200gr 357 Sig Subsonic

[McFred]

Off-season boredom and cabin fever has me tinkering in the shop.

I cast some MP 35-200 HP (conical HP, gas check heel, w/o check). I used reclaimed range scrap and had issues with the mould filling out. I ran the pot hotter, but ended up just tinning the corners of the brass cavities with lead. I scraped that out, dusted everything with graphite and haven't tried again yet. Air cooled range scrap runs about 15bhn according to an LBT tester. I sorted the good ones on appearance, then base-to-ogive, lubed them up with 45/45/10 and sized them down to .358".

The load is for a 20" Contender Carbine barrel chambered in .357 Sig (.357" groove diameter). The throat allows for a particularly long cartridge length of 1.450" which looks kind of funny.



There's very little data on projectiles heavier than 147gr in the Sig so I used 200gr .40 S&W data and compared it in Quickload for good measure. Given that the range alloy is relatively soft I tried to keep it around ~25,000psi. I tried CCI 400 primers with:

4.1gr Unique
7.0gr WC820(f) (correlates to AA#7 pretty closely)
7.6gr AA#9

Unfortunately, I had no choronograph and the range only had pistol bays available that weekend, so the target was only at 35 yards and a little R->L wind. There was some leading of the bore but it didn't seem bad, and didn't get any worse. Each group is 10 rounds. Once developed further I'll use the load in my local monthy cast pistol caliber silhouette matches. It should push over steel easily, but I might try to run the pressure up with wheel weight alloy and put them over a chrony to test velocity ES.

Left is Unique, top is AA#9, right is WC820f and the bottom is an old stand-by 158rnfpbb with WC820f with a cold/clean bore (that one shot off to the right):

[725]

Neat. What a fun plinker. Will be interested in the chrony results.

[RU shooter]

Now that's different ! Like a 35 cal version of the mini and micro whisper SSK made up have you ever tried a thing heavier ? A nose nosed bore riding design would probably work if you wanted to try.

[McFred]

I started looking into a plinker type round due to extended rimfire/component shortages. $100 a brick is motivation to research a substitute. I've gotten inspiration from others doing something similar and I have a "why not?" sort of attitude. For a number of years I could handload a plinker .357 Sig for less than .22LR at market prices. Today, I can get some brands of .22LR delivered for less than 3¢ each.

Currently, the MP 35-200 mould is the heaviest I have. I'd be happy to try different designs. At some point the pressure required to get heavies up to speed might complicate matters since there's not much case capacity.

In the past I've gotten Hornady .356" 121gr HAP projectiles up to 2000fps (sub MOA at 100yds) and played with the now-discontinued Hornady 180gr SSP (1600fps completely full of WW296). With the single-shot platform I can seat projectiles out long and use more powder. The Contender's strong enough I can safely run pressures most definitely unsafe in auto-pistols.

[dangitgriff]

I like your idea. Was thinking I could one day get a T/C with a .357 max barrel and do pretty much the same. It’s on the long list of wanna-do’s.

[McFred]

So it took a while, but I had a chance to put some of the 4.1gr Unique loads over a chrony. The Contender hammer spur broke off and I had to send it back to S&W for repair, and while it was out for repair I got interested in other things.



Here are the details, again:
MP-200-35 (gascheck omitted) cast from reclaimed range lead.
Unsized (~.360" diameter)
Lubed with 45/45/10
4.1gr Unique
CCI 500 primer
20" .357" groove barrel
Loaded long and jammed into the lands when the action closes.

10 rounds
965fps average
SD 9
ES 27
415 ftlb muzzle energy
some light leading in the throat.

All ten rounds hit inside a 8.5"x11" sheet of paper in breezy conditions at 200 yards shot from prone with a 6x scope. Drop agrees with a .250 G1 ballistic coefficient: 19 MOA holdover from a 100 yard zero. Terminal energy at 200yds is 342 ftlbs (375 ftlbs at 100yds). Not bad for a .22LR substitute.

[Nick Adams]

Interesting ...

Wonder what the same boolit would do when launched from the 9x25 Dillon?

A true 10mm case necked down to .355/9mm.

[McFred]

Case capacity is heavily dependent on the throat dimensions. If you want a 35-200 bullet to be subsonic, then the 9x25 Dillon would be the same as the SIG, just longer, potentially.

If you want to max out the performance, then the 10mm Auto could probably get a 200gr projectile up to about 1700-1800fps, again, depending on throat dimensions, barrel length and pressure you decide to run. I've run the discontinued Hornady 180gr SSP in this SIG carbine and managed 1600fps with 100% case fill and achieved sub-MOA accuracy.

Of course you could lengthen it using the 6.8SPC or .30 Remington brass and easily match .35 Remington performance.

[McFred]

I played with this some more. I loaded up as-cast, unsorted, MP-36-200 (~Ø.360") lubed in 45/45/10 over WC297 surplus powder. 9.5 grains of WC297 is subsonic, 10gr is supersonic at 50˚F ambient from my 20" barrel (~1100fps). Both loads are about 2 MOA at 100 yards with a wavering breeze and yield no leading in the bore. At 100yds the 12"x12"x3/8" steel target moves noticeably when hit (~470ftlb energy).

Using this diameter is super convenient as I don't even have to re-size the cases. Just deprime/reprime, add powder and seat another bullet. There is not a lot of neck tension, but being a single shot, there are no concerns over bullet set-back.

I tried to catch some bullets in water-filled milk jugs at 25 yards, but the hollow points blow up the first jug, shed the nose and a remaining ~140gr wadcutter goes through another 3' of water. The remains of two samples I managed to collect I had to dig out of the berm. I am tempted to try it out on one of the deer that frequent my back yard.

[Earl54]

I shoot deer at 25 to 50 yards with 38 special wadcutter's(3.5gr bullseye - scoped 17in NEF). Rib - lungs - rib full penetration, dead deer. Hunt like you are bow or pistol hunting, your load will work.

[McFred]

Alliant's Bullseye data says 3.5gr is 814fps from a 158WC in 4" .38 Special. If that'll do the job at 50 yards, then 200gr at ~1100 won't do any worse. Thanks for confirming my suspicions. I'll just have draw a tag next year... here's hoping.

[exile]

This is a very interesting thread. Please keep up with your testing and post the results. Thanks.

exile

[McFred]

Thanks, I think next chance I get I'll see about improving accuracy. I'll

• sort projectiles base-to-ogive
• try some CoW/cornmeal/bran filler (powder's peening the bullet bases) and
• put it over a chrony to check velocity consistency

Out of curiosity, Quickload says I can probably get these 200s up to 1425fps with AA#7 or AA#9, though I might have to go to a harder alloy or see about fitting a gas check.