Ok, if/when/however long the ban goes away, I hope to have enough money to build some things.  One of these is a GP rifle with the least amount of compromises.  I would like it to have a mid-length gas system, chromed-lined, 1 in 7 twist, 16 in barrel to go with the mid-length sir system.  Will this ever be available?  Can I cut down a 20?  Are the gas ports drilled before or after chroming?  Would this work?  Next question

 Would there be any advantage going to a heavy barrel?  I know they say there is no difference in accuracy with chrome?  Is this really true?  I want to shoot 75 grain bullets out to 600 meters and put them on a 18X18 steel plate.  And be able to do it 5-6 times a minute, is this possible with a heavy profile or a light profile barrel?  Of course this depends on the shooter.

 Can a TA31 reach out that far with just 4 power?  That was my choice since the Big ACOG BDC chart says it will match up with NATO pressured ammo, which is what I would like to shoot sometimes, for 0-300 it isn't important.

 I know all of Bushmaster's standard rifles carry HB for cost reason.  Can someone give me a dimensioned profile sheet for one of these barrels?  Are they .75 instead of .625?  I think this is what they are.

Anyone with a 16inch heavy barreled SIR'ed rifle care to comment on the weight and handling characteristics?

So, barrel availability, barrel weight, barrel accuracy are the questions.

Basically, I want a do-all and a be-all, without having a tricked out, expensice, CDS-afflicted(can't do shit!) rifle.  Is it possible?

Thanks!

Gotta ask the manufacturers that one


Yes if the gas port is opened up


No


No we are all lying to you... [rolleyes]


Yes.

Of course - the optic just allows you to see better.  Consider in WW1 the 'sniper optics' were in the 2.5x range.

So a 4x optic at 600M would make the target seem like they were at 150M.  If you know how to compensate for wind - and the target is stationary - it should be do-able.


BM HBVR barrels (like most mfg's) are around .98" under the handguards and .750" from the front sight to the muzzle.


16" HBARs are pigs IMHO - adding the weight of a SIR will just make it worse.

Sorry about that, I lacked clarity, could I have a 20 cut down and have the gas port moved to proper midlength configuration?



What about heating up?  If the accuracy is there even with a pencil pipe, then the issue for me would be,"For how many shots?"  I think 5 shots per minute is what I would like.  This is like 40% of sustained fire rate, so I wouldn't think it would have too much heat to open the groups.



Gee wiz... I really feel dumb now, I had never thought of it like that before, thanks!


Thanks!  I guess I will have to do some math and find out what a .75" all the way barrel would weigh.  Again, the if you guys say chrome barrels are at the same level of accuracy lightweight versus M4 versus HB, then I want [i]just enough[/i] to keep it from shotgunning at the aformentioned rate of 5 rounds per minute.




I didn't think that the SIR weight that much.  In fact, I thought that a bare SIR weighed a couple ounces [i]less[/i] than standard handguards.  It is the stuff you put on that makes it want to take a nose dive.  But as I thought, you and many have stated, HBARs are for matches and benchguns.

A Pencil barrel, if freefloated, should not give you any troubles shooting 5 shots a minute.

Far be it by me to prophesize - but I think you might be finding 16" Midlength chrome barrels becoming available.

Unless people realise that some nice SS barrels are holding up well too...

 

So I can't have a new gas port drilled?  I know they have to drill them sometime[;)]  But do they do it before the chroming process, making it a no-no to move the port?

So your 20 to 16 inch barrel looks [b]kinda[/b]    like a dissy, except without the shaved gas block under the handguards?  How much barrel is there after the port?  Do you have a flash hider?  Works great is kind of unclear, I know you said that it did everything from 40 grain V-MAXes to 75 grain OTMs, so I guess that is great.

 Normally, now, this is just what I have read on shorties, if you open up the gas port, it really rips the brass out of there too fast and batters the gun.  .110" is almost max if I remember, does this work because there is so much more cushioning volume compared to a really short upper?  How hard does it cycle?  Fast?  Sluggish?  Compare to a standard carbine or a a 20?

