After a lengthy search through past posts on this issue I am still going to ask yall this question. I have a 20 psa SS upper that I put a VGA Epsilon 6.5 break on. Bought a psa lower and a build kit. Magpul stock and what appears to be a mil spec buffer/tube/spring. I am getting more recoil than I would expect with this particular break as it reviewed well in reducing felt recoil. I am running the upper as I received it from psa as far as the adjustable gas block that came on it. Brass is thrown about 4 oclock. I pulled out the buffer and weighed it this morning and it came in at 2.990 oz. So, should I adjust the gas block before messing with the buffer weight/spring. Gun has no cycling issues and is accurate with handloads. Just looking for less recoil
07-14-2021, 04:43 PM (This post was last modified: 07-14-2021, 04:53 PM by montana.)
TedBrewer5 Wrote:After a lengthy search through past posts on this issue I am still going to ask yall this question. I have a 20 psa SS upper that I put a VGA Epsilon 6.5 break on. Bought a psa lower and a build kit. Magpul stock and what appears to be a mil spec buffer/tube/spring. I am getting more recoil than I would expect with this particular break as it reviewed well in reducing felt recoil. I am running the upper as I received it from psa as far as the adjustable gas block that came on it. Brass is thrown about 4 oclock. I pulled out the buffer and weighed it this morning and it came in at 2.990 oz. So, should I adjust the gas block before messing with the buffer weight/spring. Gun has no cycling issues and is accurate with handloads. Just looking for less recoil
I assume you have a carbine buffer tube installed with the 20" barrel?? Close the gas block and then open until the mag catch reliably catches the bolt carrier on the last round. You can open it further for reliability in different operation temperatures and increased fouling.
Don't forget to maintain your adjustable gas block by putting a little oil on the adjustment screw and screwing in and out after any significant amount of shooting...
Ejection pattern is not always a fail safe indicator of pressure in the system. What you are trying to do is slow the BCG recoil velocity with the adj gas block. Heavier buffers are the other option, but I would try the adj. gas block first...
You should also check your recoil spring for stacking and test the BCG recoil length.
After watching that video I checked the spring and it checked out fine. BCG was hitting. 2 quarters later it was fixed. Thanks for that info.I will adjust the gas system at my next range trip. Got more ammo to test.
Ted the quarters are really only a temporary fix, you should take the time now that you know you have an ill fitted receiver extension and correct it by filing/sanding/milling the leading edge of the extension. The coins may deform and end up causing a faux short stroking problem, gifted my son a rifle that I had temporarily dropped two quarters in to fix its overtravel and he ended up having a cycling issue about 300 rounds in. I was checking it out and tried to remove the buffer spring and it was hanging up, odd I thought. Took a thin rod and ran it through the drain hole to push the quarter and spring out to find the quarters had deformed and weren't playing nice with the spring. Lesson learned and the overtravel is more common than one would think.
07-15-2021, 12:04 PM (This post was last modified: 07-15-2021, 12:21 PM by montana.)
Lastrites Wrote:Ted the quarters are really only a temporary fix, you should take the time now that you know you have an ill fitted receiver extension and correct it by filing/sanding/milling the leading edge of the extension. The coins may deform and end up causing a faux short stroking problem, gifted my son a rifle that I had temporarily dropped two quarters in to fix its overtravel and he ended up having a cycling issue about 300 rounds in. I was checking it out and tried to remove the buffer spring and it was hanging up, odd I thought. Took a thin rod and ran it through the drain hole to push the quarter and spring out to find the quarters had deformed and weren't playing nice with the spring. Lesson learned and the overtravel is more common than one would think.
I'm curious how your quarters deformed? What did the back of the buffer look like. What was the length of your buffer spring? Do you have pictures? JP uses plastic plugs and thin metal washers for correcting buffer tube depth with zero problems..
So Lasrites you are effectively saying I should shorten the overall length of the extension tube by the thickness of the quarters I placed in the tube. I do prefer a real fix vs a rigged fix. I will venture over to the JP sight and review what Montana referred as well.
07-15-2021, 05:32 PM (This post was last modified: 07-15-2021, 05:36 PM by montana.)
https://www.youtube.com/watch?v=WNRYWipq6As If his quarters were deformed I'm guessing the back of the buffer tube was poorly machined or something else was going on. I have used washers and I have never had any problems..This is why I would like some pictures of the inside of Lastrites buffer tube. There is always a cause for such problems, just have to find it....
