P-01 loss of accuracy over time

[CZTom]

It seems like my P-01 is not as accurate as it used to be.  My RAMI BD now shoots much more accurately than the P-01.  I have the CGW single action and double action upgrades to both, as well as my P-06, all of which I did myself.  I had to increase the recoil spring to 22 pounds on the P-06, but I am using the stock spring weight on the P-01, (replaced the old one with a new one).  I have no malfunctions of any kind, but the accuracy just is not there.  Could it be that I should try a heavier recoil spring, such as 18 # or 20 #.  I have tried and cataloged perhaps a dozen different kinds of ammo, comparing the RAMI and P-01.  I do not have the P-06 with me to compare that.  Does anybody know what might be happening?  I thought maybe a heavier recoil spring might force the barrel & slide into a stronger battery, but I am just guessing.  I have had the gun for about 4 years, and it was 1 year old when I bought it from a friend.  I have put maybe a thousand rounds thru it, and probably 400 of that was since I installed the CGW parts and polished the trigger bar, etc.  Like I said, I have never had any malfunctions of any kind.

Your thoughts??

[CZTom]

I went to the range today.  I replaced the factory P-01 recoil spring (new spring with only about 200 rounds fired with it.  I think it was 17#) to new 18# Wolff Spring  and that did not help much.  I then installed a 20# Wolff Recoil Spring, and the P-01 was hitting bulls-eyes (1/2 inch) like again like clockwork at 21 feet.  All of the many kinds of ammo I tested were very good.  I will post a log when I get the chance.   

It seems that I may have lost accuracy when I went to the 13# hammer-spring as part of the CGW double action upgrade (which I performed).  As someone mentioned months ago when I was trying to reduce the throw distance of spent cartridges from my P-06 (same mods as my P-01), that a weaker hammer-spring does not provide as much resistance to the rearward motion of the slide, and so a stronger recoil spring may be needed to reduce the throw distance of the spent cartridges.  It also seems, maybe I am wrong though, that a stronger recoil spring may also be needed to ensure solid barrel to frame lock-up for maximum accuracy, when using a weaker hammer-spring.   At least, is seems so in my case. 

[dssharpe]

Sounds like good detective work to me.

[Alpha Sierra]

As you have found, semi auto handguns need a careful balance of spring weights to work properly.  Once people start deviating from the factory springs, it might take some trial and error to find a combination that works correctly. 

That is why I stick to factory spring weights only.  If the trigger needs to be lightened up, I will do so by polishing and lubricating every part that rubs against something and will accept whatever gains come from that.

Reliability and accuracy must be absolute in all my handguns and all other considerations are secondary.

[Joe L]

CZTom--I think your analysis is correct.  I've seen it happen on a 1911--too weak of a recoil spring resulting in just a smidgen different lock up yet the gun would still fire. 

Don't worry about the gun itself wearing much to cause any accuracy problems.   My Kadet has nearly 30k rounds through it and it is just as accurate as when new, and I have SIG P-226s and a P-09 with 5k-10k rounds that haven't changed accuracy at all since new.  I'd start checking for some degradation at 30k rounds in a centerfire gun, but won't worry about it at all through 20k at least.  Springs need to be replaced when they are too weak to always get the gun in to battery, or when the casings are thrown too far, or when the gun feels "different", or just whenever you think about it. 

Joe

[Bible2David]

I went to the range today.  I replaced the factory P-01 recoil spring (new spring with only about 200 rounds fired with it.  I think it was 17#) to new 18# Wolff Spring  and that did not help much.  I then installed a 20# Wolff Recoil Spring, and the P-01 was hitting bulls-eyes (1/2 inch) like again like clockwork at 21 feet.  All of the many kinds of ammo I tested were very good.  I will post a log when I get the chance.   

It seems that I may have lost accuracy when I went to the 13# hammer-spring as part of the CGW double action upgrade (which I performed).  As someone mentioned months ago when I was trying to reduce the throw distance of spent cartridges from my P-06 (same mods as my P-01), that a weaker hammer-spring does not provide as much resistance to the rearward motion of the slide, and so a stronger recoil spring may be needed to reduce the throw distance of the spent cartridges.  It also seems, maybe I am wrong though, that a stronger recoil spring may also be needed to ensure solid barrel to frame lock-up for maximum accuracy, when using a weaker hammer-spring.   At least, is seems so in my case. 

How can the hammer spring effect the throw distance for spent cartridges?  This should be affected by the recoil spring not the hammer spring.

