Reloader 15.5

[Burt Gummer]

Burt, this is the 5" tube I'm using: https://www.brunoshooters.com/mm5/mercha...Code=15507

It doesn't give any details but was made for a benchtop powder dispenser they no longer offer. I stuck the top end in a universal RCBS funnel and taped it; the bottom has a slanted interior like a universal funnel, although not up to 50 cal. I bought it locally and have no idea what shipping would be.

I couldn’t see the picture when I clicked on the link. Is the idea to have a tube of sorts that actually slides into the case and then fill or does anything with 5,10,15 inch tall drop give the effect even if resting on top of the case? I almost bought some pvc pipe with a brass fitting that would fit snug on my case to try but stopped.

[StoneHendge]

The idea is simply to function like a funnel but have a long tube. The one I made is basically a universal funnel with a longer tube. Think of any funnel you have and then imagine a 5" between the funnel part and bottom instead of 1/2" or so.

For whatever reason, when stick powder has to go through a longer tube, it stacks tighter in the case. I don't know the physics behind it, but it definately works.

[Burt Gummer]

I ended up going to the range today against better judgement. Let’s just say I had a late night and a few too many beverages last night. The end results were somewhat mixed. The late night could be part of it or the other mistake I made by seating the bullets deeper than before. I made up some rounds with W748 to play with and normally seat them very deep at 2.236 inches base to tip or 1.6 inches base to ogive. When loading for the RL15.5 I continued doing this. In the prior load I was loading the ammo to mag length which was around 2.289 inches base to bullet tip. I’ll just stick with the best few loads of each different brass and primer combination. Same as prior testing including 112 Matchburners. For W748 I used Hornady brass with BR4 primers over 27.1 gr and 112 Matchburners. Haven’t made a move yet on a drop tube system so loaded with a standard frankford arsenal aluminum powder funnel:


Starline Brass 4 shots:
28.6 gr = 2590 fps Avg, ES = 18, SD = 6.82, .9 MOA
28.8 gr = 2609 fps        ES  = 24, SD = 8.85, .85 MOA

Hornady Brass 5 shots for 28.4 and 28.6. 4 shots for 28.8:
28.4 gr = 2575 fps Avg, ES = 56, SD = 9  , 1.29 MOA
28.6 gr = 2575 fps Avg, ES = 14, SD = 1.9, 1.09 MOA
28.8 gr = 2590 fps Avg, ES = 16, SD = 4.8, .90  MOA

For fun I also grouped five shots of the few remaining factory Hornady 108 ELD-M’s I have left:
            = 2623 fps Avg, ES = 43, SD = 16, .92 MOA
            
And 4 shots of W748:
27.1 gr = 2482 fps Avg, ES = 57, SD = 8.1, 1.35 MOA

I didn’t think the 28.4 gr of RL 15.5 was that impressive but I wanted to provide it just to show how much the average velocity has stabilized at this point. The lack of movement in velocity between them has me wanting to really drill down on the 28.6 gr and see just how accurate I can make this load. The ES/SD’s at this point are just too good. It’s worrisome that the accuracy wasn’t there but once again I might not have been at my best today and the seating depth can certainly be experimented with to see how much tighter I can get it. This will be the next test. I’ll inevitability throw in some other powder charges when implementing but a temperature stable powder at 2575 fps out of an 18” barrel is really getting my attention at this point. 

The loads shown above are most likely over pressure. Ejector swipes are appearing on the brass slightly heavier than what I noticed on the factory Hornady rounds. Willing to push the guns limits for this powder and don’t guess I’m too much over pressure if so. I achieved a .56 MOA at 27.6 with Avg 2480 fps and an ES of 26. If further testing won’t get me around .5 MOA I might try to play around in this area but the numbers seem to be screaming at me to try out the 28.6 weight.

[Burt Gummer]

  Group size without cold bore.pdf (Size: 112.89 KB / Downloads: 13)
  Before and After Drop Tube Use.pdf (Size: 241.27 KB / Downloads: 10)
  2.2985 and 2.26 inch Seating Depth.pdf (Size: 1.77 MB / Downloads: 9)
  2.1795 and 2.11 inch Seating Depth.pdf (Size: 203.7 KB / Downloads: 5) Hello again. I made a trip to the range last week to further test out the Reloader 15.5 and try to dial it in some more for my rig. As I stated in the previous posts the load at 28.6 grains was showing very good sign as far as the velocity I wanted to obtain as well as having very good ES and SD's. The only thing lacking was the accuracy. I was short on time so this was the only powder charge I focused on. My goal for the trip was to see if I could tighten up the groups by playing with seating depth. 

Since I'm shooting a gas gun with steel magazines my seating wasn't based off of jam rather I loaded the bullets to maximum magazine length and used the Berger method of seating progressively deeper. The four seating depths were mag length which is 2.298", 2.26", 2.1795, and finally a very shallow 2.11". The 2.11" was odd looking as it seemed the ogive was below the case mouth.

I should give thanks to StoneHendge and Old Bob. The recommendation of a drop tube offered amazing results! I fashioned one out of a cheap BIC pen by pulling the guts out and forming one end with heat to the size of the case mouth. The other end used the tapered part of the pen to fit inside the funnel. There was more machining that went into it in order for the powder to flow smoothly through it but that basically sums it up. Length of drop is approximately 5-5.5 inches. There was a large noticeable difference in how much powder the case was able to accept. I have attached a photo of the result. The two cases closest to my Intellidropper were loaded using the drop tube and the two cases below them were loaded without the drop tube. It's hard to see in the picture but the ones loaded with the tube were just a hair below the shoulder of the case where as the other ones were at least halfway up the neck. I'd say that's a huge gain in capacity especially when you figure how little real estate ARC case has. It also appeared to help alleviate some of the pressure signs that I reported before.

The attached picture of the targets speak for themselves. The mag length load was my best one and came in at a .75 MOA and that's a seven shot group! It also happened to be the first group I shot so it even takes into account the cold bore shot, which by the way it was only 37 degrees that day! I think if I would have shot this group second it would have shrank down to around .6 MOA. The other groups shown were all six shot groups. I labeled the seating depth on the top of the targets in blue ink. 

Velocity for all four groups was boringly stable so I only based my ES and SD's off of my seven round group. 

AVG Velocity = 2577
ES               = 30
SD               = 4.7

Temperature stable powder, check. Low ES and SD's, check. Good accuracy, check. Yep this is the powder I'm settling on and it's time to stack it deep. I may try to tweak it a little more to see if I can get it around .5 MOA before cranking out some surplus rounds but if anyone was wondering about using this in the little ARC I would recommend it. LOAD SAFELY HOWEVER BECAUSE THERE IS NO PUBLISHED LOAD DATA FOR THIS IN 6mm ARC! THIS LOAD COULD BE OVER PRESSURE! Thank you all for your help and for reading!