Accuracy Went South in My Mod. 10 S & W

[Maven]

All, Yesterday's weather (Feb. 11) was warm enough (50 deg.) for me to venture out to our snow covered range for a bit of revolver recreation. While it was fun, I have to confess accuracy was abysmal with #358429 and the RCBS Keith CB using 4.2grs. of Unique. In fact, the last four or five outings with the Model 10 (heavy bbl.) produced no better result, yet it USED TO shoot into 1" - 2" with ease, particularly with #358311. I was blaming the sun* on the primitive sights and my own lack of practice for the Mod. 10's poor showing. Today, while I was reloading for it and with the as yet uncleaned pistol nearby, I decided to push 6 CB's, sized to .359" into the cylinders to check how well/poorly they fit. As it took a bit of effort to do this, I wondered whether they were actually too big and that perhaps that was the real culprit. After repeating the [cylinder throat] test with CB's sized to .358", I was convinced that I'd discovered the true cause of inaccuracy: CB's that were too large for the throats. I also remembered that my accuracy problem began shortly after I stopped sizing CB's to .358" in favor of .359", which my Ruger SBH and Dan Wesson particularly like. Isn't it ironic that many accuracy issues involve undersized CB's in larger throats, but this one was just the opposite?


*Our range is oriented to the south & west so that we are shooting into the sun from midday to midafternoon. The low winter sun only makes the problem worse.

[9.3X62AL]

The proof would seem to be a range day with .358" boolits. How awful! :)

[Bret4207]

That just goes to show that fit is King. Usually it's undersized boolits doing you in.

[dubber123]

I have yet to find any happiness with the 358429 at .38 speeds. Run it up to 1,100+, and it does fine. I am curious to see how you make out with the smaller boolits, or if your .38 just doesn't like that boolit/speed combo either. Let us know.

[Glen]

Some revolvers handle oversized bullets just fine. Others won't shoot an even slightly oversized bullet worth a hoot. I would definitely try .358" bullet in your M10 HB (maybe even .357").

[Maven]

All, I'm about to size 1/2 doz. or so RCBS Keith SWC's and see how they fit the cylinders. If they fit properly, I'll load 25 rounds and test when the weather is a bit warmer. (It's ~28deg. with the wind chill today.) Holding a cold piece of steel, even wearing gloves with exposed fingertips, isn't my idea of a good time.

[9.3X62AL]

About the same conditions here today, Maven. NOT a range day for sane folks.

[Larry Gibson]

I have yet to find any happiness with the 358429 at .38 speeds. Run it up to 1,100+, and it does fine. I am curious to see how you make out with the smaller boolits, or if your .38 just doesn't like that boolit/speed combo either. Let us know.

I never had any decent accuracy with 359421 either in S&W .38s. The bullet is too long for the 18 3/4" twist of the S&Ws at .38 Special velocities, especially with 4" or shorter barrels. Put the same loads in a 16" twis 4" Colt trooper and accuracy is excellent. As mentioned though bump the velocity in a .38/44 or .357 and it makes for a very accurate bullet. It's just not accurate at .38 velocities out of shorter barreled S&Ws.

"Fit" may be "king" but it doesn't mean diddly unless the bullet is properly stabilized. I 've shot lots of cast bullets that were .001-.003" larger than revolver throats with nothing but excellent accuracy.

Larry Gibson

[fecmech]

I have yet to find any happiness with the 358429 at .38 speeds. Run it up to 1,100+, and it does fine. I am curious to see how you make out with the smaller boolits, or if your .38 just doesn't like that boolit/speed combo either. Let us know.

Up until a year ago I said the same thing although I did not try too much as I was shooting mostly mags at 1200 fps. Last summer I played around with my K38 and the Keith and while it did not do as well as the H&G #39 (rn 158 gr) or H&G #50 (141 wc), it did do pretty well averaging right at 3" for 50 yd groups. I used Unique, Herco, AA5, WW571, WW540 and WSF all at max loads which ran the bullet at 850-910 fps out of the K38. The gun will avg a hair over 2" with the wadcutter and a little under 2" with the RN at 50. I think the Smiths slow (18 3/4) twist hurts the Keith bullet at the slower speeds. I have not been able to do well with it at 800 fps or less, 25 yd groups will run 2"+ at the slower speeds and are not even worth trying at 50.

