Question about bobbed hammers

[pskys2]

Update, I've run a few tests with limited rounds at this point but the results were consistent, though I will put several hundred rounds down range to verify the reliability.

 

To my mind at least I've quantified the differences between a stock hammer and a lightened one.

Created a Spreadsheet Revolver Action Test.xls the only variance in ignition parts between the 2 627's was the FP's.  The Pro was lower and had an extended blunt tip, while the PC had an Apex extended taper tip.  Will swap them and see if there is a difference.  The PC's Action "feels" better as it has more rounds and is smoothed up a bit more.

 

Anyone have a weight on the Apex Evolution IV?

 

The TK, which looks good, lists its weight at 18.50 grams (.63 ounces) which is lighter than the one I was testing with (it was at .85 ounce).

Both are a bit expensive, but I do like keeping an original hammer for a gun just in case.

 

 

[pskys2]

1.25 oz (from a 325TR) factory s&w hammer, 1.15 oz (627 PC & Pro) factory s&w hammer, .85 oz factory hammer lightened by Apex, .75 oz Apex lightened hammer (don't have one but a buddy, thanks Jim, weighed his) and .65 oz lightened TK hammer.

627 PC with either a c&s or factory extended FP (both .506" oal & .208" tip length), TK .65 oz hammer, 11 lb Wolf Rebound Spring -2 coils, 32 oz hammer fall, 24 oz rebound weight a bit above 4.5 lb action.  Fired just under 500 rounds with no FTF's.  So with the .65 oz hammer vs 1.15 oz hammer (all other springs and parts the same except hammer fall) I've decreased the hammer fall by 10 oz, the action by 1 lb and no FTF's.  Could go lower on Action Weight if I used an even lighter rebound spring, but like the snappier rebound I have.  

On Drills I've set up to measure splits & draws between the 627PC at 4.5lbs and the 627Pro at 5.5lbs I'm seeing little differences.  On Splits it looks like:

25 yd focus on Accuracy .04 faster with the PC, 25 yd focus on just hitting a 12" plate the PC is .01 faster

10 yd focus on Accuracy the Pro was .04 faster, 10 yd focus on just hitting a 12" plate the PC is .02 faster

The focus on Accuracy with the PC showed tight groups while the Pro had a few that were pulled out of the group by about 2", always to the left I need more practice for sure!  At speed focus the groups were about the same, pretty much scattered across the plate.

Raw Splits with no target the PC was only .01 faster

First shots were harder to gauge as I used a different Dot/Mount on each with the best one on the Pro and the Pro actually had better times for the Draw and 1st shot at 25 yds by .12, 10 yds by .09 and at 10 yds at speed of .01, but the PC was faster at 25 yds at speed by .06.  And I'm sure it was the different Dot/Mounts as I seemed to have to search for the Dot at times.

Had a couple of "hitches" with the Pro and not with the PC.  And a few Jerks, all me all the time, with the Pro.  Seemed the accuracy potential was better with the PC.

So I'd have to say there is a very slight advantage with the lighter Action, for me, in speed.  But not enough to stress over and probably better to practice than spend the money.  

Next I plan on testing the Accuracy at Speed in greater depth.  I do think that will be where I'll see a bit more advantage to the lighter action.

But being Retired, the weather keeping me from getting out to work on fencing, the wife wanting a break from the work inside... Well I'm doing something I enjoy and like!

Besides, note to Mike, Joe made GM in Revolver.  We both MAY have our work cut out for us!  I won't be 3rd if I can keep from it!  

Going to try the TK FP's and put a TK lightened hammer in the 627 Pro later this week.  

 

[Cherokeewind]

Thanks, keep the updates coming:)

 

Now I'm wondering if there is any advantage to using a cartridge that requires small pistol primers rather than large pistol primers.

 

Maybe I need to compare some SPP .45 ACP cases to LPP .45 ACP cases and see what happens.............

Edited March 31, 2021 by Cherokeewind
added info.

[pskys2]

15 minutes ago, Cherokeewind said:

Thanks, keep the updates coming:)

 

Now I'm wondering if there is any advantage to using a cartridge that requires small pistol primers rather than large pistol primers.

 

Maybe I need to compare some SPP .45 ACP cases to LPP .45 ACP cases and see what happens.............