[Joe L]

Slide cocks the hammer during recoil.  Weaker hammer spring, less resistance to the slide recoil.    But, once cocked, only the recoil spring will affect how the slide/barrel get back to lock up.  Only if the ejection is too far or the slide is hitting the end of its travel too hard after putting in a weaker hammer spring, will the recoil spring weight need to be increased a pound or two to compensate for the lighter hammer spring.

Joe

[CZTom]

Bible2David:
"How can the hammer spring effect the throw distance for spent cartridges?  This should be affected by the recoil spring not the hammer spring."

To answer your question. 
The ejector cage is fixed in the frame and does not move.  The extractor is mounted in the right side of the slide and pulls the spent casing back at the same speed that the slide move aft, after firing.  When the slide and spend casing travel back far enough, the left side of the spent casing hits/contacts the immoveable ejector, which thus pivots and pushes the spent casing out of the ejection port on the right side of the slide.  With less rearward resistance being provided by a weaker hammer spring as compared to the factory hammer spring, the slide (and extractor) travel rearward faster/harder, and thus the spent casing contacts the ejector harder and so get "thrown" out harder.

[CZTom]

I have deleted all the freehand shooting from the log.  Also, the items with question marks had the group so spread out, off the target, etc. to measure.  Obviously the personal protection/higher priced ammo, did better than the cheaper ammo.  I deleted many rounds with the 18# freehand shooting.  Also, my bench shooting was just resting my hands on the bench.  All the posted shooting was done at 21 feet, except for the first few rounds at 25 feet.

P-01 (9mm) Shooting Log extract                        
Date           Recoil Spring     grain   Brand                               rounds   "group        EL   Wind
 (inch)"   EL   W   
06/03/14   Factory (17#)   147   Winchester Ranger SXT JHP           9   4.00     -0.5   0   
06/03/14   Factory (17#)   135   Hornady Critical Duty JHP           4   1.25     0.5   0   
08/15/14   Factory (17#)   115   Sellier & Boulet FMJ                 10   3.5              ?   ?   
08/28/14   Factory (17#)   124   Remington Golden Saber JHP      5   ?             ?   ?   
08/28/14   Factory (17#)   147   Winchester Ranger SXT JHP         10   3.00           2.5   1 L   
08/28/14   Factory (17#)   115   Sellier & Boulet FMJ                 10   ?          -3.0   1 L   
                        
08/31/14   Installed 18 # Wolff Recoil Spring - only slightly better results                     
08/31/14   18 #   147   Winchester Personal Protection-WWB JHP   5   2.00            0   1 L   
08/31/14   18 #   115   Blazer Brass FMJ                                 10   3.00          -1.5   1 L   
08/31/14   18 #   135   Hornady Critical Duty JHP                           2   1.00           1.5   0   
08/31/14   18 #   124   Remington Golden Saber JHP                   2   1.00           0.0   0   
                        
   Installed 20 # Wolff Recoil Spring - then excellent results (below)                     
08/31/14   20 #   135   Hornady Critical Duty JHP                         10   1.00   0.5   0.5 L   excellent
08/31/14   20 #   115   Winchester White Box FMJ                         10   3.00   -1.0   0   very good-very tight
08/31/14   20 #   115   Sellier & Boulet FMJ                                 10   1.50   -0.5   0   excellent-tight group
08/31/14   20 #   124   Remington Golden Saber JHP                  7   3.50   0.0   .5 L   good
08/31/14   20 #   147   Winchester Ranger SXT JHP                         10   3.00   0.0   1 L   okay
08/31/14   20 #   115   Magtech FMJ                                         10   5.00   -0.5   0.0   fair only
08/31/14   20 #   115   Blazer Brass FMJ                                 10   2.00   -1.0   .5 L   very nice
08/31/14   20 #   147   Winchester Personal Protection-WWB JHP   10   2.50   0   1 L   good to very good
08/31/14   20 #   147   Winchester PDX JHP                                   2   1.00   0   .5 L   excellent-tight group
08/31/14   20 #   135   Hornady Critical Duty JHP                           2   0.50   0   0   excellent, 2 for 2 Bulls
08/31/14   20 #   115   Sellier & Boulet FMJ                                 10   1.50   -0.5   0   excellent-tight group, 8 Bulls

This pistol seems to like all ammo, with all but 4 ammo groups at 2.5 inches or less, including "flyers".  Notice, even 5 ammo groups were 1.5 inch groups or less. This was a big change, just by increasing the recoil spring weight.  And again, my "bench" was just resting my hands on a flat table.  To be clearer, I should have done more "bench" shooting with the 18# spring, but I did do a lot freehand with it (it was not very good), but that would not be directly comparable to the data above.