[Maven]

A couple of comments. The .357" v. .358" test clearly indicated that .358" is a better fit than .357", as the smaller ones fell right through. Second, I'll have to revisit #358429 in the Model 10 with stouter loads and @ .358" as it seems to do quite well with higher pressure in my .357mags. at .359" (11grs. WC 820). In spite of the non-adjustable sights, the Mod. 10 is or rather, was, accurate with the RCBS Keith and wadcutter (flat,"button" nose) seated backwards* and with Ly. #358311. Warmer weather will allow me to whether .358" is indeed the magic diameter. Btw, of the two Keith designs I cast, the RCBS version is consistently more accurate than -429 in the Mod. 10 as well as the Ruger BH and Dan Wesson.



*I've written about this in the past, but for reasons I can't fathom, some wadcutters don't group well when seated and crimped in the usual way. The RCBS WC is one of them. Figuring I had nothing to lose by changing only one variable, their orientation, I tried reversing them v. seating normally. Voila! Accuracy improved impressively in all 3 revolvers.

[dubber123]

A good example of a load I would have used would be something on the order of 4.0 grs. of Unique. I doubt they were much if at all, over 800 fps. I was always going to try some +P loads, but some of the guns I was using were 80+ years old, and at that point I just got a bigger gun.

I really like the looks of the boolit, but I may just have to reserve it for stouter guns/loads. That is unless Maven can show me how to get them grouping at lower speeds. That would be nice.

[Maven]

dubber123, Actually I was using 4.2grs. of Unique, but with the .359" CB's. I just reloaded yesterday's cases with 3.3grs. and 3.5grs. (Max.!) of CLAYS (original version) with both the RCBS & Lyman Keith CB's, but sized to .358". I'm hoping both will perfom better since they now are a better fit in the cylinder throats.

[Bret4207]

"Fit" may be "king" but it doesn't mean diddly unless the bullet is properly stabilized. I 've shot lots of cast bullets that were .001-.003" larger than revolver throats with nothing but excellent accuracy.

Larry Gibson

Oh Larry, that hurts. :( It all has to come together to work right. An undersized boolit won't do the best work even if it's theoretically perfectly stabilized. That's why I tend to err on the large side. Mavens experience is something to keep in mind though.

[Lloyd Smale]

could be a few things. First it sounds like you may have changed your load. If so it sure could be the problem. The sizing could be also. Alot of guys will tell you bigger is better but thats not allways the case. Some guns just dont shoot well with oversized bullets. Another thing is just a small differnce in the alloy your used to cast them could change the accuracy compared to the old bullets. Personaly i never had much luck with that 38 lyman kieth. the gas checked version did ok but the plain base was allways on the finiky side. what happens to me is just what happened to you. I can (with a lot of work) find a good load and just change one little thing and everything changes. I mostly switched to the rf lee bullet in the 38s. Its one of the only designs that lee actually got right.

[336A]

I've had the same issues with the #358429 from S&W M10 as well. The first time I shot this bullet I loaded it over 4.6gr of Unique. The results were dismal in comparison to how 158gr SWC shoot with this charge. I have some test rounds made up that start at 4.7 gr of Unique and go up a tenth of grain into the +P category to try out.

[fecmech]

I have some test rounds made up that start at 4.7 gr of Unique and go up a tenth of grain into the +P category to try out.

The Lyman manual shows 5.0 is still at the standard pressure level 0f 16700 I believe.

[336A]

fecmech,

you are totally correct. However not long ago Brian Pierce wrote an excellent article on the .38/44 S&W. In that article he provided load data for .38 SPL +P for the reader to compare with the .38/44 data. In the table provided in that article there is .38 SPL +P data for the #358429. The new Lyman Pistol & Revolver manual shows +P data for this bullet with Hodgdon Universal which is right next to Unique on the powder burn rate chart. However they do not show +P data in the new manual for Unique, they actually dumbed the powder charge for Unique down from 5.0gr to 4.2gr.

[44man]

Larry still made the best point and is what I preach all the time. Match the boolit to the twist and velocity. Too many guys shooting revolvers just forget about twist rates.
Nothing on earth about boolit diameter or alloy will make the wrong boolit shoot.

