AR Plus and RMR

[DMW1116]

I started loading some test rounds with Shooters World AR Plus and RMRs 69 grain BTHP. I started with some data on the SW website but the data for a 69 SMK is right on the bottle so I’ll go with that for now. I generally use 223 data so I’ll stop a little shy of the 5.56 max on the bottle. I think it’s 25.4 and I plan to stop at 23.6.

I started at 21.2 grains and tested that and 21.5 today. The lower group was better but there are plenty of steps before I reach my imposed maximum load. I’m hoping to find a good load that works in my 20” and 16” barreled rifles. If not then I’ll have to live with two loads.

Regarding the powder, it seems fine and measures easy. It ran my 20” reliably with good ejection and no failures. It’s rough if you spill some as it’s the very definition of spherical powder. It rolls nearly as far as a dropped primer, which I’m convinced have little motors that start during free fall.

The bullets are interesting. I don’t know what anyone else does but it’s going to be hell picking all the little bits of corn cob out of the tips. The overall length of a few was about 0.007” less than others. The base is odd too. There is a define shelf like a small rebated boat tail.

The best group was just over 2” while the next was just under 3”. There is potential with this combination. I can shoot under 1.5 with this rifle and a good load, so it’s very close. For reference I have a 77 grain SMK and a 52 grain Barnes Match Burner load that both shoot under 1.5” and a FMJ load that shoots about 2.5” from this rifle. For the price if I can get this combo under 2” consistently from this rifle I’ll call it a win. For some reason loads for this rifle seem to do well in my 16” rifle but not the other way around so I started here.

 

[Demi-human]

The little bits of cob should not affect anything too much. They will squish in the seating stem if there is not a pass through hole or cavity already. They are too light to affect flight too much either.

I would probably still be picking them out too…

 

[DMW1116]

The question is am I doing more harm than good by picking them out. There is a nonzero chance I’m affecting the bullet with the pin I’m using to get the cob out.

 

[n2omike]

I'd probably leave it alone.
You could test leaving it alone and picking it out. Of course, the differences would likely be so low that you'd have to take the averages of several groups of each to tell the difference... and then you still might not see anything. lol Of course, just a few groups of each would tell you if there was any significant difference between the two. I'd probably do that and go from there.

 

[Demi-human]

The question is am I doing more harm than good by picking them out. There is a nonzero chance I’m affecting the bullet with the pin I’m using to get the cob out.

Damage to the meplat would have more an effect than a piece of cob stuck to it for a fraction of a second before the friction with the air, and combustion gas blow by, in the barrel alone burns it off the tip. Having the interior of the hollow point filled would have no effect on flight at all.

There are better things to do for your ammunition if you’re bored.
Clean them with you fingers quick, then separate them all by weight. Then, tossing out the small lots for fouling rounds, classify each weight lot by the bearing surface length with your comparator.

This will have a greater effect on the ammunition, and you still might not notice it.

 

[Walkalong]

Forget about it and shoot them, my Benchrest gun will pile hollow points with damaged tips into the same hole at 100 yards.

 

[ParallelCode]

Forget about it and shoot them, my Benchrest gun will pile hollow points with damaged tips into the same hole at 100 yards.

What is that chambered in @Walkalong, 6PPC?

 

[Walkalong]

Yes.

With light neck tension, soft seat a quality Benchrest bullet into the lands, fill the case up to the bottom of the neck with N-133, and go shoot bugholes, if the wind doesn't get you. Tweak if you're serious and will be shooting actual registered matches.

 

[Demi-human]

my Benchrest gun will pile hollow points with damaged tips into the same hole at 100 yards.

And looks like a Hemi-Cuda doin’ it!
Nice Hot Rod!

 

[AJC1]

Do yourself a favor and look at bullet flight at above Mach speed.... this assumes you will never go transsonic witch gets very complicated.

 

[ParallelCode]

Yes.

With light neck tension, soft seat a quality Benchrest bullet into the lands, fill the case up to the bottom of the neck with N-133, and go shoot bugholes, if the wind doesn't get you. Tweak if you're serious and will be shooting actual registered matches.

I'm assuming there is the occasional disassembled cartridge in the event one chambers but needs to clear without firing.

 

[kidneyboy]

Forget about it and shoot them, my Benchrest gun will pile hollow points with damaged tips into the same hole at 100 yards.

Is that the rest you use in competitions?

