Fire lap or not?

[Rich Cronk]

I have been a member here for awhile, and only have nine posts to my credit. I hope I have this question in the correct forum. I have a Marlin 1895 "cowboy" in .45-70 caliber. I have been stocking up on hard cast bullets for this gun because it sounds as though hard cast bullets have some advantages that I am interested in. When I slugged the bore with slip sinkers, I found a couple of tight spots that squeazed the sinker down to .456. My hard cast bullets from Beartooth bullets and Doc Holiday have been sized to .460. I have been advised to fire lap my bore before shooting any lead bullets. I have had a fire lapping kit on order for over a month and still waiting. What will happen if I shoot some hard cast 350 grain bullets out of this gun before fire lapping?

[.5mv^2]

I have fire lapped a ruger 44. It was tight at the breech. I used commercially cast bullets and boiled off the lubricant. Then I rolled the bullet between two metal plates that had some valve grind compound on it. I loaded the rounds with a very light charge. It worked and took about 60 shots.

[sisterjim]

It will go bang and the boolit will hit what you are pointing at; if you've no drank too much coffee it might hit the same place for the next shot. My experience is that the second shot will be a bit lower than first for point of aim if you start with a shiny, clean bore. Thereafter they should all land about the same until accuracy is spoilt by fatigue or fouling or wind or caffeine withdrawal. I wouldn't let somebody else's opinion on fire lapping stop me shooting and finding out for myself. I was advised of the same and wondered about what to add to the melt to perform the exercise. I figured the kit includes ACME grinding potion of finest variety but of what I know not! Probably wise to clean out any copper before you indulge. ENJOY, JIM

[41 mag fan]

Worst that'll happen is getting some leading due to squeezing it down .004.
When you slugged, you said you got some tight spots....could you fell it get tight? or was it an easy slug going down?
My Marlin slugged at .458 and was the same feel all the way down the barrel.

One thing you might try is taking a 50cal buffalo bullet and use it for slugging. For the 45-70 these work perfect. Dead soft lead the really will give you an accurate slug to measure.

Also congratulations you hit post #10 [smilie=p:

[uscra112]

Welcome in, Rich,

Depends on where your "tight spots" are. Close to the breech end, yes, I'd try firelapping. Close the muzzle, leave 'em alone. Meanwhile, slug the first inch or two from the breech end. If your boolits are .001" to .002" over that, and give it a tryout. Heck, try 'em anyway if they'll chamber.

Hard boolits need pretty hot loads. And my experience with them in a .35 Remington was that they wanted a sharp pressure rise to help them obturate. Accuracy with mild loads and slow powders was poor. It wasn't until I got to 1650 fps that they started to group, using the old original XMP5744. A even faster powder might have helped, but I changed boolits before I got that round tuit.

[shredder]

From my personal experience I can not recommend fire lapping. What it does is move the throat forward from the erosioin of the grit boolits. It does not polish the entire bore. All the "lapping" happens at the throat.

If you want to polish out a couple of tight spots and not move the throat forward while doing it, hand lapping is the only way forward. I have done the traditional melted lead slug method of lapping and it is best. Also impossible for the average gun nut. For a quick and dirty version, you can also use some fine steel wool wrapped around a jag coated with abrasive. 220,320,400,600. I have not found a need to go finer than that. You will likely get all you need with a few dozen passes of a tight 220 loaded steel wool jag. Then just a bit of polish.

[Gtek]

Maybe nothing, maybe lead up like crazy. Sorry, no real way to know until it/you try with your load and combo. Usually will be found at the dovetail cuts. There are many ways to lap and everyone has a different opinion on which is best. Impregnated copper, pure PB popped real slow, casting in bore, I would and have a hard time using anything less than 400, IMHO the 320 valve is a wee bit to much for me. I think the game is best played going VERY SLOW, backing up is not an option. Can you feel with tight patch/jag? If it were mine and confirmed, I would be in for the 400ish of dead PB or so rolled in 400 grit on top of a slow Trapdoor load and take very slow. Lever off, bolt out, push out front clean, and after every shot. (Kroil anyone)? Good Luck. Gtek

[CML]

I would not hesitate one bit to go ahead and start shooting it. If you don't run into any problems then why mess with lapping.

