Revolver pressure signs - long post

[barnfrog]

Thank you! Rear gage appears to be within spec, about 0.017" by my measurement. If I push the cylinder back I can get a 0.010" feeler gage in between it and the forcing cone, but not a 0.011", so that appears to be within spec as well.

 

[.38 Special]

Measured the firing pin protrusion when I got home today and it's 0.065"+. I've seen a minimum stated as around 0.030", but haven't found a max number. Haven't checked with S&W on the matter.

The chamber recesses in the cylinder are right around 0.050" deep, and a 0.017 feeler guage fits in between the cylinder and the recoil shield. The rims of the Starline brass measures little under 0.050", so they are moving back somewhere in the neighborhood of 0.020" between primer strike and full recoil.

Hoping to get those test rounds loaded tomorrow and chrono them over the weekend. The only factory ammo I have is .38 Special, but if I can get to the store and pick up some .357 Mag to shoot as well that will give me a better set of data to assess.

If I recall correctly, maximum protrusion generally is considered .060". That's a very old memory, though, and I'm not sure where it came from.

 

[westernrover]

I've fired high pressure loads in a revolver. The primers flowed around the firing pin so that the cylinder would not easily rotate or open because the primers would hang up on the firing pin hole and against the recoil shield. Extraction was hard enough that I had to pound the shells out of the chambers.

The loads were the result of an error. Afterward, I used Quickload to estimate what the pressure would have been and my estimate suggested they were somewhere around 53,000 psi and probably not higher than 55,000 psi. It was a unique circumstance because the error resulted in cartridges that were far higher than I would have knowingly fired, but which were not high enough to rupture the chamber and destroy the top strap. They were right in that zone that no sane person would dare to go, yet we should be able to have the confidence that our revolvers can handle it because of SAAMI or CIP proof load specifications. I fully expect my 357 revolvers to handle those pressures without failure, but I would never want to fire any at that level again.

I am convinced that high-pressure is a key factor in ammo performance. In my experience, high-pressure loads with fast powders consistently outperform low-pressure loads with slower powders. I'm a big fan of high-pressure loads -- not necessarily high velocity, but high pressure. Even so, I don't intentionally load anything over SAAMI/CIP pressure. Those pressures are enough, and I choose cartridges where I don't need to be at the maximum velocities. I tend to use faster powders and give up some velocity because maximum velocity with slow powders usually results in excess recoil and poor consistency. I have never seen a bad tradeoff or negative result from high pressure within spec.

 

[243winxb]

Measured the firing pin protrusion when I got home today and it's 0.065"+. I've seen a minimum stated as around 0.030", but haven't found a max number. Haven't checked with S&W on the matter.

brownells Gauge.060" is S&W maximum when i did a search. .053" is working ok on my N frame M28.

 

[243winxb]

http://smith-wessonforum.com/s-w-smithing/548637-fitting-hammer-nose.htmlPower Custom hammer nose. I put 1 in my M28-2 . I have to look for the instructions. Found it, photo below.

The instructions included with the Power Custom hammer nose kit called for .045"-.062" measured from recoil shield to tip of hammer nose

From Link.

 

[243winxb]

 

[barnfrog]

View attachment 1179129

Measured protrusion again four or five times and repeatedly got less than 0.055". Not sure how I screwed up the measurement earlier, but I did. Good to know the gun seems to be within spec there, too.

 

[243winxb]

Rear gage appears to be within spec, about 0.017" by my measurement. If I push the cylinder back I can get a 0.010" feeler gage in between it and the forcing cone, but not a 0.011",

I am no gunsmith, but this video is worth looking at.



Found this - 38,357 w/cylinder Counter Bore .012"-.018" headspace.

 

[barnfrog]

I am no gunsmith, but this video is worth looking at.



Found this - 38,357 w/cylinder Counter Bore .012"-.018" headspace.

End shake is pretty good on this gun. I measured it in the shop before I bought the gun and it was only two or three thousandths, IIRC.

 

[GeoDudeFlorida]

End shake is pretty good on this gun. I measured it in the shop before I bought the gun and it was only two or three thousandths, IIRC.

