Mega Rad Gun Thread

  • Want to keep track of this thread?
    Accounts can bookmark posts, watch threads for updates, and jump back to where you stopped reading.
    Create account
I've been checking out the early new product reports for SHOT Show 2020. I read a range report on the new SI Ultimax Mk8, and in it the reviewer stated that SI was looking to bring it to the US to sell. It wasn't stated if it would just be Mil/LEO/Gov sales, or if they'd be making a semi-auto only version for civilian sales, but if they did offer a civie version I'd be interested if the price is reasonable. The Ultimax 100 family of weapons has a track record of reliability, and with its unique recoil system they are incredibly controllable (not that 5.56mm weapons have harsh recoil). And the new Mk8 version only weighs about 11 lbs., so the weight is reasonable. If someone made a binary/echo trigger for it, I'd really consider getting one.
I never really follow shotshow directly, I figure anything really interesting will get highlighted eventually.
 
I never really follow shotshow directly, I figure anything really interesting will get highlighted eventually.
Past 3-4 years have been AR15 with a twist!

Also holy fuck Colt what did you do? Those new Pythons are Kyber pass bad from all reviews even loving no negativity hikock had his demo BREAK on him in a video.

I also hate to be the sour grapes kinda guy but I'm pretty happy HK is neutering the new MP5, makes my PTR feel like a way better buy even if I lack as cool a roll mark.
 
Past 3-4 years have been AR15 with a twist!

Also holy fuck Colt what did you do? Those new Pythons are Kyber pass bad from all reviews even loving no negativity hikock had his demo BREAK on him in a video.

I also hate to be the sour grapes kinda guy but I'm pretty happy HK is neutering the new MP5, makes my PTR feel like a way better buy even if I lack as cool a roll mark.
Speaking of PTR, are their G3 clones any good?
 
They are the go to for clones, I've wanted one for a long time but I rather build one... getting the time is the problem, they still are G3s and can be picky at times and love to chew brass.
 
So any of you AR guys have experience shooting short barrel pistol variants?

I got a stripped lower for Christmas and I’m trying to decide what to build. I like the idea of building a pistol first just to keep the option open and like the small form factor since it’ll store easier and make a handy bugout gun. It’s my first and we’re on a budget, so I’ve really got emergency use on the brain, and was hoping to get it up and running relatively soon before VA related or election turmoil flares up. Or honestly just before the prices go up when people enter panic buy mode.

I’m looking at Palmetto since they seem to be the best value for limited funds in terms of build kits and have sales often.

In short, I wanted to know just how much extra noise, recoil, and blast there is out of an 11.5-12.5 inch barrel in 5.56 compared to a 16” rifle with a mid length gas system. Is it that much harder to manage? Is it going to limit reliability and durability? (Any more than going with a value parts kit already does that is). We have people in our household with limited shooting experience (myself included honestly) and I don’t want anything that’s going to be too intimidating, or at least considerably more intimidating than a mid-length AR. I considered 300 blackout but as a survival gun that I want trigger time on, it doesn’t make as much sense to go with a more expensive and harder to find round.

I’d like to try some out, and my brother-in-law has a few pistols in that length range I can try, but I may need to buy before we can manage to coordinate a range day. I figured I’d do some research on my own in the meantime. Opinions I’ve found online about AR pistol blast/recoil vary a lot so it’s hard to pin down anything definitive. And obviously a suppressor is out since I can’t afford the gun itself and just the tax stamp for an NFA item, much less the suppressor on top of that.

As a side note, let’s say I buy a pistol lower build kit alone then mate one of his short uppers to it temporarily. Am I good to then just get a mid length upper without reclassifying the firearm? Does that satisfy the mystical ATF voodoo bullshit? Money is tight and I want the option to switch uppers on the same platform without having to buy another complete lower.

Thanks in advance.
 
So any of you AR guys have experience shooting short barrel pistol variants?

