Cast Boolits for SIG Rattler 1/5¨ rifling, .300 Blackout

[G_Runner]

Anybody here that has any experience using cast boolits in the SIG Rattler 5,5 inch barrel in 300 BO? The rifling is 1/5 inch which I am guessing will be a bit of a challenge for a cast boolit.

My primary thought is to cast the NOE ”Taco” bullet (225 grain) and use them for subsonics. That means about 1000 fps so I am hoping it might me doable with a cast boolit?

The boolit will be PC and probably around 12-15 BHN. And if there is something wrong with my thinking there I am very open for suggestions :)

Link to the bullet in question. I am planing to use the TL-version (recommendation from the designer) even if I am going to powder coat.

https://noebulletmolds.com/site/shop/308-311/tl310-225-rn-ce3/tl310-225-rn-ce3-5-cavity-pb/

[44Blam]

Should be fine. :)
I'm shooting that TACO boolit in a 16" barrel at 1200 fps with a light spring from springco and it functions 100%. My twist is 1 in 8".

My rifle functions with that spring at 1050, but it will not lock the bolt back. I've got another spring that is slightly lighter - gonna try and see if 1050 will lock the bolt back with it...

EDIT: the powder I am shooting is Alliant 2400.

[G_Runner]

Should be fine. :)
I'm shooting that TACO boolit in a 16" barrel at 1200 fps with a light spring from springco and it functions 100%. My twist is 1 in 8".

My rifle functions with that spring at 1050, but it will not lock the bolt back. I've got another spring that is slightly lighter - gonna try and see if 1050 will lock the bolt back with it...

EDIT: the powder I am shooting is Alliant 2400.

Thanks for the data :D

It's going to be interesting to see if I get bolt lock back or not. It's a MCX so I need to look around to see what different springs I can find. They are not so easy to get as for the regular AR:s :P

Have you tried the hardness of your casts btw? And do you PC or lube?

[gunfan2]

Should be fine. :)
I'm shooting that TACO boolit in a 16" barrel at 1200 fps with a light spring from springco and it functions 100%. My twist is 1 in 8".

My rifle functions with that spring at 1050, but it will not lock the bolt back. I've got another spring that is slightly lighter - gonna try and see if 1050 will lock the bolt back with it...

EDIT: the powder I am shooting is Alliant 2400.

Just read this post wondering about 2400 powder with the same bullet, where should one start weight wise to get the 1200 fps? I have considerable amount of that powder, and less than a pound of 1680.

[JimB..]

Super interested n this.

FWIW, my rattler is much more accurate with supers than subs, but I hadn’t thought about casting for subs.

[G_Runner]

Just read this post wondering about 2400 powder with the same bullet, where should one start weight wise to get the 1200 fps? I have considerable amount of that powder, and less than a pound of 1680.

What barrel lenght do you have? I can do a quick check in Quick Load for you if you tell me your barrel lenght :)

[G_Runner]

Super interested n this.

FWIW, my rattler is much more accurate with supers than subs, but I hadn’t thought about casting for subs.

Cool! What supers gives you the best accuracy? And have you slugged the barrel? I am still waiting for mine but just to be prepared when it arrives I have already orderd several different sizers and expanders. Just hope I managed to get some that will fit my barrel :P

[JimB..]

Cool! What supers gives you the best accuracy? And have you slugged the barrel? I am still waiting for mine but just to be prepared when it arrives I have already orderd several different sizers and expanders. Just hope I managed to get some that will fit my barrel :P

Have only shot maybe 100 rounds, all factory. Best thus far were the Barnes 110 or the Sig 125. Got the fired brass ready to start working up loads when all heck broke loose in the world and I wasn’t really stocked with 30 cal projectile options. Have an MP mold, but haven’t cast any yet. Life is just busy, I really need to retire.

[G_Runner]

Have only shot maybe 100 rounds, all factory. Best thus far were the Barnes 110 or the Sig 125. Got the fired brass ready to start working up loads when all heck broke loose in the world and I wasn’t really stocked with 30 cal projectile options. Have an MP mold, but haven’t cast any yet. Life is just busy, I really need to retire.

Entirely agree with you there, work has a tendency to eat up time better suited for shooting =P What MP mould did you get, and did you have to wait a long time for it? I have been eyeballing them a while but they seems to always be sold out.

[popper]

2400 won't complete burn in the short barrel. ~8 gr cfe pistol should work. ~12 of 1680 too. It will burn dirty.

[JimB..]

Entirely agree with you there, work has a tendency to eat up time better suited for shooting =P What MP mould did you get, and did you have to wait a long time for it? I have been eyeballing them a while but they seems to always be sold out.
I think I have his MP300AAC. It has gotten mixed reviews, I think there are issues getting it to chamber when loaded to standard lengths.
“time” isn’t really applicable to Miha’s group buys, things are done when they are done regardless of how you or I might feel about it.