[Rich Cronk]

Thanks for all of the advice guys, I really appreciate it. For those who asked, yes I did feel the tight spots. One is directly below the rear sight, and one is below the spot where Marlin stamped the barrel with their machine. If I remember correctly, there is a third tight spot right under the point where the forend lug is installed. I guess I will go out and shoot a few rounds of my factory ammo, just to get some brass to load. After that, I will clean the bore real good and shoot a few hard cast lead bullets after I get em loaded. I have some 3031 and some 4895 on hand. One more question---Can I use jacketed bullet data from my Speer manual for use with cast lead bullets?

[DLCTEX]

Starting loads maybe, but why not do a search and see what has worked best for the majority of us. There is a wealth of information on the subject here.

[sisterjim]

Rich did you scroll down far enough to find link to CASTPICS at the bottom of every page. There is a load data page in there that has tousands of boolit loads. It took me a while to find it. I have developed a few loads from these and the Lyman cast manual. JIM

[Rich Cronk]

Rich did you scroll down far enough to find link to CASTPICS at the bottom of every page. There is a load data page in there that has tousands of boolit loads. It took me a while to find it. I have developed a few loads from these and the Lyman cast manual. JIM
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Thank you sisterJim!.. I will be checking that "CastPics" thing.

[Rich Cronk]

I loaded five rounds with 40 grains of IMR4895 just for a little test. I just now ordered a Lee factory crimp die because my Hornady die makes a wimpy crimp. I am also looking for some H322 because Doc Holiday's bullets are producing very good results with that power.

[uscra112]

For a quick and dirty version, you can also use some fine steel wool wrapped around a jag coated with abrasive. 220,320,400,600. I have not found a need to go finer than that. You will likely get all you need with a few dozen passes of a tight 220 loaded steel wool jag. Then just a bit of polish.

I can't think of a better way to round off the corners of the lands.

[cbrick]

For a quick and dirty version, you can also use some fine steel wool wrapped around a jag coated with abrasive. 220,320,400,600. I have not found a need to go finer than that. You will likely get all you need with a few dozen passes of a tight 220 loaded steel wool jag. Then just a bit of polish.

To each their own I guess. I would not do that.

Rick

[NVScouter]

As was said fire lapping only does so much before the compound isnt working. It is more than the throat but not much more. This creates a good boolit start and I find it helps many rifles. So go for it but you may need to hand lap the whole thing but you wont know until you shoot it.

I've had some old dark bore "junk" rifles shoot great so who knows until you try it.

[cbrick]

I've had some old dark bore "junk" rifles shoot great so who knows until you try it.

That's right! Mr Target is an expert on what Mr Firearm likes or doesn't.

Rick

[kir_kenix]

I'd go shoot the heck out of that rifle! Pretty much any mass produced (non custom, hand lapped) is going to have restrictions. Every manufacturer is known for restrictions at different places for different reasons. I do not think you can remove the 3 restrictions you are feeling by fire lapping. Firelapping is occasionally useful when thread-choke is severe, but what you are describing is multiple restrictions at different lengths throughout the barrel. To 'lap' out the restriction you are feeling under the marlin stamping and forend lug are going to lenghten your throat epically. You might be able to hand lap them out, but it will be ALOT of work, and you will probably end up rounding the lands during your effort.

I think you'll find that 99.9% of the time, we never realize there is a restriction if we don't go looking for them, and most rifles shoot just fine remaining ignorant of the affliction. If it were me, I'd load up some boolits of the correct size, wearing some good lube and go shooting. If you can't get your rifle to group after extensive testing (I'm betting you will), then it might be time to look at more drastic options. Everybody has a different opinion on lapping, and the merits of it as well, but I think you will be better served by firing a couple hundred rounds and foregoing the whole process.