I got a stripped lower for Christmas and I’m trying to decide what to build. I like the idea of building a pistol first just to keep the option open and like the small form factor since it’ll store easier and make a handy bugout gun. It’s my first and we’re on a budget, so I’ve really got emergency use on the brain, and was hoping to get it up and running relatively soon before VA related or election turmoil flares up. Or honestly just before the prices go up when people enter panic buy mode.

I’m looking at Palmetto since they seem to be the best value for limited funds in terms of build kits and have sales often.

In short, I wanted to know just how much extra noise, recoil, and blast there is out of an 11.5-12.5 inch barrel in 5.56 compared to a 16” rifle with a mid length gas system. Is it that much harder to manage? Is it going to limit reliability and durability? (Any more than going with a value parts kit already does that is). We have people in our household with limited shooting experience (myself included honestly) and I don’t want anything that’s going to be too intimidating, or at least considerably more intimidating than a mid-length AR. I considered 300 blackout but as a survival gun that I want trigger time on, it doesn’t make as much sense to go with a more expensive and harder to find round.

I’d like to try some out, and my brother-in-law has a few pistols in that length range I can try, but I may need to buy before we can manage to coordinate a range day. I figured I’d do some research on my own in the meantime. Opinions I’ve found online about AR pistol blast/recoil vary a lot so it’s hard to pin down anything definitive. And obviously a suppressor is out since I can’t afford the gun itself and just the tax stamp for an NFA item, much less the suppressor on top of that.

As a side note, let’s say I buy a pistol lower build kit alone then mate one of his short uppers to it temporarily. Am I good to then just get a mid length upper without reclassifying the firearm? Does that satisfy the mystical ATF voodoo bullshit? Money is tight and I want the option to switch uppers on the same platform without having to buy another complete lower.

Thanks in advance.
Can't speak to PSA's pistol length stuff but the complete upper (mid-length)/lower I ended up buying from them has worked great for me. Unfortunately I lost it in a boating accident after I took it to the range for the first time.
 
Last edited:
Past 3-4 years have been AR15 with a twist!

Also holy fuck Colt what did you do? Those new Pythons are Kyber pass bad from all reviews even loving no negativity hikock had his demo BREAK on him in a video.

I also hate to be the sour grapes kinda guy but I'm pretty happy HK is neutering the new MP5, makes my PTR feel like a way better buy even if I lack as cool a roll mark.
A lot of time it's not even with a real twist it's just manufacturer A is now making an AR in different caliber. Cause no one's ever seen an AR in .300 BLK out or 9mm before.
 
Got a bigger case, which now means I need more stuff to put inside.

STUFF.png
 
In short, I wanted to know just how much extra noise, recoil, and blast there is out of an 11.5-12.5 inch barrel in 5.56 compared to a 16” rifle with a mid length gas system. Is it that much harder to manage? Is it going to limit reliability and durability? (Any more than going with a value parts kit already does that is). We have people in our household with limited shooting experience (myself included honestly) and I don’t want anything that’s going to be too intimidating, or at least considerably more intimidating than a mid-length AR. I considered 300 blackout but as a survival gun that I want trigger time on, it doesn’t make as much sense to go with a more expensive and harder to find round.
I have shot 10.5" and 7" 5.56 pistol uppers. Noise and muzzle blast is significantly more than a 16" mid-length. Report and muzzle blast from the 7" was about on par with a SCAR 17. The 7" will shit fire with certain loads, in broad daylight. As for recoil, there isn't any more but it is harsher. That probably not helpful, but I don't know how else to describe it. There is a gun range near me that will let you put your upper on their SBR giggle-switch lower. We took turns mag dumping a PSA 10.5" upper and had zero malfunctions. I was honestly shocked. All that said, I think a 16" mid length is the best starter AR.