I am interested as you can tell, and I don't remember you ever posting any pictures of it, so I guess what I am saying is...[bounce]pretty[bounce] pretty[bounce] pretty[bounce] please[bounce], can you post a picture of it?

Thanks!

Kevin, what do you mean exactly on that last line?  That SS would last a long time?  I am just confused about that last line.  I know that all barrels last longer if you shoot them slow, but I want chrome because I enjoy shooting as fast as I can get a proper sight picture, and I have been told/learned through AR15.com that chrome is better for these types of things.

Kevin, what do you mean exactly on that last line?  That SS would last a long time?  I am just confused about that last line.  I know that all barrels last longer if you shoot them slow, but I want chrome because sometimes I enjoy shooting as fast as I can get a proper sight picture, and I have been told/learned through AR15.com that chrome is better for these types of things.  Would new-arguy's barrel have been able to print those awesome types of groups after the mag dumping rail systems test if it had not been chrome?

Heating up isn't really an issue.  This isn't a full-auto rifle you're building.  At 5 rounds a minute you can fire indefinately.

Will there be a shift in point of impact?  Sure but it inconsequential.  Consider if you're making 600m shots (WTF and under what circumstances would you?) it will be slow fire and it won't be an issue.  At ranges where you might conceivabley be firing 5+ rounds per minute (under 100 yards) you won't notice the change in accuracy - this isn't bench rest shooting.  The Lightweight pencil barrel will do fine (especially if you free float it).

BTW a SIR C adds more than half a pound of weight more than standard handguards.  If you're looking to loose weight then opt for the Bushmaster Aluminum 'V-Match' handguards (which will save you almost a quarter pound over a standard carbine).

Several recent military guns have been had in SS.

What do you really want out of this barrel?

As I was going to suggest one of two things if you wish to get a 16" 1:7 Midlength Chromed lined barrel int he short (less than 6month) time frame.

1) Go with a 1:8 or 1:9 Midlength Chrome barrel
2) Go with a 1:7 SS from Krieger or Douglas.

Obviously the Chrome will last longer while the SS will be more accurate (all things being equal).

Since you are not interested in full auto fire and your 'quick' rate of fire is rather slow I would suggest you would not have a life issue with a SS barrel.

I have seen rifle team 1:7 Chrome barreled guns go + of 20k (these dont go the field and rarely go F/A).  Now the SS Match barrels can go 8k+/- depending upon how you clean and if you load hot etc.

Ok, I think you guys have finally beat it into my head.  My max rate of fire that I can ever think of doing in the past and something that I will probably never exceed would be 3-20 round magazines in about 90 seconds.  So that comes out to be...90/60=.75 rounds a second, counting mag changes of course, so that is an average.  Learnt info from ARFCOM is that cook-off rate is 60 sec/180 rounds = 3 rounds per second.  So I would be doing at max, 25% of that.  I am guessing that barrel damage happens at the rate of 120-130 shots a minute?  That is using separate magazines.  So I am well in the clear.

So any time I will be doing fast enough shooting to cause an impact shift will be under 200-300 yards and thus of no real problem.  Any shooting out far will be much slower and thus no heat related impact shift.

So if a lightweight chrome-lined barrel will do this, then why do we have anything different?  What is the exact profile of the SPR barrel?

Why do I want to shoot at 600 yards?  I don't know, maybe it is so I can get some use out of the BDC on the Trijicon?  The challenge?  A sense of accomplishment if I hit it?  Why do some people take 20 seconds on every shot trying to hit a 1 inch swinger@25 yards with a mark II ruger?  Probably the same reason I like to shoot the 6 inch centerfire steel disks@25 yards 5 times in about 1 second just to watch them slowly fall over.  It makes me happy.

18x18 inch steel plate at 600 yards out of a free-floated 16 inch lightweight barrel huh?  It sounds hard when you say it, but I just got the yardstick and marked it out on the chalk board, doesn't seem so awfully bad.  It would take some doing, but not impossible.

 Kevin, you have done some long range work with 14.5s haven't you?  What is some of the stuff you have done?  Ammo?  Size of targets, range, etc?  I would like to hear what various people have done at extended ranges, +300 yards.

I have shot 14.5's out to 900m (just for shits and giggles) - and 600m regularily.