[Spokerider]

Just curious.........
What is the date of manufacture of the gun? Pre Remington or post?

[303Guy]

Two comments made; fire-lapping erodes the bore and does little more and fire-lapping rounds the corners. Those things will happen if not done just right. The boolit carrying the compound must not ear away in the bore and it must fill the grooves. I would be hesitant to fire-lap with a soft boolit. Cast it hard and over-groove diameter. I've fire-lapped with a brass slug I turned and those things will sharpen the corners (by removing rust and dirt and the sharp edges on rust pits). I'd fire-lap with a groove filling jacketed bullet. However, my preference is to fill a groove on the slug with compound, which is seated inside the case neck so no grit can get into the chamber. Just my thoughts.

[uscra112]

Good point, that bullets for firelapping should be hard. A lap should be just enough softer than the material being lapped so that it will mother the abrasive properly. That's what the machine tool builders whom I learned from years ago said. They were lapping hardened steel deVlieg boring bars, which was such a ticklish job that only two companies in the country would do it, and the other was deVlieg themselves. So using jacketed bullets would come closer to that ideal, although I myself admit to using linotype boolits, or commercial "hardcast" when I did my S&W N-frame last year. Maybe I'm too cheap to shoot away bullets that I actually had to pay out hard cash for?

[303Guy]

Just a word of caution - when seating a boolit rolled in abrasive compound, be aware that the compound could grip the case neck and rip it off, dragging down the bore like a brass jacket! If you are lucky you would have used enough powder to expel it from the bore. Remember that it is brass and somewhat larger than the groove diameter, let alone the bore and in the presence of abrasive there will be a lot of friction so it will get hot and expand making it even tighter in the bore. So use enough powder to drive it all the way through! About 8.2gr of Trail Boss should be enough.

[303Guy]

In case you don't believe me .....

64562

Oh, the bore does seem cleaner now.

[btroj]

Actually I use a very soft bullet for fire lapping. You want soft because it doesn't spring back.
A hard bullet will squeeze down in a constriction but can spring back afterwards.
A soft bullet squeezes down and stays that size.
Difference is that the soft one only laps the tight spots to start, the hard one laps the entire bore and isn't only removing tight spots.

Use an unsized case from that rifle, a soft bullet, and a light powder charge. Watch to ensure the bullet leaves the muzzle, I fire into the berm and watch for impact.

[Rich Cronk]

Just curious.........
What is the date of manufacture of the gun? Pre Remington or post?
----------------------------
I can't see a date stamp on it but it carry's the "JM" stamp and is genuine Marlin. I am a lucky old Grandpa. :-D

[BABore]

Actually I use a very soft bullet for fire lapping. You want soft because it doesn't spring back.
A hard bullet will squeeze down in a constriction but can spring back afterwards.
A soft bullet squeezes down and stays that size.
Difference is that the soft one only laps the tight spots to start, the hard one laps the entire bore and isn't only removing tight spots.

Use an unsized case from that rifle, a soft bullet, and a light powder charge. Watch to ensure the bullet leaves the muzzle, I fire into the berm and watch for impact.

btroj is very correct. A firelapping boolit should be softer. Somewhere between 9 and 12 bhn. The lapping compound does indeed break down and that's why Clover brand is recommended. As mentioned, the boolit gets sized down as it passes through the constriction and does little to no cutting beyond it. The next boolit cuts just a bit further and so on till you just barely see signs of the last 1/2" of bbl showing abrasion. It is then time to stop. This process creates a slightly tapered bore with both lands and grooves worked evenly. The Beartooth manual is a great source for the full procedure and why it should be done that way. I've done 10-15 firearms and have shown several other how to do it properly. In all cases it shows positive results.

