Boring .38 wadcutter thoughts

[alfadan]

I have a smith 67 that's always shot well, but always has a little leading problem. I think it has some thread choke. Easy target loads leave a little lead at the very beginning of the rifling, and sometimes 1/2 inch down. Accuracy does not seem to be affected, but solving it is a pleasing puzzle in a way.
I've pretty much shot only some shape of wadcutter in it. I had an Ideal lyman 358063 that was a basket case, I tried grinding out the bevel at the sprue end but these new "bases" never were satisfactory. I believe the uneven bases allowed a lot of gas cutting. I now have an rcbs that casts much better, weigh 153gr at .358 (throat size) and are lubed with BAC.
I've almost exclusively used 700x about 3.2 grains as I seat the bullet proud of the case into the throats about an 1/8th inch. Unique was tried at about 4 grains, and no leading was seen I think due to higher pressures, but these loads seemed too hot. Today, I finally decided to try 3.0 gr bullseye. Just had a hint of leading at the start of rifling and accurate. Gun was not as dirty as expected, cleaner than with 700x, so I think the pressures were higher with the bullseye.
Anyway, more playing ahead on these nice spring evenings with an age old problem with boring loads.

[tazman]

If you happen to have any on hand, try some WST. It burns very clean and works well for target loads.
I use it a lot but not exclusively for my wadcutter loads.

[Outpost75]

Have you checked the barrel at both ends with plug gages?

You suspect thread choke, but have not measured it. If it exists it can be fixed and once done the difference is miraculous.

[alfadan]

I don't have any pin gauges, maybe someday but at the moment the issue isnt enough of a problem for their purchase. I can feel the choke while cleaning. I read before that firelapping can take quite a long time with stainless Smith barrels. I think if I keep playing with different pressure curves, something may work out. Ill also look into WST. thanks

[shtur]

Have you checked the barrel at both ends with plug gages?

You suspect thread choke, but have not measured it. If it exists it can be fixed and once done the difference is miraculous.

If it exists in the forcing cone, what is the remedy, Taylor Throating?

[725]

Brownell's sells an inexpensive device to cut the forcing cone area of the barrel (which I have done on several revolvers). May help. Pretty easy to do. Also, I have fire lapped many barrels that showed various issues and have universally had good success in improving them. Most frequently 15 or 20 shots have fixed the problems. YMMV. Good luck.

[shtur]

Are you referring to the 11* cutter, or something else? The 11 degree cutter only cuts the forcing cone and does not correct any problem in the "frame/barrel constriction area"

[725]

Yep. 11 degree cutter helped me out.

[Petrol & Powder]

alfadan - I've always lusted for a model 67, I'm a bit envious.

Based on the little information available, I agree you may be dealing with some thread choke. I would recommend against re-cutting the forcing cone. That's probably not going to correct that minor leading issue and you cannot put that steel back on after you remove it.

With a tight fitting patch you can often feel thread choke and as Outpost75 suggests, gauges will tell you for sure.
If you have thread choke and want to address that issue, there are remedies. Fire lapping is one way but stainless steel barrels are hard and that may take some time. However, fire lapping is inexpensive and easy. When done correctly is safe and improves the situation. There are some other methods that are in the realm of a gunsmith.

I have some K-frames that will exhibit the same type of leading you describe with some WC loads. Some suggestions that may help:
1. I switched from BAC lube to NRA 50/50 and that reduced a lot of my leading issues in 38 Special. It's worth a try and it's cheap.

2. Using a "M" type expander of the proper diameter can make a huge difference. If the casing is sizing the bullet down during seating, you may be starting with an undersized bullet and not know it.

3. You may want to measure the diameter of the cylinder throats (all of them) and consider opening those up if appropriate. I've had good luck with S&W throats but I have run into a few that needed to be reamed to make them the correct size and uniform.

As for your load, I shoot a similar WC load with the RCBs 38-150-WC bullet cast to about 9-10 BHn hardness, sized to .357" (I was sizing to .358" but found .357" to be better in all regards). As mentioned, I use NRA 50/50 (White Label Lube). And I seat to the crimp groove over 3.1 grains of Bullseye for a target load. I bump that powder charge up to 3.5 when loading full power WC loads.

Good Luck and keep feeding that Model 67 !!!

[alfadan]

Thanks fellas, I don't think the issue annoys me enough to do any cutting on the forcing cone. A few years back I pulled some seated bullets and checked for resizing by the case and found none, but I use mixed brass and and this warrants a recheck. When I was deciding on which WLL I wanted to stick with I tried 50/50 and others but found BAC better. I've never seen another 67 for sale around here and do like it.

[USSR]

I also use BAC and have found it does the job well. I also use various size expanders to preclude high case tension from sizing the bullet.

Don

[catboat]

do a search for "fire lapping".

Shoot a couple of control groups with your "normal load", as baseline.

see if you have thread choke (lube your bore, oil/grease your bullet (ie sizing lube). Tap a soft lead bullet into the muzzle, then tap it 2" into your barrel. push it out from the breach and measure the diameter as best as possible (5 grooves, but it will give you a measure for comparison.

do it again, and tap another "unused" cast bullet 4" into the barrel. tap that one out from the breach. measure.

dot it again, and push to the frame/barrel area. Do you notice any resistance? If so, you likely have thread choke. Push the lead slugh all the way through the barrel, (through the breach). measure the diameter. If it is smaller diameter than the other two lead slugs, you have thread choke.

note: you can push the lead slug out back toward the muzzle with cut hardwood dowels about 1.5" long (so they fit in the frame where the cylinder used to be. you'll need 4 of them to get the slug totally out of the barrel.

Roll your lubed bullet in an abrasive powder (ie silicon carbide), maybe some 400, 600, 800 grit valve grinding compound. Load light charges (1-2 grains of "fast" pistol powder. bullseye, red dot, green dot etc) . Brownells sells the dry abrasive. Use enough powder to just get the grit-coated bullet through the barrel. Try 3-5 cylinder fulls of firelapped bullets. reslug your bore with soft lead bullets, and measure diameter, and evaluate if you have resistance at the frame area. If so, shoot another 12-18 rounds of firelapping bullets (400 grit or so). Then re-slug your bore. Do this until you don't feel resistance at the frame, then switch to finer grit to polish. (12 rounds 600 grit, then 12-24 round 800 grit. )

Clean your revolver well. shoot at group of your "target" or normal load. See if it helped with accuracy and reducing bore leading. compare accuracy to "control /baseline " or "pre-bore-lapping."

[fcvan]

powder coat the wad cutter, no leading. If you have thread constriction, fire lap as mentioned previously.

[MT Gianni]

I have gone to the Lee 148 gr TL and 3 gr of BE after reading the Back Creek Tales of Ed Harris. It shoots well in my guns, is super easy to make and accurate. What is not to like. Thanks Ed.
https://www.hensleygibbs.com/edharris/articles/38wadcutterQA.htm

[slide]

Talk to DougGuy. He is on this forum and can probably fix you up. I have had him work on several of my guns and does great work.

[alfadan]

I need to do more measurement on my chambers. I did pick up a plug gauge set, just haven't got around to it. I have a mkvi webley that may need some work from DougGuy.

[alfadan]

Ok, with plug gages all throats are a piston fit at .358. Interestingly, one throat I couldn't get the gage in fro the front and it caught at burr or something right at the front edge. I used a deburring tool very lightly and that fixed it. I wonder if that constriction in one throat was causing some issues.
As a note to others, absolutly clean ALL leading from each throat before measuring. Its also much easier if you remove the cylinder from the gun.