.357 Gen 1 Mrod based pistol

[JuryRigger]

-Mindblown- 640-ish total FPE out of a 60 cc tube with a 12" barrel??? That is simply amazing; thank you for putting out all the details on the build so others can learn from your achievements.
Just cooooooooooooooooool, 
Jesse

[mackeral5]

Excellent group for for 50yd, especially on first attempt!  WOW!   

Eight 80fpe shots!   You have me rethinking 357 in a pistol.  Didn't think that was possible.   I think CARM needs a 25/35 mag! 

Thanks John.  It was really a communal effort, whether others knew they were actively participating or not....

Bob gave us the SSG  I think he also partnered in developing the TJ's .357 1:26 that is used for all 3 barrel lengths this gun has. 

Don/NVreloader introduced me to the flat wire spring

Scott/Motorhead pioneered ultralight hammers and openly shared a lot of balanced valve design and tuning data.

Then you have the group of folks that contributed to the Simplified Balanced valve thread. 

The only piece I will take specific credit for is being hard-headed enough to get the Cothran to shoot a bell curve, across a broad pressure range.  Even though I was simply mimicking the efforts of those listed above. 


Next, I believe I will make a .25 caliber change kit using a cut down GM barrel and the .22 bolt/breech you sent me....I think I will make an entire top end so I can use magazines. 

[FuzzyGrub]

Excellent group for for 50yd, especially on first attempt!  WOW!   

Eight 80fpe shots!   You have me rethinking 357 in a pistol.  Didn't think that was possible.   I think CARM needs a 25/35 mag! 

Thanks John.  It was really a communal effort, whether others knew they were actively participating or not....

Bob gave us the SSG  I think he also partnered in developing the TJ's .357 1:26 that is used for all 3 barrel lengths this gun has. 

Don/NVreloader introduced me to the flat wire spring

Scott/Motorhead pioneered ultralight hammers and openly shared a lot of balanced valve design and tuning data.

Then you have the group of folks that contributed to the Simplified Balanced valve thread. 

The only piece I will take specific credit for is being hard-headed enough to get the Cothran to shoot a bell curve, across a broad pressure range.  Even though I was simply mimicking the efforts of those listed above. 


Next, I believe I will make a .25 caliber change kit using a cut down GM barrel and the .22 bolt/breech you sent me....I think I will make an entire top end so I can use magazines.

Agree 100% on all the people that have contributed to the GTA forum.     I wouldn't minimize your work, especially getting a bell curve with PH valve.  You share all your projects, successes and problems you run into.  It is much appreciated.

I don't want to think much on a 357.   Well, I do, but need to focus on getting the 30 cal done. 

PS: I do need to look into those flat wire springs.

[Nvreloader]

For those interested in flat wire springs, here is a selection for you to browse:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2499334.m570.l1313&_nkw=flat+wire+springs&_sacat=73944

FYI,
Full length spring are around 5" total overall length,
Commander springs are around 4" total length,
Officer springs are around 3",
Plus there are lots of spring for Glocks etc,

Ask the seller for length, O/S diameter and I/S hole diameter if you plan to run a spring guide etc.
I know a 5" Full length flat wire spring goes coil bound in 1.030".
If you are using these springs, use full length, then cut to fit etc, they are NOT like round wire springs..........


HTH's,
Don

[YEMX]

I may have to experiment with flat wire springs for both my .357 Brod, and my Bulldog builds!!

[mackeral5]

The spring i previously is almost perfect for Mrod use as well as the type of SSG I use in my QB/Gauntlet builds.

Something I learned along the way is use as many coils as you can, the full spring will fit in a Gen1 Mrod.    I made the mistake early on of cutting the flat wire spring too ahort.....

It is amazing to encounter a constant, steady  resistance when cocking vs cocking effort increasing as you get closer to latching the sear.

[FuzzyGrub]

For those interested in flat wire springs, here is a selection for you to browse:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2499334.m570.l1313&_nkw=flat+wire+springs&_sacat=73944

FYI,
Full length spring are around 5" total overall length,
Commander springs are around 4" total length,
Officer springs are around 3",
Plus there are lots of spring for Glocks etc,

Ask the seller for length, O/S diameter and I/S hole diameter if you plan to run a spring guide etc.
I know a 5" Full length flat wire spring goes coil bound in 1.030".
If you are using these springs, use full length, then cut to fit etc, they are NOT like round wire springs..........


HTH's,
Don

Thx, that helps some.  I did do that search on ebay, amazon and elsewhere, yesterday.   I guess I am spoiled by McC with having all the OD, ID, length, spring rate, max load, and coil bind data available.     I only found the ones made for specific guns and places that will custom make them.  I didn't start requesting the data from the suppliers, yet.


