Long story short, I'm giving KAC small frame uppers another try after getting burned by them ~10yrs ago.
This thread will showcase my findings on how the current factory KAC SR-15 11.5" [with 3.2 BCG] upper stacks up against a few known good uppers to include a 11.5" FBI ODG "Fed" upper, a Centurion 11.5" upper, and a Colt 11.5" "Old HRT" upper for the comparison.
This study will span the next 2-3 months with updates at least every other week.
In this test, I'll be observing the following,
Reliability: This will be observed through the duration of the tests and across a number of ammunition types, paying close attention to ejection patterns with different buffer weights.
Accuracy: Groups will be shot out of the uppers with multiple types of match and non-match type ammunition, and will be documented.
Felt recoil: This will be measured using split times on drills. Presumably, split times will be faster on uppers that are gassed more efficiently [this will be tested suppressed and unsuppressed]. There will also be a subjective set of notes regarding this data point.
Balance: This will necessarily be subjective, but will be tested with the uppers slick, as well as with accessories on them. Overall weights with and without accessories will be noted.
Uppers to be tested:
-KAC SR-15 11.5" Mod 2 E3 with 3.2 BCG, with Aimpoint T2 on Unity 2.26" riser.
-FBI Fed near clone upper: FCD upper, BRT 11.5" barrel, Geissele "Fed" ODG HG, LMT E-BCG, and SF 4-prong FH, with Aimpint Comp M5 on Unity 2.26" riser.
-Centurion 11.5" flat top, A2 front sight, with FF extended C4 quad, and SF 4-prong FH, with Holosun RD on MI 1.93" riser.
-Colt heavy "Fed HRT" 11.5" flat top, A2 front sight, KAC RAS M4 HG, Bootleg Adjustable BCG, and SF Closed-tine FH, with Aimpoint Comp M5s.
Lower to be tested on:
LMT MARS factory lower [SBR] with SSA-E FCG and SOPMOD stock.
Known limitations of this casual study:
The primary control for the tests will be the home-built Fed upper with BRT barrel. Though it isn't a factory upper, it is the upper I have the most recent time behind. This should allow me to use it as a reliable benchmark for felt performance. In doing this, when I compare it against the Centurion and Colt upper, it will grant perspective on the overall standing it has in the group, thus providing a useful data set to compare against the KAC upper.
All of these uppers are samples of one. Each individual upper may not be representative of its brand or type. There may be defects in parts, or these examples may be exceptional when compared to the norm from these manufacturers.
A large portion of these tests could be construed as subjective. As a human I have my explicit, implicit, and unknown biases.
Final thoughts pre-study:
Pictures will come throughout the thread. [We all know that's what everyone wants.]
Please let me know if there's a data-point you want me to include or expand upon.
I hope this study puts into perspective the performance of decent upper options and helps someone make a decision on what to buy [or not buy].
I will be adding results to this first post as I they come.
Stay tuned!
Cheers!
Session 1
Actions Observed:
I took out the KAC and Gisele uppers.
100rds of PPU 55gr were fired through each.
I put a rough 50yd zero on each and played with targets from 20yds to 50yds.
I shot from the standing & kneeling testing my perceived ability to recover, get back on target, and take another shot.
Take Aways:
Failures: 0
The recoil impulse with both was smooth for a short barrel and carbine length gas system. They felt different, but at this point I couldn't quite explain why.
Learned: The KAC upper felt fine with the H buffer that was already in the lower, but ejection was weak; rounds were just falling out of the receiver at 4 o'clock. After switching to the provided KAC buffer, the upper was ejecting at normal strength to 3 o'clock.
The Geissele upper ejected roughly the same distance at 3 to 4 o'clock with both buffers. I believe this is due to the LMT E-BCG slowing the lockup and bleeding excess gas out of the extra hole in side of the carrier.
Session 2
Actions Observed:
I brought out all four 11.5" uppers, and a token 10.3" Crane spec suppressed rifle for flavor.
300rds of PPU 55gr and 60rds of Federal M855 were fired amongst all four of the 11.5" uppers.
The goal on this outing was to fire 3-6 round fast strings to gauge reliability, felt recoil impulse, how much the dot was jumping, and and how confident I felt in the follow-up-shots after each trigger pull.
I used the KAC buffer for all of these tests to keep it consistent. Ejection for all of the uppers was from 3-4 o'clock and they ejected at normal distance.
Take Aways:
Failures: There was one stoppage in the Centurion upper. One of the PPU cartridges didn't seat all the way in the chamber and the bolt was half way cammed into battery. The cartridge would not easily extract, so I collapsed the stock and mortared it without having to apply much force. I observed that the casing was dented below the shoulder. I don't know if it was loaded into the magazine that way or if it became dented upon ejecting it, but I put it back in the same upper and it fired/extracted/ejected just fine. Until I see more of a pattern, I'm going to chalk that one up as ammo related.
Dot Jump: The movement of the dot while firing quickly was similar amongst all of the rifles in the group. The Colt [old style] HRT upper was probably the worst, but not by much. The others were very comparable.
