Reloading 300 Blackout: Ruger American Ranch Rifle 300

Though this posting could be used as a base for reloading 300 Blackout, my intent is to cover specifically 300 Blackout for the Ruger American Ranch Rifle. You ask why a reloading article specifically for the Ruger American Ranch Rifle in 300 Blackout?? Those browsing the internet looking for reviews on the RARR 300 will quickly run across forum posting about the RARR having misfire issues. Being a Ruger fan, I struggled with why Ruger would not take care of this issue as it seemed to be wide spread. Odd enough I was an early adopter of this rifle, started documenting my experience with the 300 Blackout in mid 2013 shortly after the round was released and was not having any of these issues. One look to the heavens and I thought to myself thank you lord, because things like this easily frustrate me at times. My curiosity into what seemed to be a widely spread issue got the best of me. I decided to do some testing of my own to try and get to the bottom this “misfire issue”.

After reading many great post over on what I consider to be the most advanced 300 Blackout forum on the internet. Most who frequent the forum and have observed this issue have related it back to ammunition some specifically to headspace of the ammunition. Unfortunately alot of these failure to fires were occurring with Remington green and white box ammunition manufactured here in the good old United States. Again this amazed me as I have fired this exact brand of ammunition and though I had my fair share of issues which have been documented along my journey with this cartridge. The main issue I discovered in early 2014 with the Remington Green White box ammunition was mainly blown primers. To Remington’s credit I did contact them and they had me send the remainder of the ammunition back to them. Though they never gave me an explanation, they did send me a new box of ammunition as a replacement that did not have the same over pressure issue with blown primers as the box I returned.


What really ignited the fire to get to the bottom of this was a video I came across on youtube. One of the 300blktalk forum members AP2020 Outdoor channel posted he sent his Ruger American Ranch Rifle to his gunsmith and had his barrel turned back for zero head space. Like most things I just can’t leave good enough alone and started to think about following his advice, but why do that if you aren’t having an issue? This is when I decided to test headspace and bumping the shoulder back to see if I could create the issue. Now for those of you that do not like to see a waste of reloading components you might want to stop reading here.

Before diving deep into this data let’s cover a few things. First the headspace according to SAAMI spec is listed as 1.0707Min-1.0818Max as seen by the diagram below.

Critical to my reloading process are a few tool which I have reviewed in my journey previously is my Redding National Match Die Set, Sheridan Engineering Slotted Gauge , Hornady Digital Caliper, Hornady Bullet Comperator and Headspace Comperator Set.

In an attempt to get as consistent results as possible I also purchased Sig Sauer 300 Blackout Brass. I measured all 51 brass cases with the Hornady Headspace Comperator Set using the B350 gauge. 41 cases measured 1.075 and the remaining ten cases measured 1.076, yes there were 51 cases in this bag. I would say Sig produces consistent brass cases. For this little experiment I decided to use all of the 1.075 cases though according to SAAMI spec this was below the minimal. So right out of the gate this is not starting out to well and the misfire issue starts to point right away to ammunition or even more specific out of spec headspace on the brass. To ensure I was using the right gauge I called Hornady and was instructed the B.350 is the right gauge for 300 Whisper. Keep in mind this is the brand for all Hornady ammunition 300 Whisper, the technician helping me seemed very knowledgeable and very patient but every time I would say specs for 300AAC Blackout. He would say well if you are loading or working with 300 Whisper here is what I think. I found this amusing and interesting, as if Hornady does not recognize the 300AAC Blackout specification but I digress.


After measuring my Sig brass I thought it may be a good idea just as a baseline and to satisfy my curiosity to visit the local shop and pick up a few different boxes of factory manufactured ammunition, to see exactly how consistent they were and how they performed. I picked up a box of S&B Tactical Ammunition 200gr FMJ Subsonic, Barnes Vor-TX 110gr and American Eagle 150gr FMJ.

The consistency of the factory ammunition was a little surprising there was a big gap between Barnes, American Eagle and S&B.

  1. Barnes Vor-TX Headspace measured 1.077
  2. S&B Tactical Headspace measured 1.064
  3. American Eagle Headspace measured 1.077

Next I believe this was a great time to use my Sheridan Slotted Gauge on the factory ammunition to really see if I could actually tell a difference in how the ammo rested in the gauge with the naked eye.

By the pictures it is a little hard to tell but the S&B rounds sat a little lower than Barnes & American Eagle,? below the top step of the Sheridan Gauge.

