fire lapping load

[walker77]

I got the kit from beartooth bullets. And it says to put just enough powder in to get the bullet out the barrel. I have no idea where to start. Its for a smith and wesson 629 44 mag. 4 inch barrel. Any suggestions? Oh and the powder i use is unique.

[geargnasher]

Try three grains of Bullseye. If the boolit sticks, drive it back out with a brass rod wrapped in electrical tape and go to four grains. Unique needs more pressure than that to burn reliably.

Gear

[Catshooter]

With Unique, I'd probably use three to three and a half grains. I don't mind it burning poorly. :)


Cat

[geargnasher]

As long as it burns! I had some smolder out on me trying to lap a .357 Magnum revolver once, stuck the boolits in the forcing cone and had charred flakes all over, but in it's defense the cylinder gap was pretty large.

If you want to make sure, stuff about a grain of Dacron in there, don't pack it, just poke it in on top of the powder until you can get the boolit started, then let the boolit push it the rest of the way in. This will not only help the light charge of powder go off, but will help seal the boolit a bit and might make the laps more effective due to less gas cutting.

Gear

[walker77]

With Unique, I'd probably use three to three and a half grains. I don't mind it burning poorly. :)


Cat

why would it burn poorly?

[RobS]

Powders operate best at certain pressures or energy levels and not having enough of X powder in X cartridge case results in lower than optimal operating pressures resulting in less than optimal ignition/burn characteristics.

[truckjohn]

I did my best fire lapping loading directly at the range.... I brought my hand primer seater tool.... Used a small punch and a small hammer to knock out old primers.... Used a cut-off 22lr case as a powder measure, and used really fast powder - I think I used Red dot...

The idea was to get the bullet going only fast enough to reliably exit the muzzle.... though the actual exact charge weight doesn't matter much... Be sure to take along a wood rod and a hammer to knock stuck bullets back out of the barrel..... You will probably end up knocking one back out due to a light charge....

Why load at the range? Well, that grease doesn't play nice with powder..... An afternoon in a hot car and you will end up with a box of squibs - no fun..... so you take 5 once fired shells.... load 1 and shoot it.... It is actually kinda fun - they go *pop* ... no ear plugs needed..... Just be sure to check the barrel after every shot...

Thanks

[303Guy]

A wood dowel rod or brass rod wrapped in tape to knock a boolit back out should it stick? Mmmm... Firstly, why does a fire-lapping charge need to be so low and second, I had to make a drill guide and drill out a stuck fire-lapping boolit from the breach end! I'm thinking of giving a fire-lapping boolit enough powder to guarentee it exits the muzzle. In fact, I'm thinking in terms of pretty substancial loads. Not full loads, but substancial. :Fire:

It's worked for me so far. I've only had trouble with too light a load.

[curator]

Fire lapping works best with a narrow range of bullet alloy hardness. Much over BHN12 and the alloy will allow for spring back as it encounters tight spots. Too soft (or too high pressure for the hardness) and it will result in opening the throat more that you'll want. Air cooled and aged wheel weight alloy is about perfect for firelapping and it will shoot fine at up to 15,000psi. No need to load it down to the point that bullets willnot exit the bore. Keep in mind that lapp-slugs have substantually more friction. Bring a brass rod and a heavy hammer just in case.

[white eagle]

I used 4.5-5gr unique

[BABore]

A wood dowel rod or brass rod wrapped in tape to knock a boolit back out should it stick? Mmmm... Firstly, why does a fire-lapping charge need to be so low and second, I had to make a drill guide and drill out a stuck fire-lapping boolit from the breach end! I'm thinking of giving a fire-lapping boolit enough powder to guarentee it exits the muzzle. In fact, I'm thinking in terms of pretty substancial loads. Not full loads, but substancial. :Fire:

It's worked for me so far. I've only had trouble with too light a load.

Too much velocity does a couple things. First off these are pretty much unlubed boolits. Any leading kinda defeat the whole purpose. You'll be lapping lead and fouling more than bbl steel. Secondly, a higher velocity load means more pressure. Pressure that can bump a boolit in the bbl. Your trying to remove constrictions and acheive a tapered bore. The lapping boolit should cut and be sized down as it passes through the constriction. It works on the constriction progressively, removing a bit on each pass. A higher pressure load is likely to bump the boolit up after it passes through the constriction and wear a distance ahead of it resulting in a humpty bumpty bore.

I usually start with arounf 3 grains of Red Dot and a tuft of dacron on most stuff. I would likely reduce that to around 2-2.5 grains on a 357 mag. Shoot for around 400-600 fps. You should be able to see the boolit in flight, just like a Red Ryder BB gun.

[cbrick]

I was getting leading in my new to me 629 44 Spl 6 1/2 inch. I was going to fire lap it but a careful study of the leading with my bore scope made me realize it wasn't a barrel thread restriction. What I had was leading beginning just prior to and at the forcing cone, continued shooting made this leading spread further to just past the barrel threads.

It was an incredibly easy fix. The bullets I was using were to short for the Smith's throat. Fired bullets had to find the center of the throat and move up and into the throat, it was shaving lead off the driving band and depositing it on the forcing cone. The fix was a longer (heavier) bullet, in this case the MP H&G #503 257 Gr. SWC. The bullet is long enough that when loaded the front driving band is already in the throat. The throats on this revolver measure a very uniform .431" and the groove diameter as near as I can tell on a 5 groove barrel is .4293".

Bullets sized to .4312" are a mild snug fit, the front driving band is in the throat. A couple of days ago I took 100 rounds loaded with the H&G clone to the range and fired all of them, I shot up a bunch of the steel targets and murdered more than a few rocks. I wasn't group testing, I was determined to make the revolver lead.

When I got home I examined the bore and forcing cone with the bore scope to see how much leading there was. None, nada, nowhere, not a speck, it looked like I had just cleaned it. Put it in the safe to wait for the next range session. Lube in this test was Dan's Speed Green.

The moral of this story is make sure it's a barrel restriction before fire lapping, it may be, it may not be.

Rick

[BulletFactory]

I think thats what is going on with the .40 Ive had problems with. The gunsmith wants to open up the throat a thousanth or so, because he thinks the barrel wasnt cut right. IIRC, he says its probably swaging the bullets before they enter the rifling, as we know, too small bullets will lead. What are the thoughts on this problem, should I roll the dice on 100$ and try it?

[390ish]

Those kits are great. I use a light load of AA#2 (38 special load) and it has worked for me with all my guns up to 24" rifles.