Every S&W I have seems to have small chamber throats

[Taco_Revolvo]

Have checked my
M629 6" from 2019
M686 6" from 2020
M69 4"


The only bullet that will drop through any of these throats, and still requires a modest push, is a .428/.429 Berrys in the 629. Everything else gets truly stuck.


Is this the new normal? I had hoped to shoot .430 cast bullets in the .44 Mags but these sizes are clearly machined in now hard to imagine that they're ALL out of spec. Should I just shove them all through?

 

[series guy]

Those guns will be very accurate. My Performance Center Stealth Hunter had .4285 throats and was scary accurate with .430 Berrys bullets. I have found the best accuracy in guns with the cylinder throats .001 to .002 smaller than the projectile.

 

[cowboy4evr]

Many of mine had the same problem along with the " S&W choke " . Tight spot where the barrel threads onto the frame . I've gotten them all corrected and the accuracy is phenomenal now with cast bullets . Regards Paul

 

[reddogs]

I have a 686 that the throat's in all chambers were a different size.I have bought 3 in 15 years and the throat's were tight.Cheap to fix if you don't think it shoots better undersized.

 

[StrawHat]

Tight throats are easily fixed with a proper reamer. I like the throats tube .001 larger than the maximum dimension of the bore. Measuring a five groove barrel is the hard part. That might be one reason I stay with S&W ACP revolvers!

Kevin

 

[stansdds]

From what I have read, there definitely seems to be a trend in S&W revolver chamber throats. It seems that it is more likely to find oversized throats on older revolvers of the pinned & recessed era. Those made after the P&R era are more likely to be darned close to ideal diameter, those made in the 21st century are more likely to have throats that are tight. No empirical data to support my position, just hearsay. I will say that it is a lot easier to correct a throat that is too small than it is to correct one that is oversize.

 

[22hipower]

Most folks I think complain about the other side of that problem, throats too large on their pre-25s and various 25- models. Try your cast bullets, I doubt you'll be disappointed.

Jeff
SWCA #1457

 

[Taco_Revolvo]

I really appreciate the answers so far! I had done quite a bit of searching here before and had considered some options such as finding a local gunsmith, sending the revolvers for enlarging, etc., but I really hate messing around like that and we're talking about maybe a .001 or .002 removal. It had occured to me that I could probably polish just a touch of that off the chamber throats with a dowel, some light sandpaper and metal polish, thinking that might be a bad idea

The bullets I have available are

Speer 240 JSP @ .429

Hornady XTP in 240, 200, 180, all @ .430

Acme 240 SWC @ .430

Berry's .429 (which measure closer to .428 and will drop through with a finger push. I have also noted a tendency to jump crimp with these and the diameter seems to offer a good explanation for it)

The Revolvers themselves are just excellent so far, have used the 629 for years now and typically push full-zoot jacketed reloads with max to near-max H110 since I have numerous other options for soft shooting. I had acquired the Acme bullets to save bullet costs and since they seem likely to be capable of the same velocity as the jacketed bullets, around 1300 or so in the 6" 629.

Opinions are clearly mixed but I'm gathering that I'm probably OK if accuracy is good and barrel leading doesn't seem to be an issue BUT that barrel leading is probably an issue and accuracy is probably suffering.

If I were to explore options of fixing just the throat issue, given that it looks like I'm right at .429 (since the Berry's will push through with hand pressure and those measure .428/.429) what would a good choice be for a throat diameter expansion?

I'm thinking .431 to give .001 clearance for most of the bullets I'll be using.

 

[Protocall_Design]

For leading and accuracy problems, I would first check for barrel constriction in the frame area. A barrel constriction will cause leading and kill accuracy. The bullet gets swaged smaller at the beginning, then rattles down the length of the barrel. Also, just a leaded barrel won't shoot good groups.

If you do ream the cylinder throats, I would only go .430.

 

[StrawHat]

…I really appreciate the answers so far! I had done quite a bit of searching here before and had considered some options such as finding a local gunsmith, sending the revolvers for enlarging, etc., but I really hate messing around like that and we're talking about maybe a .001 or .002 removal. It had occured to me that I could probably polish just a touch of that off the chamber throats with a dowel, some light sandpaper and metal polish, thinking that might be a bad idea ...

Yep, bad idea. Polishing with a dowel etc is a good way to elongate the throat. You want that to ba as perfect a circle as possible.

All you need do is send the cylinder of to have it reamed. PM me if interested for a referral.

…II'm thinking .431 to give .001 clearance for most of the bullets I'll be using…

You don’t want any clearance. You want a tight fit.

Kevin

 

[rockquarry]

I really appreciate the answers so far! I had done quite a bit of searching here before and had considered some options such as finding a local gunsmith, sending the revolvers for enlarging, etc., but I really hate messing around like that and we're talking about maybe a .001 or .002 removal. It had occured to me that I could probably polish just a touch of that off the chamber throats with a dowel, some light sandpaper and metal polish, thinking that might be a bad idea

The bullets I have available are

Speer 240 JSP @ .429

Hornady XTP in 240, 200, 180, all @ .430

Acme 240 SWC @ .430

Berry's .429 (which measure closer to .428 and will drop through with a finger push. I have also noted a tendency to jump crimp with these and the diameter seems to offer a good explanation for it)

The Revolvers themselves are just excellent so far, have used the 629 for years now and typically push full-zoot jacketed reloads with max to near-max H110 since I have numerous other options for soft shooting. I had acquired the Acme bullets to save bullet costs and since they seem likely to be capable of the same velocity as the jacketed bullets, around 1300 or so in the 6" 629.

