Butch Lambert
Active member
For you that don't know gasgunner, he is probably the best AR smith out there. He is also a nationally known marksman.
Welcome to the forum.
Butch
Welcome to the forum.
Butch
Drilling gas Port AR15
- Thread starter stall
- Start date
jackie schmidt
New member
Welcome, John
Good to get some info from a real expert.
While we have your attention, have you given any thought to the IBS's allowing AR's to compete at Registered Benchrest Matches. Your opinion would be highly regarded.........jackie
Good to get some info from a real expert.
While we have your attention, have you given any thought to the IBS's allowing AR's to compete at Registered Benchrest Matches. Your opinion would be highly regarded.........jackie
M
mike in co
Guest
John h ???
Butch Lambert
Active member
And you are an AR guy Mike.
Butch
Butch
M
mike in co
Guest
butch,
i quit shooting cmp/dcm about the time i started the ar br guns. there is/was a gasgunner on a couple of forums, but i never asked who he was. g david tubbs use to hang out on one of the boards till some idoits from....well company shills...started hyping stuff that was not legal for the classes. lots of people left and now hang out on us national match.
i just don't know all of them by thier screen names...
mike in co
Butch Lambert
Active member
Why don't you search John Holliger and White Oak Armament.
Butch
Butch
G
gasgunner
Guest
I had heard rumor of this, but to be honest, ever since the election we have been so swamped that I have hardly had time to stick my head out from under the lathe to see what is going on in the BR world. Without knowing details I don't really have an opinion, but I guess it would surely lead to increasing the knowledge base of what makes an AR accurate and what is a waste of time. I'd probably start with a 6PPC with whatever chamber specs popular in the BR game and go from there.
Mike, yes, it is me. I try to hide on some of these non-HP forums.
John
M
mike in co
Guest
john,
i'm a want to be expert.....and i have bought from you.
i have added a lathe to my tools and bought some reamers from ptg.
i have three ar's that are used for br competition. club for now and maybe a REAL match if i get that far.
two ar15 based rifles, a min spec short throat 223 with a 1/14 twist hart bbl, the other is a 6 ppc in a kreiger bbl......have extraction issues, going to a 6beggs...no gas system, left hand bolt handle. the third is an ar10 308 win br. 1/15 krieger, 135 bib bullets. al have 36x luepold scopes, 3" wide flat forearms.
get some more chambering experience and re-do the 6ppc to 6beggs and try again.
ohh and sort of a real gun in work ... 1000yd 300 win mag with a 30"+ broughton bbl.
thanks for adding to the site.
mike in co
aka
ar10ar15man
i'm a want to be expert.....and i have bought from you.
i have added a lathe to my tools and bought some reamers from ptg.
i have three ar's that are used for br competition. club for now and maybe a REAL match if i get that far.
two ar15 based rifles, a min spec short throat 223 with a 1/14 twist hart bbl, the other is a 6 ppc in a kreiger bbl......have extraction issues, going to a 6beggs...no gas system, left hand bolt handle. the third is an ar10 308 win br. 1/15 krieger, 135 bib bullets. al have 36x luepold scopes, 3" wide flat forearms.
get some more chambering experience and re-do the 6ppc to 6beggs and try again.
ohh and sort of a real gun in work ... 1000yd 300 win mag with a 30"+ broughton bbl.
thanks for adding to the site.
mike in co
aka
ar10ar15man
R
rcw3
Guest
Mike and all:
When I made my posting I was not trying to challenge the way others make AR's, or suggest that they don't know what they are doing. I know my findings go against the "conventional wisdom" that many respected barrel makers and rifle makers follow.
I won't debate the issue of whether it is better "in the groove" or it makes no difference being "in the groove". The evidence is visually clear that the portion of the bullets passing by the "in the groove" ports can be subjected to an impact (on the muzzle side of the port) which can rip or tear bullet jacket material off the bullet. To me that's just something to try to avoid to increase consistency and eliminate flyers, etc.
By the way, what evidence is there that all "in the groove" is somehow better than all "in the land"? Plain and simple, from the perspective of the bullet, the port all "in the land" may be better than "all in the groove" because then the portion of the bullet that passes the port is on the inset surface area of where the bullet engraved upon the lands vs being on the outside area where the bullet filled the groove. I have seen ports like that too and typically they exhibit less barrel deformation and copper jacket left behind as well.
