|
|
Post by cgbills on Aug 16, 2016 6:03:31 GMT -8
I am planning on doing a 243lbc build and I would like some input as to barrel length/contour for my needs. I want to do an SPR type build that will fill the roll between my 5.56 SBR and my 7WSM bolt gun, both in range and maneuverability. As a secondary usage I want to use it as a hunting rig. I previously had an 18in 5.56 for this role, but was dissatisfied with its wind deflection at 600 yards. I feel the 243lbc will fill this role nicely
The big thing to keep in mind is this build will be shot almost exclusively suppressed. I do not want a super long barrel as the suppressor is going to add about 8in (the can is a Specwar 7.62). I know with rounds like the 6.5 creedmoor, a suppressor makes up for about 4in of barrel velocity loss. I have read here that 20in is generally the recommend minimum for 243lbc, but I would think shooting an 18in barrel suppressed would make up for velocity loss. Would a 18 or 20 inch be more suitable to what I want to do, and what kind of velocity differences are we looking at? Also can I run a rifle length gas on a 18in 243lbc? I plan on running an adjustable gas block.
Next is barrel contour. I think I would like a SPR type contour to help with sustained fire, and to limit point of impact shift if I ever had to shoot unsuppressed. Which of BHW contours replicate an SPR type profile? Also is a SPR type contour a little heavy for my needs?
Finally, what barrel twist? I will not be shooting anything lighter than 90gr and possibly up to 105s.
Any input or insight is much appreciated as I do not has any experience with this round. |
|
|
|
Post by GLSHOOTER on Aug 17, 2016 6:50:39 GMT -8
I am planning on doing a 243lbc build and I would like some input as to barrel length/contour for my needs. I want to do an SPR type build that will fill the roll between my 5.56 SBR and my 7WSM bolt gun, both in range and maneuverability. As a secondary usage I want to use it as a hunting rig. I previously had an 18in 5.56 for this role, but was dissatisfied with its wind deflection at 600 yards. I feel the 243lbc will fill this role nicely
The big thing to keep in mind is this build will be shot almost exclusively suppressed. I do not want a super long barrel as the suppressor is going to add about 8in (the can is a Specwar 7.62). I know with rounds like the 6.5 creedmoor, a suppressor makes up for about 4in of barrel velocity loss. I have read here that 20in is generally the recommend minimum for 243lbc, but I would think shooting an 18in barrel suppressed would make up for velocity loss. Would a 18 or 20 inch be more suitable to what I want to do, and what kind of velocity differences are we looking at? Also can I run a rifle length gas on a 18in 243lbc? I plan on running an adjustable gas block.
Next is barrel contour. I think I would like a SPR type contour to help with sustained fire, and to limit point of impact shift if I ever had to shoot unsuppressed. Which of BHW contours replicate an SPR type profile? Also is a SPR type contour a little heavy for my needs?
Finally, what barrel twist? I will not be shooting anything lighter than 90gr and possibly up to 105s.
Any input or insight is much appreciated as I do not has any experience with this round. Personally I prefer the Standard barrel but BHW does mkae the MK12 that can be viewed on the sales site. If I were worried about weight I would go with that one with the appropriate threads, 5/, for the can. SPR is very nebulous. I did a review of pictures on the net and came up with looks like the Standard, the MK 12 and some odd ball in between. It's just a title like SOCOM that doesn't mean anything once you step away from the cartridge designation. Labels tend to be Ninja Mall sales different in many cases IMHO. I like velocity and since this won't be a CQB set up I would go 20" and nothing under 18" by any means. You are correct that most of us prefer 20" guns for the velocity and I am a big proponent of them. I actually tend to stay at 22" or longer for my guns but they are not suppressed. If 18" a mid length and a rifle for the 20". I don't care what anyone says about thousands of running RL 18" guns I want a wide pressure curve of usable gas and 18" won't cut it. Thousands running don't do you squat if you have that one in a thousand that doesn't run. Don't even ask how I know that!! I personally have never seen/read about that extra amount of velocity from a suppressor. I would have to look the data over but physics just doesn't support it in my mind in that the can drops the pressure as the bullet exits and dropped pressure doesn't accelerate the bullet. The 243 LBC is very good at long range in the wind shooting the 95 SMK's. A 10 twist will do fine for you although a 9 would not hurt you at all. I'm shooting both and can't see any difference. Just my early morning thoughts on this. One. The nice thing is you get a 10% discount from the Forum here. Greg |
|
204ar
Full Member
Posts: 70
|
Post by 204ar on Aug 17, 2016 14:53:59 GMT -8
I shoot my 243lbc suppressed, and you won't gain any noticable speed with the suppressor. Mine is 22" and I wouldn't go any shorter because I want the speed, I don't want 223 velocities. I have a 1-8 though I had wanted a 1-9. It shoots well enough that I don't worry about it. I'm shooting 55's at 3410 fps, though they can be pushed a bit faster, and 85's at 3000. I haven't messed with much heavier stuff because I have so many of the lighter ones and they serve my purposes. Also mine is a standard contour, I consider it about perfect.
|
|
|
|
Post by cgbills on Aug 22, 2016 9:12:53 GMT -8
|
|
|
|
Post by GLSHOOTER on Aug 22, 2016 9:52:38 GMT -8
So if I read this right as both barrels broke in they got faster. Adding the suppressor to the short barrel added 18 FPS and still was not the same speed as the longer tube. Hardly enough to lay it out as a major improvement as the short barrel increased in velocity as it broke in also. Performance wise the variation from short to long of less than 50 FPS is not tremendous in the field. Also the fly in the ointment is that these are two distinctly different barrels. The variation from one barrel to another of similar length and the same ammunition may well vary as much as 100 FPS per my testing on hundreds of 308 precision rifles in my former career. I would say that the that short barrel was a fast one for length. The only way to prove it would be to cut the long one back to 22" and try it again. An interesting study and thanks for posting it up. Velocity wise I have never seen a huge increase in speed in a BHW barrel as it is shot. I suspect the polygonal rifling does not decrease in friction as it has no sharp lands to round off. We have seen inch for inch that the speeds will pretty much equal 2" more barrel in the BHW compared to a longer barrel due to the smoothness of the bore and the three groove design. Greg |
|
