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Discussion Starter · #1 ·
Hello,

I recently built a 16" 6.8 rifle for a friend and now I am building an SBR for myself. It will be primarily used for hogging and plinking. Plan is to run it suppressed on an Innovative Arms 762 Interceptor QD with an SLR adjustable GB. My question is that with the rifle I built for a friend I came across a buffer weight issue and did not know his ARP barrel gas port was drilled smaller thus not needing an H2 weighted buffer. I expected it to shoot harder and it didnt.

With the SBR could I expect the same especially running it suppressed? I know not all barrels are created equally but are the majority of their gas ports drilled tight like the ARP? I am curious because I want it to be as efficient as possible in weight and in recoil reduction. Running the can obviously will create overgassing (but not much with the adjustable GB but still...) but unsuppressed could I run an H2 weight on a 12.5 or 10.5" barrel?

Also, quick question regarding barrels. I know 12.5 is the optimum SBR length but what am I sacrificing with a 10.5? Is it much?

Thanks for the info.

Corey
 

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I run a LWRCI UCIW stock set in my LWRC SBR with an ARP 12.5 6.8 barrel. That buffer is 3.3 oz. I also shoot it suppressed with a superlative gas block set at max bleed off with 3.00 ejection using a 6.8 Elite Iron Delta suppressor with 90 grain gold dots.

My other 12.5 has a carbine buffer and spring.

In short barrels as mentioned 10.5" vs 12.5" you'll probably average about 60 fps per inch loss from 12.5" down to 10.5"

90 grain gold dots



Sent from a final firing position, the crosshairs are on you!
 

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Discussion Starter · #3 ·
I run a LWRCI UCIW stock set in my LWRC SBR with an ARP 12.5 6.8 barrel. That buffer is 3.3 oz. I also shoot it suppressed with a superlative gas block set at max bleed off with 3.00 ejection using a 6.8 Elite Iron Delta suppressor with 90 grain gold dots.

My other 12.5 has a carbine buffer and spring.

In short barrels as mentioned 10.5" vs 12.5" you'll probably average about 60 fps per inch loss from 12.5" down to 10.5"

90 grain gold dots



Sent from a final firing position, the crosshairs are on you!
interesting.

I don't have much experience behind 6.8 rifles and forgot to mention that having the H2 weight in the rifle I just built (16" w/SLR adjustable + BCM tube + magpul stock) that I got short stroking issues. Swapped to a standard carbine buffer and BAM shot amazing. Way softer and smoother.

I was curious if similar results could be expected in 12.5 or 10.5 lengths. I haven't done much research into 10.5 but I know several well respected brands produce 12.5. Since I plan to run it pretty much 100% suppressed would I benefit from an H2 (or even an H3 weight) buffer? Especially in 10.5 I'd assume there is some decent overgassing but with the adjustable in sure it's mitigated well like my other SBRs.

The ultimate question is would I lose any real utility from the rifle if I chopped it to 10.5 VS 12.5? I wouldn't be engaging a hog further than 400yds more than likely and probably won't shoot paper or bang steel past 500 (well... Attempt to at least :p).

Yes. 2 inches is pretty petty to ridicule but I also want to recess the can under the handguards too. Would love for the OAL of the barrel profile + can to be in the ballpark of 16". 18 is pushing it for something I just want to hog with. But then again we all could benefit from the extra length (giggidy).

Im rambling. Appreciate the help and creative input.
 

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Nothing scientific or any data to support my finding, but here is what I have experienced.

My first go with a 6.8 shorter barrels, I started with 10.5 and ran that for about a year. Found that my DRT (drop right there) average dropped significantly when compared to my 16" version. Since I don't like hunting for recovery I tried 12.5" and the average I was accustomed to came back.

Keep in mind I typically never shot past 200 yards and based on the numbers I probably wouldn't unless I could put multiple shots on target. In addition I always end used standard buffers, springs, and a full auto carrier. Of course adjustable gas blocks where used to tune the rifle.

