MickB
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Posts posted by MickB
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Wanna share one of those since I got you that deal on the Swaro?
Mick
quote name='BD Williamson' timestamp='1311868956' post='1499783']
I got a couple of them and they had 3 left as of 9:02 AZ time.
B
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Dwell time is the time the bullet is in the barrel right after it passes the gas port. Think of it as the time that the gas system has available to operate under pressure.
The AR15 was optimized for a 20" barrel. When the carbines were first developed, they had very little barrel in front of the gas port and there were all sorts of problems. Basically not enough operating (dwell) time, so they opened up the gas port to compensate which led to a more violent, overgassed action. The engineers at Colt kept increasing the length of barrel to improve the reliability.
What you have with the M4 14.5" barrel is the same length of barrel infront of the gas port as on the 20" rifle.
So, in a 16" barrel, Armalite (Mark Westrom) developed the mid length gas system, keeping the same amount of barrel in front of the gas port as on a 20" rifle.
Noveske has done the same with the 18" barrel and the "intermediate length" gas system.
That's the short version, but I'm sure someone else will chime in...
Mick
I have two of Noveske's 18" barrels. One SPR profile, the other the lightweight profile.
The lightweight is definitely easier to swing around. Recoil impulse is also no different to a 20" with full length gas system from what I can perceive.
The reason for the "intermediate" gas system is to keep the same length of of barrel forward of the gas port as found on the rifle gas system in order to maintain the same dwell time.
Noveske says they do this to maintain reliability....
Mick
hmmmmm, i have heard the term dwell time used frequently to confuse idiots like me. where can i read more about this dwelling?
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I'm leaning towards the Nordic 18".
Any chance they will do this with the Xlong 14" float tube?
Are they still giving the 10% discount to forum members?
Mick
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I currently have a Tactical Solutions dedicated .22 upper, but am curious as to what else is out there.
I'm finding some annoying ejection issues with the Tac Sol unit.
Any thoughts on the Nordic or CMMG dedicated uppers?
How are these units for reliability and accuracy?
Mick
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I have two of Noveske's 18" barrels. One SPR profile, the other the lightweight profile.
The lightweight is definitely easier to swing around. Recoil impulse is also no different to a 20" with full length gas system from what I can perceive.
The reason for the "intermediate" gas system is to keep the same length of of barrel forward of the gas port as found on the rifle gas system in order to maintain the same dwell time.
Noveske says they do this to maintain reliability....
Mick
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Give my regards to my friend Ivar Edfeldt...
Mick
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How many versions of the LMOS carriers did JP make?
I know there was the aluminium alloy version, and the current steel versions, but were there any others?
Mick
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Sun Devil uppers do not have M4 ramp cuts.
I have two rifles built on Sun Devil uppers. One has a Colt 20" M16 gov profile barrel with standard rifle extension. No problems at all.
Other upper has a Noveske barrel with M4 extension. No problems with this upper either.
As an FYI, Sun Devil is now making an upper with shell deflector, but no forward assist...
Mick
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You tune the gas block to the weakest load that you will use.
That means test with all of them, with a dirty rifle.
I have just set mine up, but have yet to add the loctite. I'm planning on peening one of the screw threads slightly to add some resistance before I add the loctite...
Mick
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Young Super Light carrier and standard CAR buffer
Mick
Are you running a lightened carrier ? A lighted buffer ?
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Just put on a low profile adjustable JP gas block on a 20" barrel upper.
It's running a standard weight CAR buffer with a Young Super Light carrier (about the same weight as a JP lo mass carrier).
It took 4 and one third turns to get it to cycle with PMC Bronze, which ejected to 4 o'clock.
Winchester M193 ejected to 2-3 o'clock.
JP's instructions say to start two turns out and go half a turn out till the the bolt will hold open on the last round.
I'm wondering how many turns other folk's rifles took. Does 4 and a bit turns open sound typical?
Mick
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LOL! Should have asked you on Saturday, Eric!
On the long range stage, 560 yd bonus target, Winchester 55gr ball, one shot.
It was so easy to see with this scope...
:-)
Mick
quote name='ERIC' timestamp='1308082527' post='1473239']
Objective 02A
Eye Piece 20
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Saw your pics, but it had no specifics. Do you remember what Butler Creek part numbers you ordered?
Mick
Does anyone know which flip covers fit the Swarovski Z6i 1-6X scopes?
I've used the search function and came up empty handed...
Mick
I just measured the bell with a caliper and ordered a set and trimmed back the rear cover so it would fit.
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Does anyone know which flip covers fit the Swarovski Z6i 1-6X scopes?
I've used the search function and came up empty handed...
Mick
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So for those that have built up a bunch of lowers, whose lower parts kits do you consider good quality?
I've only used DPMS LPK's for a couple of builds with JP triggers for great results.
How about Rock River, Daniel Defense, etc?