I really think any more attempts at analysis are going to be unproductive until you see how it shoots a known pressure and components load - something from a sole source with published data like factory WW, Federal, Remington, Fiocchi, etc. I like to compare using the Fiocchi 142gr TCJ - it’s a pretty hot load made using all Fiocchi components (known quantities). But I really think everyone is operating on too little information for all the measurements and diagrams being posted. Have you shot it since the first post?

 

[barnfrog]

I really think any more attempts at analysis are going to be unproductive until you see how it shoots a known pressure and components load - something from a sole source with published data like factory WW, Federal, Remington, Fiocchi, etc. I like to compare using the Fiocchi 142gr TCJ - it’s a pretty hot load made using all Fiocchi components (known quantities). But I really think everyone is operating on too little information for all the measurements and diagrams being posted. Have you shot it since the first post?

Nope. Looking good for getting to the range this weekend.

 

[GeoDudeFlorida]

Nope. Looking good for getting to the range this weekend.

Fingers crossed it turns out to be a bad run of primers in your reloads.

 

[BW460]

1. Try factory ammo
2. Get a chronograph ( it's expensive but I like LabRadar)
3. Measure and monitor case head expansion.

Too many variables with primers to use them as a gauge. It's not really a fair comparison but if I used primer flattening as an indicator, then I'm in trouble with every round fired in my 460 S&W magnum!

 

[243winxb]

Gun in ok shape, still needs a reason for pierced primers.
1. Try different mag primers.
2. Reduce powder charge. Accurate No 9 has had many *different manufacture*, till Hodgdon took over. What vintage is your No 9 ?

Look at the many photos of Accurate No 9
https://www.ilrc.ucf.edu/powders/sample_detail.php?powder_id=17.

Photo #824.

Manufacturer	Olin/IMI Mix

 

[barnfrog]

Gun in ok shape, still needs a reason for pierced primers.

Bingo. Whether it's over pressure, gun defect, bad primers or something else, pierced primers are bad. Have to eliminate that or the gun has to go.

1. Try different mag primers.
2. Reduce powder charge.

Trying Option #2 today or tomorrow. Stopped at the LGS to get some factory ammo as well, but my background check was delayed, so I'm waiting for a call from them to tell me I can go pick it up.

What vintage is your No 9 ?

Purchased about this time last year. Lot number format doesn't match that of the database you linked to, so not sure of date of manufacture.

 

[GeoDudeFlorida]

Stopped at the LGS to get some factory ammo as well, but my background check was delayed, so I'm waiting for a call from them to tell me I can go pick it up.

This is just so tragic

 

[BushMaster-15]

If I recall correctly, maximum protrusion generally is considered .060". That's a very old memory, though, and I'm not sure where it came from.

That's close enough for Gubament work . Minimum 0.038" Max. 0.062" , revolvers have the most as head spacing is generous .

 

[barnfrog]

Got to the range today to test the lower powder charge rounds. Didn't get a call from the LGS yesterday and they were closed today, so no factory ammo to compare.

Powder was measured with a new RCBS M500 beam scale calibrated immediately prior to loading, trickled up with a FA trickler so I'm confident there was very little variation in charge weight. Chronograph is a used Chrony F-1 with a fresh battery in it and diffuser screens deployed, but I was surprised at some of the the spreads in velocity. Time of day was 12:00 noon to 1:00 pm, so sun was about as close to vertical as possible. Benches at the range face due east, so sun was off to the right, and skies were clear. Temperature was 37 degrees F. I shot five groups of six shots, and recorded velocities were as follows:

