dave...that was probably part of the 50 at 200 thread.
I was attempting to understand some of those wild strays I was producing.

Link to the beginning of the discussion...

50 at 200

The pics from the CCI VNT... https://www.rimfirecentral.com/threads/the-grid-at-50-yards.1235549/post-12729632 https://www.rimfirecentral.com/threads/50-at-100.1204943/post-12729646

www.rimfirecentral.com

 

[DaveCo]

Thanks- im sure thats it.

Appreciate it

Now I remember your alias over there it's all coming back to me. Also explains why I couldn't find it on the Hide

 

[Brisket]

Justin,

Just wanted to say I appreciate the time you took to provide this information! I've got nothing of value to add, but feel like I've learned a good bit

Thanks again

 

[justin amateur]

I may have a new definition of fun.
5 shot groups at 100 yards with a quartering headwind at 23 to 30 mph.
Between the turbulence generated by the left side wall and the gusts,
ya' just can't help giggling at the unpredictability of the trajectories.

Now 1000 shots through the barrel, this morning sent 100 of Fed AutoMatch at 100 yards.

Shooting during a spring nor'easter is highly entertaining.

455 Varmint, new barrel, heavy bags

Look, sub moa at 100 yards, all day long!

As long as you don't care where I was aiming...

and excuse that stray over there...

...and excuse the other 95 shots it took to get that one tight bunch...

I like shooting when it's nasty out there.
Range to myself and a big grin on my face from all those random results.


Bore images - After 1000 shots

I don't know about y'all, but the pictures look to me to show that abrasive wear is occuring.
I can see it eating away at the leade and can understand why these barrels do have a finite lifespan.

Final accuracy check at 50 yards when the weather cooperates.
See what happens with another box of SK Biathlon compared to the other results.

 

[justin amateur]

1000 shots fired, plenty of bore images to compare.
Final bit of information to add...50 shots at 50 yards with SK Biathlon Sport.
Good thing, it's my last box from the brick that did well at 200 yards.


CZ 455 Varmint with the new factory barrel on heavy bags

50 yards with a south wind at 1 to 4 mph.
8 am with no one else at the 50 yard range.

This factory barrel can't match the results from my Lilja or Shilen from the same setup.
Still, it does meet CZ's expected 2 moa at 50 yards results with good ammunition.
But it still keeps throwing strays even when those crosshairs stayed on point of aim.
Wasn't wind, wasn't me, maybe ammunition, but based on results from previous boxes
I'm thinking the condition of the bore from the factory is likely the cause.


Okay...it was worth the expense, time and effort.
Much useful information garnered during the discussion.

1) USB borescopes are affordable and useful in understanding what is going on inside the barrel.

2) Give it 2 bricks of rimfire before deciding if a new barrel is capable of getting the job done.
A) Let's you familiarize y'erself with the rifles quirks.
B) Allows the silica in the burn residue to knock down the burrs and tool marks.

3) Rimfire barrels do have a lifespan. Every shot fired drags silica through the bore.
It will chew up the rifling over time, mostly in the first inch or so of the rifling.

4) It's not a cold bore flyer, it's a dry bore flyer.


Images collected in sequence, starting at the leade, ending at the crown.
Links to the folders as they were created

4 images, taken at referenced intervals, 90 degrees clockwise, starting at the bottom of the bore

Bore images - from the factory

Bore images - After 100 shots

Bore images - After 200 shots

Bore images - After 300 shots

Bore images - After 400 shots

Bore images - After 500 shots

Bore images - After 600 shots

Bore images - After 700 shots

Bore images - After 800 shots

Bore images - After 900 shots

Bore images - After 1000 shots


I wonder what the bore will look like after 2000, 3000, 4000, 5000 rounds sent?
I'm OCD enough that I'll likely find out.