Would fire lapping make any difference?

[Mr Sasquatch]

My D34 has had a little over 10,000 pellets through her, and my Tx200 is approaching 7,000. I'm working on squeezing every bit of accuracy out of them, so my question is: at this point, would fire lapping the barrels make any difference in the accuracy? BTW, both rifles already have JM and Vortek kits installed(respectively) and have been DIY tuned and Krytox lubed, so there is not much room for improvement there.

[Motorhead]

Fire lapping IMO is only a valid thing with Gilded/Jacketed bullets.  Lead is so soft relative to the barrel or lapping medium it will do little if anything.

Now using a Hard Rod / Jag and snug patches with JB bore paste or more aggressive some 400 grit clover may or may not further help the barrels shoot better.

[grauhanen]

10 000 and 7 000 pellets through the barrel?  Keep shooting, they're still fine.

[K.O.]

Fire lapping IMO is only a valid thing with Gilded/Jacketed bullets.  Lead is so soft relative to the barrel or lapping medium it will do little if anything.

Now using a Hard Rod / Jag and snug patches with JB bore paste or more aggressive some 400 grit clover may or may not further help the barrels shoot better.

I humbly disagree about when fire lapping helps and would not recommend clover because of paranoid of the carbide embedding in soft air rifle barrels...

I have taken to fire lapping my new Crosman barrels with auto rubbing compound on a Q tip in front of a tight pellet to polish the manufacturing roughness/marks and such and it does seem to help a touch on all my barrels. my slightly tight 18" .22 barrel it even gained about 5fps...

I first did it to fix a slight marking/chatter mark but not quite a gouge in a barrel...

if you have a rough barrel or a barrel with tight spots it can help also...

I plan on a mild lap with bore paste on a new Crosman 22 barrel to put a slight  taper in it (for a pumper not a springer or np)...

they are a cheap D.O.M. tube with a button pulled thru and I want to make sure the muzzle is the tightest spot in the bore...



I know in certain cases it will help a springer...

I do think fire lapping can help but just not every barrel especially choked barrels need care not to wash out things to much.

http://www.gatewaytoairguns.org/GTA/index.php?topic=77016.20

(not my vid) 

with as many pellets that have been thru these barrels they are good and polished so unless there  is a problem with tight or rough spots...

[Motorhead]

In the end ... what ever works 

[Mr Sasquatch]

with as many pellets that have been thru these barrels they are good and polished so unless there  is a problem with tight or rough spots...

This is what I was thinking. After so many shots the rough spots should've been smoothed out by now.  Visual inspection of the barrels shows no obvious problems like burrs, rust or rough spots. But how do I check for tight spots? Is slugging the barrel the only way?

[Roadworthy]

Take a pellet which presents a good fit and push it through the barrel.  You'll feel any rough spots as added force will be required.

Of course if you want to pull it from breech to muzzle you could drill a small hole through the pellet, slip fishing line through the hole, and tie a fat knot.

[TooJung2Die]

Push a pellet through the bore with a cleaning rod or dowel. That'll reveal volumes about the condition of the bore.

The old '92 Diana 52 that I fire lapped using KO's suggested method using q-tips to carry the grit ahead of a pellet is once again shooting like a Diana should. I believe the barrel was probably heavily lead fouled and the only thing I tried that worked was the fire lapping. I tried all kinds of things (including things you shouldn't do to a barrel) and nothing helped. The grits I tried were JB Bore Compound, Turtlewax rubbing compound and white toothpaste. Believe it or not, the toothpaste had the most benefit. I gave the barrel a good cleaning afterwards using JB on a tight jag. Since then it has received only routine cleaning using Goo Gone on a pull through patch. The before and after targets don't lie. Check out the link Kirby posted above.

[K.O.]

Push a pellet through the bore with a cleaning rod or dowel. That'll reveal volumes about the condition of the bore.

The old '92 Diana 52 that I fire lapped using KO's suggested method using q-tips to carry the grit ahead of a pellet is once again shooting like a Diana should. I believe the barrel was probably heavily lead fouled and the only thing I tried that worked was the fire lapping. I tried all kinds of things (including things you shouldn't do to a barrel) and nothing helped. The grits I tried were JB Bore Compound, Turtlewax rubbing compound and white toothpaste. Believe it or not, the toothpaste had the most benefit. I gave the barrel a good cleaning afterwards using JB on a tight jag. Since then it has received only routine cleaning using Goo Gone on a pull through patch. The before and after targets don't lie. Check out the link Kirby posted above.

Lead tends to build up on a rough spot imo so while it may have been lead that covered it there was probably a reason for the build up.

If  it came from a humid environment it could have been stored unoiled and then shot or it could have been manufacturing roughness etc...

Then how it was cleaned or never cleaned etc...

point is it is really hard to know why on a used rifle but easy to feel...


