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Will use the 110 OTM/HPBT this season in Texas on hogs mainly, maybe a deer or two.

Ran 28.2, 28.5, 28.8, 29.1 using AA220 and CCI 41.

Couldn’t tell any difference in the 28.8 and 29.1; accuracy or pressure. Brass all good.

Firing in 18” ARP target crown; 2727fps from 29.1. Good numbers. Good accuracy. 3 shot groups touching at 100. Will reshoot for accuracy and velocity in the coming weeks.
 

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28.8 gr benchmark is more accurate in my rifle with the 110 BTHP than with the 2200. With cannelure but not seated to it and not crimped. SSA brass 7 1/2 remington primers. Never a problem from no crimp and under .5, 5 shot groups at 100 yds. This is the most accurate load I have found so far.

This is the dope load
have used the same load for years bulk puchused the bullets and powder it’s all I shoot out of my 6.8
 

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anyone using cfe-223 with this bullet, also accurate 2230. these are the powders i have on hand. thanks
I'm going to start testing Shooters World Match Rifle powder soon, which is very close to CFE223, but I shoot a 24" barrel, so it may be too slow for short barrels and 110s. If shooting 130s it might work well with shorter barrels.

-Alexander N. Holman
 

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anyone using cfe-223 with this bullet, also accurate 2230. these are the powders i have on hand. thanks
very anemic with the 110 out of a 22" bbl. 2616 fps with 33.5 gr. of CFE 223 but it might work for your purposes. Shooter world is even worse, it didn't break 2600 fps out of a 22". 2557 fps with Shooters world TAC rifle 29.5 grs. ES18, SD8
 

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very anemic with the 110 out of a 22" bbl. 2616 fps with 33.5 gr. of CFE 223 but it might work for your purposes. Shooter world is even worse, it didn't break 2600 fps out of a 22". 2557 fps with Shooters world TAC rifle 29.5 grs. ES18, SD8
Good to know. Maybe I'll just run it in my 5.56 instead.
 

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Good to know. Maybe I'll just run it in my 5.56 instead.
i settled on H322 for my 110's. i get 2800 out of my 22" and 2550 from my 16" and 2600 from my 18". But many like A2200 but i get huge SD and ES with it. good enough to hunt deer with though.
 

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Might be an old thread, but I'm getting 2569 FPS average on a 16 shot string using 110gr Hornady factory loads in a 16" ARP 3R upper that running off an Adams Arms free float short stroke piston. 64F over cast day using a Competition Electronics Pro Chrono DLX about 10ft in front of the muzzle.

Hornady advertises 2570 fps for this load in a 16" barrel, so spot on, but I was honestly hoping to get in the mid 2600's as ARP and Bison barrels supposedly run faster. Lots of variables though, could be my chrono, could be changes in their factory load compared to 8 years ago and obviously these are not hot hand loads to exploit ARP's capabilities. Accuracy is at least 1/2 MOA at 50 yards (I only have a 3x magnifier with my EOTech XPS2 and not so great eye sight, not exactly a target optic setup, it's a fighting gun).

I bedded the barrel using a hybrid method of 0.002" brass shim stock glued to the barrel extension with Rocksett engineering adhesive (good for up to 2000F). That way I can remove the barrel from the receiver if I ever needed to replace either for any reason. I did not square the receiver though, it's an Adams Arms forged upper with a few machining enhancements specifically for this piston gas system.

I honestly don't see a need for any other load unless you hunt or shoot long range paper. I specifically chose this caliber for the 110gr OTM (BTHP) as an anti-personnel cartridge with similar capacity / recoil to a 5.56 or 5.45 but with superior barrier performance and wounding in a factory load. Eventually I'd like to start hand loading and work up to Constructor's 110gr OTM loads to see if I can safely get to 2700 fps from my 16" ARP barreled upper.
 

