Insights Needed After Slugging Bbl & Gauging Throats

[alamogunr]

I've been following the 75000 Wadcutters thread since the beginning. Always meant to follow up with a similar, though less ambitious program. Now I'm finally trying to get started although at my age I doubt that I will put up those kind of numbers.

My questions center around the results I got from slugging the barrel of my S&W Model 28, Highway Patrolman. The first thing I did was to us my plug gauges to measure the cylinder throats.

All 6 throats accept the .357 gauge. One is just a tad tighter but with a little adjustment to the entry angle, it would go in and go full chamber.

I then slugged the bore. There was more resistance where the barrel threaded into the frame. The slug measured .3529. I was able to calculate that measurement using a Vee block I obtained from a member here. The calculated groove diameter is .3529".

To double check this, I used the .357 plug gauge in the Vee block and calculated a diameter of .3574(for the gauge only). I figure that is close enough.

At this point, I don't think I need to do anything. If anything is required, I could fire lap the barrel to remove what seems to be thread crush where the barrel threads into the frame.

I guess I would like to hear what members with more experience in this area think my next move should be.

[slughammer]

Take your slug and drop it through your .357 dia throats to verify that .3529 dia. It should rattle as it passes through. (I wouldn't trust that .3529 measurement)

Also, feel free to take the same slug and push it through your barrel 2x. It should pass relatively easy through most of the bore, you'll feel thread choke when you get to it.

[Outpost75]

Might also want to be sure chambers and barrel are clean. The early magnum ammo leaded heavily and you cold still have deposits.

[ShooterAZ]

I don't really think you need to do much of anything IMHO. I think your next move would be casting up a bunch of 148 gr wadcutters, size them to .358, and lube them with thinned LLA. Load em' up and shoot em'... Then report back.

[alamogunr]

Take your slug and drop it through your .357 dia throats to verify that .3529 dia. It should rattle as it passes through. (I wouldn't trust that .3529 measurement)

Also, feel free to take the same slug and push it through your barrel 2x. It should pass relatively easy through most of the bore, you'll feel thread choke when you get to it.

That is why I asked the question. The measurement seemed too small to be thread choke. I measured the slug several times, both with the Vee block and by wrapping the slug w/a .0015" feeler gauge. Both measurements came out within a few tenths. I do know how to read a mic.

Might also want to be sure chambers and barrel are clean. The early magnum ammo leaded heavily and you cold still have deposits.

I ran a tight patch thru the barrel and a similar patch thru the chamber throats. It looked clean but I suppose I could do the Chore Boy thing to the barrel. This gun has been shot very little.

One thing I would like to do before I go to the extreme of fire lapping is partially slug the barrel. To do that I need several short lengths of brass rod small enough to fit the breech and stack them until I can drive the slug back out the muzzle. I've got lots of brass rod but all if it is too large to fit the barrel.

[alamogunr]

I don't really think you need to do much of anything IMHO. I think your next move would be casting up a bunch of 148 gr wadcutters, size them to .358, and lube them with thinned LLA. Load em' up and shoot em'... Then report back.

I wish I had read your post before I went back and slugged the barrel again. I've got a bunch of 148 gr wadcutters(H&G #50) already lubed with a variation of LLA. I know I need to shoot but with a 70 mile round trip and raining to boot, I couldn't get in the mood.

[slughammer]

How does your slug fit the throats?

Have you tried pushing it through the barrel a second time? You can really feel thread choke that way.

[tazman]

Talking about small groove diameter revolvers, I have a S&W model 60 3 inch in 38 special. The throats measure .356. The groove diameter is .354 and a tiny bit.
I have never sized boolits smaller just for this gun. I shoot the same .357-.358 boolits I shoot in all my other 38 special/357 mag revolvers. It shoots those "oversize" boolits extremely well.
I doesn't lead any with the larger boolits either.
Try your loads in your gun and see how it shoots before you make any decisions about doing any work on the gun.
Things don't need to be perfect in order for the gun to shoot well. They just need to be like a funnel going from the chamber to the front of the barrel. Throats larger than the groove diameter of the barrel.
Yours seems to fit that description.