Me I feel every barrel is an individual and you need to figure out what it needs on that basis...

I do feel a polished barrel  will have less lead build up simply because there is less for it to grip and hold on to...

Here is a link that shows the best explanation of the compounds used IMO (yes I have looked at the MSDS for them and (Flitz Bore Cleaner has cristobalite))   (scroll to post #15)

research fire/hand lapping, research compounds, research barrel making and etc., and etc., and think  ... Imposable to ever learn it all but the more you know...


Me I believe both the JB and Flitz polish with al2o3 & D.E.( not flitz bore clean thats different thing, the cristobalite ) are about like taking 2500 grit wet dry to your bore..?      Many differing opinions  out there and you have to pick thru it all...

[K.O.]

oops forgot link...

http://www.shootersforum.com/gunsmithing/31150-polishing-bore-w-lapping-compound.html

[TooJung2Die]

Lead tends to build up on a rough spot imo so while it may have been lead that covered it there was probably a reason for the build up.
If  it came from a humid environment it could have been stored unoiled and then shot or it could have been manufacturing roughness etc...
Then how it was cleaned or never cleaned etc...

Most likely it's been a desert dweller. Over twenty years old, no gun case, and there was only a small hint of rust on one tiny spot on the barrel shroud. The barrel was probably rarely or never cleaned. A lot of people don't believe air rifle barrels need cleaning because they don't burn powder.

I do feel a polished barrel  will have less lead build up simply because there is less for it to grip and hold on to...

Agreed. I don't believe you can hurt a barrel with something like JB bore compound and it's more likely to help. I've used it to try to reduce tight spots in a barrel by rubbing back and forth on a tight patch on a jag. After an hour of rubbing and using a freshly treated patch every few minutes there was no detectable difference in the tightness but the bore was very bright. You will need a more aggressive grit to actually remove metal in any measurable amount. I'd like to give the Model 52 barrel another JB treatment but that requires complete dis-assembly to get a straight line to the breech.

That's an interesting discussion on bore abrasives.

Jon

[K.O.]

Well I am not really to sure about not hurting by fire lapping some of the kits start at 220 grit which is way to coarse imo...

I feel that the auto rubbing compound  is about 800-1200 grit but I am not sure what the abrasive is... The really fine rubbing compound is advertised as good for taking out 1200 grit sanding scratches so...

JB and Flitz  al2o3 & diatomaceous earth well the Mohs of synthetic aluminum oxide is about  3 if I remember correctly so it is pretty soft but harder than pb(lead) which is down about 1.5(?)...natural al2o3 mohs is 9... and the D.E. is mainly natural Silicon dioxide of a grit size(shells) but is friable(breaks down quickly)


Now comes the tooth paste which is an abrasive paste but the main one we need to think about has a mohs of ~3(I think it synthetic)(?) silica... and according to the link I found the silicon dioxide is about 8 microns in size...(.00031496063 inches)

http://www.tomsofmaine.com/ingredients/overlay/hydrated-silica


So I have a feeling Crosmans barrels are 1117 free maching steel I do not know but it is what makes sense to me...
ANd other manufacturers ?    nobody says...


but  any ways   the Brinell hardness of 1117  is ~156 according to what I read

here is a compareison chart...

http://www.cidraprecisionservices.com/mohs-conversion.html


So in the end what steel  the relative hardness of the abrasive to the steel and its grit size...

Crosman grooves and lands look shallow(Marlin MG is similarly shallow and effective) and L.W. publishes theirs...

So just what steel is any given air rifle barrel made of and we would really know what we are doing but...

 

[TooJung2Die]

Well I am not really to sure about not hurting by fire lapping some of the kits start at 220 grit which is way to course imo...

I wouldn't say fire lapping is perfectly safe either. I thought you were talking about the benefits of polishing a barrel by hand.

The abrasive in the toothpaste I tried is hydrated silica, which naturally occurs as diatomaceous earth. It's very soft stuff as abrasives go. I figured if it's safe to swallow it probably won't harm the barrel either. The barrel was uselessly inaccurate to begin with so what did I have to loose?

When working with a barrel I believe it's probably best to start off as gentle as possible, progressively getting more aggressive as the situation indicates.

[K.O.]

Well if ya hand lapped for a couple weeks strait...

I just posted the rest to inform others about how I see it...

as far as it being soft well natural crystalline silicon dioxide(saltwater diatoms) is hard (used in JB and Flitz?) but breaks down to  micron size almost  ~.00012" if I remember right...

 the tooth paste is synthetic amorphous silica ... natural Freshwater diatomaceous earth is amorphous silica and has been/is used as toothpaste also, once again would have to make sure

http://www.colgate.ca/Colgate/CA/EN/Corp_v2/ContactUs/MSDS/pdf/2013/COLGATE%20MY%20FIRST%20INFANT%20&%20TODDLER%20TOOTHPASTE.pdf