Now its time to get down to business, I loaded 30 rounds with different headspace

  1. Sig Brass shoulder bumped back — headspaced at 1.055. Winchester Small Rifle Primer. Interesting fact about these reloads, the full length sizing die was setup exactly as stated in the directions, screwed in until the die touched the shell houlder. None of these rounds would fire in the RARR300Blkout Rifle.
  2. Sig Brass shoulder bumped back — headspaced at 1.058. I backed the Redding die out just a little to achieve this headspace, note the die and shell holder is not touching. Winchester Small Rifle Primer. None of these rounds would fire in the RARR300Blkout Rifle.
  3. Sig Brass shoulder bumped back — headspaced at 1.063. I backed the Redding full length sizing dies out just a hair to achieve this headspace. Winchester Small Rifle Primer. 6 of the 10 rounds would fire in the RARR300Blkout Rifle.
  4. Fire 10 rounds of the S&B Factory ammunition headspaced at 1.064. All rounds fired in the RARR300Blkout Rifle.
    1. Interesting enough the S&B ammunition fired flawlessly in my built 300Blkout AR15.
  5. Fire 10 rounds of the American Eagle ammunition headspaced at 1.077.?All rounds fired in the RARR300Blkout Rifle.
  6. Fire 10 rounds of the Barnes Vor-TX ammunition headspaced at 1.077.?All rounds fired in the RARR300Blkout Rifle.

If this weren’t a test to try and get to the bottom of this misfire phenomenon I would have never attempted to fire the reloaded ammunition headspaced at 1.055 and 1.058. In using my Sheridan gauge you could clearly see they sat below the lower step showing out of spec. I believe what is happening in the case of these misfires, the extractor is holding the brass but as the firing pin strikes the brass has the shoulder bumped back so far that it allows the firing pin to ever so slightly push the round forward in the barrel preventing an ignition.

So it is my conclusion as many have mentioned previously, this misfire issue I believe is related to two things – ammunition out of spec headspace and excessive barrel headspacing on the RARR300Blkout. AP2020 Outdoor Channel Adventures may have the ultimate fix in sending your rifle in to a gunsmith to have the barrel setback to 0 headspace. For me my permanent headspacing for all my reloads will be 1.075-1.078. I was amazed at how much the supersonic brass stretched in the RARR300Blkout — 1.077 stretched to 1.083. In my AR the brass actually had it’s shoulder bumped back a little 1.077 to 1.0765


Just as I thought I had got to the bottom of this misfire debacle and solving any issue I may run into. I came across more reading indicating Ruger had changed the design of the bolt. Comparing pictures it looked as if I had an early revision or first generation bolt. Again here I go can’t leave well enough alone. I spoke with and emailed Ruger about this little experiment I was conducting and the technician was very interested in what I was doing. He said look if you are having an issue just send your bolt back in, but if not if it ain’t broke don’t fix it. I asked if he would be kind enough to email me his thoughts via email to be included in this article and he said sure but first I would need to email him which would grant him authority to reply.

Ruger Email Reply


The 300 black out round was originally designed for the AR platform which has a free float firing pin which hits the primer a lot harder than a spring loaded firing pin like the Ruger American. This being said, most 300 black out ammunition is made for a free floating firing pin which may not work in this Ruger American Rifle. What Ruger recommends is that you contact the ammunition manufacturer and ask if their primers are made for a free floating firing pin or standard spring loaded firing pin.

If you are still experiencing an issue with the rifle, we would like to have your firearm come in to our factory for inspection. If you are at home on a regular basis you may contact us for a return authorization and we can schedule a UPS pick up at your home. You may reach us at 336-949-5200 and choose option 2 and option 1 for the American Rifle. If you are not at home on a regular basis you may take the firearm to a local dealer and have them contact us for a return authorization. Please provide the serial # to your firearm when contacting customer service.

Thank You,

end Ruger Quote

Though we spoke about this on the phone I was still a little baffled by the reply as I had not heard of primers specifically made for free float firing pins. Of course we all know of the difference in cup hardness by the different primer manufactures. Though I have been told by a friend of mine in the ammunition making business that Federal and CCI cup hardness are the same now that they are owned by the same company but the primer mixture is different.

All in all my decision is to not send my rifle or bolt out to any one and to make sure all of my reloads have a headspace of 1.075 to 1.079, validating this with my Sheridan Slotted Gauge. By the way the proper use of this gauge is important, just dropping the round into the gauge could give false results. I drop the finished rounds into the gauge and then apply a little pressure to the head of the case.

As I continue my journey with the 300 Blackout, chronographing and testing for groups in different rifles I will now be adding headspace readings to this page moving forward.

I truly hope this helps someone, though your results may be different in your rifle the same principles apply. Matching? the proper headspace with your rifle , just like matching COAL to your rifle is critical to accuracy and proper function.