Here we are halfway through June and so far in 2021, it seems like we cannot go a week without some sort of major announcement, or new law change in the firearms community. This time we get to look at a new proposed change by the ATF in regards to how it will classify firearms that use an AR brace.
Now, I have probably made it somewhat known that I am not a huge fan of pistol braces in general. Personally, it is worth it to me to pay $200 and get a stamp to put proper stock on a firearm. When I do an AR build I likely will have $800+ into it, and while it is silly to have to pay $200 to mount a $50 piece of plastic, I figure it in as a cost. Overall the larger stock fits me better, and it is generally more comfortable to shoot. I have also objected to the fact the widespread use of the brace as a “wink, and nod” circumvention of current NFA laws does more harm to the initial purpose of the brace. Mainly to allow veterans and shooters with a disability to stabilize and shoot an AR pistol build. As I stated in December, when a proposed rule change was brought out by the ATF, the harm this does to those with legitimate disabilities is the true story, not curtailing rights for the average shooter.
Well, as we know they retracted the initial rule change. Many in the firearms community celebrated this as a win. I was far more sanguine about it. I saw it more as a political ploy, that the Biden Administration would resubmit the proposed rule in some form or fashion to claim they were making good on campaign promises. We did not have to wait long for that to happen. On June 7th, 2021 the ATF announced their proposed rule change for Pistol braces. This is a completely different document than what we saw in December. In some ways, it is a bit more lenient as it allows the majority of pistol braces to be kept in circulation so long as the build they are placed stay within certain criteria. The full proposal can be read here.
The rule change boils down to this; firearms WITH a pistol brace will be subjected to a point system in order to determine if they are a legitimate use of a pistol brace or if they are an SBR. The ATF provides examples of the forms as part of the rule change that gives an overview of what the criteria are. I have included the forms below. They include items such as, does the firearm have a forward grip stop, or does it have flip-up rifle style sights. The firearm must also weigh between 64 to 120 ounces.
It is important to note that a total of 4 points or more indicate the pistol is an SBR. If we look at some of these examples, they can be pretty subjective, and you can see how someone really gets into trouble pretty quickly. If anything that ATF has at least finally provided the firearm community with a really good illustration as to how absurd and ridiculous Short Barrel Rifle laws are. While the ATF bills these builds as being particularly deadly, anyone who is familiar with them knows the opposite is true. In nearly every case a shooter is better off with a 16in barrel rifle and a proper stock than a 10.5in pistol build with a “pistol brace”.
The thing that is the most troubling to me, is how many shooters will get themselves in trouble accidentally. Firearm laws are already somewhat confusing. SBR and SBS laws are excellent examples of this. The illustration to the right is meant to be both comical and true. It really is that nuanced and this point system is not going to help, as you can have a perfectly legal pistol build and then decide to swap out sights, and have an illegal SBR. Do not put it past the ATF or any other Federal Agency from looking a social media pictures of people firing their “Pistol Builds” and using that as evidence against them. I do believe this law will end up getting otherwise law-abiding people into trouble. Unfortunately, as with any other firearm, the law is backed by felony charges.
Still it is important to note this only applies to pistols with pistol braces. A lot of false reporting has happened to say this will kill red dots on pistols, and that does not appear to be true. As egregious as this proposed rule changed is, we have to be honest in how we report it. The chances the ATF will back down this time are pretty slim, still it is worth leaving a well thought out and well worded comment. As with what most of the Biden led ATF is doing, we will need to fight this in the courts.
While back I mentioned that the Civilian Marksmanship Program put out a letter about the proposed pressure of 30-06 Springfield rounds to be a fire in the M1 Garand and 1903A3 rifles. They had stated that anything with pressures greater than 50,000 CUP was too high for these old warhorses. At the time I was displeased that they would use Copper Units of Pressure since that unit of measure has been retired for 20+ years. No ammunition manufacturer is using CUP to measure pressure in 30-06 ammunition. I reasoned that they should at least limit pressure to the 50,000psi that is specified in the Mil-Spec for M2 ball ammunition.
Well I was recently working on a project with 30-06 doing a bit of load development and happened to run across the SAAMI spec. While CUP is not longer in use, SAAMI maintains the record for these loads. Please pay attention to the bullet weights and velocities in the following section.
