Slugging barrels on new guns necessary?

[Namerifrats]

Gearing up to start casting again. Wanting to get my sizing dies and things ordered. So I ask this....is it always necessary to slug new barrels? Wouldn't they be pretty much all be to spec from the factory in proper size? Always though sugging needed to be done with barrels that have had thousands of rounds through them and had some wear. Reading here it sounds like everybody does it for every gun they cast for. When I was loading and casting before, I admit I never slugged any of the 5 guns I casted for. Just went with one over diameter sizing dies from spec bore diameters or just shot unsized as cast if it drop spec size from the mould. Never noticed any issues with leading or accuracy then. Plan to do a bit more this time and will slug barrels in the next few days. Doing the following loads this time around starting off... 9mm Luger, 45/70, 357 Mag (rifle and revolver), 44 Mag (rifle and revolver), and likely 223 (plinking loads). A few more calibers will be added, but this is the starting line up.

[sureYnot]

Personally, I'd just go with an oversized boolit to begin. Keep fingers crossed, and if the gods are against you that day, you get to do all the fun stuff.... Starting with slugging the barrel.

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[tazman]

With 9mm in particular, bore dimensions are all over the map. I own 9 different 9mm handguns and have 3 distinctly different size bores. I am fortunate that the chambers on all of them are generous enough to accept the boolits sized for the largest diameter.
If you tailor the loads for each individual weapon, I would have 3 sizing dies I would use for 9mm and a bunch of ammunition to keep separated. The guns with the smallest bores are match grade pistols. Those I have a mold that drops precisely what they need for best accuracy. They will chamber and shoot reasonably well with larger sized boolits though.
It all depends on what your individual gun needs in order to work properly. The only way to find out, is to slug the barrel.

[Char-Gar]

No slugging gun barrels either rifle or pistol is a waste of time and will give you no important information. Here is what is important

1. On revolvers you need to know the diamter of the cylinder throats and size your bullets to match and provide a good seal for the bullet as it passes through the cylinder into the barrel.

2. On rifles, you need to know the diamter of the chamber throat/free bore/leade and size your bullet to match as close as you can get, but not larger than. This will enable to bullet to enter the barrel straight and give the best chance for accuracy.

Getting cast bullets to shoot in any kind of firearm is not guess work, but follows long understood principals.

[Dusty Bannister]

If you are going to shoot cast bullets, you are probably going to either lube and size or powder coat and size. You can try a size at the going cost for the lube die, and maybe end up buying two or three to get it right. Or just slug the barrel or cylinder throats and know what you will need.

[dubber123]

It can provide very good information, and doesn't take much work to do. If your .44 revolver has say, .428" throats, (not uncommon on new S&W's for example), good luck to you finding cast happiness with a .430-.431" barrel. Ruger .45 revolvers are another good example with their all too common .449" or smaller throats, coupled with .451" barrels. The 44-40 revolvers they sold were even farther off, just sizing to the throats simply won't do in these cases. DougGuy here on the forum has a thriving business fixing these problem children for a reason. Rifle barrels can have a multitude of issues too that slugging will reveal. I've used a throating reamer to fix 2 Marlin 30-30's recently that had a very tight spot right in front of the chamber I discovered when they were slugged. Both shot MUCH better when properly fixed. I'd suggest don't guess and hope, measure and KNOW.

[Namerifrats]

Not sure how I can go with an oversized bullet in most cases. Take 9mm for example. On Midway USA there are 29 molds at .356 and 2 at .357. The designs I want are in .356. So whats the work around here? I know bullets be be made a bit smaller by sizing.....but how would you go larger and not severely limit options?

[tazman]

Not sure how I can go with an oversized bullet in most cases. Take 9mm for example. On Midway USA there are 29 molds at .356 and 2 at .357. The designs I want are in .356. So whats the work around here? I know bullets be be made a bit smaller by sizing.....but how would you go larger and not severely limit options?

Try looking at the products from NOE or some of the other premium mold producers. The NOE molds drop the size they claim and are larger than the minimum size needed to do the job. For instance, most of the 9mm molds are listed as .358 and drop at .358 from the mold.

[Mr_Sheesh]

Namerifrats - Look up "Beagling", Beagle here invented it I gather; Put a shim (IIRC he may have used metal tape? Not sure though) between the pair of die blocks, that gives you a slightly out of round, but larger, boolit. Another way is to use a cast boolit and abrasive and gently grind the mold slightly larger IIRC. Not sure what that's called, but SURE someone will know in here

[NathanHoln]

I have never done it, probably never will, except maybe to say that i've done it, but that's pretty unlikely.

Here's an idea that i've had to get the same result, hypothetically:
Make the lowest power load you can without getting a squib and fire it into a deep bucket or barrel of water.
Shouldn't the result be the same?