Felt Recoil Impulse and Confidence Getting Into the Gun: The felt recoil to my shoulder was similar between the KAC and BRT Geissele Fed upper, as was the Centurion similar to the Colt HRT upper. The interesting part was how the impulse displayed itself in each upper. The KAC seemed to have the most notable delayed impulse. It felt like it was punching my shoulder all the same as the Fed upper, but it was doing it in such a way that I felt more confident in driving the gun on target, getting into it, and shooting quickly. I'll have to repeat this test with a timer to determine if this is mostly perception or it I was faster on it.
The felt recoil impulse on the Centurion and the Colt were similar to each other, but the gross recoil was slightly more from the Colt. This was expected.
The Centurion and the Fed upper felt just as fast, but the recoil impulses were just different. The Centurion [by comparison with the Fed upper] had a more abrupt recoil impulse. With the dot jump being about the same, I found that I could knuckle down into the gun and shoot as fast wit the Centurion as I could with the Fed upper [just with more effort in thinking about controlling the gun through the string].
Suppressed: I couldn't help myself, so I fired 6rds through each upper with a Surefire SB2 [except I didn't shoot the KAC upper suppressed because I haven't changed out the muzzle device yet]. All of the uppers ran reliably without adjusting or changing anything. They all ejected to the 1 to 2 o'clock. The Fed upper felt the best so far a recoil impulse out of the bunch. There will be dedicated suppressor tests down the road.
Session 3
Actions Observed:
All four 11.5" uppers went out again, and 240rds of Patriot Sports 55gr FMJ was shot through them.
Patriot Sports ammo is Czech made and can be found for "cheaper" right now.
The goal was to shoot all of the uppers suppressed for this session, but time was tighter, so instead I ran reload drills and 3-10rds fast fire strings.
The KAC buffer stayed in the lower the entire time for all uppers.
Ejection with this ammo was at 3-3:30 [~5ft] for all of the uppers except the SR-15 which was at 4-5 o'clock and 7ft. This was interesting.
Take Aways:
Failures: 0
Felt Recoil & Dot Jump: I want to amend a previous observation. The more that I shoot these uppers, the more that I'm realizing the KAC upper is just different. The recoil in the SR-15 upper isn't less than the Fed upper with the BRT barrel. The recoil is certainly more, but the impulse is unique and inspires confidence in shooting quickly when getting into the gun. If you hold the gun [SR-15] loosely, almost like a novice would, then you definitely feel that it recoils more. The Fed upper recoils smoothly, and now I can confidently say has the least dot jump out of any of the uppers. The Colt upper and Centurion upper are still perceived as very similar.
I do have a SF muzzle device on the KAC now so hopefully we'll get some suppressed results soon!
Cheers!
This thread will showcase my findings on how the current factory KAC SR-15 11.5" [with 3.2 BCG] upper stacks up against a few known good uppers to include a 11.5" FBI ODG "Fed" upper, a Centurion 11.5" upper, and a Colt 11.5" "Old HRT" upper for the comparison.
This study will span the next 2-3 months with updates at least every other week.
In this test, I'll be observing the following,
Reliability: This will be observed through the duration of the tests and across a number of ammunition types, paying close attention to ejection patterns with different buffer weights.
Accuracy: Groups will be shot out of the uppers with multiple types of match and non-match type ammunition, and will be documented.
Felt recoil: This will be measured using split times on drills. Presumably, split times will be faster on uppers that are gassed more efficiently [this will be tested suppressed and unsuppressed]. There will also be a subjective set of notes regarding this data point.
Balance: This will necessarily be subjective, but will be tested with the uppers slick, as well as with accessories on them. Overall weights with and without accessories will be noted.
Uppers to be tested:
-KAC SR-15 11.5" Mod 2 E3 with 3.2 BCG, with Aimpoint T2 on Unity 2.26" riser.
-FBI Fed near clone upper: FCD upper, BRT 11.5" barrel, Geissele "Fed" ODG HG, LMT E-BCG, and SF 4-prong FH, with Aimpint Comp M5 on Unity 2.26" riser.
-Centurion 11.5" flat top, A2 front sight, with FF extended C4 quad, and SF 4-prong FH, with Holosun RD on MI 1.93" riser.
-Colt heavy "Fed HRT" 11.5" flat top, A2 front sight, KAC RAS M4 HG, Bootleg Adjustable BCG, and SF Closed-tine FH, with Aimpoint Comp M5s.
Lower to be tested on:
LMT MARS factory lower [SBR] with SSA-E FCG and SOPMOD stock.
Known limitations of this casual study:
The primary control for the tests will be the home-built Fed upper with BRT barrel. Though it isn't a factory upper, it is the upper I have the most recent time behind. This should allow me to use it as a reliable benchmark for felt performance. In doing this, when I compare it against the Centurion and Colt upper, it will grant perspective on the overall standing it has in the group, thus providing a useful data set to compare against the KAC upper.
All of these uppers are samples of one. Each individual upper may not be representative of its brand or type. There may be defects in parts, or these examples may be exceptional when compared to the norm from these manufacturers.
A large portion of these tests could be construed as subjective. As a human I have my explicit, implicit, and unknown biases.
Final thoughts pre-study:
Pictures will come throughout the thread. [We all know that's what everyone wants.]
