To help me understand the recoil spring question, I measured three pistols: P-64, PA-63, & Makarov. Altho my methods were crude (fish scale, postage scale, ruler, etc) the numbers are at least valid for comparisons and discussion.
I've drawn no conclusions from these numbers yet, but want to post them for all to chew over.
P-64 PA-63 Makarov
free length (mm) 80 107 132
ID (in) .505 .498 .505
wire dia (in) .055 .050 .055
coils 9 14.5 15.5
rate (#/in) 6 3.5 4
pre-load (#) 6 5.5 10
at full recoil (#) 15 10 16
sllide mass (oz) 8 9 10
Recoil Spring Study
Recoil Spring Study
My random thoughts on the Spring Study.....
First, thanks to "jbailey" for taking the time to provide the information. It does not matter what type scale was used, as long as the same scale is used for each spring, so we now have some data to work with. My thoughts as follows:
1. ID of Spring the same, .505 - good
2. ASSUME the wire material is the same????? This is a big "Caveat"
3. Wire Diameter the same. .055 (see 2. above) - good
4. Free Length and Number of Coils appear to corrolate with each other based on No. 1 and 3 above.
5. ASSUME the barrel length of the P-64 and Makarov from the Muzzle to where it enters the Trunnion are the same.
6. The difference in the Slide Mass is approx. 20% less for the P-64
7. If everything above was true, and taking into consideration the 20% Slide Mass difference, you should be able to use a Makarov Spring and cut it to approx. 100-110mm Free Length and it should work fine. This would provide less shock on the entire pistol when firing.
8. IF the free length of the barrel length is different, this would have to be calculated and the modified Makarov cut Spring length I stated above would have to be adjusted.
One item in Spring design is the "Collapsed Length" of the Spring. This is where the spring is completly compressed without crushing the coils. You want the Collapsed Length to be close to full collapse, but not fully collapsed. The BIG ASSUMPTION is what the spring material is and the heat treating. I would assume the two SHOULD be similar.
With the above said, why did the original designers use this particular spring length and number of coils on the P-64????? They had to have a good reason
First, thanks to "jbailey" for taking the time to provide the information. It does not matter what type scale was used, as long as the same scale is used for each spring, so we now have some data to work with. My thoughts as follows:
1. ID of Spring the same, .505 - good
2. ASSUME the wire material is the same????? This is a big "Caveat"
3. Wire Diameter the same. .055 (see 2. above) - good
4. Free Length and Number of Coils appear to corrolate with each other based on No. 1 and 3 above.
5. ASSUME the barrel length of the P-64 and Makarov from the Muzzle to where it enters the Trunnion are the same.
6. The difference in the Slide Mass is approx. 20% less for the P-64
7. If everything above was true, and taking into consideration the 20% Slide Mass difference, you should be able to use a Makarov Spring and cut it to approx. 100-110mm Free Length and it should work fine. This would provide less shock on the entire pistol when firing.
8. IF the free length of the barrel length is different, this would have to be calculated and the modified Makarov cut Spring length I stated above would have to be adjusted.
One item in Spring design is the "Collapsed Length" of the Spring. This is where the spring is completly compressed without crushing the coils. You want the Collapsed Length to be close to full collapse, but not fully collapsed. The BIG ASSUMPTION is what the spring material is and the heat treating. I would assume the two SHOULD be similar.
With the above said, why did the original designers use this particular spring length and number of coils on the P-64????? They had to have a good reason
Recoil Spring Study
Abwehr - Several things I left out in the interest of keeping it short: Mak bbl length is 70 mm vs 60 for P-64 and the compressed length at full travel is 68 vs 78. Also, both springs are flat faced, tight at breech end and slightly flared at muzzle, so if cut, must cut breech end. Since I am not changing mainsprings (cocked and locked modification), I'm going to wait for Wolff.
I strongly suspect the designers, based on experience and a whole box of different springs, selected the one that "worked" (sort of like how I adjust the gas port on my FN/FAL - start wide open, close one click at a time until it functions, then two more to be sure)?