As a side note, let’s say I buy a pistol lower build kit alone then mate one of his short uppers to it temporarily. Am I good to then just get a mid length upper without reclassifying the firearm? Does that satisfy the mystical ATF voodoo bullshit? Money is tight and I want the option to switch uppers on the same platform without having to buy another complete lower.
As long as the lower still has a pistol buffer and your state doesn't have weird pistol rules, I think you should be good. @Club Sandwich should be the person to answer this question though
 
As long as the lower still has a pistol buffer and your state doesn't have weird pistol rules, I think you should be good. @Club Sandwich should be the person to answer this question though
thanks for the notice.
In short, I wanted to know just how much extra noise, recoil, and blast there is out of an 11.5-12.5 inch barrel in 5.56 compared to a 16” rifle with a mid length gas system. Is it that much harder to manage? Is it going to limit reliability and durability?
"blast" is generally perceived gas volume outside the barrel when the bullet immediately passes the crown or muzzle device. ports in compensators and brakes redirect, slow, and cool blast in order to achieve various effects. recoil boosters and suppressors with blast chambers do this as well. the gas volume will depend very strongly on the precise chemistry of propellant you are using. a 5.56x45 NATO cartridge will be different between barrel lengths or gas port size (more on this later) because the powder charge, bullet mass, and so on is slightly different. this is because propellant used to force the bullet through the rifling will expand faster or slower, will be hotter or cooler, and this expansion difference is felt/experienced blast/noise/recoil. you've already probably assumed a shorter barrel will have more unburned powder compared to a longer barrel, and the lack of barrel length will allow most of this unburned powder to expand outside the barrel. this creates, generally, more noise, more blast, lower velocity (typically), and in some cases more perceived recoil from the lack of weapon mass that help mitigate recoil (heavy guns recoil less as it takes more energy to move greater mass).

the rule of thumb is about 100 fps loss per inch traveled, assuming all other factors are equal and the barrel is an ideal length and twist for the powder charge and bullet mass. because many 5.56 designs rely on high velocity fragmentation on penetration of a target (with secondary effects being tumbling inside the target), you must be aware of the velocity threshold your particular bullet requires for optimal performance. bullets that aren't meant for that purpose (or are for some other application) would not have this requirement in mind when choosing a barrel length.

as far as durability is concerned, shorter barrels have less mass to absorb heat and on long strings of fire can experience more deflection at longer ranges, which "opens" a given group up. at the same time, counter-intuitively, shorter barrels are "stiffer" and do not experience as much "barrel whip" from harmonics as the pressure wave passes through the barrel (like a sound wave). this stiffness can be a good thing if you're only taking a few shots here or there, or you use a bipod frequently. likewise the lighter weight might shift the balance of a rifle (or pistol as the case may be) into an awkward position. it is often true that shorter barrels have shorter useful life spans as well, because erosion from hot gases that are at higher than average pressure will "cut" into the gas port opening, slowly increasing it's size until the gas system fails to function reliably.

that being said, "blast" will generally not throw off a bullet (unless the muzzle or crown is damaged or something), and will instead generate additional flinch on the part of the shooter - the powder expansion and fireball some find to be uncomfortable or startling, likewise with the concussive pressure wave from very short barrels, and possibly a fireball from ignition of the powder outside the barrel - especially at night where you have darkness-adapted vision.

for "reliability", you must keep in mind that you're dealing with a pressurized system:
1. the trigger disengages from the hammer's sear and the hammer, driven by a spring, impacts the firing pin, which strikes the primer of the chambered cartridge. that primer ignites the powder in the cartridge case, which attempts to expand in all directions.
2. because the case is supported by the chamber, and the bolt is locking the rear of the cartridge in position, the only exit for pressure is forward, overcoming the crimp at the cannelure to push the bullet down the barrel, engaging the rifling to impart spin.
3. this pressurized system continues to expand from the propellant until the bullet passes the gas port in the front sight block. this allows some expanding gases from combustion to travel through the gas port and back through the gas tube to begin expanding in the bolt carrier, against the rear of the bolt. this begins unlocking the bolt from the barrel extension.
4. the time from when the bullet passes the gas port to the time the bullet exits the barrel entirely, is known as "dwell time", typically measured either in units of length or units of time. it is during this period that the gas system is pressurized enough to drive the action, and excess gas is vented out the end of the barrel - no longer contained by the bullet in flight.
5. a longer length of barrel between the gas port and the muzzle will increase dwell time, allowing the action to be gentler, and operate smoother.
6. too short of a dwell time can lead to under-pressure of the system, causing short strokes of the bolt carrier assembly, failure to unlock, extract, eject, cock, feed, or lock.
7. too long of a dwell time can lead to over-pressure of the system, causing premature movement of the bolt carrier assembly, failure to unlock, extract, eject, cock, feed, or lock.