Please let me know if there's a data-point you want me to include or expand upon.
I hope this study puts into perspective the performance of decent upper options and helps someone make a decision on what to buy [or not buy].
I will be adding results to this first post as I they come.
Stay tuned!
Cheers!
Session 1
Actions Observed:
I took out the KAC and Gisele uppers.
100rds of PPU 55gr were fired through each.
I put a rough 50yd zero on each and played with targets from 20yds to 50yds.
I shot from the standing & kneeling testing my perceived ability to recover, get back on target, and take another shot.
Take Aways:
Failures: 0
The recoil impulse with both was smooth for a short barrel and carbine length gas system. They felt different, but at this point I couldn't quite explain why.
Learned: The KAC upper felt fine with the H buffer that was already in the lower, but ejection was weak; rounds were just falling out of the receiver at 4 o'clock. After switching to the provided KAC buffer, the upper was ejecting at normal strength to 3 o'clock.
The Geissele upper ejected roughly the same distance at 3 to 4 o'clock with both buffers. I believe this is due to the LMT E-BCG slowing the lockup and bleeding excess gas out of the extra hole in side of the carrier.
Session 2
Actions Observed:
I brought out all four 11.5" uppers, and a token 10.3" Crane spec suppressed rifle for flavor.
300rds of PPU 55gr and 60rds of Federal M855 were fired amongst all four of the 11.5" uppers.
The goal on this outing was to fire 3-6 round fast strings to gauge reliability, felt recoil impulse, how much the dot was jumping, and and how confident I felt in the follow-up-shots after each trigger pull.
I used the KAC buffer for all of these tests to keep it consistent. Ejection for all of the uppers was from 3-4 o'clock and they ejected at normal distance.
Take Aways:
Failures: There was one stoppage in the Centurion upper. One of the PPU cartridges didn't seat all the way in the chamber and the bolt was half way cammed into battery. The cartridge would not easily extract, so I collapsed the stock and mortared it without having to apply much force. I observed that the casing was dented below the shoulder. I don't know if it was loaded into the magazine that way or if it became dented upon ejecting it, but I put it back in the same upper and it fired/extracted/ejected just fine. Until I see more of a pattern, I'm going to chalk that one up as ammo related.
Dot Jump: The movement of the dot while firing quickly was similar amongst all of the rifles in the group. The Colt [old style] HRT upper was probably the worst, but not by much. The others were very comparable.
Felt Recoil Impulse and Confidence Getting Into the Gun: The felt recoil to my shoulder was similar between the KAC and BRT Geissele Fed upper, as was the Centurion similar to the Colt HRT upper. The interesting part was how the impulse displayed itself in each upper. The KAC seemed to have the most notable delayed impulse. It felt like it was punching my shoulder all the same as the Fed upper, but it was doing it in such a way that I felt more confident in driving the gun on target, getting into it, and shooting quickly. I'll have to repeat this test with a timer to determine if this is mostly perception or it I was faster on it.
The felt recoil impulse on the Centurion and the Colt were similar to each other, but the gross recoil was slightly more from the Colt. This was expected.
The Centurion and the Fed upper felt just as fast, but the recoil impulses were just different. The Centurion [by comparison with the Fed upper] had a more abrupt recoil impulse. With the dot jump being about the same, I found that I could knuckle down into the gun and shoot as fast wit the Centurion as I could with the Fed upper [just with more effort in thinking about controlling the gun through the string].
Suppressed: I couldn't help myself, so I fired 6rds through each upper with a Surefire SB2 [except I didn't shoot the KAC upper suppressed because I haven't changed out the muzzle device yet]. All of the uppers ran reliably without adjusting or changing anything. They all ejected to the 1 to 2 o'clock. The Fed upper felt the best so far a recoil impulse out of the bunch. There will be dedicated suppressor tests down the road.
Session 3
Actions Observed:
All four 11.5" uppers went out again, and 240rds of Patriot Sports 55gr FMJ was shot through them.
Patriot Sports ammo is Czech made and can be found for "cheaper" right now.
The goal was to shoot all of the uppers suppressed for this session, but time was tighter, so instead I ran reload drills and 3-10rds fast fire strings.
The KAC buffer stayed in the lower the entire time for all uppers.
Ejection with this ammo was at 3-3:30 [~5ft] for all of the uppers except the SR-15 which was at 4-5 o'clock and 7ft. This was interesting.
Take Aways:
Failures: 0
Felt Recoil & Dot Jump: I want to amend a previous observation. The more that I shoot these uppers, the more that I'm realizing the KAC upper is just different. The recoil in the SR-15 upper isn't less than the Fed upper with the BRT barrel. The recoil is certainly more, but the impulse is unique and inspires confidence in shooting quickly when getting into the gun. If you hold the gun [SR-15] loosely, almost like a novice would, then you definitely feel that it recoils more. The Fed upper recoils smoothly, and now I can confidently say has the least dot jump out of any of the uppers. The Colt upper and Centurion upper are still perceived as very similar.
I do have a SF muzzle device on the KAC now so hopefully we'll get some suppressed results soon!
Cheers!
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