So I have some Alfa precision barrels inbound for the RTI Prophet (needs a transfer hole 15mm OD) and L2 (not a problem 14mm OD). How would I index to know where the transfer port should be drilled or can the gunsmith do this on a bench?
Tuning Barrel indexing before machining?
- Thread starter Riaandw79
- Start date
I always machine the breech fitment first, that done minus transfer port. Fit barrel to breech and then rotate barrel 360* AND Note "IF" OR "WHERE" barrel at muzzle gets highest at 12 o'clock position. felt pin mark barrel next to receiver on top. Then when placing transfer port do so 180* from the mark.
FYI ....
FYI ....
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Thanks. Sounds logical, this one was doing my brain in. Thought maybe I should mod a leshy 2 receiver to take 15mm barrels. Would make the job easy
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I did not understand that. Can you explain in a little more detail please?!!!
I'm doing a project and will be putting an Alpha Precision barrel blank into a Fх.
How to determine the position of the blank as it is not possible to shoot and see the hits after rotation tests at 12, 3, 6 and 9 o'clock?
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You do not need to shoot it. If you rotate the barrel in the action you will see the bore will basically be wobbling. Find the spot where it is the highest at 12 o clock. That is where you would want the barrel to be. The transfer port would be 180 degrees from that. Its as good as you can get with a barrel that has a transfer port it in. Thats why I like the indexable sleeve/transfer port method
A simple measuring or visual of the barrels run out at muzzle. "IF" run out is present ? Clock it to the 12' o'clock position applying transfer & set screw flat accordingly.
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Thanks for the answer, but I still can't understand what you want to say, probably the translator is not doing his job. Please try with more words. I dare to say that during the time that I have spent with the hobby, I have created many things and I have helped many people in Bulgaria regarding pcp pneumatics and installation of different barrels in such rifles, but ... nevertheless, I do not understand what you told me and I would like you to explain it in detail, it seems important to me !!!
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Thank you. However, I can't understand the first 3 sentences of what you wrote. How does a barrel rotate in motion and which bore is wobbly ??? Do you mean to roll the barrel on a flat surface and look at the front and end where the projectile exits when fired???
If there is video material on YouTube please attach a link with this indexing please ???
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If you machine a good slip fit on the barrel there shouldn’t be any wobble. Put the action in a vise and rotate the barrel. With some kind of pointer near the bore at the muzzle you will notice it will move in a circle. Find the highest point, mark it and machine the transfer port 180 degrees from it.
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”Wobble” is probably throwing the translator for a loop, maybe deflection would translate better?
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Better is to place a close-fitting pin in the barrel and indicate off that. Deltronics sells pin sets that are +/- 0.001" around a nominal diameter in 0.0001" increments. There is little point indicating the outside of the barrel.
GsT
GsT
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Well my PC was down and I'm on a phone or I would have drawn and scan but the team effort comes through! I swear I can program 5 aixs cnc but my phone is a challenge.
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Friends, either I'm not explaining well or you can't understand what I'm asking unfortunately !!! Let me try again, now in more detail. You probably know what the beginning of the Fx barrel is, the bronze detail with the transfer port that is wound on the tube with a thickness of φ13.6 mm. In my case, when I have to roll this part onto the machined rear of the Alpha Precision blank, how do you think I can assemble it to the barrel box (receiver) and be able to rotate the blank to determine the front highest position??? You do realize that the moment the blank thread is cut and the bronze piece is put in, the blank will already have a certain position to the receiver and it can no longer rotate because it has a precise position on the transfer port, how is it supposed to rotate the blank in the receiver and it will be possible to determine the highest point in front? Doesn't the bronze detail entering the receiver have a blocking zone at its beginning which determines the position of the transfer port? I don't see how this indexing can be done, I think it is possible only fh liners, where there is a rotating nut that tightens the liner in its tube!!!
P.S. The drawing my friend is great, but I don't see how this rotation of the blank is going to take place after the input is processed and to the receiver.
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Do not machine the transfer path until you mark where it needs to be from the indexing task shown above.
Dave
ETA:
If you are using a ‘bronze detail’ from another barrel that the transfer path is already machined into….you will need to machine carefully the blank barrel to ‘time’ it. This may take a few attempts to get it correct. This is commonly done in the powder burner world to time barrel to receiver fit.
Brass (bronze) is pretty easy to work with, so making a new one should be easy enough if you already have the equipment to fit the barrel anyway.
Dave
ETA:
If you are using a ‘bronze detail’ from another barrel that the transfer path is already machined into….you will need to machine carefully the blank barrel to ‘time’ it. This may take a few attempts to get it correct. This is commonly done in the powder burner world to time barrel to receiver fit.
Brass (bronze) is pretty easy to work with, so making a new one should be easy enough if you already have the equipment to fit the barrel anyway.
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Interesting, didn't think that measuring indicator run-out on the barrel or bore would properly show the bias. Figured that there were too many variables (depending on where the barrel was supported, how many places and how it was rotated) to be valid.
I always test-shoot to determine the high side.
Cheers!
I always test-shoot to determine the high side.
Cheers!
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There are definitely ways to trick yourself with a badly considered setup. If you want to test your setup, find what you think is the index, mark it discretely, then break the setup and do it again to see if you get the same answer. If you do, you can proceed with relative confidence. If you don't, there's an issue with the setup (like you're flexing the barrel). Sorry for being vague - how you go about it depends a great deal on your lathe.
GsT
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You beat me to it. The likelihood of the Outer diameter of the barrel being concentric with the bore is always suspect. While Inches matter, 0.001 matter more.
Smitty
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Отговора е намерен . Показвам ви го в прикачената снимка. Само с многократно добавяне на алфа пресижън бланката може да се направи индексиране на бланката бързо и ефективно. Всякакви други варианти за напасване и премерване с цел на индексиране за мен са неразбираеми и бих казал почти невъзможни. С червено отбелязвам зоната в която просто трябва да се обработи дължината на стругата и дълбочината на трансфера на мултита, по този начин завит на бланката завинаги,това позволява бланката с трансфера да се върти в ресийвъра и да се позиционира така,както трябва според теста от стрелба .
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