300BLackout Journey Page 4

December 7, 2014

The 300 Blackout Bug is relentless and it still has a firm grasp on me. I continue to look for new reloading supplies to develop loads for. On this search I came across blackoutbrass.com. I decided to give them a try and placed my order. Immediately I received and email confirmation that my order had been received and is processing, with 48 hours I got a shipment notice with a tracking number to be delivered by USPS 2 day flat rate shipping. The product arrived nicely packed within 3 days, I do not blame the company for this, any product I order that comes through USPS 2 day shipping never arrives in 2 days no matter who I may be doing business with which has been a little frustrating.

The product was packed nice and tight, it was a little heavy and you could clearly see the postman was a little frustrated, he asked if I was ordering rocks. Right there I opened the package on the front porch. The bullets seemed to have a nice thick red coating and most of the brass was marked WCC12 with a few marked WCC14.

DSCN0371

I gathered up the goods and right away headed for the reloading room. I retrieved my weight set and both scales to calibrate them and zeroed my caliper.

After calibrating the scales I would check 50 pieces of brass with my Sheridan Case Guage and they all were perfect. I then weighed 20 bullets 17 of them weighed in at 203.5, 2 of them weighed in at 203.3 and 1 weighed in at 203.7.

If you have been following my 300Blackout Journey you already know that I use Redding Competition Dies for all of my 300 Blackout loads. When loading lead bullets you must bell the case mouth the same as you would pistol cases to prevent shaving the lead or coating off. For this job I use a RCBS .311 case expander and use my Redding Taper Crimp Die to get the case mouth back in alignment to chamber in my Sheridan Guage approximately .0331. The load I started out with 10.2gr of A1680 was pulled from the Hornady #9 reloading manual and was originally developed for the 208gr Hornady AMAX bullet. Each one of the charges was thrown by a RCBS unilfow (20 years old) the first 10 charges weighed and was spot on at 10.2gr. This I expected as A1680 powder is very fine and should measure consistent through any brand of powder measure.

In my seating stage I encountered a little strangeness.  The recommended COAL of this loaded round is 2.008 I found this length would not chamber in my Sheridan Case Guage so I disassembled my AR and neither would the round fall into complete battery without a slight push, when extracted the round I noticed rifling marks on the nose of the bullet. With Hornady recommending a start load of 10gr of A1680 for a 208gr bullet I felt comfortable seating this bullet a little deeper again with my load being 10.2gr of A1680 this should not be a problem. I continued to seat the round deeper until it would chamber in the Sheridan Guage, I ended up at 1.950 a little under 2.000. The cause of this is simply the shape of the bullet, please keep in mind seating a bullet deeper into the case will cause additional pressure so be careful in working up your loads with a shorter COAL, also a round jammed tight against the rifling of your barrel will have the same effect — causing additional pressure. For my plinking rounds I try to have a.010 jump on precision rounds I utilize a Hornady OAL guage to determine proper length.

After loading up 18 rounds, I packed up my AR 300 Blackout and headed to the range. I have made a few changes to the AR for identification and functionality purposes. I added a dust cover, new trigger guard and extended punch pins for easy takedown and they do make a big difference. Previously I mentioned I like the C Product Magazines, they continued to be flawless. I run nothing but these mags in my 300 Blackout and use PMAGS for my 223 AR this is easy for identification also. I made sure to really clean my barrel before going as I would be checking it for lead fouling/build up after firing these rounds. I setup my chronograph and would fire 5 groups, the first group would be shot across the chronograph and not testing for accuracy purely fouling shots. All shots were at a distance of 50 yards with the scope set at 6 power, from a bench with rear bags. I was not terribly impressed with the groups though I am not sure I can totally blame the ammunition as it was 35 degrees out with 10mph winds and I felt myself shaking while behind the rifle. I will work up a ladder test working my way back down from 10.2gr of A1680 on a nicer day to try and tighten up the groups.

 

These rounds did not show any signs of pressure. They all ejected fine, they all collected in a nice pile very close to the bench I was shooting from. I did notice the barrel and chamber was very dirty, this was not lead but powder residue. A1680 powder is supposedly very clean so my guess is that running these loads at such low pressure to keep them subsonic was the cause. There was no obvious leading that I could detect with the naked eye. I intend on borrowing my friends bore scope to get a close look before making up or firing any more of these rounds so stay tuned.

December 8th, 2014

Previously I stated I was going to take a look down the bore with a bore scope before cleaning, but it is going to be a while before I can have it in hand. If there were leading I wanted to make sure not to let it sit to long so I decided to go ahead and clean the rifle. It wasn’t dirty as I thought mainly unburnt powder residue, though you can see some flakes of the red coating that was left behind in the bore. I utilized Ed’s Red from Brownell’s for lead cleaning purposes. It only took 2 wet patches and 2 dry patches to get the bore back in good shape.

Chronograph Results:

 

Rifle Barrel Length Gas Tube Length Ammunition – Powder-Manual COAL Bullet Weight/Bullet Type Velocity FPS Average Velocity FPS ES SD Group Size Weather Conditions Bolt Lock Back
Sun Devil Lower CMMG Barrel 300BlackOut 16′ 1/7 Twist Pistol Reload Accurate 1680- 10.2gr 1.950 Palmetto Coated Bullets 203gr 1096 1100 19 8 2.836 35 Degrees Windy Y
Low 1092
1097
1108
Hi 1111
Sun Devil Lower CMMG Barrel 300BlackOut 16′ 1/7 Twist Pistol Reload Accurate 1680- 10.2gr 1.950 Palmetto Coated Bullets 203gr 1085 1083 18 6 3.804 35 Degrees Windy Y
Low 1072
1083
Hi 1090
1087
Sun Devil Lower CMMG Barrel 300BlackOut 16′ 1/7 Twist Pistol Reload Accurate 1680- 10.2gr 1.950 Palmetto Coated Bullets 203gr Low 1059 1076 36 14 1.774 35 Degrees Windy Y
1075
1077
Hi 1095
Sun Devil Lower CMMG Barrel 300BlackOut 16′ 1/7 Twist Pistol Reload Accurate 1680- 10.2gr 1.950 Palmetto Coated Bullets 203gr Low 1066 1076 20 9 4.535 35 Degrees Windy Y
1072
Hi 1086
1083
Sun Devil Lower CMMG Barrel 300BlackOut 16′ 1/7 Twist Pistol Reload Accurate 1680 – 9.7gr 1.950 Palmetto Coated Bullets 203gr 1024 1010 53 22 3.596 47 Degrees Bad Overcast Y
1022
1011
Hi 1024
Low971

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