Further measurement and calculations indicate that the cocking of the hammer by the slide represents about 20-25% of the total energy in the firing cycle, at least with stock mainspring. And remember, this energy is NOT returned to the slide. I don't have an alternate spring to repeat the measurements, but I still suspect that different ammo makes as large a change in behavior as lighter mainspring? At any rate, this is my 2 cent contribution to the debate.
I strongly suspect the designers, based on experience and a whole box of different springs, selected the one that "worked" (sort of like how I adjust the gas port on my FN/FAL - start wide open, close one click at a time until it functions, then two more to be sure)?
Further measurement and calculations indicate that the cocking of the hammer by the slide represents about 20-25% of the total energy in the firing cycle, at least with stock mainspring. And remember, this energy is NOT returned to the slide. I don't have an alternate spring to repeat the measurements, but I still suspect that different ammo makes as large a change in behavior as lighter mainspring? At any rate, this is my 2 cent contribution to the debate.
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mikethewreck
- Member
- Posts: 172
- Joined: December 3rd, 2005, 3:34 pm
- Location: Chattanooga, TN
Recoil Spring Study
Is there any way we can pass our data to the GOOD folks at Wolff springs or are they light years ahead of us?
Recoil Spring Study
jbaily,
I agree with you 100%; wait on Wolf Springs. But it sure is fun to discuss the "possibilities" for changing.
Thanks for the additional information, I was not sure if the Makarov barrel was longer or not, but I thought it was. Again, you are right about only cutting the breech end if it were to be cut. Taking into account the additional information, you could calculate what length needs to be cut, but I am not going to do this on my pistol! A spring company SHOULD be the ones to make this decision for us guys and I will wait for Wolf!
IF, and a big IF, I were to start playing with the Recoil Spring, I would cut very short sections until the collaped length would work in the P-64. Then fire the pistol remotely to see what happens. Even with cursory calculations, it would be a trail and error experiment. Me do this, no, Idon't think so.
The suggestion from "mikethewreck" about passing the info along to Wolf probably would not do much good. These guys have the instruments, tools, and computer programs that can spit out the correct spring in a few minutes. Actually, there is a spring calculator on the Century Spring website. Here is a link if anyone wants to give it a shot: www.centuryspring.com
Go to the "Compression" spring section and a number of boxes show up where you fill in the data for the spring and the correct spring will be shown. This is sort of fun, give it a try.
I agree with you 100%; wait on Wolf Springs. But it sure is fun to discuss the "possibilities" for changing.
Thanks for the additional information, I was not sure if the Makarov barrel was longer or not, but I thought it was. Again, you are right about only cutting the breech end if it were to be cut. Taking into account the additional information, you could calculate what length needs to be cut, but I am not going to do this on my pistol! A spring company SHOULD be the ones to make this decision for us guys and I will wait for Wolf!
IF, and a big IF, I were to start playing with the Recoil Spring, I would cut very short sections until the collaped length would work in the P-64. Then fire the pistol remotely to see what happens. Even with cursory calculations, it would be a trail and error experiment. Me do this, no, Idon't think so.
The suggestion from "mikethewreck" about passing the info along to Wolf probably would not do much good. These guys have the instruments, tools, and computer programs that can spit out the correct spring in a few minutes. Actually, there is a spring calculator on the Century Spring website. Here is a link if anyone wants to give it a shot: www.centuryspring.com
Go to the "Compression" spring section and a number of boxes show up where you fill in the data for the spring and the correct spring will be shown. This is sort of fun, give it a try.
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duhawki647
- Posts: 7
- Joined: February 12th, 2006, 5:31 pm
Recoil Spring Study
Today I did test fit the E.G. Makarov recoil spring on the P-64 barrel. Fits like it was made for it apart from being too long. The P-7 spring is huge in diameter by comparison. Heavier than standard Makarov recoil springs cut to length ought to be OK.
Duhawki
Duhawki
Recoil Spring Study
Yes, the Makarov Recoil Spring probably would work IF we knew how much to cut off, but doing this may endanger you when firing the pistol. A cut spring may work initially, but may cause problems that show up later.