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As stated numerous times, the benefit of the ARP and other good barrels is that they run at lower pressure than the SAMMI barrels which allows them to be loaded with higher charge loads and that is where the additional velocity comes from.

Sounds like yours is running well to me.
 

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Discussion Starter #90
Might be an old thread, but I'm getting 2569 FPS average on a 16 shot string using 110gr Hornady factory loads in a 16" ARP 3R upper that running off an Adams Arms free float short stroke piston. 64F over cast day using a Competition Electronics Pro Chrono DLX about 10ft in front of the muzzle.

Hornady advertises 2570 fps for this load in a 16" barrel, so spot on, but I was honestly hoping to get in the mid 2600's as ARP and Bison barrels supposedly run faster. Lots of variables though, could be my chrono, could be changes in their factory load compared to 8 years ago and obviously these are not hot hand loads to exploit ARP's capabilities. Accuracy is at least 1/2 MOA at 50 yards (I only have a 3x magnifier with my EOTech XPS2 and not so great eye sight, not exactly a target optic setup, it's a fighting gun).

I bedded the barrel using a hybrid method of 0.002" brass shim stock glued to the barrel extension with Rocksett engineering adhesive (good for up to 2000F). That way I can remove the barrel from the receiver if I ever needed to replace either for any reason. I did not square the receiver though, it's an Adams Arms forged upper with a few machining enhancements specifically for this piston gas system.

I honestly don't see a need for any other load unless you hunt or shoot long range paper. I specifically chose this caliber for the 110gr OTM (BTHP) as an anti-personnel cartridge with similar capacity / recoil to a 5.56 or 5.45 but with superior barrier performance and wounding in a factory load. Eventually I'd like to start hand loading and work up to Constructor's 110gr OTM loads to see if I can safely get to 2700 fps from my 16" ARP barreled upper.
2700 should be easy IF you choose the right powder. Back in 2008 we were going as high as 2800 with H335 powder. Now H335 isn't the hip powder to use but it still works great for me.
 

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I also wanted to point out a simple reality in terms of anti-personnel loads, I know the typical mentality is more bigger better...except that increased muzzle energy also equates to increased recoil and reduction in follow up shot times. While that doesn't matter for most hunting applications (except maybe hogs), it does matter for two way range applications.

I know Constructor defined some criteria for military / LE loads a while back which I saved, he can chime in and confirm if necessary. Proper 6.8mm velocity is 2600 FPS +/- 50 FPS average for 110 / 115gr projectiles in 16" barrels with a minimum muzzle velocity of 2500 FPS. The factory 110gr Horandy OTM (BTHP) at 2570 fps easily meets those criteria. Pushing more energy may be mildly beneficial at closer ranges and slightly extend the expansion range (by about 50 yards), but it also increases recoil impulse which increases your split times. At what point is the energy and velocity in the optimal range?

At what point is more less optimal under combat conditions where speed is just as important as accuracy? Combat environments are very dynamic and my primary purpose for building a 6.8 SPC upper is to provide over-match capability against the vastly more common 5.56x45mm (AR-15's), 5.45x39mm (AK-74's) and 7.62x39mm (AK-47's).

There is a point of diminishing returns and it seems that based on velocity and energy available anywhere in the 2550 fps to 2700 fps range is about ideal for 110gr OTM. Take a look at the .pdf I attached from Frogspad with more of the original testing results from the 6.8 development, particularly page 3 at the wound profile for 110gr Horandy OTM at 2600 FPS (that's pretty much the 110gr OTM factory load I'm using, which my highest was 2605 fps in the 16 shot string).

Of any military loading it by far produced the most destructive results in soft tissue. While the original military loading most tested was 115gr OTM @ 2700 fps, it seems the higher BC 110gr OTM at 2600 fps has the same energy delivery at longer ranges as the hotter but less aerodynamic 115gr OTM @ 2700 fps. This gives it the same wounding capability but with a softer recoil impulse and lower splits.