Frankly I think the whole "in the groove" thing may have been developed a while ago by a barrel or rifle maker who used it to set their product apart and market barrels set up with "in the groove" ports. Now it almost seems like a form of repeated legend, people are convinced of it without any real conclusive information or evidence to support it (but it still keeps getting repeated and repeated and people keep believing in it).
For me, for an accuracy rifle, I'll take a 50/50 the port in my barrel every time over an "in the groove" port if I have a choice.
Robert Whitley
When I made my posting I was not trying to challenge the way others make AR's, or suggest that they don't know what they are doing. I know my findings go against the "conventional wisdom" that many respected barrel makers and rifle makers follow.
I won't debate the issue of whether it is better "in the groove" or it makes no difference being "in the groove". The evidence is visually clear that the portion of the bullets passing by the "in the groove" ports can be subjected to an impact (on the muzzle side of the port) which can rip or tear bullet jacket material off the bullet. To me that's just something to try to avoid to increase consistency and eliminate flyers, etc.
By the way, what evidence is there that all "in the groove" is somehow better than all "in the land"? Plain and simple, from the perspective of the bullet, the port all "in the land" may be better than "all in the groove" because then the portion of the bullet that passes the port is on the inset surface area of where the bullet engraved upon the lands vs being on the outside area where the bullet filled the groove. I have seen ports like that too and typically they exhibit less barrel deformation and copper jacket left behind as well.
Frankly I think the whole "in the groove" thing may have been developed a while ago by a barrel or rifle maker who used it to set their product apart and market barrels set up with "in the groove" ports. Now it almost seems like a form of repeated legend, people are convinced of it without any real conclusive information or evidence to support it (but it still keeps getting repeated and repeated and people keep believing in it).
For me, for an accuracy rifle, I'll take a 50/50 the port in my barrel every time over an "in the groove" port if I have a choice.
Robert Whitley
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MilGunsmith
Member
In the groove
The standard on all the US Gov. drawings I work with for barrels is in the groove. I do weapon barrels and EPVAT pressure barrels, if the port is not in the groove, we have problems with fouling in the transduser holes.
The standard on all the US Gov. drawings I work with for barrels is in the groove. I do weapon barrels and EPVAT pressure barrels, if the port is not in the groove, we have problems with fouling in the transduser holes.
C
criver600
Guest
Hmmm?
Whats a transduser? Does Brownells have them yet?
Whats a transduser? Does Brownells have them yet?
R
rcw3
Guest
When I read your post it almost seems suggestive that since official "US Gov. drawings" show the port "in the groove", that is somehow the conclusive and the indisputable word of God that it should be there. I might add, that's also the same "US Gov." that decided not to put chrome lining in the bores too that resulted in all kinds of M-16 functional issues and people dying because of it (i.e. the US Gov. has made mistakes too). Now the "US Gov." specifies a chrome lining, but for an accuracy build up no self respecting accuracy AR builder would use a barrel with a chrome lining.
We are on a benchrest forum, so I don't know that what the "US Gov." does on "weapon barrels" is even relevant. Speaking for myself, we only build up and sell premium accuracy uppers with premium accuracy barrels (Krieger, Bartlein, Hart, etc.), and we have no "tranduser" (sic) holes in our barrels (on your prints it should be "transducer"). Maybe for test and pressure barrels they want the port always in the same place in a barrel to try to obtain barrel to barrel uniformity to try to rule out potential port location variances that might skew their results for pressure or other testing purposes. In truth, we have no idea why the designer and drawer of those particular drawings did what he/she did, and your post does not offer any clues.
For me the issue is all about consistently great accuracy - nothing else!
Robert Whitley
www.6mmAR.com
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Butch Lambert
Active member
Guys,
Robert and John have been around the block a time or 2. Their track record stands by itself.
Butch
Robert and John have been around the block a time or 2. Their track record stands by itself.
