Sinterfire Frangible .308 Load???

[N2rockets]

Hi All,

I have been trying to develop a load for .308 Frangible Sinterfire bullets. I would like to use Reloader 15 powder but I cannot find data on it anywhere. I know I cant use regular load data for a 125gr FMJ because it would be a compressed load since the frangible projectile is longer.

I called SinterFire directly, and I was advised to start around 37gr, but they had never heard of RL15 powder so it was a guess. I tried this and got 5-6 primers backing out of their pockets several thousandths (enough to feel). I dont have a chrono but they seemed to have less recoil than factory frangible I have shot. I am using a M14 variant and it still cycled the action.

Anyone have recommendations or where I can get data on the SF308-125 Projectile with RL-15 Powder?? Thanks in advance!!

Bullet 125gr Sinterfire .308 Frangible
RL15 Powder: ??
Brass: Winchester
Primers: CCI
Rifle: M25 EBR - 1/11 22"

 

[LARMIKE]

Re: Sinterfire Frangible .308 Load???

I used BLC-2 but I dont remember the charge, I'll look it up. Just dont crimp them very much or you will have two holes in the target.

 

[N2rockets]

Re: Sinterfire Frangible .308 Load???

I put a light Lee Factory Crimp in it, no Roll Crimp. Thanks for the help!

 

[Jerkface11]

Re: Sinterfire Frangible .308 Load???

Can't you do compressed loads with the frangible bullets? If not try a faster powder.

 

[N2rockets]

Re: Sinterfire Frangible .308 Load???

Compressed loads with a frangible round just seems scary to me. Something about the sound/feel of crunching RL15 underneath my die is unsettling...

would it be dangerous to run fairly underpowered loads? the primers were backing out, but would that cause unsafe operating pressures? If not I dont really care because I only shoot them at 150 feet, and accuracy was still spot on and cycled my action. I just dont want a KB!

 

[Mike Casselton]

Re: Sinterfire Frangible .308 Load???

Those bullets are long enough to need 168gr load data. The longer the bearing surface, the higher the pressure generated. Do not roll crimp, use a taper crimp. To find out if your crimp is OK there are two things you need to do Crimp it, then using the edge of your bench, try to push the bullet further into your case. Once you get that correct, you need to make sure you don't over crimp and break the bullet internally. Here's how to check for it.

Using a dummy cartridge (no primer, no powder) seat and crimp a bullet. Then holding the cartridge on the primer end, throw the cartridge on to a cement floor hitting on the bullet. If you over crimp, the bullet will shear off at the case mouth. if it's OK then it will chip around the tip. If you can do 5 or 6 without shearing, then your crimp is correct. The reference to having two bullet holes in your target is the reason for doing this seemingly silly check.

There is a very fine balance between under and over crimp with frangible bullets...

 

[Jerkface11]

Re: Sinterfire Frangible .308 Load???

The only danger in an underpowered load is getting a bullet stuck.

 

[noahmercy]

Re: Sinterfire Frangible .308 Load???

Agreed that RL 15 isn't a great choice for a bullet which could come apart if driven too fast after being subjected to compression. Have you considered Trail Boss? Reduced loads are available for it, and being a "fluffy" powder, it still fills the case well so ESs are kept down. SR4759 and IMR 4198 also seem to do well with reduced loads, but often need a filler to keep the powder back on the primer (to avoid big ESs due to the small charge of powder shifting around in the case). I have seen Dacron (polyfill) and even toilet paper used for this purpose, but I prefer Super Grex or PuffLon since they're actually intended to go down the barrel of a firearm.

As for primers backing out; if you drill the flash holes a little bigger, it should take care of this problem with low pressure loads. Big caveat...<span style="font-weight: bold"><span style="font-style: italic">DON'T USE THE DRILLED CASES WITH STANDARD LOADS!</span></span> Keep them segregated and marked clearly so they don't get into a batch of standard pressure handloads.