Is this 200gn nrfp seated too deep in a 300blackout case?

[jptechnical]

Please take a look at the image below, it is a round I want to develop, and I am unfamiliar with this case to know if this is compressing the load or not. My intention was between 10 and 11gn of imr4227 (plinking load) depending on chrony and some thorough testing. The overall length is 1.855 (despite what the picture says), it feeds from a magazine just fine.


What do you think? Can I crimp it here, on the crimp groove? I can crimp it at the next lube groove. I tested loading one that was crimped at the in the middle groove (bringing the base just to the shoulder), but it needed some assistance closing the bolt.


Please tell me what you think.


Thanks,
JP

[runfiverun]

Maybe but I doubt it
i use a plain base boolit seated pretty deeply that shoots we'll at lower velocitys
the lower pressure and velocity seem to let me get away with it just fine.

[Jailer]

Personally I don't like exposing filled lube grooves to the powder so I try to keep them in the neck. Not an easy task with this cartridge and it's short neck.

Save yourself some money and skip the gas check. You'll run into pressure issues with a 200gr bullet before you are running fast enough to need a gas check.

[StratsMan]

Personally, I prefer to load as long as possible with normal function for 300 BO... I don't like the long jump to the first driving band... Just because there's a crimp groove, doesn't mean you have to use it... I'd crimp farther back...

[Scharfschuetze]

I'm with Stratman on that. I'd load it as long as possible so that it will both function through the magazine as well as chamber. Of course there will probably be some compromise between those two requirements. That approach may also get your lube and gas check out of the powder chamber too.

By seating it further out, you may also note some reduction in chamber pressure for any given load.

[jptechnical]

Good points on the exposed lube, and jumping the gap. I think my unrational brain was telling me that the further into the case I set it the better it gripped. Most of my loading comes from heavy 45colt, 454 and 45-70, where you need a really good crimp. My initial instinct was to crimp as far as would feed or fit in the magazine, but I evidently second guessed myself.

Seeing as my chief concern was compressing a load, and that likely won't be an issue anyway, I will make a few and test a few different depths. Looks like I am taking my press to the range

Thanks for the replies.

JP

[ipijohn]

I'm with Stratman on that. I'd load it as long as possible so that it will both function through the magazine as well as chamber. Of course there will probably be some compromise between those two requirements. That approach may also get your lube and gas check out of the powder chamber too.

By seating it further out, you may also note some reduction in chamber pressure for any given load.

You can also keep the lube out of the powder chamber by powder coating.

[jptechnical]

I still haven't jumped on that particular bandwagon... I am pretty lazy, and it looks like a lot of work for diminished returns (personally speaking, from the aspect of the way I shoot and for my purposes. I am too lazy to pan lube). But, I suppose eventually I will succumb to the pressure But you make a good point.

[jptechnical]

Save yourself some money and skip the gas check. You'll run into pressure issues with a 200gr bullet before you are running fast enough to need a gas check.

So far in my check loads I was able to avoid flaring out the case mouth when using the GC, at least it hasn't shaved any lead on the dozen or so I loaded up to check feeding. I might keep the check if nothing more than to avoid the extra step of flaring the case mouth. On the other hand, I am extremely cheap... so I suppose when I run out of GCs I will probably do as you suggets

[Moonie]

That is a good looking boolit but in my experience with the 300BO this would not be a good boolit for this cartridge. 1. crimp groove and full diameter band too far forward. 2. too much boolit inside the case. And 3. too short COL, this can cause feeding issues out of the magazine. If this is intended in a bolt or single shot some of this can be mitigated but in an AR platform I'd look for something else. I've tried about half a dozen cast boolits in this cartridge and the ones that have worked best are loaded to close to the max COL for the magazines and do not have the gas check/lube grooves in the powder space. The COL on this one reminds me of the Lee 170fp, looks great but is so short it nose dives in the magazine at every shot, loading them longer and they don't chamber because of the groove diameter bands being too far out and jamming into the rifling.

[jptechnical]

I am finding that to be the case. I don't have my sheridan gauge yet, so I was loading by feel and I hit the lands on a couple ams had to seat deeper. The ogive is too blunt. I all looking at other moulds now. Lee makes one specifically targeting 300 blackout it seems. I might try one of those. I just eat up aluminum moulds to fast, but at $25 a pop it isn't too bad.

[Moonie]

That Lee 230gr mold is not known to be a good one. It has some design aspects that while are great for jacketed bullets they cause issues for cast boolits. A long unsupported nose and a boat tail, both of which are known to be problematic in cast. I have that mold but dropped it because I couldn't get it to shoot well in 2 uppers. The boolits I use that work very well are the Lee 312-155, Accurate Molds 245gr and I've loaded up some ACE 235gr for testing.

[beltfed]

I am having some good luck with the Lyman 311299-short body, long bore ride nose. Cycling good,
GC and all lube grooves in neck of the 300 BO case.

[jptechnical]

Thanks, that looks like a good mould!

I am having some good luck with the Lyman 311299-short body, long bore ride nose. Cycling good,
GC and all lube grooves in neck of the 300 BO case.

[Elkins45]

Maybe but I doubt it
i use a plain base boolit seated pretty deeply that shoots we'll at lower velocitys
the lower pressure and velocity seem to let me get away with it just fine.

Do you mind sharing what plain based design you are using in the blackout?