in most short barreled AR-15 pattern rifles, the gas port is fairly close to the muzzle and the gas system requires balancing to ensure smooth operation. this is achieved in three primary ways:
1. adjust the gas port size to allow more or less gas into the gas tube. shorter barrels, being closer to the chamber, will often need a smaller than normal gas port to maintain a consistent volume of gas for the dwell time allowed by the position of the gas port in relation to the muzzle. because it is often unfeasible to adjust gas port size by the end user, this option is only relevant for gunsmiths or experienced users comfortable with the procedures to enact this change.
2. adjust the reciprocating mass of the bolt carrier assembly. a heavier mass requires both more time and more gas to move than normal. shorter barrels will often have a combination of a heavier recoil buffer (starting at H1 for carbines and moving to H2 and H3 for shorter barrels) and a heavier recoil spring (unless you have a very unusual configuration, the default Rifle or Carbine recoil springs will be appropriate). this option is both the easiest and most appropriate for the end user, but requires either experience or experimentation to tune a gas system and reciprocating mass to function reliably. short barrels will typically already have an appropriately sized gas port for most ammunition, and a recommended buffer to use with it.
3. lastly, certain combinations of carriers, muzzle devices, and gas tubes can be installed to meet specific requirements. this option is typically tailor-made for a specific weapons system.

i would suggest sticking with option 2.

this is a handy chart for determining a reasonably reliable SBR build for a given barrel length, gas port size/position, and bullet:
1579758980876.png


As a side note, let’s say I buy a pistol lower build kit alone then mate one of his short uppers to it temporarily. Am I good to then just get a mid length upper without reclassifying the firearm? Does that satisfy the mystical ATF voodoo bullshit? Money is tight and I want the option to switch uppers on the same platform without having to buy another complete lower.
in the US, for the AR-15, the lower receiver is considered the "firearm" in the legal definition of "firearm" and was transferred to you either as a pistol, rifle, "firearm" (bare frame, stripped lower), or some variety of NFA/Title II item. if the receiver is a frame, and you build it into a pistol, from the point where it is operable, it is considered a pistol. likewise this is true if it is built into a rifle. there is a narrow clause where you can start with a pistol lower, rebuild it as a rifle, and freely return it to a pistol configuration (https://www.atf.gov/firearms/qa/can-i-lawfully-make-pistol-rifle-without-registering-firearm). this is not true if the lower was transferred as a rifle, originally. it sounds as if it was transferred to you as a "firearm" or frame/bare receiver. this is noted on the 4473 paperwork for the original transferee if you would like to be sure. such a frame can be freely built into either a pistol or rifle, but you cannot legally build a short barrelled rifle without obtaining your tax stamp first - likewise having the necessary parts to assemble an SBR can be seen as "constructive intent", and the BATFE has prosecuted people for that.

the safest bet would be to assemble your lower and an upper into a legal pistol configuration if you want to try out a short barrelled upper. this would allow you to later choose if you want a pistol or rifle for that particular lower.
 
Last edited:
you cannot legally build a short barrelled rifle without obtaining your tax stamp first - likewise having the necessary parts to assemble an SBR can be seen as "constructive intent", and the BATFE has prosecuted people for that.
Keeping at least one pistol lower around mitigates this issue, correct? Always appreciate your gun posting.
 