Any bullet, not matter what caliber (yes even .50 BMG) can fail to incapacitate a determined target even vital organ hits (unless sit's a CNS hit which is always the exception), the speed and accuracy with which you can deliver a second blow is vital. It seems to me that if you want a bulk combat load, the current 110gr Horandy OTM factory load at 2570 FPS is pretty ideal for typical military and civilian use.
 

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BTW, the original 115gr OTM-E from a 16" hit 2675 FPS, but by 500 yards slowed to 1420 fps / 553 ft-lbs in the 6.8 SPC II Missile Wounding pdf I linked above. In contrast 110gr OTM at 2570 FPS from the muzzle slows to 1517 FPS / 562 ft-lbs from the same 16" barrel at 500 yards. Less muzzle energy from the 110gr OTM, but anything toward the longer 50% of distance there is no appreciable difference.

Basically what I'm saying is there's another way to use a higher BC projectile, that is to produce the SAME energy / velocity at longer ranges but less velocity / energy at the muzzle to reduce recoil impulse and reduce you split times with affecting it's performance to any significant degree. In contrast M855 62gr steel tip (aka green tip) only produces 1612 fps / 358 ft-lbs form a 16" barrel. That's a pretty decent over-match for 110gr OTM at 500 yards.

Or as many do on this forum, you could push the higher BC projectile out at the higher velocity and provide gains at all ranges at the expense of recoil impulse / longer split times. It's just another way of looking at it. I'd love to get into hand loading at some point and see what I can do with the ARP barrel, but even if I don't, it shoots great even not tapping into it's hand load / mil load capabilities and at the same or lower cost of competitors.
 

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What!?!?!? How darest thou slighteth the Fifty! Even if it passes within a foot of the intended victim an extremity will blow off, they will die instantly, and the round will dig their grave for them!
 

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Its great to have choices. I remember when I was debating on my 1st non 5.56 AR build one of the knocks on the 6.8spc was lack of quality .277 projectiles in that weight range. Components for the round have come a long way since then. I currently run 110 accubonds and 115 gold dots. They've both killed many deer and given me no reason to try other bullets. However, I find myself wondering about barnes monolithic projectiles. They've got their dedicated following so they must be pretty good.

Sent from my SM-G973U using Tapatalk
 

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Gents, finally got some info on the question of how "leaky" the Adams Arms free floating piston system is back from my thread on factory load performance in an ARP 3R 16" scout barrel. Well at least it answers ONE question, is the piston op-rod a leaky system and could it account for the differences in velocity between what I measured with 110gr Hornady OTM factory load and what another forum member measured in his DI Bison barreled 16" upper?

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Warmer day this time, 87F vs. 64F the last time I got 2569 FPS average (what Hornady advertises for this load in a 16"). Got another 29FPS average in velocity this time. Same gun, same ammo, same chrono, same distance between the chrono and the muzzle (10 ft measured) and same gas key setting. I also then turned the gas key to 0% or fully off. The answer to weather the piston system is leaky is an emphatic NO. At least not in terms of when the system in on vs. fully choked off.

There was only an 11 FPS difference between the gas key being set to 0% and 75% (where I have it tuned to eject at 3 o'clock in warm weather). The only other sources of a possible "major leak" would be between the gas block itself and the gas block seat of the barrel or between the gas key and gas block, but I see no evidence of a big leak, nothing out of the ordinary for this system. I suppose I could remove my hand guard and gas block, seal it with Rocksett and then re-test one more time, but I'm highly doubtful it will make any difference.
 

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Also here are some pics of the Adams Arms P-series free floating piston system that I used with my 16" ARP 3R Scout barrel (mid-length):

Note that you will need to drill out the gas port to 7/64ths, the piston cup is much smaller in diamter than the gas rings / bolt head in the carrier of a traditional DI system.