 

[Demi-human]

I'm assuming there is the occasional disassembled cartridge in the event one chambers but needs to clear without firing.

Depends on the tension and situation.
Hard tension shoves the bullet further into the lands where it can get stuck. Or a case full of powder that backs the bullet up and sticks it good and the neck can’t pull it out.
A loose tension means the bullet is snug against the lands and will have the same start pressure every time, while being able to slide into the case instead of jamming.

 

[JEBruns]

I have some of the RMR 69gr .224 "corn cob" bullets also. I've tried a few different loads with them using Varget and CFE223, but nothing I'm at all happy with so far. I need to try to work up a ladder with some H335 I have. The H335 is the only powder I've used with the RMR brand 55gr .224 that gave good results, so I'm hopeful. I thought about trying to pick the media out also, but even with a dental pick, I did more harm than good. So I shoot them as-is.

 

[DMW1116]

That’s basically where I am. I’ll see how the next increments shoot. I have MANY more to try. I have three more loaded and enough cases to load 5 more increments. I don’t want to load too many at a time. If I find one that meets my requirements I’ll stop and try it in my other rifle.

 

[DMW1116]

On the other hand I’m quite pleased so far with the powder as a supplement to H335 and TAC. It seems I’ll find a good load somewhere.

 

[DMW1116]

I tried the next three increments today. I think I’m up to 22.4 grains of powder and just started seeing some primer flattening on the primer face. The corners are still rounded and the they look like some factory ammo primers I grabbed to check for comparison. I think I still have room to keep going up.

The reason to keep going up is I haven't found a load I’m really happy with yet. Granted I’m shooting iron sights on a 20” barrel, but I think/hope I can tighten it up just a bit more. The best groups have been just at 2 MOA. Fortunately the first one was at the lowest charge with good function and lock back on empty. I would like to do a check group with the 77 grain Sierra load to see if it’s me. I’ll load up the next 2 or 3 increments and take some of those next time to check against. Those 77 grain Sierras have consistently shot under 1.5 MOA.

 

[DMW1116]

I’m officially out of room for loading. I started hitting pressure at the next to last load which is 23.6 grains of AR Plus. The last load I’ll have to pull to be sure I don’t shoot them by accident.

The groups were about 2.5-3 inches so I didn’t magically hit a node and find a great load. There are two loads that grouped around 2 MOA. Now I need to decide if I want to try another powder or just go with these. I may try H335 with these and try the AR Plus with the 55 grain soft points.

 

[DMW1116]

I think I'm going to try the AR Plus with some 168 grain Hornady Amax bullets in 308 Winchester. Shooters World has data with that bullet and powder combo.

I'm trying to decide what to try with the RMR bullets next. I have TAC, H335, CFE 223, and IMR 4064. I'm leaning toward TAC and H335. I'd really like to use H335, as TAC runs pretty high pressure relatively speaking and I have a TAC load I need to put into production: 55 grain soft point at minimum charge, but it's a smooth shooting load from my 16" barreled rifle.

I will say this about the AR Plus - its a nice shooting powder. There were no surprises on the way up the charge ladder. Next to top load showed enough signs I don't want to try the top load. The loads below that showed a smooth progression, so one can tell when the top is near. If TAC or H335 don't work out, I'd be ok with loading these at one of the two best AR Plus loads and going with it. 2 MOA from an iron sighted rifle isn't anything to really complain about, and I haven't tried them in my scoped rifle. They could just as easily tighten up as go to pieces in that one. I do still want to shoot a control group with either then Barnes or Sierra load I have for this rifle. Those loads shoot under 1.5 MOA from the same rifle, but that difference could just be me on a bad day.

I think I mentioned it above, but for some reason loads developed in the 20" rifle shoot as good or better in the 16" barreled one, but the reverse is not true. That's why I started with the 20" first. For example, the 75 grain Hornady load shoots 0.5-0.6 MOA from the 16" rifle, but balloons up to 2.5 to 3 MOA in the 20" rifle. The 77 grain Sierra load shoots under 1.5 MOA from the 20", and dropped down to 0.75 in the 16".

 

[Demi-human]

I like TAC.
But, I love CFE223!
I hope it works as well for you.

 

[DMW1116]

I do like it, and it’s been accurate in both 223 and 308, but CFE 223 is easy to become over gassed in my rifles. I could just trade the AR Plus to 308 and CFE 223 back to 223.