In my own personal experience between the 45 ACP and 38's is yes and no?  I've shot the 45 acp in both SPP & LPP and my guns took about 4 oz more hammer fall than my 627's in 38.  And I noticed no difference between the size of the primers being used in the 45, I did try it for a short time.  My observation is it has more to do with the 38's having a rim, even with moon clips, that make for a less cushioned blow.  Whereas the rimless rounds have to deal with the springing of the moon clip.

The only way to reliably test it would be to have a 38 cylinder cut to "also" take 9mm and shoot both with successive lower hammer fall weights until ftf's begin.  

Or shoot ACP & Auto Rims in both SPP & LPP.  Since they don't make a SPP in Auto Rim the results wouldn't probably be in question still.

TK actually can ream/cut a 38 cylinder for 9mm and will shoot both.  It's expensive, $350, and would only be of value if the 38's kept some portion of their rim in contact with the cylinder.

I'm not going to do that though.  And my supply of SPP's is too low to play anymore than I've done so in the past with the 45 ACP to see.

 

But I'd be interested in the results of such a test too.

[PatJones]

19 hours ago, pskys2 said:

Could go lower on Action Weight if I used an even lighter rebound spring, but like the snappier rebound I have.  

 

I too like a snappy rebound. I cut 4 coils off an 11 lb rebound spring and drop it into the rebound slide with the largest detent ball that will fit in there with it. This changes the spring rate, It's a little stiffer at full compression due to the springs shorter length.

[Cherokeewind]

In my 625's, the cartridges headspace on the case mouth (even when using moons), same as they do in a bottom feeder.

What that means is that the variation in cartridge case length can effect the headspace of individual cartridges and, as a consequence, change how hard the firing pin hits the primer.

 

The variation in headspace probably requires a slightly higher mainspring tension than if all the cases were identical. 

 

I have no experience with other revos that use moon clips, maybe they headspace on the moon.

Edited March 31, 2021 by Cherokeewind
added info.

[MikeBurgess]

22 hours ago, pskys2 said:

1.25 oz (from a 325TR) factory s&w hammer, 1.15 oz (627 PC & Pro) factory s&w hammer, .85 oz factory hammer lightened by Apex, .75 oz Apex lightened hammer (don't have one but a buddy, thanks Jim, weighed his) and .65 oz lightened TK hammer.

627 PC with either a c&s or factory extended FP (both .506" oal & .208" tip length), TK .65 oz hammer, 11 lb Wolf Rebound Spring -2 coils, 32 oz hammer fall, 24 oz rebound weight a bit above 4.5 lb action.  Fired just under 500 rounds with no FTF's.  So with the .65 oz hammer vs 1.15 oz hammer (all other springs and parts the same except hammer fall) I've decreased the hammer fall by 10 oz, the action by 1 lb and no FTF's.  Could go lower on Action Weight if I used an even lighter rebound spring, but like the snappier rebound I have.  

On Drills I've set up to measure splits & draws between the 627PC at 4.5lbs and the 627Pro at 5.5lbs I'm seeing little differences.  On Splits it looks like:

25 yd focus on Accuracy .04 faster with the PC, 25 yd focus on just hitting a 12" plate the PC is .01 faster

10 yd focus on Accuracy the Pro was .04 faster, 10 yd focus on just hitting a 12" plate the PC is .02 faster

The focus on Accuracy with the PC showed tight groups while the Pro had a few that were pulled out of the group by about 2", always to the left I need more practice for sure!  At speed focus the groups were about the same, pretty much scattered across the plate.

Raw Splits with no target the PC was only .01 faster

First shots were harder to gauge as I used a different Dot/Mount on each with the best one on the Pro and the Pro actually had better times for the Draw and 1st shot at 25 yds by .12, 10 yds by .09 and at 10 yds at speed of .01, but the PC was faster at 25 yds at speed by .06.  And I'm sure it was the different Dot/Mounts as I seemed to have to search for the Dot at times.

Had a couple of "hitches" with the Pro and not with the PC.  And a few Jerks, all me all the time, with the Pro.  Seemed the accuracy potential was better with the PC.

So I'd have to say there is a very slight advantage with the lighter Action, for me, in speed.  But not enough to stress over and probably better to practice than spend the money.  

Next I plan on testing the Accuracy at Speed in greater depth.  I do think that will be where I'll see a bit more advantage to the lighter action.

