Pardini HP shock absorber + O rings

by WillH Fri Dec 09, 2022 11:16 am

I have a new model Pardini HP with around 1,000 round count. Recently I've been having some FTFs with 32 SWL loads that used to cycle fine when the pistol was new but now won't. The problem loads in question (1.6 BE, 98 gr Bear Creek HBWC, loaded flush, roll crimp) would not be what I would call hot as they are running around 750 per chrono. Trading some emails with Pardini have indicated that among other things I should inspect the condition of the O rings under the shock absorber rod contained in the bolt assembly. This advice was based on logic that the bolt may be moving too fast. I see from the on line parts diagram it is held with a drift pin and there are 13 o rings in there.

Questions: When removing the shock absorber pin, will it want to shoot across my garage? How does one go about removing these O rings from the bolt assembly without damaging them? It would seem they would want to stick in that small hole. Or, maybe they are a bit undersized and just fall out? My gut says I should probably buy a new set of O rings to have on hand in the event they become damaged on removal since I'm using it for weekly league shooting.

Any guidance on this from those who have worked on this item before would be appreciated. There could also be be other reasons for the FTFs (such as too strong mag springs or something else to do with my reloads) but looking to address the items one at a time. I've got some reduced loads that are cycling fine (1.3 BE - same as above bullets) but the higher velocity rounds mentioned above grouped better and would like to be able to go back to shooting them at least for slow fire stages.

Note that I have confirmed my powder scale is accurate with check weights (at 1.5 gr level) and my powder dispensing system is pretty precise (+/- 0.1 gr over 10 consecutive throws) - so I don't think I'm getting too high velocity due to powder charging errors.

by NukeMMC Fri Dec 09, 2022 12:50 pm

That absorber (PC. 870) is not spring opposed. Once the roll pin (PC. 869) is pushed out with a drift punch, and the punch is still in the hole in place of the pin, slowly remove the punch while putting a rag or your hand over the back of the boat to catch the absorber.

by BruceV Fri Dec 09, 2022 1:53 pm

Another thought, if you take your time don't push the pin all the way through, just enough to release the absorber. The pin is not flat, so if you drive it out completely it is a little bit tricky getting it started.

Also the o-rings put forward pressure on the absorber making it hard to drive the pin out, get yourself a small wood c clamp , put the bolt in it and press the absorber in, makes it really easy.

by BruceV Fri Dec 09, 2022 1:56 pm

Best directions I've seen.

Attachments

: Pardini SP Buffer O-Rings.pdf You don't have permission to download attachments.(601 Kb) Downloaded 40 times

by BruceV Fri Dec 09, 2022 2:04 pm

One other thing McMaster Carr has the O-rings, I bought 200 delivered to my house for $15. I've replaced my O-rings 3 times with them, they work perfectly, pistol functions perfect. Search here someone posted the part # for McMaster Carr.

by WillH Fri Dec 09, 2022 2:31 pm

Thanks for the materials and advice here. Just what I was hoping for! I can't seem to find the post where the McMaster Carr part number is listed for the O rings tho. If anyone has that part # or can find the post I'd appreciate it to save some $$.

by BruceV Fri Dec 09, 2022 3:08 pm

It is a sticky on this forum - Equipment Discussion - you will see it. When you open equipment discussion the top several post are stickies.

by BruceV Fri Dec 09, 2022 3:09 pm

BruceV wrote:It is a sticky on this forum - Equipment Discussion - you will see it. When you open equipment discussion the top several post are stickies. Pretty sure the o-rings are the same in the .32 bolt as the .22 bolt. someone here will know or of course ask Alex at Pardini.

https://www.bullseyeforum.net/t18260-o-ring-stack-in-the-buffer-on-the-pardini-22

by WillH Fri Dec 09, 2022 3:25 pm

Duh, I didn't even think to look at the sticky section. If it was a snake I'd be bitten for sure. I'll check with Alex if someone doesn't chime in on whether HP and SP o rings same or not. Good point. Thanks!

by BruceV Fri Dec 09, 2022 6:56 pm

WillH wrote:Duh, I didn't even think to look at the sticky section. If it was a snake I'd be bitten for sure. I'll check with Alex if someone doesn't chime in on whether HP and SP o rings same or not. Good point. Thanks!

I went on the Pardini website and brought up the HP parts list. All th HP part #'s start with 8, the part number for o-rings is 871. When you pull up the schematic for the HP click on the number - it brings up the part - but now it calls it part # 771 - SP .22 o-rings.