The other thing I liked about a 12.5" vs 10.5" is that I could get one in mid length gas, which created a similar recoil impulse as a 16". Also with my K can it was the same length as a non suppressed 16". So in a way it created a gun that performed about the same and had the same length but suppressed.

Like I said nothing scientific or hard data just my personal experience with short barrels in the 6.8.
 

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Discussion Starter · #5 ·
Nothing scientific or any data to support my finding, but here is what I have experienced.

My first go with a 6.8 shorter barrels, I started with 10.5 and ran that for about a year. Found that my DRT (drop right there) average dropped significantly when compared to my 16" version. Since I don't like hunting for recovery I tried 12.5" and the average I was accustomed to came back.

Keep in mind I typically never shot past 200 yards and based on the numbers I probably wouldn't unless I could put multiple shots on target. In addition I always end used standard buffers, springs, and a full auto carrier. Of course adjustable gas blocks where used to tune the rifle.

The other thing I liked about a 12.5" vs 10.5" is that I could get one in mid length gas, which created a similar recoil impulse as a 16". Also with my K can it was the same length as a non suppressed 16". So in a way it created a gun that performed about the same and had the same length but suppressed.

Like I said nothing scientific or hard data just my personal experience with short barrels in the 6.8.
sometimes it doesn't matter how much data you post it's all about the perception end of day results. I am surprised there is a significant DRT difference between the two lengths and this is very important to me. So I think you helped me make my decision with that. But if it's +/- 60fps per inch do you think 120fps is the deal breaker?
 

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sometimes it doesn't matter how much data you post it's all about the perception end of day results. I am surprised there is a significant DRT difference between the two lengths and this is very important to me. So I think you helped me make my decision with that. But if it's +/- 60fps per inch do you think 120fps is the deal breaker?
Not sure, on paper it shouldn't.

When I say less average in DRT's that doesn't mean everything I shot at didn't DRT, just noticed recovery difficulty become more apparent when switching from 10.5 to 12.5. Now that 10.5 was a noveske and the 12.5 was an ARP, perhaps that had something to do with it? Don't know I don't have the time figure out why, I am more interested in results than data and my current set-up with a 12.5 ARP puts them down just as good as my 16" ARP.

Maybe it was because I was only using 120gr pills and never tried anything else, however I am not interested in changing my favorite pig round that does so well on pigs plus they are cheaper than say 100 accubonds and easier to find.
 

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Nothing scientific or any data to support my finding, but here is what I have experienced.

My first go with a 6.8 shorter barrels, I started with 10.5 and ran that for about a year. Found that my DRT (drop right there) average dropped significantly when compared to my 16" version. Since I don't like hunting for recovery I tried 12.5" and the average I was accustomed to came back.

Keep in mind I typically never shot past 200 yards and based on the numbers I probably wouldn't unless I could put multiple shots on target. In addition I always end used standard buffers, springs, and a full auto carrier. Of course adjustable gas blocks where used to tune the rifle.

The other thing I liked about a 12.5" vs 10.5" is that I could get one in mid length gas, which created a similar recoil impulse as a 16". Also with my K can it was the same length as a non suppressed 16". So in a way it created a gun that performed about the same and had the same length but suppressed.

Like I said nothing scientific or hard data just my personal experience with short barrels in the 6.8.
TLM recently noticed the same thing with his SBR

OP--400 yards is pretty far for a 10" barrel, it's even pushing the 12" barrel a little to, heck, its even a push for some 16" barrels -- you might look at your expansion thresholds and energy retained before shooting at those distances on game
 

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I have an 11.5" barrel and with an YHM ULT it is roughly the same length as a 16" w/ A2.

Carbine buffer, adj gas block. Don't notice a difference with an unsuppressed 16 upper on the same lower.

I suspect DRT ratio vs a 16" coulld be maintained by using a softer or easier opening bullet. Finished the SBR a little bit ago but haven't taken it hog hunting yet.

JPK
 
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