But being Retired, the weather keeping me from getting out to work on fencing, the wife wanting a break from the work inside... Well I'm doing something I enjoy and like!

Besides, note to Mike, Joe made GM in Revolver.  We both MAY have our work cut out for us!  I won't be 3rd if I can keep from it!  

Going to try the TK FP's and put a TK lightened hammer in the 627 Pro later this week.  

 

Question on your drills,

between the 2 guns do you have more reps on one of the actions you are testing? I ask because for me predictability is a much bigger deal then pull weight. If I know when the guns going to fire it doesn't make much difference what it takes to get it there because most of that is happening during recoil or while driving the sights to the target.

 

 

[pskys2]

2 hours ago, MikeBurgess said:

Question on your drills,

between the 2 guns do you have more reps on one of the actions you are testing? I ask because for me predictability is a much bigger deal then pull weight. If I know when the guns going to fire it doesn't make much difference what it takes to get it there because most of that is happening during recoil or while driving the sights to the target.

 

 

Good point, sure for the last several years I worked with a 5.5 lb action on all of my Revolvers.  What I am noticing is a "feel" that there is more potential with the lighter action.  It seems to take less focus/work. I also see less hitches in the lighter action, I had mentioned before that in the past the lighter action seemed to lead me to short stroking more.  I think it may have been due to a lighter Rebound.  I've dropped the Action by lowering the Hammer Fall and leaving the Rebound alone.  So far it seems to have solved the original problem. 

As I get more comfortable with it I'm hoping to see an improvement. I keep feeling glimpses into it now.

Of course I'm going to now put the same action into the Pro.  So I won't be comparing 4.5 vs 5.5 actions.

[pskys2]

4 hours ago, Cherokeewind said:

In my 625's, the cartridges headspace on the case mouth (even when using moons), same as they do in a bottom feeder.

What that means is that the variation in cartridge case length can effect the headspace of individual cartridges and, as a consequence, change how hard the firing pin hits the primer.

 

The variation in headspace probably requires a slightly higher mainspring tension than if all the cases were identical. 

 

I have no experience with other revos that use moon clips, maybe they headspace on the moon.

I tend to not believe that in a 625.  I shoot GAP brass with no difference in Actions. When I was still shooting Major I liked using the 45 GAP brass over ACP.

The way to see if your theory is correct is to shoot ACP without moon clips.  My experience has been that it is hit or miss whether a non-moon clipped 45 ACP round will fire.  

[Cherokeewind]

I think the moon clips in the .45 are only to facilitate extraction (Makes for faster reloads too).

 

I don't think the ACP headspaces on the moon so the presence or absence of the moons shouldn't be a factor with regard to reliable trigger pull weight.

[Cherokeewind]

The .45 GAP cases might allow a lighter action than the ACP cases, if the moon clips do a better job of controlling headspace than is achieved with the variance found in the ACP cases.

[revoman]

1 hour ago, Cherokeewind said:

I think the moon clips in the .45 are only to facilitate extraction (Makes for faster reloads too).

 

I don't think the ACP headspaces on the moon so the presence or absence of the moons shouldn't be a factor with regard to reliable trigger pull weight.

????This was all explained in another post. Try shooting a cylinder full and then let us know how well the extractor works. In fact you don’t even have to shoot them just place them in there. Please take a video and attach when you do this.

Edited March 31, 2021 by revoman

[Cherokeewind]

Revoman,

Thanks for not understanding my comment:)

 

With years of experience with 25s and 625s I know what the moons are for.  My point was that, regarding hammer fall force, the moons aren't a factor when using ACP cases.  When using GAP cases the moons would set the headspace since the GAP cases don't reach the "shoulder" in the chambers which are cut for the ACP case. 

[pskys2]

15 minutes ago, Cherokeewind said:

Revoman,

Thanks for not understanding my comment:)

 

With years of experience with 25s and 625s I know what the moons are for.  My point was that, regarding hammer fall force, the moons aren't a factor when using ACP cases.  When using GAP cases the moons would set the headspace since the GAP cases don't reach the "shoulder" in the chambers which are cut for the ACP case. 

I've not been able to reduce Hammer Fall with ACP vs GAP cases, they started giving FTF's at less than 40 oz.

As an aside I have had a Ruger 45 LC Blackhawk with a convertible 45 ACP cylinder.  In years past I tried shooting the 45 ACP cylinder with factory ACP's and would consistently have FTF's, from 1 to 4 each cylinder.  It was so consistent that I've never even tried more than the odd round in my 625PC, with the same results.