Butch
R
rcw3
Guest
To throw another practical smithing aspect in the mix, the "in the groove" port may be workable with something like a traditional 4 groove barrel (like a Krieger) where you have a pretty big groove width to try and put the port into, but when you also get to some of the 5R Bartlein barrels and the 6 groove Hart barrels we do, the degree of difficulty to try to squeeze a port between the lands becomes somewhat unmanageable (with 6 grooves there's almost not enough room there to even do it).
Robert Whitley
Robert Whitley
G
Gundog 64
Guest
I have AR uppers from both John (4) and Robert (1). All I can say is they all shoot great.
To Robert,
Keep putting the gas port wherever you feel it does best. This 6 AR upper shot a 200 13x at 600 last year.
To John,
I only use your service uppers. Keep putting the gas port wherever you want. The upper you made on my Bartlien barrel shot a 199 7x at 600 the first time out.
As you can tell I like both of these guys work. If it makes any difference I cannot see it but they both have their own views and both seem to work at least for me. Keep up the good work and I will do my best to burn up the barrels.
John Luitink
To Robert,
Keep putting the gas port wherever you feel it does best. This 6 AR upper shot a 200 13x at 600 last year.
To John,
I only use your service uppers. Keep putting the gas port wherever you want. The upper you made on my Bartlien barrel shot a 199 7x at 600 the first time out.
As you can tell I like both of these guys work. If it makes any difference I cannot see it but they both have their own views and both seem to work at least for me. Keep up the good work and I will do my best to burn up the barrels.
John Luitink
D
dpapadimitrio@g
Guest
Mike in CO - range?
Was wondering at what ranges you shot at (benchrest), have been a long time member over at Aurora, shooting in other disciplines, and have thought of joining one of the BR matches. If you shoot over at Aurora, do you shoot your ARs there form time to time?
Thanks!
Was wondering at what ranges you shot at (benchrest), have been a long time member over at Aurora, shooting in other disciplines, and have thought of joining one of the BR matches. If you shoot over at Aurora, do you shoot your ARs there form time to time?
Thanks!
M
mike in co
Guest
yes, you can find me in the news letter under "military bolt action br"
and yes i shoot them in the club br matches
mike in co
and yes i shoot them in the club br matches
mike in co
How about the people with an unlimited budget – the USAMU?
The following is from Precision Shooting – April 1995, THE U.S. ARMY MARKSMANSHIP UNIT, Part II: Rifles and Riflesmiths by John Feamster.
“… USAMU tests have shown no significant difference in accuracy between barrels with the gasport located in a groove and barrels with the gasport located elsewhere.”
From the day I read that article, I haven’t sweated gas port location. I drive a 22 rimfire bullet to the gas port location and drill and ream – no burr, but this probably isn’t possible for high volume production.
I like Robert’s idea, simply because the worst divots I’ve seen have been in the groove downstream of the port. One divot was so bad that I sent the barrel back to the manufacturer. He was staggered and promptly sent another barrel. Unfortunately, he didn’t send it contoured, chambered, etc.
HPC
The following is from Precision Shooting – April 1995, THE U.S. ARMY MARKSMANSHIP UNIT, Part II: Rifles and Riflesmiths by John Feamster.
“… USAMU tests have shown no significant difference in accuracy between barrels with the gasport located in a groove and barrels with the gasport located elsewhere.”
From the day I read that article, I haven’t sweated gas port location. I drive a 22 rimfire bullet to the gas port location and drill and ream – no burr, but this probably isn’t possible for high volume production.
I like Robert’s idea, simply because the worst divots I’ve seen have been in the groove downstream of the port. One divot was so bad that I sent the barrel back to the manufacturer. He was staggered and promptly sent another barrel. Unfortunately, he didn’t send it contoured, chambered, etc.
HPC
L
Louis Boyd
Guest
Fouling at the gas port
Have any of you tried drilling a gas port so that it tilts toward the muzzle?
_________________________
_____________\ \__________
Toward muzzle --->
_________________________
_________________________
I did this on a barrel for a 300 Whisper used use to shoot subsonic with cast lead rather than jacketed bullets on the idea that the reduced angle would scrape off less lead as the bullet passed over the port, Noticing that a lathe bit at 0 degrees will cut but at -30 it won't cut well at all I drilled the port at 30 degrees from vertical. I did not worry about it being on a land or groove. I'm not making any claim that it's "better" but so far it seems to work as I hoped. The reason for shooting cast bullets is primarily to reduce bore friction.