[Larry Gibson]

Oh Larry, that hurts. :( It all has to come together to work right. An undersized boolit won't do the best work even if it's theoretically perfectly stabilized. That's why I tend to err on the large side. Mavens experience is something to keep in mind though.

Bret

Certianly not meant to "hurt", just pointing out a fact. We can have the best 'fit" in the world with a cast bullet but if it's not stabilized it still won't shoot good. Certainly agree on the 'fit" and stabilization both being necessary for the best accuracy. However I've shot some soft cast bullets in .38, .357, .41, .44 and .45s that were as much as .003-.005" undersize and they shot perfectly well. Obviously the reason is the soft alloy obturates. However, I might add that i've shot numerous M1917 S&Ws and Colts with .453-4" throats using hard cast commercial .451" sized bullets with excellent accuracy and no leading (I relubed with Javelina). I do agree that bullets that fit the throats will generally give the best accuracy. However in this case I don't think its that .001" on Maven's 358429s that is causing the inaccuracy. Remains to be seen and either way we can enjoy a brewskie together, eh? :drinks:

Larry Gibson

[9.3X62AL]

Interesting idea, Larry.

To date I haven't seen this issue with my current copy of the #358429. I should add that my boolit is one of the lighter variants with a relatively short base band, going 163 grains in WW metal. This shorter OAL might explain why the boolit shoots well in both S&W and Colt revos. I generally run them about 850-900 FPS in 38 Special, too. Maybe that's another or "the" difference. The "test" would be to try them at 700-750 in the Ruger Blackhawk--they have a 1-20" pitch, don't they?

I'm one who DOES note twist rates in handgun barrels, and I've hacked at you all about the 9mm and 40 S&W ad nauseum. Real food for thought, from Larry et al.

[Bret4207]

No prob Larry, just yanking your chain a tiny bit. I'm in complete agreement that stabilization comes into play with fit. In fact, it's kind of part of "fit" isn't it? Either way this is an unusual case if it proves out.

[Larry Gibson]

No prob Larry, just yanking your chain a tiny bit. I'm in complete agreement that stabilization comes into play with fit. In fact, it's kind of part of "fit" isn't it? Either way this is an unusual case if it proves out.

Ya got all that right, as usual!

Larry Gibson

[9.3X62AL]

You've got me to thinkin' here, Larry. Gonna empty out some loaded 357s pretty soon, and refill 'em with #358429 at 700 FPS or so through the BisHawk. I would just go buy some new 357 brass--but there is none to find in The Entire Known World at present.

Aw, shucks--another range day required. Just hate that.

[Maven]

I just returned from a rather chilly (because of the wind) range session with the Model 10, this time trying RCBS Keith SWC @ .357" v. .358" seated over 3.5grs. CLAYS and Rem. 1 1/2 primers. The results were pretty much as expected. I.e., the CB's sized to .357" essentially fell through the cylinder throats as per my earlier post and were all over the target (25 yds.), while the .358" CB's grouped rather well, but hit low on the target at the same distance. I also had a few #358429's @ .358" to play with (3.3grs. CLAYS) and saw no evidence of instability in them. Truth be told, the biggest problem I had today was keeping my target frame standing in the hard-packed snow and wind.* From now on, I'll have to separate the .358" CB's for the Model 10 from the .359" ones for the .357mags.


*Our range has rails and spacers that allow you to place a target frame within them, but they're now covered with snow and ice and essentially useless. I'll rig up something with galvanized 8" nails and eyebolts so that I can hammer the target frame into the packed snow.

[TCLouis]

I was going to post and pose a question for all tonight and stumbled across this thread first.

I have not been able to get any of the three 357s to shoot cast with the use of 4 different molds and at least 4 different powders. I had thought it might be a combination of my shooting ability and the lack of my ability to shoot open sights since all my 44 Mag testing is done with a scope.

Just to prove how bad things are, I loaded up three different coated 158 grain bullets since this was about the weight range I had been using in the boolits. Dang three pretty fair goups that responded as expected with change in powder weight until all shot good groups.

These boolits are all sized 0.359" and maybe that is the issue. I ordered pin gauge set recently just to check all my cylinders throat dimensions. I know the GP 100 has at least three different throat sizes.

Can't wait to see if sizing these down to 0.358" makes a difference.


ANY other suggestions gladly accepted.