1/2 inch stroke length, you can see how much of the piston cup remains over the gas block sleeve. This prevents flash for a no visibility NV signature, keeps the op rod in line (unlike the Syrac system which has a lot of issue with wear because the op-rod is not guided and can tilt upwards causing wear on the upper receiver) and maintains gas seal for the entire time the barrel is under pressure. The op-rod only weighs 2oz.
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You can see that the gas key is not threaded, so it does NOT seize up like many DI adjustable gas blocks using a set screw or wear out. It's all heavy duty but not overly bulky like PWS long stroke system. heavy were it needs to be, but nothing more. Similar in design to the HK416's gas system but a little more simplified. Everything is nitrided for high wear resistance.
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Using a certified Mitutoyo ABS0LUTE series calibrated (goes out for cal once a year) digital micrometer, the machining is spot on.
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Adams Arms proprietary one piece forged carrier (they also make a forged one piece DI carrier to help reduce buildup of carbon in the gas passage ways and prevent carrier key issues such as leaks or sheared off screws). If I was going DI, I'd probably use their one piece carrier.
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And the end of the op-rod with the stopping collar and return spring (yes it does cycle without the spring, so even if the return spring broke, the gun would still cycle, I had a defective spring snap once on a new build). It's purpose it to make sure the op-rod fully returns over the gas block sleeve and there's a very small gap between the end of the op-rod and carrier. Once the gun goes into storage and the carbon starts to harden and make the op-rod stick a bit (same thing occurs with DI or any where tight clearances and fouling occur), the op rod only has to over come the stiction from the carbon and the spring force to start moving before it has to push the heavy BCG / buffer spring. This aids in reliability after you fire a gun, store it and then take it back out weeks or months later without cleaning it.
61913
 

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Load data. Aa2200

Where is the published data for this load. My max shows 28.6. Is this a SPC II difference? New to this caliber,.....
Depends on what you are willing to risk. I load 30 gr of AA2200 with COAL of 2.260 with no issues on my rifle. I worked that load up. Im at the upper limit of whats safe for that gun though. 30.8 and I'm blowing primers out. ARP and Bison have a proprietary chambers. So its something you have to determine if you want to take the risk.
 

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Risk seems to be an inappropriate term as used above. It seems to suggest how dangerous one is willing to be.

First, book loads for the SPCII chambers do not exist as they are for the original SPC chamber and current chambers from ARP or Bison typical develop less pressures for a given load than did the SPC sammi chamber. Second, the book always suggests that one start low and work up for any caliber that one is loading for.

Working up means we examine the brass for signs of flattening primers, gouged heads, cracked brass, etc. before going to a heavier load. We do the same for the SPCII. Typically we see higher powder loads in the SPII before we start seeing signs of over pressure and this is due to the improved chamber.

Most of the experienced reloaders here qualify their offerings with the warning, Start lower and work your way up. This worked in my gun, it's not guaranteed to work in yours.

Higher loads impart higher wear and tear on the bolt and other parts. Use commonsense and err on the low side when in question.
 

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Risk seems to be an inappropriate term as used above. It seems to suggest how dangerous one is willing to be.

First, book loads for the SPCII chambers do not exist as they are for the original SPC chamber and current chambers from ARP or Bison typical develop less pressures for a given load than did the SPC sammi chamber. Second, the book always suggests that one start low and work up for any caliber that one is loading for.

Working up means we examine the brass for signs of flattening primers, gouged heads, cracked brass, etc. before going to a heavier load. We do the same for the SPCII. Typically we see higher powder loads in the SPII before we start seeing signs of over pressure and this is due to the improved chamber.

Most of the experienced reloaders here qualify their offerings with the warning, Start lower and work your way up. This worked in my gun, it's not guaranteed to work in yours.

Higher loads impart higher wear and tear on the bolt and other parts. Use commonsense and err on the low side when in question.
Sorry thats the engineer in me, we always talk about design decisions in terms of risk haha
 
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