RTI Prophet Performance 1 (1st gen) - Grub screw that holds the barrel in place - M7x1.0??

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jdanvers

jdanvers

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Jul 7, 2019
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South Central Upstate NY, United States
I have (three actually) of the subjected guns - .177, .22, and .25. In a nutshell I managed to strip / round out the allen / hex key on the grub screw that keeps the barrel in place. Fortunately I was able to get it out and just for the heck of it I took it into a nearby Lowes as I know they have "sizers" in the hardware isle to help you figure out just exactly what thread / pitch / etc .... you need when looking for stuff. According to that sizer this grub screw is the above subjected - M7x1.0. It is apparently a VERY odd size - and is proving to be extremely challenging to find a replacement. I can probably get one from the rti shop in Spain but fer cryin' out loud - that'll wind up costing me $40 or something stupid with shipping. NOT. I did check that rti arms shop in Spain and all they have for an exploded parts diagram is for the newer P2. ( from memory . . . part #44 on that diagram - I think ) is the grub screw. According to them though / that drawing / part # - it's an M8. ( which is MUCH MUCH more common and very easy to find via google searches )

Those of you who happen to own a first gen prophet . . . . and maybe your not shooting it a lot? It's just sitting there collecting dust AND there happens to be a Lowes near where you live . . . . ( see where I'm going with this? lol ) Any chance you could take your grub screw with a 3mm allen into said Lowes and run it on their sizer to confirm that it's this, apparently, odd M7 thread??

I know for a fact that RTI has changed the designs of the guns over the years - in sometimes unexpected ways. Wondering if they too had issues with, what I'm thinking, is this odd ball M7 sized thread and they 'standardized' on the seemingly much more common M8.

If you know where I can score an M7x1.0 threaded set screw / grub screw - I'm all ears!
 
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Spinach said:
The Prophet 1 barrel screw is definitely a M7x1.0,
Prophet 2 is M8.

Like yourself I was struggling to find a M7, a email to RTI, few days later I had spares.
RTI arms, not RTIarmshop.

I have a spare, M7, if you don't get sorted, I can try and ship it to you.

Bulgaria to USA.

Good luck.
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@Spinach - yes - actually RTI ( the company - not the store ) replied to my inquiry and like you, they are going to send me a couple of spares ( so long as I cover the shipping - fair enough ).

** Possible winter time project ** -- break down all three of them, give 'em all a good clean, replace o-rings, etc . . . . and maybe (maybe) bore out that M7 hole and re-tap it for the much more common and easy to find M8. Ideally I'd prefer it to be a torx style head too as regular allen heads seem to strip / round off to easy.
 
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jdanvers said:
@Spinach - yes - actually RTI ( the company - not the store ) replied to my inquiry and like you, they are going to send me a couple of spares ( so long as I cover the shipping - fair enough ).

** Possible winter time project ** -- break down all three of them, give 'em all a good clean, replace o-rings, etc . . . . and maybe (maybe) bore out that M7 hole and re-tap it for the much more common and easy to find M8. Ideally I'd prefer it to be a torx style head too as regular allen heads seem to strip / round off to easy.
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Pleased you are getting sorted.👍

A bit of RTI trivia. 🙂
The barrel retainer stud/grub screw is the size of the transfer port. It's just what sizes RTI decided for the transfer port.
It's the way that they machine the breech block.

Early Priest, 6mm, prophet 7mm, P2 8mm.
P3 is also 8mm but the barrel has a extra two fixing points, the first hex stud is actually almost redundant, it was just a way of drilling the transfer port.
The later RPB barrel shows the flat spots for the additional fixings.

Trivia over, 😄.
 
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jdanvers said:
:) I kind of wondered about the machined "flat" section on the RPB barrels . . . I have RPB's in my .22 and .25
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It had me scratching my head, 🙂.
Then I saw a P3.

