Fire lapping ?

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Last Post 12 January 2011

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Wayne S posted this 06 December 2010

I have a 30 Cal. 15” Contender Bbl. with a 1-8 twist. It is supposed to be a Shelen match bbl. To date, I've tried getting it to group useing several 200 +- gn.cast bullets as well as 150,168 & 190 gn.Match bullets with no success. All loads were between 1050 and 1200 FPS according to the loading data I got with the Bbl.and there was no leading after shooting the test loads.

I've read ere about rolling bullets in 400 grit. valve grinding compound, both cast "J” bullets. BUT there is where the water gets muddy, I've read that 4 or 5 should do, and I think I remember reading to shoot 20 impregnated bullets, at low speed, clean and re test .???????????????????????????????????????????????????????????.

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billwnr posted this 06 December 2010

I had someone tell me the .30 Herrett barrels have long throats. You didn't say what caliber yours was, but have you done a cerrosafe cast to see what your chamber and throat looks like?

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hunterspistol posted this 06 December 2010

Because of the way TC cut barrels, the 32-20 and 32 magnum are both .308 barrels. Which begs the question, which 30 Caliber? I can honestly tell you that all my contender barrels shoot best with the lightest bullet I can find, within reason, of course.

Were it me, I'd try the lighter bullets. I don't guess I'd have to tell you to seat the bullets out to within .020” of the rifling and oversize them 2 thousandths. Before I'd firelap an expensive barrel, I'd dip a patch in 500 grit and give it 20 or 40 strokes, then, pour mineral spirits through it. I prefer hand polishing to fire lapping, myself.

Maybe that starts a thought,

Ron

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Wayne S posted this 06 December 2010

It's chambered in a case based on a 38 Spl. necked down to 30 cal. I've sluged the chamber and come up with .3095.

My 3 cast bullets, 311365,RG-4 and Saeco 311 are sized to 310. the 311365 and RG-4 are seated to ingrave the lands whan the action is closed, the 311 ingraves the throat when the action is closed.

None of the BTHP bullets touch the rifleings

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billwnr posted this 06 December 2010

you have a long throat, hence the query about chamber casts.

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mike morrison posted this 06 December 2010

no expert here. when i was where you are and thought i needed to firelap a bbb. i followed the instructions like you stated. no good so i kept firelapping. still severe leading. the next throat slug revealed a throat that was .004 larger. finally took the gun to a smith that had a bore scope. instructions said to clean all jacket fowling. yep i did that. used j-b's and all. still leaded. the scope showed lotsa copper stillin the bbl. this i could not see with anything i had. ruined a good bbl. finally with this info. i started using a softcheck under the bullet and no leading. just info here based on my experience. hope it is helpful. would i firelap again? yes but verry carefully. good luck m

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Wayne S posted this 06 December 2010

My cerosafe should be here Sat. And I think I'll try H/P's method, wrap an old 357 bore brush in cleaning patch material, coat it in polishing compound and give it 20-40 + strokes.

The long throat might be the problem with the cast, but even Herrett Bbl's with longer than life throats shoot “J” bullets pretty good

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mike morrison posted this 06 December 2010

good move. keep us posted. m

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billwnr posted this 06 December 2010

is.... your case a .30 Miller variation and depending on where the end of the chamber is would a .357 Magnum or Maximum tapered down give you a longer case for your bullet?

Also, have you considered just seating the bullet to the depth of the gascheck?

If your barrel isn't leading then the only thing you might gain by firelapping is additional throat wear.

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gunarea posted this 07 December 2010

Hey Wayne

While your particular caliber is unfamiliar to me, I do have quite a bit of T/C experience in several different 30 caliber configurations. Some of them have been frustrating to figure out. Send me a pm with an address for package delivery, I will give you some light slugs of mine to try. They were the trick for me in a 32 mag barrel with a similar twist rate. You could end up like me, with a bunch of moulds that didn't work. If it does work, the mould is a Lyman, still produced and offered at most outlets.

With a lack of barrel fouling I would be hesitant to begin grinding it out. Have you recovered any bullets for examination? The faster twist rate may need some very fine tweaking to make it perform. Another aggravating possibility is long barrel vs powder burn. Geez, let's not get into that. My offer is merely an option, not an answer.

Roy, usmc

Shoot often, Shoot well

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Wayne S posted this 07 December 2010

billwnr wrote: Bill, the 311299, 311365, and S 301 are all ingraving into the lands and the GC is at or above the case body/neck junctionis.... your case a .30 Miller variation and depending on where the end of the chamber is would a .357 Magnum or Maximum tapered down give you a longer case for your bullet?

