357 rifle

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mtngun
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357 rifle

Postby mtngun » Sun Feb 10, 2008 6:50 pm

This was the maiden voyage for the Marlin 1894 357. I haven't had time to make a proper 180 gr. GC mold for it, so I used a 160 gr. GC mold with 80% meplat that was laying around, based on the assumption that a GC would be needed for rifle velocities (that remains to be seen).

The canted front sight was temporarily fixed by gluing it with one of the experimental Loctite superglues that I bought for strain gages. It seems to be holding up just fine. The Mark One homemade peep sight was installed at the rear.

Compromises were required to mount a strain gage under the barrel where it would not be an eyesore. The gage is only 0.25" from the receiver. If it is too close to the receiver, the receiver will screw up the stress calculations and lead to inaccurate pressures. Also, the gage was mounted right next to the flat that is milled on the bottom of the barrel. Also, I ran unshielded wires the entire length of the forearm. The long, unshielded wires are susceptible to noise. Alternatively, I could have mounted the gage on top of the barrel, and likely gotten a better, more accurate trace, but who wants to break up the clean lines of the Marlin with an ugly strain gage?

Here's the 160 gr. GC with felix lube. 10 shots at 50 yards formed a 5" group. Actually, most of the shots were in a decent cluster. Quickload predicted 1926 fps @ 34.3 ksi. Without a calibration offset, pressures were in the high 20's. I elected to use a +6000 psi calibration offset. Note the mild secondary spike. The noise is probably due to the long, unshielded wires. Shot #7 had normal velocity, so I don't have an explanation for the unusual pressure.
Image

Here's the 160 gr. GC with Rooster HVR lube. Velocity averaged 9 fps higher than felix lube. Standard deviation was 3 fps lower than felix. That doesn't appear to be a significant difference. I was surprised, because Rooster usually gives 100 fps higher velocities in wheelguns. The 10 shot group ws 4.4" at 50 yards, with most shots in a smaller cluster.
Image

Here's the same bullet, with incremental charges of Lil Gun. Last year I tried Lil Gun in my snub nose and couldn't cram enough powder into the case to give normal velocities. Convinced that my jug of Lil Gun must be unusually slow, I started at Hornady's max charge of 18 grains and work up from there. Oooops. :roll: Lil Gun rocks in a long barrel. :D
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Despite the mediocre paper groups, I had no problem making pop cans dance 50 yards away, from the standing position. Only one round failed to feed, and it went in after jiggling the lever -- the chamber entrance may require a little more polishing. Recoil was light except that the lever rapped my fingers pretty badly. That was solved by placing the fingers on the outside of the lever instead of the inside. The gun was difficult to load due to an overly stiff loading gate spring.

The next step is to tear into the action and see if the carrier can be modified to feed longer cartridges. While I'm at it, I'll try to bring the trigger pull down under 4 pounds and take a look at the loading gate spring.

Then I'll cut a 180 gr. mold and see what it'll do with Lil Gun. :P

Harvey57
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Re: 357 rifle

Postby Harvey57 » Thu Oct 22, 2009 3:01 pm

I have loading problems in my Marlin .357. I am using NEI's #160. It is a 198 grain RNFP with three grease grooves. My alloy is WW+range lead+2%tin. This bullet is very accurate by my simple testing standards (MO coffee can at 185 yds). The difficulty is in chambering. These bullets have a wide meplat that catches on closing the breech. I have to trim the riffle brass short enough so that the lever will close the breech reliably. With 13.5 grains of Lil' Gun, velocity was above 1650 fps. The same loads were in the 1200 fps range from the 6" S&W 686 used for testing.

Back to bullet dersign. This bullet's meplat is .30 or .31. Bullets with the same nose legth and smaller meplats, function perfectly.

I, like many of you, am on a quest it seems, for the best smack at the other end. The .357 was the first big revolver that I purchsed. I hope these insights are of use to all.

Yours, HP

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mtngun
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Re: 357 rifle

Postby mtngun » Thu Oct 22, 2009 4:17 pm

A 0.300" meplat would be 83%. That is excessive and totally unnecessary for a rifle, since a modest meplat will rivet to full caliber at rifle velocities.

For what it is worth, the meplat shown on the NEI website doesn't look anywhere near 83%. More like 70%.
Image

My Marlin feeds an 80% meplat with ease, but my Marlin has been tuned. Out of the box, it would not feed ANYTHING.

You don't state the COL of your problem load. :?:

Like you, I have found that smaller meplats will cycle with a slightly longer COL than big meplats.

However, my 80% meplat loads will feed at 1.60" COL (Marlin recommends a 1.59" max COL). If I could go longer, I would, but it doesn't seem to be in the cards.

Read my other 357 threads if you haven't already. This thread was early on in my load development.


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