Can a Walther OSP be converted to 22LR?

What parts are required to make a Walther OSP shoot 22lr? Just magazines and upper?

It's possible, but difficult. I believe Sandy Santibañez did it for his daughter, Lauren. I think there are some old posts on TargetTalk about it.

john bickar wrote:It's possible, but difficult. I believe Sandy Santibañez did it for his daughter, Lauren. I think there are some old posts on TargetTalk about it.

Thanks for the good lead.

https://www.targettalk.org/viewtopic.php?t=27198

https://targettalk.org/viewtopic.php?t=10998&highlight=osp+conversion&sid=710eecb549d1922e991674bb09ef42e7

https://www.targettalk.org/viewtopic.php?t=16537

Since this is a project I plan to figure what I need, make a list and then wait for opportunities. I expect in the mean time it will shoot 22 Short Target very well. 

I kinda fell into the pistol and a lot of ammo. I think you may know what I mean. The grip has a lot of stickers.

Sa-tevp wrote:I think you may know what I mean. The grip has a lot of stickers.

Haha, let me know if you are looking for two more OSPs, and a few cases of .22 short

I Hiya,

There are 2 ways to get an OSP to shoot 22LR, one is to buy a “conversion kit” which is simply a GSP receiver, bolt, barrel and mags, in essence the pistol becomes a GSP. The grips will need to be modified as the GSP receiver is not angled as the OSP is at the rear so material will need to be removed. 

The second way is to modify the OSP to chamber and fire LR, this is what Sandy did for his daughter’s pistol. It’s not a cut and dry conversion, there is a lot of trial and error along the way. I talked to Sandy and other people that assisted him with this several years ago before I attempted my own conversion POC. 

One of the hardest aspects they had was the reciprocating mass of the bolt, balancing sufficient bolt speed so that fired cases would be ejected properly while not being too fast and giving enough time for the mag follower to elevate a round into position to feed. He used modified GSP-C bolt weights to accomplish this and IIRC he had inserts that could be added or removed to make corrections quickly if needed.

Based on what I learned from talking to Sandy and others I decided to try a different approach for my POC. I used the OSP bolt with an earlier steel GSP cocking handle to add a little weight but no additional weights from a GSP-C, I rechambered a damaged OSP barrel I scrounged up to LR, changed the ejector to a GSP type so that GSP mags would fit and eject cases. The ammo I based my POC on was CCI “Quiet” which has a velocity that approximates CCI 22 Short target, about 770fps. Since I wasn’t radically altering the velocity and pressures, I felt it would be doable with a minimum amount of mods. The tests were successful, the pistol cycled reliably but the accuracy was just as Sandy had found with his conversion, 25m is acceptable but 50m is not. As he told me, if it doesn’t shoot at 25, somethings wrong. My results were less stunning as the barrel was damaged and I wasn’t using match ammo. (And I doubt I could without increasing reciprocating mass)

In the end, it’s something you can do if your goal is to maintain the Pardini-type grip angle, the short overall length and lighter weight of the OSP but keep in mind that it’s not a “get it and shoot it” type pistol, Sandy said his daughter fired thousands of rounds of R50 through it every year, it took him work to get to that point.

I'm like 99% certain I have an old OSP .22 short barrel (probably "barrels," plural) that are free to a good home if anyone wants to take this on as a project.

I'm not sure the .22 short barrel will be very accurate. The twist rate is different in addition the short barrel used in the OSP had holes drilled on the top into the bore to vent combustion gas and I assume lower recoil. Back when I was making a copy of the Russian IZH-35 I machined a barrel from a rifle barrel I had. I was not worried about accuracy, later I could get a high end barrel, my concern was function. However the bullets would keyhole at 25 yards! No matter what I tried I couldn't stop the keyholing! I called Floyd Aikman, he told me he had the same issue when he used a .22 short barrel to re-barrel a High Standard pistol the owner wanted for non target shooting and didn't like the long 7" barrel. It wasn't accurate and would key hole at 25 yards so he replaced the barrel with one intended for long rifle velocity. Floyd did have a .22 barrel that he was using in a Free Pistol for Dr. Young but it would only group a Nickel size group at 50 meters, Young wanted Dime size. Sent it to me and it cured the problem!
 I'm thinking if an OSP were to be converted to Long Rifle the barrel would have to replaced with one intended for Long Rifle velocity.

At this point since the OSP was part of a deal for a free pistol, I think it will join my collection of old Olympic competition firearms I shoot now and then. If I chance upon a GSP upper and a trigger group I may consider converting.

Thanks for the comments.

john bickar wrote:I'm like 99% certain I have an old OSP .22 short barrel (probably "barrels," plural) that are free to a good home if anyone wants to take this on as a project.

I'll take one if you have a spare. Would like to be able to make some test targets for 22S. If you could spare a few boxes of ammo to go along with, I'll pay for them and the shipping of all.

Be neat to see what could be done "from the old ways."

PM me if amenable, we can set up arrangements.

-Chase