Keeping at least one pistol lower around mitigates this issue, correct? Always appreciate your gun posting.
1579761400332.png



generally speaking, no. having all the parts necessary without some reasonable excuse can be seen as constuctive intent. if you happen to have both a rifle lower and an pistol lower and only a short barrelled upper, there is no useful purpose for the rifle lower except to possibly manufacture an unregistered NFA weapon. if you have fully assembled rifles and a pistol lower and a short barreled upper, there is some legal defense to constructive intent... which would have to be brought before a judge and jury for prosecution, should the BATFE choose to do so.
 
in the US, for the AR-15, the lower received is considered the firearm and was transferred to you either as a pistol, rifle, "firearm" (bare frame, stripped lower), or some variety of NFA/Title II item. if the receiver is a frame, and you build it into a pistol, from the point where it is operable, it is considered a pistol. likewise this is true if it is built into a rifle. there is a narrow clause where you can start with a pistol lower, rebuild it as a rifle, and freely return it to a pistol configuration (https://www.atf.gov/firearms/qa/can-i-lawfully-make-pistol-rifle-without-registering-firearm). this is not true if the lower was transferred as a rifle, originally. it sounds as if it was transferred to you as a "firearm" or frame/bare receiver. this is noted on the 4473 paperwork for the original transferee if you would like to be sure. such a frame can be freely built into either a pistol or rifle, but you cannot legally build a short barrelled rifle without obtaining your tax stamp first - likewise having the necessary parts to assemble an SBR can be seen as "constructive intent", and the BATFE has prosecuted people for that.

the safest bet would be to assemble your lower and an upper into a legal pistol configuration if you want to try out a short barrelled upper. this would allow you to later choose if you want a pistol or rifle for that particular lower.
Thank you for the very informative response. If I’m going to play with short uppers at all it sounds like the best bet legally is to build this first receiver as a pistol.

So in short:
1) Buy pistol lower build kit
2) Go to range with brother-in-law, mate his short upper to it and get it operational. Maybe shoot a few mags one handed with the brace to document that I actually did assemble as a pistol.
3) Keep saving my pennies and get my own 16” mid length upper.
4) Use the mid-length gun as a daily shooter since it has smoother recoil and less startling blast.
5) Eventually get an 11.5” upper or similar to switch back and forth on if need arises.

I’ve heard good things about the SBA3 brace and Palmetto has reasonably priced pistol lower kits that use it. What exactly is the difference between a carbine buffer tube and a pistol tube? I thought I remember reading that the SBA3 attaches to a carbine tube, but it sounds like the buffer assembly has a lot to do with whether the completed firearm is classified as a pistol.
 
Thank you for the very informative response. If I’m going to play with short uppers at all it sounds like the best bet legally is to build this first receiver as a pistol.

So in short:
1) Buy pistol lower build kit
2) Go to range with brother-in-law, mate his short upper to it and get it operational. Maybe shoot a few mags one handed with the brace to document that I actually did assemble as a pistol.
3) Keep saving my pennies and get my own 16” mid length upper.
4) Use the mid-length gun as a daily shooter since it has smoother recoil and less startling blast.
5) Eventually get an 11.5” upper or similar to switch back and forth on if need arises.

I’ve heard good things about the SBA3 brace and Palmetto has reasonably priced pistol lower kits that use it. What exactly is the difference between a carbine buffer tube and a pistol tube? I thought I remember reading that the SBA3 attaches to a carbine tube, but it sounds like the buffer assembly has a lot to do with whether the completed firearm is classified as a pistol.

Carbine tube has the channel and holes in the bottom for a collapsible stock. Pistol tube is just the buffer tube.
 
Carbine tube has the channel and holes in the bottom for a collapsible stock. Pistol tube is just the buffer tube.

Thanks!

I’m still confused then, because this SBA3 brace lower build kit clearly has a carbine tube. It’s got the channel and everything. The brace itself is also adjustable.


It’s still a pistol right? Is this because the stand alone retail version of the brace ships with a buffer tube? I think the ATF ruling originated with the SB tactical braces, so do they just get a pass.

Really not tryna end up in prison over a technicality.
 