I don't know if it would help to reduce jacket damage with jacketed bullets but it might be worth a try.
Have any of you tried drilling a gas port so that it tilts toward the muzzle?
_________________________
_____________\ \__________
Toward muzzle --->
_________________________
_________________________
I did this on a barrel for a 300 Whisper used use to shoot subsonic with cast lead rather than jacketed bullets on the idea that the reduced angle would scrape off less lead as the bullet passed over the port, Noticing that a lathe bit at 0 degrees will cut but at -30 it won't cut well at all I drilled the port at 30 degrees from vertical. I did not worry about it being on a land or groove. I'm not making any claim that it's "better" but so far it seems to work as I hoped. The reason for shooting cast bullets is primarily to reduce bore friction.
I don't know if it would help to reduce jacket damage with jacketed bullets but it might be worth a try.
flatlander
New member
Louis,
The angled port was what NesikaChad was referring to when he said they tilted the barrel 2* off axis.
That's something I never thought about before drilling the port in a 28" 6.5mm bbl. I just finished contouring & chambering for a DPMS AR10 in 6.5x47. I set it up as level as I could get it in the mill vise, dimpled the port location with the smallest center drill I had, then drilled through with a 1/16" cobalt drill. Followed that up with a #49 (.073"), then borescoped to see how rough it looked. The Hawkeye showed nothing to worry about, but I bronze-brushed it anyway, then worked a patch saturated with IOSSO bore paste over the port location a few times, wiped the bore clean, then assembled the rifle and took it out to test fire. Like Chad said, I just kept enlarging the port dia. one # drill size at a time until it locked the bolt back on an empty mag.
I'm sure I'm not the first one to do a 28" AR10 bbl. in 6.5x47L, but some of this stuff is a little off the beaten path, so you're kinda on your own when it comes to figuring things out. I asked for and got some advice on port dia. & location for the longer bbl. from one of the guys who's posted on this thread, and it turned out to be very good advice - the rifle cycles smoothly & reliably with bullets from 120-140grs. using RS Hunter or N160, with good velocity, and without rim lift or ejector smears on caseheads.
Oh yeah - I decided not to worry about where the port came out, and it wound up being half & half, on the driving edge of a land. It did copper foul for awhile, but stopped after 5-6rds. had been fired. Based on the port's appearance after approx. 100rds., I'd rather it had come out on the non-driving side of the land, or set the barrel up for the angled port. Not sure whether it's going to make any difference in the long run - only time will tell.
The angled port was what NesikaChad was referring to when he said they tilted the barrel 2* off axis.
That's something I never thought about before drilling the port in a 28" 6.5mm bbl. I just finished contouring & chambering for a DPMS AR10 in 6.5x47. I set it up as level as I could get it in the mill vise, dimpled the port location with the smallest center drill I had, then drilled through with a 1/16" cobalt drill. Followed that up with a #49 (.073"), then borescoped to see how rough it looked. The Hawkeye showed nothing to worry about, but I bronze-brushed it anyway, then worked a patch saturated with IOSSO bore paste over the port location a few times, wiped the bore clean, then assembled the rifle and took it out to test fire. Like Chad said, I just kept enlarging the port dia. one # drill size at a time until it locked the bolt back on an empty mag.
I'm sure I'm not the first one to do a 28" AR10 bbl. in 6.5x47L, but some of this stuff is a little off the beaten path, so you're kinda on your own when it comes to figuring things out. I asked for and got some advice on port dia. & location for the longer bbl. from one of the guys who's posted on this thread, and it turned out to be very good advice - the rifle cycles smoothly & reliably with bullets from 120-140grs. using RS Hunter or N160, with good velocity, and without rim lift or ejector smears on caseheads.
Oh yeah - I decided not to worry about where the port came out, and it wound up being half & half, on the driving edge of a land. It did copper foul for awhile, but stopped after 5-6rds. had been fired. Based on the port's appearance after approx. 100rds., I'd rather it had come out on the non-driving side of the land, or set the barrel up for the angled port. Not sure whether it's going to make any difference in the long run - only time will tell.