Tuning The underappreciated Beeman 1357

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Neu

Neu

Member
Oct 27, 2021
350
337
NC, United States
Picked this little bullpup up a few days ago on the cheap. First time putting it across the chronograph it was shooting at 1070 fps with 10.5 grain pellets and had a horrible cliff and only about 30 shots from 3000psi to 1200psi. Spent a few days playing with different hammer springs (size and strength ratings) and did a bstaley o-ring mod on it. So far it's gotten a 1000% better. Settled on the stock spring with 2 coils cut 2 turns in from flush and 2 2.4mm orings 1 behind the hammer stop that the valve pin sits in and 1 in front of it. This string was with crosman 10.5's from 3000 psi to right around 2000. I'll try 2.5 turns in tomorrow.

Beeman 1357 updat.jpg
 
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elwoodblues said:
It doesn't get any better than that 100+shots in the mid 700's I'm getting about the same on my 1357 got a 1358 that gets about 70 shots about 700 fps
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Yeah I am pretty happy for the $180 I paid for it I am super happy with it. 40 yards @ .57 on a 10 shot group. Unfortunately that's about the limit for my yard. It's built like a tank, not a huge fan of the picatinny that's on it wish it was more like the tipan's or similar. Definitely thinking about the getting a .22 or .25.
 
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Neu said:
Picked this little bullpup up a few days ago on the cheap. First time putting it across the chronograph it was shooting at 1070 fps with 10.5 grain pellets and had a horrible cliff and only about 30 shots from 3000psi to 1200psi. Spent a few days playing with different hammer springs (size and strength ratings) and did a bstaley o-ring mod on it. So far it's gotten a 1000% better. Settled on the stock spring with 2 coils cut 2 turns in from flush and 2 2.4mm orings 1 behind the hammer stop that the valve pin sits in and 1 in front of it. This string was with crosman 10.5's from 3000 psi to right around 2000. I'll try 2.5 turns in tomorrow.

View attachment 362566
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That shot string looks great for target shooting up to about 50 yards.

My 1358 is really accurate with CPHP at about 50-60 yards.

And the 1357 and 1358 barrels have 1/2-20 UNF threads, which is important if you want to make them quiet.
 
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1handwill.gc said:
Looks like you’re here in Washington if you don’t mind watch your tune for your 1358
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I put a lighter spring in both the 1357 and 1358 let me see if I can find the size and length

edit ok found it
This is too easy to call it a mod. 1.0 mm wire, OD 10 mm, cut to length 84 mm.

This was from a gta post on a 1358, I did cut mine to 83mm and turned hammer adj in one full turn from all the way out.

I get about 75 -80 shots on a 3100 psi fill in the 850-900 fps range

For the moderator I used a TKO22 .875 1/2-20 very quite
and edit once more

I got mine from aliexpress but in later threads seems mbmastercar has one that is just about the same

https://www.mcmaster.com/compression-springs/compression-springs-7/length~3-1-2/od~3-8/3.5 lengthOD 0.375" ID 0.293" wire 0.041" 2.5" 2.87 2.87 Zinc-Plated Spring-Tempered Steel Closed 6 9657K228 $9.77
 
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