Also, have you considered just seating the bullet to the depth of the gascheck?

If your barrel isn't leading then the only thing you might gain by firelapping is additional throat wear.

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CBA Member

James S posted this 07 December 2010

Hi Wayne, I would definitly give Veral Smith an enote and check out his LBT sight. I have a Marlin 357 mag rifle that has some tight spots in the barrel, Veral steared me straight on fire lapping this barrel.

Fire Lapping can help but it is a distructive process. You certainly don't want bumps and wiggles caused by uneven polishing or removal of too much material !

Good Shootin, James.

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Wayne S posted this 07 December 2010

James,

I'll see if I can “feel” any tight or loose spots this evening when I start cleaning it prior to the range session thurs. or friday.

Since all of the loads will be between 1050 & 1200 FPS, recovering bullets shouldn't be that hard. Not sure what I can learn from fired bullets but I'll have some to look at .

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James S posted this 07 December 2010

Wayne, when I slugged my barrel to determine groove dia. The slug did not move through the barrel smoothly after I got past engraving the rifling, which tells me I can get better accuracy from this rifle by “fire” lapping. My next step is to check throat with a soft slug method or a cast to find the best CB to use. Yours maybe the same steps needed.

James

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gunarea posted this 11 December 2010

Hey Wayne

Sorry for the lag time in getting a reply on the 30 cal mould I found to deliver accuracy. After consulting my latest Lyman catalog, I found no current listing for this particular mould. The identification stamped into the mould block is 311359AV. From my alloy, it yields a 134.7gr. spire point of gas check design. Sizing makes a difference in several of my barrel/caliber combinations and I treat each one specifically. My experience with 30s has led me to cast at or below #2 hardness and use the gas check option. The hardness checker I use is of Saeco name brand. Florida deer and turkey fall handily when sent out at around 1600 fps. It has proven very accurate in 32 mag as well as 30-30 and I did use this bullet for a few of the different gun games. 30 carbine and 30-06 both shot this slug with good results but I didn't do a lot of experimenting with the 30-06 caliber. The 30-06 wasn't in a contender but rather a Lone Eagle produced by Magnum research.

The lighter bullet advice given may well be the ticket with the fast twist rate. I don't promote this bullet as grail to 30 caliber, just an option that worked for me in a couple fast twist rate barrels I use. My previous offer stands. Best of luck in your endeavors, let us know how it proceeds.

Roy

Shoot often, Shoot well

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.22-10-45 posted this 11 January 2011

Hello, Wayne S. I wouldn't use valve grinding compound..I fire lapped an 1898 Krag & 1903 Spgf. Using the NECO kit. Both came out fine, throat wasn't lengthened as far as I could measure. Bore increase was as close as I could measure with a Starrett .0001” mic. .ooo1..1/10 of 1 thousand of inch..if that. The NECO abrasive is non-imbedding, even so, I used a hard, stainless uncoated rod when cleaning between grit sizes.

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hunterspistol posted this 11 January 2011

:coffee Here's an article just written by Fermin Garza, the shootist. This helps a little by taking some of the mystique out of firelapping. Seems it isn't such a bad ordeal.

http://www.gunblast.com/FerminGarza-Firelapping.htm>http://www.gunblast.com/FerminGarza-Firelapping.htm

Ron

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jppr26 posted this 11 January 2011

have you tryed honing the crown of your barrel i have a 3006 that was all over the map, 4+” group at 100yrd, then i used a steel ball barring hot glued to a brass tube with some fine laping compound on the muzel now i got .5” groups at 200yrds.

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cityboy posted this 11 January 2011

What kind of rifle was it?

Jim

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Wayne S posted this 11 January 2011

JPP, the ball bearing trick, thats next to try, just as soon as I find some different size ball bearings. The person that told me about useing a ball bearing on the crown said to use a small steel plate and just put some fine grinding compound on the bore hole at the muzzle and roll the B B around and around. .

I'll have to find several B B and try both methods

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billwnr posted this 12 January 2011

Here's what I'd do before I did a single thing to that barrel. I'd borrow a Hawkeye probe and poke it inside the barrel to inspect it for any irregularities. I'd also get a magnifying glass and inspect the crown. Then... I'd pop it off the “action” or whatever the main part of a Contender is called and do a cerrosafe cast.

You said it's a MATCH barrel. Match barrels aren't supposed to have any issues. I'm back to thinking you have a long throat and you are encountering problems with a long throat. If it's truely a match barrel then the firelapping suggestion will only make things worse.

My “humble” opinion.

One question and an important one; was the barrel new when you bought it?