Most of the shooting was done on the fig 11 and fig 12 tgts  - with most stuff past 400M being a 4ft screen with the 11 or 12 on it.  One (very good) day I was hiting head tgts and head shaped ballows at 600m, and same at 400m in the sitting (very close to 1 MOA tgts at 600M) close enough for gov't work...


Ammo has been majority of SS109 type, along with 75 and 77gr.


As far a a midlenght goes - I would like a 1:7 Chrome - but until then a Krieger or Douglas 1:7 SS Match barrel would not leave me feeling underarmed.

I've done a bunch of shooting on military ranges out to 500M.  Targets were the 'Plastic Ivan' types about 19" wide by 40" tall.

My rifle was a Bushmaster M4/AK (14.5" M4 barrel) with a C7 type upper.

With a Reflex (6moa dot) I could get hits to 400M and occasionally 450m.  Shooting position was usually supported in some way (I rested the rifle on 'cover').

When I popped on a Leapers 4x (Colt clone) scope I could farily consistantly get hits at 500M with Q3131A (assuming I was prone and using my bipod).

Now when I used my buddies 24" VMATCH with a decent scope I was getting hits at that range was much easier (fewer targets needed a second attempt).

Forrest,

What is a "plastic Ivan type"  I am guessing it is some kind of a maniquin?  I have seen plastic man targets that are 3D.  Not all the way around, just a plastic shell so they can all fit in a stack.  I might get some of those.

Kevin, hitting almost 1 MOA at 600 meters? Is this with iron sights? That is really good either way.  How often did you just hit the body of the target?  I don't know what fig 11 and fig 12 mean so please tell me.  Do you see an advantage of accuracy and easier to hit at long range with 75-77 grain versus SS109?  Wind drift?  Trajectory?

Thanks everyone!  This is really helpful!

The 'Plastic Ivan' is a plastic shell kind of target.  Its 3Dish - only the front half is there (back half is hollow).  Its one of the types of targets that are used on electronic 'pop up' ranges.

The targets look like Warsaw Pact soldiers carrying an AK.  Some were completely green (tough to see) others were colored in (i.e. face/hands were peach, wood on AK was brown etc).

The targets you've seen sound like the Ivans - if you have a source could you let me know?  Thanks!

123,

No optics (I only use Irons for Back ups these days)

Th 75/77 will have less wind drift - but the major advantages are terminal performance (not a big reason to switch if you just plan on shooting paper) and accuracy as the US M855 ammo is not too good in that department.

I prefer the most accurate combo of rifle and ammo that I can get as long as it does not affect realiability or terminal potential.

Me too.  I couldn't find anybody who made one.  

Here's what I did find:
Mid-length, chrome-lined, but 1/9 from Armalite.
Mid-length, 1/8, stainless from RRA.
Chrome-lined, 1/7, but shorty HGs from Colt, BM, DPMS.
You could take the chrome 1/7 shorty and put on a second gas block in the mid-length position; sort of a mid-length Dissipator.
You could take a chrome 1/7 20" and cut it down to 16" sorta like a Dissipator but w/o the second gas system.  (I think Troy had KKF do this.)

I couldn't find anybody that had a chrome-lined 20" w/o gas port drilled to turn into a 16" and Kurt thought the extra gas port would cause accuracy problems if he did it to one with the port.  

I went with the 1/8 SS mid-length from RRA.  1/8 should be fast enough for the 75/77gr ammo (I just orded some 75gr from GPSS so I'll find out as soon as I get a free weekend).  I plan to send it to KKF this fall and have it turned down to an "A2" profile.  

If you can live with 69gr and lighter I'd go with the Armalite since it's already an "A2" profile.

Another option might be to go with the shorty barrel, mill the sight base so a mid-length rail system will fit over it and then put a sight on the top rail.

Thanks!  Especially about drilling another gas port in a barrel.  If that is what Kurt thinks, I would guess that it would most likely be true.  However, if a person [b]could[/b] find a 20 without the gas port drilled...that would be hot ticket.  

But as kevin said, they will probably be out soon enough.

Let everyone know how that rifle shoots when you get a chance!