Cold Bore Shots - Any definitive Expert Articles?

[Michael Courtney]

200 passes with a bronze brush??? Shirley you can't be serious. Do you also remove the brush at the end of every pass to protect the crown (as advised by some barrel makers). There are bore cleaning products that could reduce that scrubbing regimen by 10 fold.

I am serious. No the brush isn't removed every pass. Chemistry can remove copper, but not carbon, and some of the copper is hiding under the carbon. Bronze is much softer than steel, so if only the bronze touches the crown, there is no significant wear. Contact with the rod and grit in the solvent/fouling mix carried by the brush can cause wear, which is why we are meticulous in cleaning the brushes, rod, and solvent/fouling mix out of the bore at each step.

We've developed the most accurate techniques available for measuring barrel friction, and consistent barrel friction is a key to consistent velocity. We may well be causing some invisible damage to the crown that is turning 0.2 MOA groups into 0.5 MOA groups, but our interest is more in low velocity variations and low BC variations needed for our experimental work and to maintain 0.5 MOA groups at long range rather than benchrest group sizes at 100 yards.

 

[Michael Courtney]

We are careful that the brush stroke is only long enough that the brush barely clears the crown with no room for the rod to rub.

How is this possible?....the bristles either remain in contact with the crown (in which case you are reversing the direction while still in the bore) or the bristles clear the bore (in which case the rod contacts the crown). Whether you allow the rod to contact for 1/4" or 1", with a minimum of 200 passes every cleaning ....that a lot more rod contact that most seasoned competitors subject their crowns to.

Good questions, thanks for the chance to clarify some of the subtleties. It is possible that there are strokes where the backmost bristles are reversing direction while still in the bore, but from the feel of it, it is much easier to reverse direction than if the whole brush is in the bore. By sound and by feel, most of the bristles have cleared the muzzle before direction is reversed.

Wear is caused by friction which is a rubbing with a harder material over a distance, not by barely touching if the brush is slightly pulled down by gravity. Some of our rifles have muzzle brakes that centers the brush when it exits and prevents the rod from touching. We also use a 1" brass extension at the end of the cleaning rod, so if there is incidental contact, it's with the brass extension rather than with the stainless steel rod. Finally, we use rods that are well matched to the bore diameter. This provides a stiff rod that is less likely to bend and make a lot of contact on the push stroke, and it also means that contact between the barrel and rod is more likely to occur in the bore than at the crown.

These factors combine so that even if there is some contact with the rod, it is minimal and there is nothing hard, the distances are small, the forces are small, and the crown is unscathed.

I have no doubt that careless cleaning can ruin rifle barrels. But I also have no doubt that careful and complete cleaning is key to obtaining consistent velocities from our barrels.

 

[LHSmith]

IMHO, based on over a dozen years competing in short range BR, it is the mirage conditions at the time of the shot that vary that will change POI....much more so than a BR rifles ability to hold a cold bore POI. Place a high power scoped rifle on a solid rest ,on a solid bench , sighted on a target, and record where the crosshair/ dot location is every hour from sun-up to sun down.
Then you have the atmospheric affect on the "tune" of the load which invariably is different than your last tuning session.

 

[LHSmith]

For your consideration : The current trend amongst the BR crowd is to use HARD stainless steel cleaning rods (Ivy Rods) .....the theory is that the softer metals and coatings IMBED the grit. The patch holders are also stainless or delrin to avoid the false positive that accompanies brass holders.

 

[Michael Courtney]

Michael -

I would agree as you point out with your method, as long as the cleaning ritual used is guarantying the barrel is totally cleaned, then yes you would not need a bore-scope to see if it truly is cleaned.
But what a bore-scope will tell you also is: how much you need to clean and if you are over cleaning.

From reading your cleaning method/ritual, I can't help but feel, in many circumstances, you would be over cleaning. And that you are also falling it to the "only guessing at the truth", by not using or at least periodically using a bore-scope, to credit your method/ritual effectiveness and efficiency.

In a closing: I agree with Jim and is my experience also, to hurting the crown with a brush.... but is another subject itself.
Donovan

There may be a difference between what we need in a laboratory barrel where we are working to minimize velocity and BC variations and what most shooters need in match barrels to minimize downrange group dispersion and improve barrel life.

If we were overcleaning, there would be less blue on the dry patches after the Shooter's Choice stage and less black on the patches after the Hoppes #9 stage. And there would be fewer occasions where we have to repeat the procedure from the beginning. Back in 2011 and 2012, we cleaned and cleaned and cleaned the .223 Remington used in our friction studies, because it took a bit extra to get all the MS2, WS2, HBN, and Lubalox out of the barrel when switching between bullet lubricants in the friction study. (See http://www.dtic.mil/dtic/tr/fulltext/u2/a568594.pdf) We were also cleaning it heavily from 2010 to 2012 for all the armor studies we were doing, as well as for the lot to lot variation study in Varget. Shooting solid brass, solid copper, and steel core bullets causes more fouling and requires more careful cleaning than thin jacketed lead core bullets.

