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View Full Version : OK...How many of you have experience slugging top grade barrels, and how do you do it



Boyd Allen
12-17-2012, 09:08 PM
Inquiring mind wants to know. (I ran out of room in the title, and lost the question mark.)
I went back and inserted CF in the title, but it didn't make it in. I have used a .22 rimfire bullet to slug a rimfire barrel. What I am looking for here is how to do a 6mm, without pouring a lap.

Thanks ,

Boyd

JerrySharrett
12-17-2012, 09:43 PM
I slug every barrel I buy before it is even chucked up in the lathe.

You will need a couple o grease soaked patches, a bare ended cleaning rod, an appropriate size greased pure lead slug, (make some or buy them),

This is how Ed Shilen told me to do it;

-clamp the barrel lightly in a barrel vise.

-run a grease soaked patch through the bore several times

-I use a Dewey rod with just the bare end to push the slug.

-After starting the slug, put the rod handle against your tummy so you can push gradually and feel any variations.

-If you find a tighter place on either end, reslug from the other end.

-As the late Dr Frank Murphy said, walk with it-get to know it (he was talking about wind flags but a slug in the barrel ....you get the idea)

Note-if the slug fits properly and you clamp the vise too tight (even 30 ft/lb so), you can even feel the vise!!!

Boyd Allen
12-17-2012, 10:36 PM
Jerry,
Thank you very much. Two questions: How do you come up with your slugs, and how many hand lapped match grade barrels have you found to have problems, buy slugging them?
Boyd

Bob Brushingham
12-18-2012, 10:01 AM
For 6mm barrels I use fishing sinkers 1/8 oz. bullet weights from Bullet Weights,PO Box 187,Alda,Nebraska 68810

JerrySharrett
12-19-2012, 06:33 AM
Jerry,
Thank you very much. Two questions: How do you come up with your slugs, and how many hand lapped match grade barrels have you found to have problems, buy slugging them?

Boyd
I took an old 22 cal 2-cavity mold and reamed it out to make 6mm slugs. I cast them out of chemical grade (pure) lead. For 22 cal slugging I disassemble (carefully) 22 rimfire loads.

Early on I took the 22 RF bullets and mashed them longways in a vise, inserted them in a barrel,then took 2 bare-ended Dewey rods and bumped the slug up to a snug fit.

zeke mccune
12-20-2012, 04:09 PM
Hi Boyd:

Back in the 50's I was taught to use a lead core from a bullet and two pieces of drill rod.

The lead core was handy as the shooter was also swaging bullets. The drill rod stock was polished and the ends free from any burrs etc. The bore was oiled with an oily patch and the core was placed into the bore. The core was pushed down the bore to about the middle where it was "upset" by tamping on the core from both ends while backing the core up with the other piece of drill rod. This checked the barrel for loose or tight spots and when pushed out of the barrel, one could measure the slug to determine the groove size.

Was this a good method? I have no idea but it was top secret in those days! Lol

Stay well.

Zeke

David Halblom
12-20-2012, 06:27 PM
I slug every barrel I buy before it is even chucked up in the lathe.

You will need a couple o grease soaked patches, a bare ended cleaning rod, an appropriate size greased pure lead slug, (make some or buy them),

This is how Ed Shilen told me to do it;

-clamp the barrel lightly in a barrel vise.

-run a grease soaked patch through the bore several times

-I use a Dewey rod with just the bare end to push the slug.

-After starting the slug, put the rod handle against your tummy so you can push gradually and feel any variations.

-If you find a tighter place on either end, reslug from the other end.

-As the late Dr Frank Murphy said, walk with it-get to know it (he was talking about wind flags but a slug in the barrel ....you get the idea)

Note-if the slug fits properly and you clamp the vise too tight (even 30 ft/lb so), you can even feel the vise!!!

Jerry,

How often do you find a choke in 6MM or 30 Cal. barrels. Or let me re-phrase, how often in ANY quality BR supplier, centerfire supplier?

Boyd Allen
12-20-2012, 08:18 PM
From what I gather, very few are checking, and because of that, data is scarce.