I think they are the same, but confirm before buying.

by rbwillnj Sat Dec 10, 2022 10:47 am

So, while we are on the subject, is there a recommended replacement interval for the O rings for 22 and/or 32?

I shoot an SP and an HP in 32 ACP, both new models. I'm well over 1000 rounds in each and haven't noticed any issues.

Bruce Williams

by BruceV Sat Dec 10, 2022 11:04 am

rbwillnj wrote:So, while we are on the subject, is there a recommended replacement interval for the O rings for 22 and/or 32?

I shoot an SP and an HP in 32 ACP, both new models. I'm well over 1000 rounds in each and haven't noticed any issues.

Bruce Williams

Bruce,

There are varying round count recommendations out there from 5,000 to 10,000 to once a year. The .22 will not be as often as the .32. What I have found upon inspection of my .22 at 7,500 rounds half the o-rings are showing wear. The o-rings furthest in the bolt get the most wear.

I have always changed them all even if the others looked good.

Of course if you are having any issues with the gun, stove pipes, not feeding due to bolt timing, then of course that is a good time to check the o-rings.

I just change them out between 7,500 and 10,000 part of PM. I also replace the recoil spring at 10,000. Many shooters don't do it this way, they go with the if it ain't broke don't mess with it.

The only issue I have with my gun, is with the magazines not liking certain ammunition, specifically CCI SV in the colder weather. CCI hangs up in the magazine well - causing FTF.

by rbwillnj Sat Dec 10, 2022 11:46 am

Thanks Bruce,

I haven't been able to get CCI SV to work reliably in any weather. That's unfortunate as I have quite a bit, having stocked up on it after the last ammo shortage. But I don't want to Hijack the O Ring topic

by NukeMMC Sat Dec 10, 2022 12:14 pm

Look at CCI SV length as the culprit in a Pardini magazine.
My CCI measures 0.987-0.995"
Eley Target 0.972-0.980"
Norma Match 0.966-0.969"
Eley Bullseye X 0.972-0.978"

by NukeMMC Sat Dec 10, 2022 12:45 pm

Pardini HP shock absorber + O rings 16706910

This Pardini mag measures 1.010" in the center and 0.970" on either side of the "trough"

by WillH Thu Dec 15, 2022 12:03 pm

I heard back from Pardini and they said the .22 / SP O ring sizes are the same as 0.32/HP - if anyone else is wondering about that. I haven't gotten to the removal and inspection step of the O rings yet since my lower velocity reloads and fiocchi factory are running fine.

Regarding the longer .22 CCI ammo I've found it is sometimes necessary to open up the front edge of the magazine to keep the bullet tip from dragging on the edge. I modified mine with a small round file (that fit the trough/groove pretty well) until the rounds didn't drag and then polished the filed surface with 600 grit sand paper. It doesn't take much material removal to make it pass so go slow with trial and error. I too had a bunch of CCI standard and needed to use it. Funny thing is, the 2 mags I got with the 22 conversion kit worked fine as is but when I ordered a 3rd I had to work on it. So perhaps it is a combination of longer ammo and some mag manufacturing variances more than say old or new mags as all of mine were bought new.

by BruceV Thu Dec 15, 2022 12:33 pm

WillH wrote:I heard back from Pardini and they said the .22 / SP O ring sizes are the same as 0.32/HP - if anyone else is wondering about that. I haven't gotten to the removal and inspection step of the O rings yet since my lower velocity reloads and fiocchi factory are running fine.

Regarding the longer .22 CCI ammo I've found it is sometimes necessary to open up the front edge of the magazine to keep the bullet tip from dragging on the edge. I modified mine with a small round file (that fit the trough/groove pretty well) until the rounds didn't drag and then polished the filed surface with 600 grit sand paper. It doesn't take much material removal to make it pass so go slow with trial and error. I too had a bunch of CCI standard and needed to use it. Funny thing is, the 2 mags I got with the 22 conversion kit worked fine as is but when I ordered a 3rd I had to work on it. So perhaps it is a combination of longer ammo and some mag manufacturing variances more than say old or new mags as all of mine were bought new.