Thanks!

I’m still confused then, because this SBA3 brace lower build kit clearly has a carbine tube. It’s got the channel and everything. The brace itself is also adjustable.


It’s still a pistol right? Is this because the stand alone retail version of the brace ships with a buffer tube? I think the ATF ruling originated with the SB tactical braces, so do they just get a pass.

Really not tryna end up in prison over a technicality.
Yes it's still a pistol, the brace is fine. What happens to most people busted on nfa charges are they are committing another crime like armed robbery, murder, or drug dealing and the cops get fed charges on illegal guns on them. You won't get bothered unless you make an sbr and post on YouTube and Facebook like some retards. That configuration you posted is completely legal.

The buffer tube is not considered the stock unless it has the hokes drilled in for a collapsible stock to be locked in different positions. Those pistol buffer tubes are gonna lack that. Or if does have an adjustable brace, you should be fine. Just don't slap a collapsible stock on it. There are folding collapsible braces and other stuff that really is on the line of brace and stock but they're legal.
 
Last edited:
generally speaking, no.
I should know better by now not ask general questions about guns. I have 3 lowers, 2 rifle and 1 pistol, and 5 uppers, 3 rifle and 2 pistol. Would always storing the rifle lowers with an attached rifle upper be enough to keep the ATF from shooting my dog? Probably going to sell my Evo and buy a Jakl at some point, so I'll be at 3 and 3 with uppers.
 
I should know better by now not ask general questions about guns. I have 3 lowers, 2 rifle and 1 pistol, and 5 uppers, 3 rifle and 2 pistol. Would always storing the rifle lowers with an attached rifle upper be enough to keep the ATF from shooting my dog? Probably going to sell my Evo and buy a Jakl at some point, so I'll be at 3 and 3 with uppers.
I would keep anything, that isn't your regular weapon, separated just as a matter of routine (I never know what combo I am going to take to the range next).

But in the end, unless you have someone gunning for you, or you are stupid on the internet, it really doesn't matter.
_
Edit: I guess I could ask here.

I have an old Para-Tac 4, and it is starting to have some feed issues after many thousands of rounds have been put through it.

For Reference:
reference.jpg

It was a fairly nice .45 acp handgun with a 13+1 rd capacity.

I was wondering if any of you guys knew a modern upgrade/replacement that won't break the bank.

Preferably in the same caliber just so that I can have something that shoots .45 that isn't a 1911.
 
Last edited:
5) Eventually get an 11.5” upper or similar to switch back and forth on if need arises.
you would also need to remove the stock or otherwise return the lower to a "pistol" configuration. switching back and forth can be argued as constructive intent if both the lower in rifle configuration and the short barreled upper are stored in such a way as it is trivial to combine them.
I should know better by now not ask general questions about guns. I have 3 lowers, 2 rifle and 1 pistol, and 5 uppers, 3 rifle and 2 pistol. Would always storing the rifle lowers with an attached rifle upper be enough to keep the ATF from shooting my dog? Probably going to sell my Evo and buy a Jakl at some point, so I'll be at 3 and 3 with uppers.
if they are fully assembled at all times, it's unlikely to raise any eyebrows to have both pistol and rifle configured weapons, regardless of how "compatible" they are to make into a legally questionable configuration. it seems to cross that line if you have a rifle lower with a ready-to-use short barreled upper in your control in such a way that they could be assembled as such.
 
you would also need to remove the stock or otherwise return the lower to a "pistol" configuration. switching back and forth can be argued as constructive intent if both the lower in rifle configuration and the short barreled upper are stored in such a way as it is trivial to combine them.
Noted. For a while at least, I’d just be sticking with the lower with a pistol brace and tube with a mid length 16” upper, so no harm there. I think the ATF ruling said that rifle length barrels or other extensions on a lower originally designated as a pistol do not change the firearm classification.

If I do switch out for a a stock though, your point is helpful, it pays to be safe.

Just take SBR’s off the NFA registry already, geez.
 
Back
Top Bottom