Gordy Gritters
12-21-2012, 08:46 PM
Hi, Boyd

I have been slugging every barrel that comes through my shop for quite a few years now. In fact I've shown this process in great detail in my "Evaluating Rifles for Accuracy Problems" DVD, and I'm showing it again in the "Lapping and Slugging Barrels" DVD I'm just finishing up. I feel this is such an important and easily learned process that I make sure I teach this in my precision gunsmithing classes also.

Slugging is not only for factory barrels, which usually show a variety of issues (most of which can be corrected or improved by lapping them), but definitely includes all new high-grade barrel blanks. I've always been surprised at the number of custom barrels that have "issues". These issues range from barrels that have loose and tight spots (sometimes towards the muzzle, which is the absolute worst place to have the barrels get looser (larger) since this is where you want to crown it) - this definitely happens at times. I also frequently have found fluted barrels to be tight, then loosen up when the slug gets in the fluted area, then tight again when it gets past the flutes again. Another very frequent issue I find with lighter hunting contour barrels is the bore is tight where the barrel is large diameter at the chamber end, then as the barrel contours down, the slug loosens up noticeably because the bore enlarges - not good! As long as the bore forward isn't too large, I usually just lap the barrel myself to even this up since this is much easier than sending them back to the barrel-makers all the time.

As far as the slugs, you can buy pre-made "slugging bullets" directly from Neco in any caliber you want (www.neconos.com - they are hard to find in their sub-menu's, but they are there), or you can just cast your own lead slugs in the barrel. To do this, oil the bore, push a patch on a cleaning rod and stop it about 1/2" - 3/4" from the muzzle, and pour molten lead into the bore against this patch to form the slug. Then push this slug out and remove the patch. Oil the slug and bore with 10w-40 or 20w-50 motor oil and re-insert the slug - it normally goes back in easily if you carefully line up the grooves. But if you can't get the grooves to line up, just tap it in anyway with a plastic hammer.

Then I "bump it up" lightly to expand it and get it to fit tighter in the bore. To do this, I use a short brass rod up against the slug from one end, set this end of the barrel on your bench or a smooth surface on the floor, then tap lightly a couple times against the slug from the other end with a long brass rod. This will expand and tighten the slug up very easily. Then push the slug back and forth through the bore, making sure not to come out either end. This works very well with chambered barrels (don't have to remove the action either), as well as new barrel blanks.

You may have to push the slug back and forth a time or two to get it to loosen up enough to feel good, but then you'll be able to feel what's going on inside the bore very well for the next 2-3 passes back and forth before the slug loosens up too much. If needed, just bump it up again to get the feel back.

Hope this helps!

Gordy Gritters
www.ExtremeAccuracyInstitute.com

JerrySharrett
12-21-2012, 09:19 PM
Jerry,

How often do you find a choke in 6MM or 30 Cal. barrels. Or let me re-phrase, how often in ANY quality BR supplier, centerfire supplier?

David, the last detectable flaw I found was about 2 years ago so the barrel makers I use seem to do a good job. The flawed barrel had an oversize place in it about 6" long that started about 4" from the muzzle. The barrel would shoot great for about 6-10 shots then it would go wild. Coppering in that oversize place. Clean the copper out and it would do OK for another few shots.

I found the flaw before I chambered the barrel and called the manufacturer. We decided to finish it and see what happened. After the barrel was shot in a small match, I sent it back and they sent me a replacement. We guessed there may have been a slight occlusion and it caused the person lapping it to give that area a few more strokes.

Is it a waste to not slug a barrel and not find but about 1 in 20 or so with an irregular place? No, because if you do not do this and chamber a barrel with bad place, then shoot it a hundred rounds or so trying to get it to work, take it to a few matches trying to get it to shoot and fail, how much time and money are you out?

IMO, I think that it is really more important to slug a rimfire barrel. If a rimfire barrel is larger at the muzzle than the breech or middle, it will definitely will not shoot.On a centerfire barrel that is slightly funnel shaped there is most times enough pressure for the bullet to expand and fit. Again, IMO, match ammo for rimfires does not generate enough pressure to expand a bullet.

Boyd Allen
12-21-2012, 09:31 PM
Fellows,
I am so glad that I asked. These responses are exactly what I was looking for. It looks to me like I need to look around for some pure lead, and a convenient way to melt a little. Thanks to all, and if anyone has something to add, please do.
Boyd

alinwa
12-22-2012, 02:17 AM
HOlycowBoyd!!!

