No luck with the 129gr Interbonds

[TxAggie94]

Hoot - OK I've been kicking it around for a week. I think I'll give it a shot. In the absence of load data for AR-Comp, is it a fair bet to start with RL-15 or Varget data? Obvious caveats of starting on the low end and watching closely...

Hey, I was needing an excuse to slip out of work early and make a Cabelas run anyway.

[TxAggie94]

Well, I picked up a lb of AR-Comp. Capacity is going to be an issue. I tried starting at 25, thinking I could get up to about 27.5. But the 129s are such long bullets, I'm already crunching powder at 26.

[Hoot]

Hoot - OK I've been kicking it around for a week. I think I'll give it a shot. In the absence of load data for AR-Comp, is it a fair bet to start with RL-15 or Varget data? Obvious caveats of starting on the low end and watching closely...

Hey, I was needing an excuse to slip out of work early and make a Cabelas run anyway.

I have yet to massage another powder's parameter and get QL to work based on back engineering what I've chronicled using AR-Comp. Some times it's like N-530 in velocity, but N-540 in pressure. Some loads hit QL's results for 2520 spot on. Since how it behaves WRT QL varies from caliber to caliber, I'm assuming I have not properly succeeded in characterizing it.

It is volumnous for it's weight, which is usually the kiss of death in the Grendel. I too, do not like crunching when I'm seating a bullet. I vibrate my charges to align and integrate the granules and settle out the voids before seating a bullet. I've been meaning to write up a "How-To" article for modifying an adjustable electro pencil for that task. I started off using a labratory variable vibrating table and migrated to the electro pencil as it's easy to have next to the press. I buzz each charge for 5-seconds and can gain amazing amounts of wasted space back. The key is turning the pencil down until you just barely feel it vibrate the case. You can then watch the powder sink down. Bigger granule extruded powders benefit the most. Somewhere, I have a before/after image of a WSSM case filled to the mouth with Varget before and down to the neck/shoulder junction after. Forget the drop tube.

Not having ever worked with the 129 Interlock, I did not consider it's length when recommending AR-Comp. I modified my electro pencil permanently, but if anyone's keen on giving that a try with theirs, you can remove a new pencil eraser and shove the electro pencil tip into it, far enough that it won't fall off and holding the upright, charged case in one hand, press the eraser up against the head from below, with it adjusted down to barely buzz. With a little experimentation, you can optimize the degree of vibration and time of application for a particular powder and caliber.

Sorry for digressing on the vibrator... Suffice it to say, for bullets of 120gr or more, you can not put enough AR-Comp into a Grendel case to cause a problem, so have at it. I have not tried it with bullets lighter than 120gr, though Alliant has recipes out for it for the .223, .223 WSSM, .22-250 and .243. I have not tried it with those calibers (yet).

Hoot