As a "caveat" to anyone making this critical change by experimentation, be careful!!!!! This would be a change you are making at your own risk. This is one spring, as I have stated on other threads, that I will wait for Wolff to sell. Then, any liability will be on them.
As a "caveat" to anyone making this critical change by experimentation, be careful!!!!! This would be a change you are making at your own risk. This is one spring, as I have stated on other threads, that I will wait for Wolff to sell. Then, any liability will be on them.
Recoil Spring Study
FYI ... the P64 spring is JUST short enough as issued to allow for reassembly of the pistol. This is an important constraint in the design of a replacement. I agree that the Mak spring could be cut down to allow it to be used as a substitute (and it would fit a WHOLE lot better!), but since it has the same wire diameter as the P64 spring, it will have the same number of coils when you get it to finally fit. Since (assuming all other things to be equal) it has a smaller distance between coils, it will then be a shorter spring than the P64 (less pre-load) and will provide LESS energy storage than the STOCK p64 spring. If you are looking for a spring to use when shooting super light target loads, the Mak spring conversion should be perfect. But it, unfortunately, will not be a stiffer replacement.
I'm hoping that Wolff comes through with a good one ... I searched all the major spring manufacturers' sites and couldn't find one stock spring that would fit in the P64 and be stiffer. The gritty (slightly oversized) HK spring was actually the ONLY option that I could come up with.
Saands
I'm hoping that Wolff comes through with a good one ... I searched all the major spring manufacturers' sites and couldn't find one stock spring that would fit in the P64 and be stiffer. The gritty (slightly oversized) HK spring was actually the ONLY option that I could come up with.
Saands
Recoil Spring Study
Saands - I couldn't agree with you more. There's just too many variables in this spring business to be hacking away at other springs, trying to obtain a mechanical fit, and hoping the other parameters fall into place somehow. Also, lets not forget that for the same length, a flat-faced spring has a different rate than one with unfaced ends.
Recoil Spring Study
Very informative thread and thanks, jbailey, for the springs comparison data.
Most of my comments on this forum has been based upon shooting this fun little pistol at the range. My two CZAKs definitely handle the S&B ball better than the Fiocchi ball ammo, i.e., the Fiochhi is ~ 100 fps hotter than the S&B (1050 vs 940); and I do not have to walk to the next county to retrieve the S&B brass. Obviously, if I settled upon the hotter brands I would be looking for more help from the recoil spring, especially if an exchange to a lighter main spring was made. For now, I will enjoy using and finding the S&B.
I do not know why I had a light primer hit shooting the Fiocchi using a 20# PPK main spring (described earlier) , but I do know that my unaltered P-64 has not demonstrated an inability to go BANG with every trigger pull. This would be of paramount importance in my selection of any carry modification - is it going to fire reliably after getting thru that first DA trigger pull. Trouble normally runs in packs!
I will fool around with springs at the range, but, as you guys are strongly suggesting, Wolf has the expertise to give us the best spring combination and even then Wolff may provide guidance on suggested ammo characteristics.
Most of my comments on this forum has been based upon shooting this fun little pistol at the range. My two CZAKs definitely handle the S&B ball better than the Fiocchi ball ammo, i.e., the Fiochhi is ~ 100 fps hotter than the S&B (1050 vs 940); and I do not have to walk to the next county to retrieve the S&B brass. Obviously, if I settled upon the hotter brands I would be looking for more help from the recoil spring, especially if an exchange to a lighter main spring was made. For now, I will enjoy using and finding the S&B.
I do not know why I had a light primer hit shooting the Fiocchi using a 20# PPK main spring (described earlier) , but I do know that my unaltered P-64 has not demonstrated an inability to go BANG with every trigger pull. This would be of paramount importance in my selection of any carry modification - is it going to fire reliably after getting thru that first DA trigger pull. Trouble normally runs in packs!
I will fool around with springs at the range, but, as you guys are strongly suggesting, Wolf has the expertise to give us the best spring combination and even then Wolff may provide guidance on suggested ammo characteristics.