Mike, Do you have a pointer to the one you purchased?  Might save me some trial & error headaches. 

[YEMX]

I just bought one of those flat-wire springs.  They're recoil springs for 1911's.  Part number is: 614G20.  Here's the ebay link:
https://www.ebay.com/itm/Wilson-Combat-1911-Flat-Wire-20LB-Recoil-Spring-5-Full-Size-45-ACP-P/231789667525?hash=item35f7bda4c5:g:C~oAAOSwUdlWdtWZ

[mackeral5]

I just bought one of those flat-wire springs.  They're recoil springs for 1911's.  Part number is: 614G20.  Here's the ebay link:
https://www.ebay.com/itm/Wilson-Combat-1911-Flat-Wire-20LB-Recoil-Spring-5-Full-Size-45-ACP-P/231789667525?hash=item35f7bda4c5:g:C~oAAOSwUdlWdtWZ

That's the one, a 20# spring. 

I will likely pick up another of the 25#er's to try in my Bulldog's SSG.

[Sbak]

Flat wire springs are amazing, my last two builds cut about 30% off max cocking effort for the same hammer energy with nothing other than a change to flat wire.

[FuzzyGrub]

Thx guys for the link and confirmation.  It happened to be one of the few I put on the watch list to get more info on.  Going to order it.    Thx again.

[mackeral5]

I finished prepping the muzzle of the 8.5" barrel this morning.  I am running very low on ammo so I decided to test with some 110gr slugs from Desperado Cowboy Bullets.  I've never had much success with these, so I figured why not use them.  I ran a dozen or so through the .357 NOE sizer.  Then put a few over the chronograph without any SSG adjustments and found them to start around 460fps and peek a little over 500fps.   It is terribly loud with no LDC.  While I do plan to mount a muzzle adapter and a removable muzzle brake, and I may make up a small extension to be able to install an LDC.  The length of this barrel is slightly too short, this is not by design.  it was simply a matter of priorities when dividing a 21" barrel into 2 barrels.  This is all that was left. 



I pulled my target back in to 20 yards and took a sighter, which was high and to the right.  I guessed at a pretty extreme elevation and a slight windage adjustment and fired off a shot.  It was close enough to do a 5 shot group. 



Have I mentioned this thing is LOUD?  The sound is a very sharp CRACK, it sounds almost like shooting a small caliber PB pistol.  If it weren't so loud I would stretch it out to 50 yards.  My ears are still ringing, should have worn hearing protection.....

[FuzzyGrub]

I bet it was LOUD!     My experience with that tube length, a 10" barrel is about right.   How's the jump? 

[mackeral5]

I bet it was LOUD!     My experience with that tube length, a 10" barrel is about right.   How's the jump?

It was surprisingly easy to shoot, compared to what I was expecting. 

I chose the 12.5" length for a future configuration, remember the current tube is going to be replaced.  it isn't always going to be a pistol, either.  Try to picture  this combo: 12.5" barrel w/ Ronin, 7 inch tube, 220cc bottle, AR collapsible stock.

[FuzzyGrub]

Wasn't sure if that was still the plan.     Going to be quite the powerful little carbine.   

[mackeral5]

Wasn't sure if that was still the plan.     Going to be quite the powerful little carbine. 

The short tube is still the long term plan, it just became a little longer term originally thought. 

With the 12.5" barrel and 220cc bottle, should be approximately 25-30 shots of 80fpe, call it 34" long including moderator with stock fully extended, around 30" collapsed.  Then there are the options of a 16" or 8.5" barrel.  The 16" barrel will allow for a 350cc bottle.

[YEMX]

I forgot how short you're going to go!!  I thought my carbine was going to be short w/a 18" barrel!! 

[redlined_b16a]

Epic build!

[FuzzyGrub]

FWIW: I did start a conversation with Darko about a possibility of a Mrod 25/35.  I think the mag would be deep enough for the JSB 82g and those 88g GT slugs, but not much more.  Should be able to hold 5 shots.  Just my eyeballing it.  He is going to look into it. 

I think that having a mag available would solidify what to do with that other short tube, drop block, and .22L bottle.     

[mackeral5]

FWIW: I did start a conversation with Darko about a possibility of a Mrod 25/35.  I think the mag would be deep enough for the JSB 82g and those 88g GT slugs, but not much more.  Should be able to hold 5 shots.  Just my eyeballing it.  He is going to look into it. 

I think that having a mag available would solidify what to do with that other short tube, drop block, and .22L bottle.     

Very cool.  I previously measured a jsb .35 vs the thickness of the wheel in Darko's .30 mag, it will work, lengthwise.  Note those 88gr slugs I like are shorter than JSB pellets.