Thank you ALL!

Al

WSnyder
12-22-2012, 02:45 PM
As far as the slugs, you can buy pre-made "slugging bullets" directly from Neco in any caliber you want (www.neconos.com - they are hard to find in their sub-menu's, but they are there)

http://www.neconos.com/category/Accuracy-enhancement-23

Boyd Allen
12-22-2012, 03:49 PM
When you consider that a slug could be bumped up and reused in several barrels, the 10 that they sell for about $5, could last a looog time. I just got off the phone with a friend that had a premium barrel, chambered in 6BR put on a short action Remington, several years back, that never shot as well as many of the factory rifles that I have had. It was bedded, and a lot of load testing was done, to no avail. After the first, I think that it will be at the top of my list to slug.

Gordy Gritters
12-22-2012, 04:43 PM
David Halblom, you asked "How often do you find a choke in 6MM or 30 Cal. barrels. Or let me re-phrase, how often in ANY quality BR supplier, centerfire supplier? "

In my experience after having slugged thousands of barrels in the past quite a few years from most of the barrel-makers out there, barrels from some makers have never had a "choke", and other makers have had it to some varying degree. A slight choke is not a bad thing at all, but if it isn't in the right place, or if it opens up again after that (which does happen), then you are much more limited where you can crown it. I agree with Jerry that this may be more important in a rimfire, but a centerfire barrel with a slight choke will shoot just as well as one that is dead level all the way through.

I almost never see this with any of the cut barrel makers like Krieger and Bartlein - they are just usually exactly the same feel on the slug from one end to the other, so you can pretty much crown them anywhere you want in the far majority of cases. I can go for several hundred barrels before finding one of these that has any issues at all that I am concerned with, so I have come to prefer using cut-rifled barrels the majority of time, since I have had the least amount of issues with them.

I do use a lot of button barrels also, and barrels from some makers almost never have a choke, and ones from some other makers often have some degree of choke present. The ones I find almost always have a choke seem to be from the makers who purposely taper-lap the bore. If this is done correctly, it can be awesome. If not, then this can easily become an issue. But as long as they slug good I think button barrels, tapered or not, are just as good as cut barrels.

I think to get a choke into a barrel, whether done purposely or just as a result of finish-lapping, it has to be lapped there. This means the whole length of the bore behind the choke has to be lapped larger, and since this has to be done by hand in most cases, this is one of the reasons for a lot of the issues I have found in the past. When I found barrels from one particular maker all of a sudden start having issues a few years ago, I called and talked to the owner about this, and he said he lost one of his top lappers and was in the process of training a new lapper. This definitely explained the issues I was feeling with their barrels for awhile, and their barrels now seem to be just fine again.

If lapping the bore is done nice and evenly with either a smoothly tightening taper from the chamber to the crown (taper-lapped), or a straight bore transitioning into a gentle tightening up in the choke near the muzzle, they will shoot great and be a winning barrel. But too often I find where they are not even all the way through with loose and tight spots caused by uneven lapping, which I either re-lap myself or return to the maker. The other main thing I have found was they transition into way too much of a choke, sometimes between .0005" and .001", which is way too much in my opinion. When I find this, I measure to make sure the bore hasn't been lapped oversize behind the choke, and if not I crown it where the choke has just started tightening up. These will be match-winners also.

I often taper-lap factory barrels if they aren't too large inside already or bell-mouthed beyond where I want to crown them. This isn't all that hard to do and works extremely well in most cases if you slug them along with the lapping process to make sure you end up with a good even bore. I have explained in detail how to do this in my upcoming DVD also.

The importance of slugging barrels really came back to me this morning. I'm like Jerry, it has been a long time since I've had a problem barrel come through here since I almost always use the barrel-makers I have had the least amount of issues with. But I had a customer recently send me 2 barrels from one of the top barrel makers to put on his competition rifle. It has been a long time since I've used barrels from this maker, and have never had much issue with their barrels in the past, but boy did that change this morning. Both barrels were nice and even for the first half going forward, and one opened up just ever-so-slightly ahead of the half-way point. But it wasn't enlarged over .0001" or so (I could barely measure any difference on slugs from either end), and the slug from the loosest area near the crown area measured .3080", so I can lightly taper-lap it to remove the tighter area in the first half and be just fine. A lot of extra work, and some additional expense for my customer, but that's the only way to get his rifle to him soon.

