crosman 357w 6" barrel

crosman 357w 6" barrel

Joined: March 12th, 2010, 4:53 am

June 30th, 2012, 10:29 pm #1

Ok so my first outings with this thing wasn't great. Inconsistant groups and velocity. Gamo wad cutters seemed to do the best and can hold 2.5"@10 paces when I'm doing my part. Velocity is another story out of the box out of 100 rounds only the 1st shot on fresh powerlet would even approach 400fps. And it was all over the place. I decided to modify the mag a bit. Sanded the forward face of the mag flats 220,400,600 paper. This seamed to help as velocity now creeps into 400s more often plus I was getting misfires. I decided to try and chamfer the pellet holes on the rearward face of mag. Bingo this brought velocity way up but the spreads where even higher. This did seem to stop the misfires except very fast trigger pulls.
Now I noticed several of the pellet holes in the mag are tighter than others. For a short fix I coated several pellets in tooth past and passed them through the mag many times.
So test went on like this. Ten shots 10 missip between shots.
one mag was loaded till pellets where flush with rear of mag.
H vel 446fps L vel 396.7 spread 67.3 average 421.7 much better.
2nd mag was loaded pushing pellets through till flush with forward face. H vel 457.2(6th shot) L vel 394 fps spread 63.2 Av vel 412.4

Can anyone tell me if the velocity is. More affected by the snug fitting pellets vs loose in the mag. Seems I got higher velocity with pellets flush close to valve vs loose fitting pushed into mag.

Also I find it funny that there's always one really high vel. Generally its the 1st shot but not always. If I drop the high and low in each ten shot string I really like the numbers. I don't see a huge difference in grouping any more now that the velocity is behaveing better.
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Joined: January 17th, 2010, 12:03 am

July 1st, 2012, 2:28 pm #2

I was banging my head against the wall for the longest time. What I ended up doing was to replace the barrel with a standard 7/16" Crosman barrel off an old 1377 I had. I needed to cut the OD on each end and modify the shroud to fit it. The trick was to make the gap between the barrel and magazine very very close without having it bind. I also increased the tension on the TP port spring so that when it make contact with the mag, there would be a more positive contact of the surfaces. All in all, I got it shooting better, but it is never going to be great. Here is the thread about mine.

Rich

http://www.crosman-air-pistol-owners-fo ... pic=5433.0
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Joined: March 12th, 2010, 4:53 am

July 1st, 2012, 4:15 pm #3

What was really getting to me was the low power and inconsistant vel. I mean I was getting out of the box 100fps+ spreads. I wouldnt have cared much if the vel. it self was in the low to mid 300s if it was just consistant.
I was shocked at how just a few minutes cleaning up the mag helped with consistantcy and vel gains. I got 42 shots before it dropped below 390fps on the last Co2 cartridge. Need to order more co2.
My barrel seems to look really good. rifleing is much better than my friends 357. I pushed a pellet through the barrel and it had some decent resistance and I did get some rifleing on the pellet. I will try to post pics of that at a later date.
I have fun with these cheap plinkers. I enjoy bringing old abuse cheaper units back to life. Plus its practice for when I find the better models.
Im going to order some light pellets and see what happens. I hope the light pellets increase shot count a bit.....im not sure if this helps with the co2 valve ?
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Joined: April 12th, 2002, 5:26 am

July 1st, 2012, 5:19 pm #4

your cylinder tune is just about the methodology I came up with when I was heavily into the 357's a few years back. The chamfer at the rear helps register the chambers, and the flat front face reduces leakage.I also taper ream the chambers, with a stop on the reamer, to "blueprint" the pellet fit. If you also choke the barrel, put a longer taper in the throat, and align the breach with the valve nose/transfer port before gluing it in place, quite good accuracy(single action) is possible.

There are wreaks to the sights and trigger that will help as well.

Note that pellets pushed through the factory issue chambers will not bite the rifling at all...that's one of the major contributors to the out of the box inaccuracy of these guns. The other is the sloppy fit of the barrel in the barrel housing.

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Joined: March 12th, 2010, 4:53 am

July 1st, 2012, 8:30 pm #5

I think I have gone as far as I will with this 357. I need more Mag's, I may play with different reamings on the pellet ports. I wont bother with the trigger until something breaks and the unit is out of warrenty....
Minute of beer can is acceptable for now. Before it was as dependable as the trajectory on my red Ryder....I think a few more pellet choices and some bench rest shooting might do it. For tighter groups..
Really before it was 1shot left one shot right one shot high one shot really low.? At least now its consistantly hitting with in 2" bulls eye SA free hand.

Only other mod I would like is some sort of bulk fill adapted of some sort. Even if it was just a 88 gm tank. I don't know anything about proper fittings for such a task....I have some paintball hose parts but cant seem to figure out what can be done....just think it would be cool to just have a long hose down to a large tank. Like the gun shooting games at the fair.
Last edited by mac1911 on July 1st, 2012, 8:44 pm, edited 1 time in total.
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Joined: April 12th, 2002, 5:26 am

July 2nd, 2012, 5:13 pm #6

basically a 12 gram cartridge machined out of solid aluminum, and ported to take a paintball hose from the left side of the grip.So long as the OD, length and end profiles are correct, the rest doesn't matter, so it's a fairly easy lathe operation to make one. They are also available off the shelf.

Another option, that involves modding the frame, is a 1/8NPT pipe nipple up through the bottom of the grip frame, with the upper end reshaped to seal against the valve body at the cartridge seat, and the lower end extending far enough to take a foster fitting.
Last edited by classicalgas on July 2nd, 2012, 5:13 pm, edited 1 time in total.
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Joined: March 12th, 2010, 4:53 am

July 3rd, 2012, 2:45 pm #7

I dont have a lathe so thats out for a DIY. Im not familure with the different fittings and thread pitches ect ect. Something to dig into.
I could not find any off the shelf 12gm co2 eliminator/bulk fill adapters on line ?
Found plenty to go bulk down to 12gm though.
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Joined: November 21st, 2007, 2:16 am

July 4th, 2012, 2:24 pm #8

basically a 12 gram cartridge machined out of solid aluminum, and ported to take a paintball hose from the left side of the grip.So long as the OD, length and end profiles are correct, the rest doesn't matter, so it's a fairly easy lathe operation to make one. They are also available off the shelf.

Another option, that involves modding the frame, is a 1/8NPT pipe nipple up through the bottom of the grip frame, with the upper end reshaped to seal against the valve body at the cartridge seat, and the lower end extending far enough to take a foster fitting.
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Joined: March 12th, 2010, 4:53 am

July 4th, 2012, 6:46 pm #9

I searched high and low and didn't come up with anything like that!!
Thank you
Locally machine shops are hard to get go do any one off type jobs. Most want a 125 min set up fee plus a minimum parts run. That should work.
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Joined: November 21st, 2007, 2:16 am

July 5th, 2012, 4:13 pm #10

that drozd adapter is $50 & the reviews of it are not too favorable.

I already have a remote line with check valve (from my paintball pistol), all I need is the co2 cartridge adapter. I will experiment with this & post the results.

http://www.ebay.com/itm/ws/eBayISAPI.dl ... 142wt_1052

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why am I trying to bulk fill, pistol already gets about 60-70 shots per 12gr cartridge...?
i guess if this setup is successful, I could use it on the other 12gr pistols I have.
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