The keen eye will notice something. The velocities for a Maximum Average Pressure of 50,000CUP or 60,000psi are exactly the same for any given bullet weight. Since velocity is a product of pressure, it can be reasonably asserted that the peak pressure is identical. This is confusing, to say the least, if the CMP recommendation is suppose to be a “Softer load” then this comparison would refute that. They again would be better off publishing 50,000psi maximum that the M2 Ball load is spec’d out at.
Anyone who is familiar with CUP versus PSI will know that there is not a direct comparison that can be made between CUP and PSI as you are effectively measuring two different things. CUP measures the Area Under the Pressure/Time Curve, while transducers measure a true Pressure/Time curve. However how CUP has been treated by SAAMI is highly variable, if you flip through the SAAMI catalog you will find some CUP pressures appear to be identical to the peak pressure in PSI. Other times the CUP will be a little lower. The easiest place to see this is in the Rifle Cartridge Catalog where I lay it out. With that said if CMP was trying to provide a spec for softer ammunition, I think they have missed the boat.
I do believe the CMP has a point, even if they have not communicated it well. A service pressure of 60,000psi or 50,00 CUP may very well be a bit much for these antique firearms and you are better offloading down a bit. However, there is not much in the way of 30-06 loads published at 50,000 PSI. Stick to the min loads, and I think you will probably accomplish the same thing.
Well this has been a decent update. This week I do hope to carve out some time to do a Burn Rate Chart update. I came across some information on some Russian powders that I have not seen before and wanted to add those to the spread sheet. I am also planning on hammering out a couple book reviews so look for those to be posted this week.
As always if you are looking to get in touch, the best way is to send me an email at jay@theballisticassistant.com. You may check us out on Parler, Facebook, Instagram, and Reddit. If you’d like to submit a load to our load database, the instructions are here.
As always, shoot straight and stay safe!
The Ballistic Assistant
Milspec for M2 ball was 50k CUP…same as SAAMI spec at the time of the Garand rifles development. It’s also valid to point out that M2 ball came AFTER the garand was in service and had nothing to do with the design of the rifle.
The confusion has continued because at the time (1930-40s etc) they did measure using the copper crusher method (CUP) but they universally said “psi” based off the CUP measurements. So the SAAMI max was 50,000 psi (CUP).
Later when the piezo transducers came out and they retested everything the numbers changed even thought pressure was the “same” only testing methodology changed.
So the garand has always been made to SAAMI spec and therefore it can safely handle 50k cup or 60k psi ammunition.
The biggest issue with garands is selecting the correct burn rate powders not bullet weight. Garands can shoot any weight bullet providing you are using powders in the 3031- varget range without any issue.
Hey Jeremy,
I appreciate the comment. I had not considered that they may have referred to CUP as PSI, which makes sense and I can see how that would add to the confusion. With that said, the M2 Ball Spec lists 50gr of IMR 4895, and a velocity of 2,740fps 24 meters from the muzzle. This is a very soft load, and if you run it through QuickLoad you will see that it is a bit shy of 50,000psi chamber pressure. Now I know that 50gr could be a “start charge” and manufacturers would adjust the charge up, but the velocity spec does not seem to be a “Minumim 2,740fps” just a flat out 2.740fps. Which would indicate to me that the military was truly looking for a softer load than what SAAMI MAP would allow for.
When I originally read the notice put out by CMP, it seemed to indicate that 50,000CUP was the limit, which does not make sense given it is equivalent to the 60,000PSI SAAMI MAP, so the CMP was essentially just saying stay within SAAMI Spec. However, when I reread the letter this evening I realized I had misread the notice. It says pressures exceeding 50,000CUP AND bullet weights more then 172-174gr. This falls in line with what you are saying in terms of being cognisant of port pressure. This is controlled impart by powder burn rate in combination with a bullet weight. A heavy bullet and a slow powder burn rate do result in higher port pressure, but heavier bullets can be safely shot if you back the load off some. I think we need to look at the M72 Spec ammunition which utilized a 172-174gr bullet. Velocity Specs look to be quite soft compared to what is achievable with IMR4895 when
loaded to 60kpsi.
It is an interesting discussion for sure. Again, I appreciate you taking the time to comment, prompting me to do a bit more digging I would not have done otherwise.
Jay