The other barrel from this maker I have flat rejected and am refusing to install. It measures around .3084" at the crown end, which means it's too large inside to lap out, and it's reverse tapered to boot - no way would this barrel shoot good! The slug noticeably loosens up at the 20 1/2" mark and then loosens up even more at 25 3/4" - not good at all, especially since the customer wants a 30" barrel. So this has put a definite damper on my day (and played havoc with my schedule), but even worse, this is going to cause problems for my customer who is on a very short time-frame for needing this rifle. But I am sure glad I found this issue before spending all my time chambering and installing this barrel, and the customer having to spend much frustrating time and expense shooting load after load trying in vain to get it to shoot good. This is exactly why I feel slugging new custom barrels is so important!

Gordy Gritters
www.ExtremeAccuracyInstitute.com

Mike Bryant
12-22-2012, 07:02 PM
Fellows,
I am so glad that I asked. These responses are exactly what I was looking for. It looks to me like I need to look around for some pure lead, and a convenient way to melt a little. Thanks to all, and if anyone has something to add, please do.
Boyd

Boyd, today I took a piece of barrel steel that I had cut off a barrel for a .308 AR. Took and faced off both ends and placed it on a surface ground recoil lug (that was just what I had that was flat) placed it on a hot plate turned it on high and placed three or four lead cores into the piece of barrel until they melted. Turned off the hot plate. Then after it cooled off , oiled it and pushed it down the AR barrel to the place I wanted to drill the gas port. Drilled into the piece of lead and then pushed the lead core out. Wasn't checking for tight or loose spots. It was pretty easy to do especially since the barrel stub used was from the same barrel. The slug didn't look all that great, but did what I needed it to do.

alinwa
12-23-2012, 12:25 AM
It just gets better!

And better :)

kiwi smith
12-23-2012, 02:18 AM
Great response there Gordy, i'm sure Boyd will be happy with that. Only thing i would add is that the problem of gradual (or sudden) bore enlargement does seem to be alot more critical on lead-bullet guns. But as you state, a uniform bore from breech to muzzle - or a very slight constriction right at the crown - is best.

Button-rifled barrels can sometimes be made to create a choke by profiling them with a slightly enlarged OD section for a few inches long at the muzzle (i.e. like older anshutz target model .22's). This has worked well in practice for me - as long as you can get your barrel maker to do it for you.

Let us know when the DVD is ready Gordy, that's been awhile on the schedule, hasn't it??? ;)

Cheers,

Dean.

Bill Ohio
12-23-2012, 03:18 PM
Great response there Gordy, i'm sure Boyd will be happy with that.

Cheers,

Dean.

Had I known Tauranga had a riflesmith, I likely would have abbreviated our tour of your sulphur springs during a cruise itinerary a few years ago, and popped in to say hello. OTOH, we had linked up with a group of retired American firefighters (and their spouses), so maybe the smoke made them feel young(er) again. :)

That's a lovely country and nice people you have down there, Dean. One of my favorite memories is of popping into the RSA in Napier, after a local suggested it when we asked for a recommendation for fish/chips. (Upscale, I know!). As I liberally doused my food with malt vinegar, a woman sitting nearby said "My goodness, why don't you just drink it, dearie?" I spluttered and laughed, and her husband said not to mind her sharp tongue. After we ate, they offered us a ride to Penny Madden Pottery (near a vineyard as I recall), where we wanted to buy local crafts.

Best regards from California, land of fruits and nuts (which is not a commentary on our agriculture).

bill larson
12-25-2012, 09:01 PM
What kind of lapping compound are you guys using........????

Charles E
12-25-2012, 10:31 PM
Well, I don't know about slugging them, but I saw Wayne Campbell pound one into the ground once...Believe Wilbur salvaged it after everyone had left. A while later, he threw it into the woods.

Now the story gets a bit of urban legend-ish. Somebody (HFV? Roy Darnell? or ???) retrieved it, cut an inch off the end, and started winning matches...