New 300blk Core 15 rifle

[Babs0404]

Got out to the range yesterday to try out my new CORE15 rifle in 300blk. My brother-in-law and I prepped brass and loaded our own ammo. I used 17gr H-110 powder with 150gr FMJBT Hornadays, 2.055 OAL.

The issue is the rifle seems to be short stroking, sometimes not picking up the next round. Also, the bolt doesn't lock back on an empty mag sometimes.

My brother-in-law has a DD and it's working fine with the same load.

The problem is we're already above the max load, so I'm not sure where to go from here.

Do I change the buffer or spring?? Any suggestions would be appreciated thanks.

PS>>The funny thing is last fall I shot my .223 AR with some hand load 69gr and it was doing the same thing, when it shoots 55gr fine.

 

[BenL]

How does it perform with commercial ammo?

Re locking issue - have you tried with different brands of mags? Out of spec mags or bolt catch in the magwell is quite possible

Doesn't cost much to try different spring & buffer combos.

 

[Mark-II]

Try a slower burning powder perhaps?

Do both rifles have the same lengtth gas system?

 

[Babs0404]

I can't get any commercial ammo anywhere here so I'm not sure.

I did try all my mags and there was no difference. These ones I have used for a year in my .223.

Both rifles are identical except for the fact ones a 300 and other 223.

I did disassemble and lube up the rifle, but I'm thinking I better take it apart and really clean it in case there is some kind of packing grease on the BCG.

I will also check and make sure the gas ring gaps are staggered.

How can I tell which spring to go to if noone lists spring rates?

Do I remove the buffer tube to get the spring pin out or does it come out from the top?

 

[*MALICE*]

I can't get any commercial ammo anywhere here so I'm not sure.

I did try all my mags and there was no difference. These ones I have used for a year in my .223.

Both rifles are identical except for the fact ones a 300 and other 223.

I did disassemble and lube up the rifle, but I'm thinking I better take it apart and really clean it in case there is some kind of packing grease on the BCG.

I will also check and make sure the gas ring gaps are staggered.

How can I tell which spring to go to if noone lists spring rates?

Do I remove the buffer tube to get the spring pin out or does it come out from the top?

We need to stop with the staggering of gas rings lol. It's a myth.

My guess is unde-rpowered reloads, but if you can remove the gas block, check to see if the gas port is the correct size.

 

[knuckleduster]

what is your barrel length?

 

[Babs0404]

We need to stop with the staggering of gas rings lol. It's a myth.

I'm new to this, and I would agree that these aren't 4" bore piston rings!

Barrel length is 18"

UPDATE: I disassembled and washed in varsol. Checked for any sharp edges, etc. I did remove some parkerizing from the bolt bearing service as it seemed very thick. I lubed with oil and shot it today and it seemed to work a lot better. I shot in a match and put 90rds and had one stoppage when a primer popped. The bolt didn't fail to lock back once. I'm just going to shoot the crap out of it and see.

Now...........where oh where can I buy some powder and bullets...........

Thanks guys.

 

[BenL]

Can't help you on the reloading supplies, but you can get commercial ammo from a number of places, granted you'll have to have it shipped - which I know might not be something you want too, but it's a reality most have to deal with I'm afraid.

 

[Trinimon]

What position are your brass ejecting out at?
Is the gas block on tightly and aligned with the gas port?
What weight buffer is in the rifle?
Is it a full auto BCG or lighter semi-auto BCG?

Since you're shooting 0.8gr hotter than recommended max load, could it be that your rifle is heavily overgassed and the bolt is cycling faster than your magazine spring can pop a new round up or before the follower can arrest the bolt catch? Maybe a heavier buffer or buffer spring is in order?

 

[cr5]

Try using LiL'Gun or A1680 powder for 150 grain bullets. My best load for my NR ACR 300 Blackout conversion is with A1680 and 155 grain A-max bullets.
I have found H110 is best with the lighter bullets (110-130 grain) even though some guys can get their rifle to cycle the heavier loads with it. I still need to do some load development on my new 300BLK build, my other 300BLK rifles (ACR and my 9.75 inch PWS piston upper) behave a little differently than a DI 300BLK.

If you are over max book load then you need to do something different. Your brass will not last long if you are popping primers.

Good luck

 

[Trinimon]

I've had good success using H110 and 150gr FMJ.