Opinions are clearly mixed but I'm gathering that I'm probably OK if accuracy is good and barrel leading doesn't seem to be an issue BUT that barrel leading is probably an issue and accuracy is probably suffering.

If I were to explore options of fixing just the throat issue, given that it looks like I'm right at .429 (since the Berry's will push through with hand pressure and those measure .428/.429) what would a good choice be for a throat diameter expansion?

I'm thinking .431 to give .001 clearance for most of the bullets I'll be using.

My 29s and 24-3s are all all hovering on one side or the other of forty years old. I've found a .431" or .432" cast bullet works very well in all of them. When I fired some benchrested groups with both bullet sizes, my results were inconclusive. More testing might have revealed a difference, but I can only go so far with hairsplitting. I size all bullets to .432". Bullets smaller than .431" don't shoot as well, but that's in my guns only with my alloy mix and my loads.

I don't remember if I've fired jacketed bullets in any of my .44s, but if I did, it was a long time ago. Diameter is not critical with jacketed bullets; undersized (in comparison with cast bullets) may work very well.

 

[WILDPIG]

Many of mine had the same problem along with the " S&W choke " . Tight spot where the barrel threads onto the frame . I've gotten them all corrected and the accuracy is phenomenal now with cast bullets . Regards Paul

How were these "corrected"?

WILDPIG

 

[rockquarry]

From what I have read, there definitely seems to be a trend in S&W revolver chamber throats. It seems that it is more likely to find oversized throats on older revolvers of the pinned & recessed era. Those made after the P&R era are more likely to be darned close to ideal diameter, those made in the 21st century are more likely to have throats that are tight. No empirical data to support my position, just hearsay. I will say that it is a lot easier to correct a throat that is too small than it is to correct one that is oversize.

You might be right. With the exception of three revolvers, (one .38 Special, two .45 ACP/ Auto Rim) all my S&Ws are more than twenty-five years old. With the older guns, some have large throats, most don't. But most of the .38s and .357s have chamber throats as tight as the more modern guns. Regardless, I shoot .3575" (that's how they come out of my .358" bullet size die) cast bullets in all of them.

With Colt DA revolvers (.38s and .357s, all from the '50s and '60s), I use the same bullets. Colt bores are always tighter (.355" or so) than S&Ws .357" bores, but the oversize bullets generally shoot well. Colt chamber throats are usually very slightly larger than S&Ws.

 

[Paul105]

You are probably worrying about a non existent problem. Try shooting the bullets you have before modifying the gun(s).

I've measured 7 model 69s with plug gauges say .4295 (.429 go, .430 no go) mfg from 2014 until fairly recently. Two M329s bought over the last 15 yrs at .430 and two 629s over 20 yrs old at .4295 and .430.

Here's group shot at 50 yds rested over my range bag with 260gr WFNGC that miked .432 with a 2.75" M69 with throats at .4295. The group was verified on a different day.
.

.
Try the bullets you have - I think you will be pleasantly surprised.
.
Good luck
.
Paul

 

[Taco_Revolvo]

You are probably worrying about a non existent problem. Try shooting the bullets you have before modifying the gun(s).

I've measured 7 model 69s with plug gauges say .4295 (.429 go, .430 no go) mfg from 2014 until fairly recently. Two M329s bought over the last 15 yrs at .430 and two 629s over 20 yrs old at .4295 and .430.

Here's group shot at 50 yds rested over my range bag with 260gr WFNGC that miked .432 with a 2.75" M69 with throats at .4295. The group was verified on a different day.
.

.
Try the bullets you have - I think you will be pleasantly surprised.
.
Good luck
.
Paul

Thanks for the info! I am really amazed by and appreciative of
quality and depth of the information I've gotten here, logical explanations and considerations from everyone!

As a follow up question to the above it occurs to me to ask: The accuracy is clearly great, but are you getting any barrel leading with that combination and the .002 throat squeeze you're describing?

 

[series guy]

Shooting plated bullets such as Berry’s there won’t be any leading. I shoot my guns a lot. When cleaning the guns that I use lead projectiles in I usually run a Lewis Lead Remover down the barrel as part of my cleaning process. Never saw more than a few slivers of lead.

 

[StrawHat]

A properly alloyed, lubed and sized bullet will not leave lead in the barrel. Use a bullet that is too small, not lubed properly or cast too hard or too soft and you are asking for problems.

Kevin

 

[stansdds]

A properly alloyed, lubed and sized bullet will not leave lead in the barrel. Use a bullet that is too small, not lubed properly or cast too hard or too soft and you are asking for problems.

Kevin

I would also opine that velocity and powder selection will influence a lead bullet's ability to deposit lead in the bore.

 

[Green Frog]

The only contrary observation I’ll submit is that I have seen a couple of rare situations where a fat bullet won’t enter a tight chamber (as part of a loaded round). My custom Model 16-3 recreation has .313” chambers and it will not accept a loaded round with a .314” projectile in the front. This is the worst “offender”, but it was built that way.

Froggie

 

[BLUEDOT37]

Berry's .429 (which measure closer to .428 and will drop through with a finger push.

Are you using a caliper or a micrometer?

You'll be surprised at what a difference using a micrometer can make in these measurements, I was.

A pin gage is a better source to confirm throat sizing than most bullets, especially Berry's.

Your observation on Berry's .44 bullet sizing is why I quit buying bullets from them years ago.

.