[JBinMN]

Namerifrats - Look up "Beagling", Beagle here invented it I gather; Put a shim (IIRC he may have used metal tape? Not sure though) between the pair of die blocks, that gives you a slightly out of round, but larger, boolit. Another way is to use a cast boolit and abrasive and gently grind the mold slightly larger IIRC. Not sure what that's called, but SURE someone will know in here

I believe it is called, "Lee-menting" a mold.

http://www.castpics.net/subsite2/Cla...20a%20Mold.pdf

[Grmps]

Powdercoating can add 1 to 3 thou and HiTek coating can add 1 -2 thou depending on powder and number of coats

[Namerifrats]

Good info all. I do plan to powder coat most if not all pf the 9mm bullets. Gonna do some barrel slugging when I'm off again. Are fishing weights soft enough to use?

[JBinMN]

Good info all. I do plan to powder coat most if not all pf the 9mm bullets. Gonna do some barrel slugging when I'm off again. Are fishing weights soft enough to use?

The "egg" sinkers I have used have been soft enough. You will have to check the hardness yourself to be sure, I would reckon. It could be that different sinker makers use different lead alloys. Some may be harder than pure lead.

A person can also take a cartridge of the size caliber & pour pure lead in it to make a "slug" to use to do it as well.
Removing the slug from the cartridge without altering the circumference & then driving the slug thru the cylinder or bore to get a measurement. If you are concerned that the slug is not big enough, just take the slug & give it a good tap on the flat end while it is sitting on a hard surface & you will increase the diameter slightly to ensure it is large enough.

You can also use a mold that is caliber specific, use pure lead & make a boolit, then smash it a little bit like described above, and use that slug to slug your cylinder or bore.


You can also drill a cavity that is slightly over your bore size into a 2/4, etc. & pour lead into the cavity to make a slug.

I have used the first 3 methods(sinker, cartridge slug, smashed boolit). It is up to the person if they want to do whatever method, but you are likely going to be closer to the diameter of the cylinder or bore with the cast "slug" from an empty cartridge, or a "smashed" boolit than some egg sinkers, meaning more force may be necessary to squeeze down an egg sinker than the slug that was made for the proper caliber if the sinker is a bit large for the cylinder or bore..

Hope I helped...

G'Luck!


P.S. - there are a lot of tips & info on sluggin cylinders and bores on the site here. Use the search engine & you will likely get more info on it that you will ever need.

[sureYnot]

I just fatten up a soft bullet for slugging. Set it on its base and give it a few light taps with a hammer until you're sure it's big enough.
Unlike brass, lead work softens, so this also helps in that regard.

[northmn]

I have slugged some barrels and not others. If the firearm has an odd number of lands you have to go through some additional steps. I slugged my Marlin CB 38-55 and every one keeps telling me they are 379, my slugging was a little less and one claims 378 was the Marlin standard. Mine shoots 379 sized bullets very well and has trouble chambering anything larger. It has 7 lands. On a new firearm? When you say rifle/pistol as in the 44 mag, you might have some issues as Marlins are noted to require larger diameter bullets than revolvers. I don't know if I have slugged a 30-30. They seem to shoot 309-310 bullets pretty well, except those that claim micro-groove barrels like them larger. However, based on what I have read I likely would not slug a MG barrel but start with a 311. When I was trading old military rifles and shooting them, they were often all over the place. One Russian that didn't shoot cast slugged at something like 317. Couldn't even chamber a fnullet big enough to shoot in it. Up to you.


DEP

[jsizemore]

Most gun manufacturers do not include the specs on their barrels and use any number of reamers from different suppliers. Same for barrel manufacturers. Guessing ain't knowing. A once fired boolit doesn't tell you much about the throat/leade. You have the materials at your disposal to know for sure. If you use lead for the life of the barrel then erosion should be minimal.

[HangFireW8]

Muzzle slugging tells me if I have a cleaning rod worn, funnel shaped bore.

Through slugging tells me of tight spots (cleaning issues, rifling issues, roll stamp/out of round issues).

Breech slugging tells me about the critical fit in the leade/throat area.

So I do all 3 on each gun going into cast boolit service. If you wish to deny yourself all this knowledge, go right ahead, you may still get lucky with some rules of thumb and some well known loads.

[ShooterAZ]

No slugging gun barrels either rifle or pistol is a waste of time and will give you no important information. Here is what is important

1. On revolvers you need to know the diamter of the cylinder throats and size your bullets to match and provide a good seal for the bullet as it passes through the cylinder into the barrel.

2. On rifles, you need to know the diamter of the chamber throat/free bore/leade and size your bullet to match as close as you can get, but not larger than. This will enable to bullet to enter the barrel straight and give the best chance for accuracy.

Getting cast bullets to shoot in any kind of firearm is not guess work, but follows long understood principals.

I agree with Charles on this. There may an exception or two. Particularly when it comes to foreign milsurp rifles such as Mosin and other fat 30's. They can be all over the map too. What he says about chamber throat/free bore/leade still apply. On current American made rifles or pistols, I don't bother to slug the bores.

[wmitty]

When you discover your .45-70 is a .46-70 and requires cast boolits .004” larger than spec. you see the need to slug a barrel.