Diana Have a German dated 2007 Diana 48 .177 Springer purchased new with a question:

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1911Tex

1911Tex

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May 5, 2025
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Texas Hill Country
Never been dry fired...I know the rule! Beautiful dark Stock. After shooting today, I lightly clean it from muzzle to butt and from the breech end, run a couple of light patches with cleaner/protector down the bore. Annually I put a couple drops of oil on the spring and bolt...and fire a pellet to release the compression. I take extreme care of this rifle and it looks as if factory new...aim (not a pun) to keep it that way after almost 17 years. I know of no better way to prepare this rifle for storage. Is this S.O.P. with 48 owners? One last question: There are 6 clicks or stops when you cock the side lever (spring)....I have never tried it, but is is o.k. to short stroke the spring for a short distance target? This is one powerful rifle and twice a year, I compete with my grandson with his .22 magnum in accuracy at a 100 yd. range. I always surprise him and he is an accurate shooter!!!!

Here are a few pics:

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1911Tex said:
Never been dry fired...I know the rule! Beautiful dark Stock. After shooting today, I lightly clean it from muzzle to butt and from the breech end, run a couple of light patches with cleaner/protector down the bore. Annually I put a couple drops of oil on the spring and bolt...and fire a pellet to release the compression. I take extreme care of this rifle and it looks as if factory new...aim (not a pun) to keep it that way after almost 17 years. I know of no better way to prepare this rifle for storage. Is this S.O.P. with 48 owners? One last question: There are 6 clicks or stops when you cock the side lever (spring)....I have never tried it, but is is o.k. to short stroke the spring for a short distance target? This is one powerful rifle and twice a year, I compete with my grandson with his .22 magnum in accuracy at a 100 yd. range. I always surprise him and he is an accurate shooter!!!!

Here are a few pics:

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That is a beauty ! i do not think you can short stroke that gun . OR have you already tried that ? i think you need the full stroke to set the trigger and safety if it has a safety .
I only have a D54
 
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no, it is cocked, or it is not no in between
the spring is under tension and held by the bear trap and when cocked it is held by the trigger assemble and at that time you push the bear trap and bring the cylinder forward
will it nee a piston seal at some point sure, age will do that as well as shooting
could it use a new breech seal now after 17 years that could be true as well
but as they say if it is not broke don't fix it
 
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In my experience, old sidelever Dianas pretty invariably need a new breech seal. It can truly make or break the performance, be it velocity or consistency. Many breech seals have been compromised by burning lubes, factory or other.

Adjacent to the breech seal, the cocking lever tension is critical with these guns, and it's not unusal for that to be out of whack.

Once dialed in (or checked to be so already), they are fantastic guns, capable of great deeds.
 
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Toxylon said:
In my experience, old sidelever Dianas pretty invariably need a new breech seal. It can truly make or break the performance, be it velocity or consistency. Many breech seals have been compromised by burning lubes, factory or other.

Adjacent to the breech seal, the cocking lever tension is critical with these guns, and it's not unusal for that to be out of whack.

Once dialed in (or checked to be so already), they are fantastic guns, capable of great deeds.
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Toxylon I need to take the terrific feedback from you and others from this post in a positive manner.....could you advise how I can approach replacing the breech seal, both how-to instruction and source of breech seal once I can determine if my seal is leather or synthetic? Also how to determine cocking lever tension? I am skilled in a lifetime of aircraft mechanical work, so once I have the instructions, I am comfortable in doing the job correctly. Is there a YouTube instructional video? Thank you! Thanks to all of you!!!
 
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The breach seal is synthetic. I have a Diana 48 that was made in 1987. I didn't replace my breach seal until around 7 years ago. I couldn't tell you how to replace it with out tearing the rifle apart like I did when I installed a vortex spring kit in it. The piece that slides back when cocking the rifle is where the breach seal is located. Hopefully Hector will chime in with a method as he's the guru of Diana guns.
 
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DesertSilver said:
The breach seal is synthetic. I have a Diana 48 that was made in 1987. I didn't replace my breach seal until around 7 years ago. I couldn't tell you how to replace it with out tearing the rifle apart like I did when I installed a vortex spring kit in it. The piece that slides back when cocking the rifle is where the breach seal is located. Hopefully Hector will chime in with a method as he's the guru of Diana guns.
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Thank you! At least now I know the breech seal is synthetic!
 
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i had read that the 48-52-54 have 3 breech seal sizes, and they do 2.5-3.0-3.5mm
now from what i read that most or all come with 3.5mm seals so why the other, a question would to adjust the cylinder to the nipple
now some company that make seals offer one, like Vortek
Knibbs has 1
Chambers has 3 listed but only the 2.5-3.5mm
and the more i looked the more i wondered
now there was a post here or somewhere that the owned of one of these rifles was having sealing problems and i forget what he did but at the time there was the mention of the 3 sizes
also Air rifle headquarters has just 1
so just want to add that seeing that i did mention the breech seal
and at this point i am ever confused if a needed to replace one on my rifles
 
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marflow 777 said:
i had read that the 48-52-54 have 3 breech seal sizes, and they do 2.5-3.0-3.5mm
now from what i read that most or all come with 3.5mm seals so why the other, a question would to adjust the cylinder to the nipple
now some company that make seals offer one, like Vortek
Knibbs has 1
Chambers has 3 listed but only the 2.5-3.5mm
and the more i looked the more i wondered
now there was a post here or somewhere that the owned of one of these rifles was having sealing problems and i forget what he did but at the time there was the mention of the 3 sizes
also Air rifle headquarters has just 1
so just want to add that seeing that i did mention the breech seal
and at this point i am ever confused if a needed to replace one on my rifles
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Now isn't this interesting....makes me wonder if .177 .20 .22 or .25 has anything to do with the 3 sizes? I'm trying to find out the cost of the breech seals and if cheap enough to buy all 3, use the one that fits, then stow the others until someone on this forum needs one!
NOTE: The breech seal part number of the 48/52 is DIA303621 and cost is $13.95; manufactured by Diana. No clue as to size or caliber, only model number 48/52. Available at several retailers in the USA.

EDIT: At least that was the pre-tariff price......
 
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OP here...just installed in my 2007 RWS Diana 48, a Vortek PG4 Delrin-Glide Lite Silent Tune Kit with optional new Diana 28mm Moly Piston Seal and Diana 48 Breech Seal....all as a package for $103.50us; as DesertSilver did above in post #7. Wish I had done this long ago...not difficult at all; in fact much easier than I originally thought! The seals fit perfectly.

Have to say that cocking the side lever is so much easier and very, very smooth. Cut down the decibels considerably...very quiet...almost like a Red Ryder BB gun! Highly recommended!!! I used the enclosed Vortek grease as stated in the instructions for the kit and black moly grease on other parts. When I spoke with Vortek, they said not a problem using both types of grease.
 
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