The other approach to modify the magazines to accept CCI SV. On the top back side of the magazines you can see the indented V, this is the area that pushes the bullets forward causing the tip of the bullet to drag/hangup in the front of the magazine well. You can push the V out until it is flat on the inside of the magazine, of course be careful as to not screw up the magazine.

by **PhotoEscape** Thu Dec 15, 2022 1:35 pm

FWIW - I'm using 14 O-rings instead of 13 in my SPs because I use Aguila SE for training. Works fine with Aguila and no issues with other ammo (BTW - I have no issues with fitting CCI SV in my mags). One issue I noticed is that magazines "will let you know" when it is time for deep cleaning. This "Notice" will exhibit itself in FTFs, normally in 3rd to 5th rounds. After taking mags apart, cleaning (making sure all lead and lube residue removed!!) and lubing, FTFs go away. Recommended maintenance cycle for mags is 5000 rounds. I do it as necessary. That's me. With shooting SW Long wadcutters, I assume, there is quite a bit lube getting deposited in mags as well. So, I'd suggest checking and cleaning mags as see if it helps with FTFs.

AP

by BruceV Thu Dec 15, 2022 4:00 pm

PhotoEscape wrote:FWIW - I'm using 14 O-rings instead of 13 in my SPs because I use Aguila SE for training. Works fine with Aguila and no issues with other ammo (BTW - I have no issues with fitting CCI SV in my mags). One issue I noticed is that magazines "will let you know" when it is time for deep cleaning. This "Notice" will exhibit itself in FTFs, normally in 3rd to 5th rounds. After taking mags apart, cleaning (making sure all lead and lube residue removed!!) and lubing, FTFs go away. Recommended maintenance cycle for mags is 5000 rounds. I do it as necessary. That's me. With shooting SW Long wadcutters, I assume, there is quite a bit lube getting deposited in mags as well. So, I'd suggest checking and cleaning mags as see if it helps with FTFs.

AP

Alex,

You are fortunate that your mags handle CCI SV. I have 12 mags and not one of them will cycle CCI SV - well not until I altered them. And yes keeping the mags clean is important especially when using CCI. I clean the mags all the time - 1,000 rounds would be a lot.

Interesting you have added an o-ring. I have experimented with 12 o-rings in the past, have since gone back to 13.

Tell me why 14 especially with Aguila SE?

by **PhotoEscape** Thu Dec 15, 2022 4:48 pm

BruceV wrote:Tell me why 14 especially with Aguila SE?

Aguila Super Extra is rated at 1130 fps velocity wise, and 113 ft/lb energy wise. It is about 5% higher than most other brands we commonly use. That is with stipulation that I can't find data for the length of the barrel used for testing. The only comparable to Aguila SE ammo by parameters I could find is SK Semi-Auto Rifle (1132/114), was tested with 26" barrel. Thus, I assume, same is the case for Aguila SE. So, it would be less out of 5-6" barrels, and in line with i.e. CCI SV(1070/102), Tenex (1070/101), Lapua X-Act (1073/102), etc. Yet, I decided to put extra donut just in case and because I put many rounds through.

AP

by BruceV Thu Dec 15, 2022 5:47 pm

PhotoEscape wrote:
BruceV wrote:Tell me why 14 especially with Aguila SE?

Aguila Super Extra is rated at 1130 fps velocity wise, and 113 ft/lb energy wise. It is about 5% higher than most other brands we commonly use. That is with stipulation that I can't find data for the length of the barrel used for testing. The only comparable to Aguila SE ammo by parameters I could find is SK Semi-Auto Rifle (1132/114), was tested with 26" barrel. Thus, I assume, same is the case for Aguila SE. So, it would be less out of 5-6" barrels, and in line with i.e. CCI SV(1070/102), Tenex (1070/101), Lapua X-Act (1073/102), etc. Yet, I decided to put extra donut just in case and because I put many rounds through.

AP

Curious have you inspected the o-rings and seen more wear? How many rounds a week? I shoot a brick a week myself.

by **PhotoEscape** Thu Dec 15, 2022 6:26 pm

BruceV wrote:Curious have you inspected the o-rings and seen more wear? How many rounds a week? I shoot a brick a week myself.

800-1000 / wk. Not sure if wear matters, as I'm after protection. Although I see more wear at the front of the stock, and rings at the back can be safely re-used. However, I'm buying o-rings in bulk from McMaster and cost is negligible.

AP

by BruceV Thu Dec 15, 2022 6:35 pm

PhotoEscape wrote:
BruceV wrote:Curious have you inspected the o-rings and seen more wear? How many rounds a week? I shoot a brick a week myself.

800-1000 / wk. Not sure if wear matters, as I'm after protection. Although I see more wear at the front of the stock, and rings at the back can be safely re-used. However, I'm buying o-rings in bulk from McMaster and cost is negligible.

AP

What I have found the first 6 or 7 o-rings going in the bolt get noticeably flattened the others appear fine. I'm thinking once this starts they are not providing the cushion as when new. And subsequently possibly changing the bolt timing. Like you I change them all, I also bought from McMaster - Carr.

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