Mick
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Not sure if mirage would be that much of a factor in AZ? I've never experienced it with a Larue handguard. I'm wondering if it is a factor in places like FL?
When I lived there, it was not uncommon to see the contrails of a pistol bullet due to the humidity!
Mick
No holes, no mirrage. I currently run a 15" no holes on my game gun. Never experianced mirrage with it. I have experianced mirrage as heat was escaping from the holes with other guns I have that have them.
I have used both and prefer no holes. You can not tell a differance in weight.
The sun is most responsible for heat buildup in non covered bare carbon fiber. Paint or cover it with grip tape and it will stay much cooler. Your hands will thank me when its sunny out. If you already have one with holes just cover them up with grip tape. Thats what I do with my others. A roll of 2" grip tape can be found in the paint section at Home Depot for pretty cheap.
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LOL! 14" handguard with holes on the way...
Mick
Get the holes. It looks way more coolerest!
. Plus the whole point of the carbon tube is light weight so why not make it aS light as possible? -
Talked to PRI today. Apparently their 14" and 15" handguards can be had with or without holes (the non hole versions are not listed on their website - you have to ask).
The non-hole versions are also much cheaper.
For 3-gun, does the presence of holes matter?
PRI indicated that the non-hole versions are more suited for slow fire precision rigs, but that holes would be much better for cooling in rapid fire.
Anyone have any thoughts on the subject?
Mick
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So, it comes back to overall weight of the carrier determing felt recoil impulse and reliability, then...
;-)
Mick
You guys are seriously overthinking the significance of the contact points of the bolt carrier. The hamer and buffer spring exert so much more friction and drag to the operation of the firing cycle that the tiny differance in the surfaces you are talking about would be practicly unmeasurable. Those contact surfaces do not actually make any contact at certain times during the firing cycle.
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Not quite sure I understand the first paragraph, Mark. We're talking about the force required to move the recoiling parts. The area of the carrier bearing up against the buffer face should be similar for the JP and Young SL, should it not?
Mick
So it looks like the Young's SLC setup is a tad heavier than the JP.
Maybe that will give the Young's SLC a reliability edge for those rifles without an adjustable gas block?
Mick
Actually, the reliability edge will go the other way given the same gas volume. The one thing everyone is forgetting, or ignoring, is the contact area of these carriers. They are essentially doubled (F STILL equals ma). The force to move a lighter JP given the surface area and mass is reduced as compared to a Mil-Spec. However, the momentum is reduced since it weighs less. With the SuperLight Young's, the force is slightly MORE as compared to a Mil-Spec. Both will "wear" the upper receiver less.
All of these things have interplay: barrel, bullet, powder (charge and burn rate), springs, lube, gas port size, gas reduction via adjustment, buffer weight. Get too light with a non-suitable mix of variables and you start to have extraction issues or worse. Too heavy and you only short stroke. The window is pretty large, but if you get too close to the edge...
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What would last longer out of the LW, noveske or Johnson nitrided?
I'm building another rifle and was leaning toward the 18" Noveske lightweight.
Mick
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So it looks like the Young's SLC setup is a tad heavier than the JP.
Maybe that will give the Young's SLC a reliability edge for those rifles without an adjustable gas block?
Mick
PS - tell your uncle I'll give him $200 for that old AR
:-)
Here is the weight of each carrier COMPLETE(carrier, bolt, firing pin, retaining pin), at least on my scale. NIB, no carbon build up or deposits, just oil on each from the manufacturer.
JP JPBC-3 QPQ 8.45 oz
Young MFG SLC(super light carrier) 9.30 oz
Young MFG AR-15 NM Light 10.55 oz
All of them are great carriers, pick one, tune your operating system to your liking via springs, buffers, comps and even adjustable gas and shoot more. Good technique will allow you to shoot almost anything fairly well. My uncle shoots a Colt AR-15 he bought NIB at Yellow Front(yep, that long ago) for around $135, better then I can shoot my "high-tech" modern AR. Of course he did shoot Camp Perry quite a bit, only proving my point further.
edited for typos
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Looks like the Young's Super Light carrier weighs the same as the JP LMOS carrier.
I'll measure an M16 and AR15 carrier on the same scales for additional point of reference - although I suspect I'll get the same numbers you just quoted.
Mick
The Devil is in the details. Todds post refers to BCG (bolt carrier group) and includes the bolt,firing pin, etc. His weights are only off from mine by .1 oz. for a complete BCG.
My JP Lmos carrier only weighs 6.6 oz
M16 carrier weighs 9.3
AR15 carrier weighs 9.1
Bolt group adds 2.1
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Fitted bolts = load of bollocks.
AR barrels are pre headspaced in the barrel extension.
Just get a good bolt and be done with it.
I'm sure others with more experience than myself will chime in shortly...
Mick
Surefire 60 rd mags
in Rifle - Technical
Posted
Works for me! I'm interested in seeing how well these mags run...
Mick