Rather than rethreading your prophet, get some Wera pro hex keys.
I've never stripped a hex as long as I have used them. Used almost daily.
Highly recommended.

Gary
 
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Spinach said:
It had me scratching my head, 🙂.
Then I saw a P3.

Rather than rethreading your prophet, get some Wera pro hex keys.
I've never stripped a hex as long as I have used them. Used almost daily.
Highly recommended.

Gary
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I have a set of Wera Hex-plus wrenches, they are the best I’ve used. Between the cheap hardware and cheap tools, the hexes are most apt to give fits. I sometimes find a torx bit will have a better bite in a rounded hex head. I’m afraid standards and accuracy are a thing of the past most times.
 
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Scotty1 said:
I have a set of Wera Hex-plus wrenches, they are the best I’ve used. Between the cheap hardware and cheap tools, the hexes are most apt to give fits. I sometimes find a torx bit will have a better bite in a rounded hex head. I’m afraid standards and accuracy are a thing of the past most times.
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@scotty - yeah - thats actually how I was able to back this one out ( torx bit ). Didn't (don't) dare put it back in - fortunately RTI is hooking me up with some spares. Just gotta wait for them to arrive . . . . I'm going to have to look into these Wera-Hex-Plus wrenches you guys keep mentioning.
 
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I use both mcmaster and grainger a lot myself, mostly grainger since they have a store within 25 miles. I just looked, and grainger does not have any m7 fasteners at all. mcmaster does, and they are good ones tougher than grade 8. That's another problem with pcp's, it seems they use cheap fasteners for grub screws and such, they all fail fairly easily. I'd try to find out what grade fastener RTI is sending you, if not grade 8 or better I'd just keep the ones they are sending you as emergency spares and order from grainger. Shortest one they have is 16mm long, if that is too long you would have to cut it, and run a die to clean up the cut. They are expensive, no fear of having to buy a large pack. Each pack is only one screw, they shortest one costs 3.91 each. You get what you pay for. https://www.mcmaster.com/products/screws/thread-size~m7/
 
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karl_h said:
I use both mcmaster and grainger a lot myself, mostly grainger since they have a store within 25 miles. I just looked, and grainger does not have any m7 fasteners at all. mcmaster does, and they are good ones tougher than grade 8. That's another problem with pcp's, it seems they use cheap fasteners for grub screws and such, they all fail fairly easily. I'd try to find out what grade fastener RTI is sending you, if not grade 8 or better I'd just keep the ones they are sending you as emergency spares and order from grainger. Shortest one they have is 16mm long, if that is too long you would have to cut it, and run a die to clean up the cut. They are expensive, no fear of having to buy a large pack. Each pack is only one screw, they shortest one costs 3.91 each. You get what you pay for. https://www.mcmaster.com/products/screws/thread-size~m7/
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Thanks for the link and yeah - those would have to be trimmed down. Agreed on you get what you pay for. ( not always - but most of the time . . . )
 
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Solo1 said:
Well i thought for a moment id save your butt but my kit doesn’t have m7 it has 2-3-4-5-6-&8. Oh well
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lol - thanks! That 7 is a *weird* ass size. Greg says ft is next Sat the 12th - not this coming one on the 5th. ( which is good - I haven't even looked at my ft gun, let alone shot it since the last meet . . . I need to practice! ) I mostly just want to do the XFT stuff though . . . :cool::ROFLMAO:
 
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jdanvers said:
lol - thanks! That 7 is a *weird* ass size. Greg says ft is next Sat the 12th - not this coming one on the 5th. ( which is good - I haven't even looked at my ft gun, let alone shot it since the last meet . . . I need to practice! ) I mostly just want to do the XFT stuff though . . . :cool::ROFLMAO:
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Thats why i implyed this sat to get you moving!😂😂
 
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Update - check it out. Lookie what showed up in the mail today - from Slovenia. How cool are these guys? :cool: ** NICE **

rti_m7_grub_screws-2.jpg
 
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