[CZTom]

CZTom--I think your analysis is correct.  I've seen it happen on a 1911--too weak of a recoil spring resulting in just a smidgen different lock up yet the gun would still fire. 

Don't worry about the gun itself wearing much to cause any accuracy problems.   My Kadet has nearly 30k rounds through it and it is just as accurate as when new, and I have SIG P-226s and a P-09 with 5k-10k rounds that haven't changed accuracy at all since new.  I'd start checking for some degradation at 30k rounds in a centerfire gun, but won't worry about it at all through 20k at least.  Springs need to be replaced when they are too weak to always get the gun in to battery, or when the casings are thrown too far, or when the gun feels "different", or just whenever you think about it. 

Joe

Thanks Joe

[copemech]

Mine just keeps getting better! I think I may have it working well now!

I do not get to the range often enough, and when I went last weekend it was really to run some break in time on another poorer shooting bug gun.

It did not like cheap steel cased stuff and locked up on me! Oh well, I had the P-01 for a backup after some sight changes. Needed to ck it out!

Got a fresh target up at 15 yds, 6" red bull, rip off a mag and cannot see but two hits on the paper(because the rest were in the red dark area), throw in another mag for rapid fire(as best I can) and see three hits on paper.

I could not see them buried in the red against the black background, but they were all there, so I think that works!  Next trick, blow off some expensive stuff and a box of Horny CD!
 I can live with that!

[Skookum]

CZTom,


You may be correct in concluding your recoil spring change has increased the precision of your pistol, but, statistically speaking, I don't see that the data from your shooting log support your conclusion.


You are apparently using extreme range of a given group, in inches, as your metric of precision, where a large range denotes poor precision and a small range denotes good precision.  By using a variety of cartridges, you seem to be acknowledging that precision is cartridge-specific.


To make a meaningful comparison between two treatments -- in this case a 17-lb recoil spring and a 20-lb recoil spring -- one must compare the differences within treatments to the differences between the treatments.  To assess differences within, one needs replication.


For example, you have two 10-shot groups of Sellier & Bellot 115-gr FMJ for both the 17-lb and 20-lb springs.  Unfortunately, one precision estimate for the 17-lb spring is not quantified, and the estimates of the precision for the two 20-lb spring groups are of a level of detail such that they are quantitatively identical, obscuring the variance that undoubtedly exists among the two.  These data insufficiencies prevent a parametric statistical analysis to determine whether the stronger spring results in an improvement in precision.


A better way to assess any difference with 40 rounds of ammo would be to fire ten 2-shot groups with each spring, giving you a sample size of 10 precision measurements for each of the two treatments.  This would allow you to conduct a simple one-sided t-test at your desired confidence level (typically chosen to be 95%) to objectively determine whether precision is better with the 20-lb spring or not.


You have some other cartridges that were shot with two springs, but one can't meaningfully compare the group range from a 2-shot group with that from a 10-shot group.  Everything must be kept identical except for the difference in treatments, which in this case is the strength of the recoil spring.

[CZTom]

Skookum,

You are obviously much more knowledgeable than me on this.  I did not intend to do an actual parametric comparison, but afterwards decided to post my actual shooting measurements, as I have been measuring (actually "eyeballing") shooting groups to find out which cheap ammo was best in each of my pistols, and which defense rounds were most accurate and reliable in each of my pistols.  The comparison for recoil springs was an afterthought, and the measurements are not precise, as I mentioned-just eyeballed.  When I could not even find some of the bullet holes with the 17# spring, I knew I had a problem, which was corrected with the heavier 20# recoil spring.  And, my RAMI was much more accurate than my P-01, until after I went to the 20# recoil spring in the P-01.  And, my info included "flyers" and some ammo was very expensive, comparatively, so I only fired a few of those rounds.

What you say would best for a real comparison of apples to apples, but I don't want to go back and spend the money to quantify the accuracy or inaccuracy with the 17# spring.  But, I might do like you said, with just one brand, say the S&B. If I do that, I will post an update.  But, in any case, if someone else has this problem, they might want to consider increasing the recoil spring weight and see if that helps.

[Grendel]

When I went down two pounds on the hammer spring in my 226, I went up two pounds on the recoil spring to keep the relative difference the same.