This 3 piece AR10 buffer tube shim kit is designed forbuilders to address the non-standard AR10 market by allowing for adjustment in bolt carrier travel to avoid potential interference and impact of an AR10 bolt carrier with the lower receiver. Three different thickness shims are provided (.070, .100, and .140) that can used individually, or in any combination to obtain a wide variety of shim thickness, from .070 up to .310. These synthetic shims should be placed in the buffer tube, prior to installing the buffer spring and buffer. It is important to verify clearances, and function of bolt carrier, including lock back whenusing these shims.
This 3 piece AR10 buffer tube shim kit is designed forbuilders to address the non-standard AR10 market by allowing for adjustment in bolt carrier travel to avoid potential interference and impact of an AR10 bolt carrier with the lower receiver. Three different thickness shims are provided (.070, .100, and .140) that can used individually, or in any combination to obtain a wide variety of shim thickness, from .070 up to .310. These synthetic shims should be placed in the buffer tube, prior to installing the buffer spring and buffer. It is important to verify clearances, and function of bolt carrier, including lock back whenusing these shims.
The TDP spec between the gas key and lower receiver in full recoil is .138 This is approximately the same thickness as 2 quarters..
Quarters, washers, etc they are all good to go. I wouldn't over think this....
07-15-2021, 10:32 PM (This post was last modified: 07-15-2021, 10:38 PM by Lastrites.)
I had previously used the quarter trick on two other rifles for short periods of time prior to fitting the tubes properly and never had a problem. I didn't take pictures of this issue as I went into repair mode, either it was a fluke or jr. goofed up when loading the second quarter and it happened to be standing up and fell into the first coil as he reinstalled the spring and buffer. Bent the heck out of the quarter though, after I got it out I took the tube off and faced it to the proper length. Had to replace the rubber bumper on the buffer as it was mangled from the beating it was giving to the quarter. My son may still have the quarter, I'll ask when I see him. I don't recall asking him if he had removed the buffer or spring when he handed me the rifle to look it over, I don't think so though.
The rifle was a fairly new build at the time with about 200rds through it, jr put about 300 in about 4 trips, buffer tube on that one likely came from PSA, colt buffer spring from the start with proper coil count and length, eta H buffer.
TedBrewer5 Wrote:After a lengthy search through past posts on this issue I am still going to ask yall this question. I have a 20 psa SS upper that I put a VGA Epsilon 6.5 break on. Bought a psa lower and a build kit. Magpul stock and what appears to be a mil spec buffer/tube/spring. I am getting more recoil than I would expect with this particular break as it reviewed well in reducing felt recoil. I am running the upper as I received it from psa as far as the adjustable gas block that came on it. Brass is thrown about 4 oclock. I pulled out the buffer and weighed it this morning and it came in at 2.990 oz. So, should I adjust the gas block before messing with the buffer weight/spring. Gun has no cycling issues and is accurate with handloads. Just looking for less recoil
If youre running a 20 Im assuming it has rifle length gas? If so I would use an H2 or H3 buffer, whichever weighs the same as a rifle buffer. IIRC, a rifle buffer is 5.2 oz. it makes a difference. I would adjust my gas after installing the new buffer. Theres a reason rifle length gas systems use a rifle weight buffer. Just my $.02. Hope this helps.
Lastrites Wrote:I had previously used the quarter trick on two other rifles for short periods of time prior to fitting the tubes properly and never had a problem. I didn't take pictures of this issue as I went into repair mode, either it was a fluke or jr. goofed up when loading the second quarter and it happened to be standing up and fell into the first coil as he reinstalled the spring and buffer. Bent the heck out of the quarter though, after I got it out I took the tube off and faced it to the proper length. Had to replace the rubber bumper on the buffer as it was mangled from the beating it was giving to the quarter. My son may still have the quarter, I'll ask when I see him. I don't recall asking him if he had removed the buffer or spring when he handed me the rifle to look it over, I don't think so though.
The rifle was a fairly new build at the time with about 200rds through it, jr put about 300 in about 4 trips, buffer tube on that one likely came from PSA, colt buffer spring from the start with proper coil count and length, eta H buffer.
