HTC 310/312-135-RN

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Starting this thread so we can track results, compare notes and bounce some ideas around.

I received my 310 mold and took it for a test drive this evening, will be using it for supersonic 300 blackout plinking loads. Got the youngin’ to sleep a little while ago and loaded just enough to hopefully get some initial chrono numbers tomorrow.

Dont mind the seating stem ring on the dummy round, for initial testing I ran the alloy I already had in the pot. Once I get my initial testing done I will adjust my alloy accordingly if necessary.

The dummy round OAL is 1.885″, which puts the .250″ ogive measurement near the magazine rib. This is a method explained by dryflash3 on the ar15.com 300 blackout master thread for bullets under 180 grains.

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[ericstevensParticipant]

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I found my package in the mailbox last evening, so cleaned it and put it in the oven for heat cycling.  As I type this, the Lyman 20# is heating up for a casting session.

[brettsevertParticipant]

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I found my package in the mailbox last evening, so cleaned it and put it in the oven for heat cycling.  As I type this, the Lyman 20# is heating up for a casting session.

Which size do you have and what will you be loading them in?

I didn’t get a chance to shoot yesterday due to rain, maybe tomorrow after work.

[ericstevensParticipant]

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I ordered and received the .310″ GC version, and they drop right at .311″ in my mix.  IF  .308″ or .309″ had been an option, I would have chosen a smaller diameter for use in a 300BO carbine.  I’m thinking that I will run these through a Ruger Gunsite Scout .308 to see how fast they can be pushed accurately before pushing them hard in the AR.  Oh, I’m using the shake-n-bake powder coat method rather than HTC.

[brettsevertParticipant]

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Got a chance to test these out this evening, temperature was about 40 degrees.

300 blackout
Powder coated sized .310″
1.885″ OAL

16.0 grains Win 296
7.5″ – 1851, second round double fed twice, did not fire it.
16″ – 2075, 2057 fps

16.3 grains Win 296
7.5″ – 1890, 1911 fps 
16″ – 2063, 2098 fps

I think the double feed was gun related. My short barrel has had some issues the last two trips out but the 16″ never skips a beat in the same trip with same ammo.

No pressure signs to be concerned about but I started a bit higher than I intended. I was looking for 1900-2000 out of a 16″ barrel so I will dial them back a bit and test again. 

[Full.Lead.TacoKeymaster]

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I got my molds too, but haven’t cast with them yet.  I was thinking about starting out with about a 15-15.5 gr charge of h110/296 for the PB bullet.  It would be cool to keep this thread updated with everyone’s experiences.  What velocities are you guys hoping to push these little bullets?

[ericstevensParticipant]

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I have no problem with accurate 160gr  at 1900fps+ in my 8″ twist, so was hoping to make this 135gr go a bit faster. 

[ericstevensParticipant]

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My first casting session with this mould was relatively short, but those bullets are PC’d and waiting to be loaded.  It was cold/rainy/foggy here today, so I heated up the pot and cast about 600 more.

I may run these through my 308 before the 300BO, but will be using IMR4227 in the BO.

[brettsevertParticipant]

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The rain hasn’t given me any breaks but I finally shot a few more this afternoon.

70 degrees

300 blackout
Powder coated sized .310″
1.885″ OAL

15.3 grains Win 296
7.5″ – 1784, 1781 fps 
16″ – 2015, 1975 fps

15.6 grains Win 296
7.5″ – 1857, 1870 fps 
16″ – 2034, 2044 fps

Since I have the PB version I am going to back them off a bit more and settle around 1850 fps in my 16″ barrel for plinking ammo.

[ericstevensParticipant]

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I would expect 4227 to yield better results in reduced charges than WW296 or H110.  2400 should be good in pistol length gas, and Blue Dot might be worth trying.

[brettsevertParticipant]

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I would expect 4227 to yield better results in reduced charges than WW296 or H110.  2400 should be good in pistol length gas, and Blue Dot might be worth trying.

You’re right about that, I know 296 becomes finicky when you get near the lower end of things. I may venture out soon but for now I am just running what I have. I usually only get off about 20 rounds before dark when I have the chance to shoot lately, such as tonight.

7.5″ Barrel
Win 296 –
14.5 grains – 1678, 1809 fps
14.8 grains – 1757, 1773

16″ Barrel
Win 296-
14.5 grains – 1863, 1911

At this point light had faded too much, the chrono didn’t pick up any of the 14.8 grain load for 16″.

Excess, you have my curiosity with blue dot. I have some for 10mm but I will most likely stick to Accurate No. 9 for that, never would have thought blue dot would work.

[Full.Lead.TacoKeymaster]

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My guess would be that bluedot would be slightly too fast… But until someone tests it, we won’t know for sure.

[Author]

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