We all understand the intent, but the reality is I've never had any luck getting rounds to fire The ACP in a Semi-Auto barrel definitely does headspace on the case mouth, made a world of difference in 38 supers when we ditched the factory barrels and used properly set up barrels, but the FP on a 1911 has a lot more reach than any Revolver.  Could be a very tight chamber with rounds not tightly crimped, a whole different problem, could be made to work.  

Edited March 31, 2021 by pskys2

[pskys2]

Ran some drills of draw and put 8 rounds on a Bianchi D1 and using ICORE Time Plus Scoring the results at 10 yards was the lighter action gave me .30 better scores.  Not huge and draw/finding the Dot could easily eat that up.  Now at 25 yards the difference was a whopping 2.85 better score.  I ran the drill 9 times at 10 yards and 5 times at 25 yards, then averaged the times for each Revolver and compared.

At 25 yards I was pretty surprised as the end result of a string of 8 vs 2 should have had quite so large a spread.  At 10 yards it seemed closer to what I expected.

The raw times were pretty close, but the scores shot differed.  The main difference was in the number of B's with the heavier action.  Had 1 more C with the heavier action, but each C was definitely a result of either aiming issues (in my defense the winds were 30+mph from the North at 40 degrees and my eye kept watering up?) or I know I heeled one and jerked a couple too!

So the cumulative effects seem to be more than a single draw and split.

 

Now wonder if a lighter Rebound will make any further difference?  Back to the Bench!

 

At least this is keeping me enthused to shoot!!!  Now if I could just beat that minute of sun dial speed I have! 

[Cherokeewind]

So it comes down to using ACP cases from the same manufacturer/same lot if possible and uniforming primer pockets like the bench rest rifle guys do.........

 

Ain't gonna happen here:)

 

I'm willing to run a heavier hammer fall if necessary to reliably pop primers in mixed cases.  If I were a competitor I would have to take a more serious approach like some one we know (Hi, Dave).  

[pskys2]

58 minutes ago, Cherokeewind said:

So it comes down to using ACP cases from the same manufacturer/same lot if possible and uniforming primer pockets like the bench rest rifle guys do.........

 

Ain't gonna happen here:)

 

I'm willing to run a heavier hammer fall if necessary to reliably pop primers in mixed cases.  If I were a competitor I would have to take a more serious approach like some one we know (Hi, Dave).  

[PatJones]

11 hours ago, Cherokeewind said:

In my 625's, the cartridges headspace on the case mouth (even when using moons), same as they do in a bottom feeder.

That's not the case in my 625-4

[Cherokeewind]

Pat, it looks like  your picture shows exactly what I explained.  You don't have a moon clip on that cartridge yet the cartridge is in place, apparently supported in the position shown in your picture, by resting the case mouth against the shoulder in the chamber, same as a semi auto would.

 

What am I missing?

Edited April 1, 2021 by Cherokeewind
added info.

[pskys2]

11 minutes ago, Cherokeewind said:

Pat, it looks like  your picture shows exactly what I explained.  You don't have a moon clip on that cartridge yet the cartridge is in place, apparently supported in the position shown in your picture, by resting the case mouth against the shoulder in the chamber, same as a semi auto would.

 

What am I missing?

Nothing really it's the way it is supposed to work BUT... for factory ammo in a Revolver with factory, heavy, Hammer Falls it "usually" works too.  With reloads of varying case lengths and crimps it becomes a lot more problematic, even with factory weights.  As I noted earlier the difference between the 1911 and Revolver Firing Pins is length.  The Revolver only extends a little way into the Primer, in a 1911 the Firing Pin can extend up to triple the length of the Revolver FP.  Therein lies the issue.

So you're not wrong, it's just the real world applications have too many variables.  And at the weight of the Actions we run, it takes very little to cause issues.

[Cherokeewind]

Yeah, I understand what you're saying.....the margin for error is very narrow for a revolver, even those that headspace on the cartridge rim.  

With the ACP case, excess crimping of the case mouth will cause problems even in the semi autos; much more so in revolvers.

 

I have no experience with 9mm in revos but I do know that the 9x19 case is tapered so there are several factors to be considered regarding headspace:

Case length, any crimp that might be applied to the case mouth and the taper of the case.  So "plunk" tests are commonly used for 9x19 cartridges to make sure that all parameters are satisfied.  