Yet I went out after all that and won a long range precision rifle match with the rifle. The rifle still holds 0.5 MOA at long range with 62 grain Berger flat base varmint bullets when the wind does not blow. I am saddened a bit that my daughter has an experiment scheduled that is likely to ruin the throat, and I've already asked her to order a new barrel so that we don't have a long stretch without an accurate .223.

 

[Michael Courtney]

For your consideration : The current trend amongst the BR crowd is to use HARD stainless steel cleaning rods (Ivy Rods) .....the theory is that the softer metals and coatings IMBED the grit. The patch holders are also stainless or delrin to avoid the false positive that accompanies brass holders.

Yep. Makes sense. Some good ideas if my daughter gets more into this BR thing she's toying with.

 

[johara1]

Michael, In 1996 when i started bench rest i was buying equipment, among the things were a dozen 6mm brushes. The end of 2013 i replaced the first dozen brushes. That is a lot of barrels,if i use a brush i make three passes and unscrew it at the muzzle. I have been using Ivy rods for a lot of years and aluminum tips, and this year i will use a false muzzle to screw on after removing the brakes. I can totally clean two guns in 15 minutes. I you should rethink your cleaning method, you are putting more wear on from cleaning……… jim

 

[josh.rizzo]

While this has changed to a cleaning thread, the OP asked for articles, so here is the video that got me started thinking about cold vs clean bore:

[youtube]http://www.youtube.com/watch?v=lV9QvEm1nFc[/youtube]

This also goes into why the 100 stroke cleaning routine may be doing too much damage. Cleaning for lab consistency is good, but if you errode the barrel significantly, it may affect your results more than the fouling.

 

[josh.rizzo]

More on the cold vs clean bore:

[youtube]http://www.youtube.com/watch?v=qbMuknl677A[/youtube]

I believe this is from one of the Magpul series.

 

[Romulus]

I appreciate all the discussion, but my principle focus was really cold bore shots not clean bore shots.

In the spirit of discussing cleaning, I used to use etchants with all my hunting rifles like I was shown by my father and grandfather. When I got some "target" rifles I began researching stuff and started using a lot of the KG products with ease of use and great results IMHO. I used to use KG until all the copper was gone, but found my clean bore shots were a lot more consistent if I only cleaned out the copper to a certain point - where to copper holding out in the trenches. With THAT rifle I had no cold bore issues, but as it was a medium range gun, a 308 Win, I never really HAD to find out just what my CBS velocities were. They were in group, but that simple description could be misleading if the FPS was low for long shots.

Now I rarely do full blown get-it-all-out cleaning. I prefer the consistency; if I can't keep my seating length off the lands anymore, or the chrono tells me my bore is shot, I'll screw another tube on.

Most shooters I know claim their guns don't shoot any type of CBS but most guys I know shoot steel and I know hardly anyone that collects their paper for a log. There's not many paper punchers or HP guys left out here anymore.

I appreciate one poster's comments about bedding. That is what I just did. I bedded it all around the lug and since 400 vlds came in the mail today, I am no longer out of ammo .

I'll see if the different torque setting on my action screws (which placed my CBS in-group 0.1" low but I have not considered this a trend as it was the last outing I shot)and the bedding job help reduce this -1 moa CBS. BUT STILL - I need to chrono these things over time.

I mean no disrespect to all the guys online or that I hear IRL with the common sniper advice to KEEP A LOG BOOK YOU DUMMY and you'll know where to shoot depending on the ambient conditions, but shot displacement at 100yds with no velocity info is basically only valuable to me for a few hundred yards. A lot of guys moan that they don't want to keep a separate ballistic profile for their CBS. If I do find a FPS discrepancy, which I expect, that is what I'll do with no problem.

Depending on the significance of the discrepancy, I may try out some HBN bullets and bore treatment. On a friend's rifle we treated his bore with KG's Molybdenum Bore Prep after every thorough cleaning and he could shoot FAST and he had no visible CBS at 100 yds. I had good consistency with my kit then so I didn't want to add any variables. I've done it on other rifles with no detrimental effects, and let me tell you those bores clean soooo fast.

I think it is overkill, but I was even considering, in terms of thinking/wondering, what bedding the area between my unimount lugs and the picatinny rail just in the spirit of experimentation. I had my rail pinned to the action recently since it's such a cheap job - made me feel a lot better for ultimate consistency since I don't baby this rifle at all.

Once again I really appreciate the discussion. I'll drag the chrono out tomorrow and test my CBS. So far, if I cannot eliminate the CBS visual discrepancy at 100 yds I HAVE to know the FPS, and yet I still want to know the FPS discrepancy even if it's in-group.

Wouldn't it be nice if rifles came with a piezo/magnetic/magic chrono installed that never ran out of batteries, failed to read, or created any POI shift lol? ;D

 

[Romulus]

Oh and to Josh.Rizzo when I started rolling that Vid I said to myself, "I've drilled a well on that scab land" and lo and behold the main speaker said "when I leave Canadian" later in the video.

Small world. I drive by Tubb''s shop daily in Canadian just envious of all the knowledge wrapped up in one guy and all his shooting pals.

 

[smoooth]

I've read a few articles by Todd Hodnett, excellent writer and extremely knowledgeable in all aspects of shooting.

For cold bore shot info, your best bet would be a USMC sniper or Navy SEAL.