12.2 grains AA#9
Min 1107 fps
Max 1166 fps
Avg 1136 fps
ES 59 fps

12.4 grains AA#9
Min 1093 fps
Max 1169 fps
Avg 1144 fps
ES 76 fps

12.6 grains AA#9
Min 1090 fps
Max 1226 fps
Avg 1178 fps
ES 139 fps

12.8 grains AA#9
Min 1078 fps
Max 1210 fps
Avg 1147 fps
ES 132 fps

13.0 grains AA#9
Min 1066 fps
Max 1243 fps
Avg 1179 fps
ES 177 fps

No pierced primers on any of the brass, and extraction was easy with just a tap of the extractor rod, with the exception of the 13.0-grain load, which took just a touch more effort to get the shells to drop out. 12.8 grains shot under 2", which is plenty good enough for me to hunt with at the ranges I'm limiting myself to. Of the half-dozen sources of load data I checked, three used this bullet and this powder (XTP 158-grain, AA#9), but only one used the same primer (CCI 550). Two indicated a max velocity over 1350 fps and one indicated max velocity of 1450+. (I would note that Speer's data, using their 158-grain JHP and AA#9 with a CCI 500 primer shows a max velocity of 1136 fps, though.) So I think I'm safe loading up 12.8 grains as my hunting load, with a max velocity just over 1200. Hornady indicates the 158-grain XTP will reliably expand without excessive fragmentation between 750 and 1400 fps, so bullet performance on game should be acceptable.

Still, it's a Model 19 and I don't want to beat it up. I definitely see a 6" barreled 586 or maybe a Model 27 in my future so I can save the 19 for targets.

I'm also curious about the increasing spreads in velocity as the charge increased. Is this normal for revolver loads? Does it indicate anything I should be concerned about? Interested to see if anything jumps out at others who know more about smokeless propellant behaviors than I.

 

[AJC1]

Got to the range today to test the lower powder charge rounds. Didn't get a call from the LGS yesterday and they were closed today, so no factory ammo to compare.

Powder was measured with a new RCBS M500 beam scale calibrated immediately prior to loading, trickled up with a FA trickler so I'm confident there was very little variation in charge weight. Chronograph is a used Chrony F-1 with a fresh battery in it and diffuser screens deployed, but I was surprised at some of the the spreads in velocity. Time of day was 12:00 noon to 1:00 pm, so sun was about as close to vertical as possible. Benches at the range face due east, so sun was off to the right, and skies were clear. Temperature was 37 degrees F. I shot five groups of six shots, and recorded velocities were as follows:

12.2 grains AA#9
Min 1107 fps
Max 1166 fps
Avg 1136 fps
ES 59 fps

12.4 grains AA#9
Min 1093 fps
Max 1169 fps
Avg 1144 fps
ES 76 fps

12.6 grains AA#9
Min 1090 fps
Max 1226 fps
Avg 1178 fps
ES 139 fps

12.8 grains AA#9
Min 1078 fps
Max 1210 fps
Avg 1147 fps
ES 132 fps

13.0 grains AA#9
Min 1066 fps
Max 1243 fps
Avg 1179 fps
ES 177 fps

No pierced primers on any of the brass, and extraction was easy with just a tap of the extractor rod, with the exception of the 13.0-grain load, which took just a touch more effort to get the shells to drop out. 12.8 grains shot under 2", which is plenty good enough for me to hunt with at the ranges I'm limiting myself to. Of the half-dozen sources of load data I checked, three used this bullet and this powder (XTP 158-grain, AA#9), but only one used the same primer (CCI 550). Two indicated a max velocity over 1350 fps and one indicated max velocity of 1450+. (I would note that Speer's data, using their 158-grain JHP and AA#9 with a CCI 500 primer shows a max velocity of 1136 fps, though.) So I think I'm safe loading up 12.8 grains as my hunting load, with a max velocity just over 1200. Hornady indicates the 158-grain XTP will reliably expand without excessive fragmentation between 750 and 1400 fps, so bullet performance on game should be acceptable.

Still, it's a Model 19 and I don't want to beat it up. I definitely see a 6" barreled 586 or maybe a Model 27 in my future so I can save the 19 for targets.

I'm also curious about the increasing spreads in velocity as the charge increased. Is this normal for revolver loads? Does it indicate anything I should be concerned about? Interested to see if anything jumps out at others who know more about smokeless propellant behaviors than I.

I watch number nine numbers reduce in its happy spot and open back up again. I make 6 round groups around the charge I'm interested in and work the best areas.

 

[barnfrog]

I watch number nine numbers reduce in its happy spot and open back up again. I make 6 round groups around the charge I'm interested in and work the best areas.

If I understand what you're saying, that dip in avg velocity between 12.6 and 13.0 jibes with 12.8 grains shooting well?

 

[243winxb]

Chronograph

I dont have one or i would test for powder position sensitivity. Powder back, powder forward.