Marlin 357

454cl
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Re: Marlin 357

Post by 454cl » Sun Feb 17, 2008 5:11 pm

I have a 180 pb secant and a 185 ogfgc molds that you made last year and have used them quite a bit in my marlin 357CB.They both have 70% metplats and 80 thou driving bands. I size them .3595 and use Lar's BAC lube.The gc mold has a .325 crimp to nose and feeds very well with the lifter mod being done to allow the .335 nose of the secant bullet which feeds even better.Both have shot very many half inch 3 shot groups at 50 yards using H-110 and cci 550 primers.13.4 grains for the secant and 14.0 for the gc mold using air cooled WW.I went to 16.0 with water-quenched bullets oven heated at 450 degrees and same accuracy but the 14.0 air cooled WW is very consistant and no leading at all.I have settled on that load since it is very accurate and easy on the gun. I will drill them with my Forster hollow-pointer if more expantion is needed for hunting.These bullets shoot very well in my S&W also.I neck size my brass to help with the big throat and I use a redding profile crimper.I really enjoy seeing those 3 shot clover leaf's.I really like my Marlin 357.I've shot rabbits with the gc bullet and it puts a big hole in them.I want a 35 Rem to go with my 357 for more range next hunting season.Fun guns for sure.

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mtngun
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Re: Marlin 357

Post by mtngun » Sun Feb 17, 2008 5:15 pm

454cl,
Thanks for the data in your Marlin. They are indeed a pleasure to shoot.

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Re: Marlin 357

Post by mtngun » Sun Feb 17, 2008 5:21 pm

from the old forum, seems to be missing a picture:

I ran out of Federal #200 primers but the local stores only carry CCI brand. Hunting season starts next week so it seemed like a good time to try CCI magnum primers in the Marlin.

The usual load, except I weighed every powder charge so that any velocity variation could not be blamed on the powder charge.

190 gr. cast GC, 0.359", 32 BHN, Rooster HVR
15.3 gr. Lil Gun
CCI 550 magnum pistol primer
1704 fps average
0.94% standard deviation
3.27" average 5 shot group at 100 yards

Hey, pretty darned good for a ghost ring sight. :D

The velocity was 15 - 30 fps lower than usual, but that could be due to a tiny difference in the powder charge, seating depth, or crimp.

Here's a pic of the best group. The cartridge in the picture has an 80% meplat but I think the group was shot with a 75% meplat.

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mtngun
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Re: Marlin 357

Post by mtngun » Sun Feb 17, 2008 5:34 pm

update on Marlin 357 hardware issues

The screw holding the band on the barrel shattered in two somewhere along the way. The other half of the screw fell out and was lost. I'm guessing the screw had been heat treated but not tempered correctly, so that it was as brittle as glass. I'll try to remember to get some spare screws for the Marlin the next time I place an order with Brownells, but for now it is held together with electrical tape.

Image

The Williams FP sight has two pairs of screw holes for the windage adjustment. Originally, it was set up to use the outer pair, but I moved the screws to the inner pair because it looked more secure and was easier to adjust. However, now the screws protrude enough to hit the receiver, interfering with the elevation adjustment. I'll grind the screws shorter so they don't protrude. Otherwise, I really like the FP sight. The windage is a pain to adjust but you only have to do it once. The sight is low profile and very rugged.

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mtngun
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Re: Marlin 357

Post by mtngun » Wed Feb 20, 2008 9:08 pm

OK, two new strain gages mounted on the Marlin.

One is centered 0.400" from the receiver, about even with the base of the bullet. We'll call it the "base gage" for lack of a better name.

The other is centered 0.800" from the receiver, about even with the throat. We'll call it the "throat gage."

Both were installed with Devcon "flex" superglue. The throat gage worked fine from the get-go. The base gage gave suspiciously high pressures that got higher as more shots were fired. Back at home, while I was giving the base gage a look-see, one of the solder connections broke loose. Maybe that connection had been weak all along????? After resoldering, the base gage started giving reasonable pressures.

Note to self: the next time a gage acts funny, check the wiring and/or replace the connector before blaming the gage or the adhesive.

Alliant publishes some PSI data for 2400 and unique, so I duplicated a couple of the Alliant loads as closely as I could.
  load    fps    Alliant    QL-vel    QL-pow    base    throat  
  180 FMJ / 12.5 2400    1407    32,700    26,847    38,632    25,817    22,101  
  160 GC / 6.8 unique    1305    33,900    21,033    24,250    23,125    18,318  
  160 PB / 18.2 WW296    1926    --     36,301    36,301    30,084    27,599  
  190 GC / 15.3 Lil Gun    1739    --    35,473 (for WW296)    --    31,225    29,598  
"QL-vel" means the pressure Quickload predicted to reach the actual velocity with that powder, and never mind the powder charge.

"QL-pow" means the pressure Quickload predicted for the actual powder charge.

The base gage averaged 3159 psi or 13.2% higher than the throat gage. The bad news is that the two gages do not agree exactly. The good news is that they are in the same ballpark. I could live with 3000 psi uncertainty.

But when you compare the Alliant data, the Quickload data, and the gage data, the discrepancy is a lot more than 3000 psi. What's a reloader supposed to go by, if different sources of data aren't even in the same ballpark? :?

I don't know the answer. I'd like to see more 357 strain gage data from more guns and more loads. Maybe if we had tons of data, we'd start to see some trends and be able to draw some conclusions, but right now I am puzzled and I don't have a lot of confidence in the 357 pressure data from any of the sources.

I also fired a few firelapping loads with a 0.5cc scoop of Unique (approximately 4 gr. but I didn't bother to weigh it) pushing a 160 gr. PB. They clocked about 800 fps and the base gage averaged 7752 psi. Quickload predicted 5053 psi for the actual velocity or 8303 psi for 4 gr. of Unique. The itty bitty pressure curve looks cute.
Image

Here's a typical trace from the throat gage.
Image

A typical trace from the base gage.
Image

454cl
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Joined: Sun Feb 17, 2008 4:36 pm

Re: Marlin 357

Post by 454cl » Mon Mar 17, 2008 12:13 pm

Got to shoot the 185 grain GC OGF bullets again yesterday and I got a quarter inch group at 50 yards.The 180 secant PB bullets won't do better than half inch.Guess that isn't too bad for a plain base.I think the OGF bullets are closer to the lands and fill the throat better and I'm sure the Gas Check helps.I didn't think a levergun could shoot so well.I wish I would have went with the OGF and a 90 thou front band on the plain base and up to 190 grains also.I was wondering if the nose on my secant mold could be recut to OGF and if you would do it.I think that would make a tighter fit in the throat and be as accurate as the 185GC that is shooting so well in my Marlin.I shot some 280 grain OGF bullets from a mold you made in my S&W 44 mag today and they were shooting ragged hole groups.Same with the 255 OGF mold in 41 mag you made also.I'm very impressed with Your OGF molds and ordered another in a 45 cal PB a few days ago.I'm sure am glad you are making molds again,I'm getting great accuracy from them.

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