[curator]

An ideal alloy to fire-lap is ACWW that has age-hardened two weeks. This usually gives a BHN of 10-12. Anything harder will have some spring-back and not give the results you want. Don't make the mistake of soft lap-slugs and powerful loads as this will exacerbate the wear in the rifling's throat area. Use just enough powder to pop the bullet out, no more. Unique is a good powder for this. Have a stout brass rod and heavy hammer on standby in case a slug gets stuck in the bore. Make sure every one exits the bore before loading the next one. I have fire lapped many rifles using Veral Smith's system and all showed improvement in both accuracy and reduced fouling. Some very much so.

[303Guy]

I must admit to thinking of COWW as being quite hard - the hardness I was thinking of. So hard enough to resist obturation and soft enough to not have spring back? And not shotgun powder or Trail Boss or was it that I had too much powder?

[Rich Cronk]

I decided to shoot a few of Doc's 430 grainers without fire lapping. My starting load of 40 grains of IMR4895 was pretty weak and I got a lot of unburned powder residue, but one tight and dry patch down the bore made said bore shine like a mirror again.
http://img.photobucket.com/albums/v108/cronkcalls/DSCF1726_zps2e8e3797.jpg

I have five more rounds loaded a bit stiffer, so will be headed back out to try again real soon.

[Rich Cronk]

I don't think that I will bother with fire lapping.
http://img.photobucket.com/albums/v108/cronkcalls/DSCF1728_zps79fb24de.jpg

[Iron Mike Golf]

I must admit to thinking of COWW as being quite hard - the hardness I was thinking of. So hard enough to resist obturation and soft enough to not have spring back? And not shotgun powder or Trail Boss or was it that I had too much powder?

Yes. You want the obturation to be from initial boolit size only. You don't want propellant pressure to be a factor. You can achieve that by harder alloy or by a small charge of fast powder (to get past peak pressure quickly). You do want it soft enough that you don't get springback.

I firelapped my Rossi 92 in 357 using 358477 boolits at 11 BHN. Charge was 1.5 gr Bullseye. They would go halfway through pine 1x6.

[.5mv^2]

In the end much adu about nothing. Looks like nice grouping. After shooting a few hundred rounds maybe your barrel will be slicker and have less "ruts".

On my 44 Ruger I got a lot of leading down the barrel. After a bit of treatment the accuracy is improved and is my best shooter now, a real tack driver. The rifling looks great and soft lead pushes through nice and even.

Over the years I keep thinking about a 45-70 but when I think about the amount of lead per shot, it exceeds my resources.

[303Guy]

What I like is that a problem was identified and a possible solution found. In the end the problem wasn't an issue and the guns shoots well with no medicine and so every one is happy! :drinks:

Had the rifle not shot well there was a solution at hand. And I learned something about fire-lapping.

[uscra112]

Over the years I keep thinking about a 45-70 but when I think about the amount of lead per shot, it exceeds my resources.

[smilie=l: Why I don't shoot shotguns. Can't handle throwing 500 grains of lead downrange knowing that 90% of it isn't even expected to hit the target!

[303Guy]

The 45/70 is the optimum large bore for the Lee Enfield (well actually, the 45/90 is) but it's the amount of lead that put me off it. Mind you, the amount of recoil comes into it as well. :shock: 375 or 40 is a good compromise with a straight case using the 303 case. I want a straight case that doesn't use too much lead and kick too hard.

[cbrick]

I want a straight case that doesn't use too much lead and kick too hard.

There is just such a caliber, they call it a 22 LR. A nice rim fire cartridge. :mrgreen:

Rick

[303Guy]

I should have been more specific. [smilie=1:

[jonp]

Something along this line? http://www.brownells.com/gunsmith-tools-supplies/rifle-tools/receiver-tools/finalfinish-system-prod12715.aspx

I've never done it but I bought a surplus Mosin Nagant once that almost made me go that route. Scrubbed and scrubbed with JB Bore Paste and Montana Xtreme. Finally after several hundred patches I got it clean enough to group into 3 inches at 100yrds and called it good. For $89 what more could I ask?