If the quarters are not placed correctly in the tube, I'm sure it did mangle the buffer....It is also wise to use a washer, since the quarter has no drain hole..
07-16-2021, 01:04 AM (This post was last modified: 07-16-2021, 01:30 AM by montana.)
ricsmall Wrote:If youre running a 20 Im assuming it has rifle length gas? If so I would use an H2 or H3 buffer, whichever weighs the same as a rifle buffer. IIRC, a rifle buffer is 5.2 oz. it makes a difference. I would adjust my gas after installing the new buffer. Theres a reason rifle length gas systems use a rifle weight buffer. Just my $.02. Hope this helps.
Rifle length buffer tubes have rifle length buffers. The Vltor A5 Recoil System mimics the the rifle length recoil system for carbine rifles.. The Vltor A5 recoil system has much more recoil impulse than my standard buffer tube with a JP SCS and no tungsten weights. These are in 5.56 cambering. The Grendel may need a heavier buffer, but not always..
It has been my experience, "to reduce recoil" the lightest buffer used with mitigated gas results in the lightest recoil. The advantage of an adjustable gas block is the ability to adjust the ammunition to the rifle. If possible, I would test both buffers, "at optimum gas setting" to find the sweet spot with reliability..
Recoil spring strength and manufacturer can also make a difference. For a standard carbine spring, the length should be between 10 1/16 to 11 1/2 inches long.
I have a rifle length gas system and a carbine buffer w/6 position stock. I ordered a Kaw Valley Precision Heavy Tungsten Buffer - 4.3oz to try. Up in weight from the 2.9 oz that I currently have. Will install and adjust gas block and report results. As always, yalls feed back is invaluable.
Y'all have brought up a problem I might have never considered in my 6 AR rifles. It turns out - after checking - that none of my rifle's BCG gas keys are striking the back of my lower receivers. I measured the gaps between my lower receivers & fully inserted BCGs: .141" to .169". The .141" is with a JP buffer spring assembly; the rest of my ARs have David Tubb springs.
So, if a BCG is hammering the back of a lower receiver, it's caused by an out-of-spec buffer tube/too short recoil spring? Eh? How common is this?
I refuse to be victimized by notions of virtuous behavior.
Old Bob Wrote:Y'all have brought up a problem I might have never considered in my 6 AR rifles. It turns out - after checking - that none of my rifle's BCG gas keys are striking the back of my lower receivers. I measured the gaps between my lower receivers & fully inserted BCGs: .141" to .169". The .141" is with a JP buffer spring assembly; the rest of my ARs have David Tubb springs.
So, if a BCG is hammering the back of a lower receiver, it's caused by an out-of-spec buffer tube/too short recoil spring? Eh? How common is this?
It is more common than many realize.. A bolt carrier that is shorter than 6.700 in length can also cause this problem, with everything else near or under spec...This can also fall under the stacking tolerance issue...
TedBrewer5 Wrote:I have a rifle length gas system and a carbine buffer w/6 position stock. I ordered a Kaw Valley Precision Heavy Tungsten Buffer - 4.3oz to try. Up in weight from the 2.9 oz that I currently have. Will install and adjust gas block and report results. As always, yalls feed back is invaluable.
That should help alleviate most of the problem with recoil. Anxious to hear your results.
montana Wrote:It is more common than many realize.. A bolt carrier that is shorter than 6.700 in length can also cause this problem, with everything else near or under spec...This can also fall under the stacking tolerance issue...
Yeah, that makes sense a too short carrier could be a problem. But that raises another question... who is making too short bolt carriers? All of mine, all made by different manufacturers, are close to the 6.7" figure you mentioned (they are all approximately 6.67"). I looked all over the place & can't find a spec for carrier length. The one diagram I found was barely readable. The length was undecipherable. Here's the drawing...
[ATTACH=CONFIG]18050[/ATTACH]
I refuse to be victimized by notions of virtuous behavior.
A good test is to see if the rear of the bolt carrier pushes the buffer back as the upper is closed on the lower. If the front of a buffer is chewed up by the buffer retainer pin or the pin itself is bent or broken, it is a sign the buffer retainer pin hole was drilled improperly or a short bolt carrier...The buffer should not impact the buffer retainer pin until the upper is opened..