 

I built 1911s for several years so I understand the differences between the two designs relative to firing pin length and hammer striking force.  Generally, the hammer striking force on a 1911 is far higher than we would ever have on a revolver; the DA revolver trigger pull would be very high! 

[revoman]

The shoulder as you call it in the cylinder is the start of the cylinder throat it is not the same as a semiauto barrel which uses head space. Revolvers head space on the back of the cylinder hence rimmed cartridge and that is why a 38 special can be shot through a .357 cylinder. When a cylinder is cut for moon clips a rim around the edge is left so the revolver can be fired with or without moons. Now when they came up with rimless ammo to fire in a revolver the moon clip was invented to get proper head space and without the moon clip FTF will happen and extraction will not happen at all. 

Again I say fire away with the 45ACP, 9mm or 38 super in a revolver without moon clips and have fun. But word of warning please don't try it during a match as there is not enough time in a day to complete the match.

By the way I did understand your comments. 

[Cherokeewind]

Not to be argumentative but the .45 ACP case will headspace on the case mouth in MY 25 and 625s.  Fired cases will NOT be extracted by the extractor since the ACP cases don't have the normal rim of cases designed for revolvers (.45 Auto Rim).

 

The comparison of .38 Special/.357 Magnum cases is an entirely different situation.

 

FWIW, the half moon clips that were developed during WWI (I think) were designed to allow ACP cartridges to be extracted from the S&W and Colt revolvers which were used to supplement inadequate supplies of 1911 semi autos.

 

https://en.wikipedia.org/wiki/.45_Auto_Rim

[PatJones]

10 hours ago, Cherokeewind said:

Pat, it looks like  your picture shows exactly what I explained.  You don't have a moon clip on that cartridge yet the cartridge is in place, apparently supported in the position shown in your picture, by resting the case mouth against the shoulder in the chamber, same as a semi auto would.

 

What am I missing?

What you're not looking at is the space behind the case. Headspace literally means the space behind the head. Different cartridge types control this through different surfaces.

 

All firearms, even bolt action rifles need a little space behind the casehead to operate the action. SAAMI specifies cartages with an appropriate headspace measurement after taking into account their pressure and action type. As an example, a revolver needs more clearance around the casehead to turn a cylinder full of cartridges against the breechface than a bolt action rifle needs to rotate the bolt closed. Engineers handle this for us, that's why we have SAAMI.

 

If you look at the SAAMI spec for 45 ACP, the maximum allowable headspace is 0.032. This is a huge number in headspace world, 40 S&W has a maximum headspace of .022. many rifle cartridges allow only .010. I didn't measure it, but the photo shows a gap larger than .032 inch.

 

With the shoulder at the front of the chamber, it provides a great place for crud to build up. We don't have a big spring to chamber the round, revolvers only use gravity. Smith solved this problem by cutting the chambers deeper than the SAAMI spec. There's still a shoulder in there, but the cartridge doesn't touch it. This allows the cartridge to drop freely into the chamber. The late model 625s headspace off from their moonclips. I believe the old model 25s headspace off from the case mouth, but when they're dirty you might need to seat the clip with a little push. That's not ideal in practical shooting.

[Cherokeewind]

Good Morning,

 

I just did some measuring on revos that I have available to me.........

1 S&W 25-2

2 S&W 625 JM

1 625 Model of 1989

1 625 Model of 1988

3 625 PC

 

To summarize, in each gun an empty sized ACP case, without moon clip, seated against the chamber shoulder with a positive "stop".  

In each gun, with the same empty case in a Moon Clip (.040 thick), there was a difference in the amount of case standing above the chamber........none of them were the same.  In no instance was there .040" difference between clipped or unclipped measurements.

 

In the 25-2 there was significantly less difference in the measurements.

 

In the 625 PCs there was the most difference, but again not .040" difference.

 

So.........what have I learned??

 

It is probably a really good idea to use the moon clips if running a lightened hammer fall as on a competition revolver (not even considering the extraction factor) but if using the stock set up (heavy hammer fall) reliable ignition should no be a problem (again, no consideration being given to extraction/ejection).

 

As for me, I will continue to use moon clips to facilitate extraction/ejection and to benefit from any reduction in headspace that the moons provide.