[DougGuy]

A soft enough boolit, with magnum levels of pressure will very often pass through a choke and then obturate to fill the bore. This is what j words do when they shoot good through a known thread choke because they have a soft lead core swaged into the jacket.

Push a soft lead ball through the bore and then see how it fits in the throats. It should go through the throats easily. If you then push this same ball back into the bore, and it fits loosely, I would consider firelapping. If it goes through the bore then fits relatively snug the second time, you don't have much choke and I likely would just shoot the gun if it was mine and not worry about it.

[alamogunr]

Per post #2, I dropped the slug thru the throats. As I said, it just dropped thru without hesitation. Tomorrow I will slug the barrel a third time and then follow DougGuy's suggestion and if it drops thru the cylinder throats, push it thru the barrel again and feel for restriction.

The slugs I'm using are barrel shaped lead fishing weights. In the past, I've always tried to keep the slugs I used on rifles. I'm going to keep at least one that I used on this pistol. Regardless of the results, I'm going to shoot it with .357 wad cutters when it stops raining and see how it works. I'll get some loaded up this weekend. I don't shoot weekends. Range too crowded and I'm kind of a loner anyway.

tazman, If the groove diameter was within .002" of the throat, I would forget all this. I'm finding .004" difference. I'm not sure obturation can make up that kind of difference. That difference is why I posted the OP. I wanted someone to tell me if that was normal for thread crush. Shooting should prove one way or the other.

I'll return next week.

[tazman]

Unless I am misreading your first post, all the throats are larger than your bore. Anything that goes through the throats with a snug fit should get squeezed down by the barrel. That isn't a problem. It may be a smaller bore than most but still not a problem.

[alamogunr]

tazman, You are correct. The throats are larger than the bore, especially the area where the barrel threads into the frame. This pistol is in very good condition, the chambers are recessed for the rims and the barrel is pinned. It is one of two I picked up several years ago. I sent what I thought was the lessor of the two as far as condition to Jim Stroh, since retired. He converted that one to a .44 Spec.

I am satisfied with the throats. They are all as consistent as I have ever seen and , thank goodness, larger than the bore. Given some decent weather, I'm going to shoot next week. I don't want to depend on obturation since I want to shoot light loads and lots of them.

I do remember a quote(sort of) by Veral Smith in his book. "When the big light hits the bullet, it will fit".

[tazman]

Now all we need to see is what you get when you shoot it.
Enjoy.

[9.3X62AL]

I think all will be well once the weather allows for some range time.

[dubber123]

The throats larger than the bore is a great start. If it has thread choke, it needs to go in my opinion. I've never seen a barrel with a thread choke as being a positive thing, and it's easy to get rid of. Enjoy your new project

[alamogunr]

Just in case I think I need to do something about thread choke, I spent about an hour casting up some soft lead boolits. If shooting indicates that I need to lap, I plan to load about 20-25 rounds. I looked at my molds and the De Carli wadcutter seems to have the most drive band area(carry more lap compound), so that is what I cast. Didn't pre-heat the mold because I figured that a few wrinkles wouldn't hurt anything.

[skeettx]

HOW does she shoot??
Lots of measurements and no data yet
Click, bang, data
Mike

[alamogunr]

Easy there! No more measurements until I get to shoot. I've got to load up some H&G #50's and then find a day when I don't have something hanging over my head and can make that 70 mile round trip to the range. Today was the first day w/o rain in several.

Plus, I want to load some lapping rounds just in case. The boolits that I cast today have to be sized. They came out .360 and I don't want to lap my throats.

I'm spending today preparing my Sunday school lesson for tomorrow. That takes a lot longer now than it did 15 years ago.

[dubber123]

If you decide to lap, the wadcutters will work well. I use them for all my 35 cal fire lapping loads.

[44MAG#1]

Are you always going to shoot from the bench or are you going to shoot offhand? There is a difference in the type shooting making a difference in what you need, right?

Again I mean no hurt, harm, anguish or turmoil by my post I have posted on this posted subject. I am not baiting, trolling or calling out anyone. I am making a post based on my experience, knowledge and/or belief or opinion. That is all.