Soft primer strikes?

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gun'sRgood

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I've been trying everything you guys have told me to try on this .AR10 .308. While I feel I know a lot more about them I'm still running into problems. Now it's soft primer strikes. I was happily enjoying adjusting the gas block - as suggested by you folks - and was in wonder as I watched how more gas, starting from no gas, had begun to advance the cycling. A round would fire, and the bolt moved back. Add more gas and watch the bolt further retract. Just when I thought I had the right amount of gas this happened: I hand charged a round from a mag It fires and the next round is picked up and put into battery. Pull the trigger and click. No bang! I'd put another round into the mag to see if it fired and then locked back but the only way I could get a round into battery was by the charging handle. Several attempts at this all with the same results. A soft dimple to the primer. If my phone would send pics, I'd post what I'm working with. Ideas?
 
Factory ammo or reloads?

Beating the bolt open tells me the ammo is out of spec. Shoulder not in the correct position and /or bullet jammed into rifling.

Normally when you get a click and no bang, the bolt is not fully closed. This prevents the hammer from hitting the FP as it should.

Will your gun load off the magazine, and fire, lock the bolt back?

Did you check the head space of the chamber when you assembled the gun. I know from experience depending on which side of the tolerance things are at, when assembled it's out of spec.

Which part of the country are you in?
 
Did you check the head space of the chamber when you assembled the gun. I know from experience depending on which side of the tolerance things are at, when assembled it's out of spec.
Click to expand...

Let me add, did you use cartridge head space gauges in setting up your sizing dies?

ODsYmCL.jpg

90HAZQi.jpg

For a gas gun, I recommend small base dies, as you want the cases sized as closely as possible to factory dimensions. And then, you set up the dies with these cartridge head space gauges, and size to gauge minimum.

It is my opinion, your cases are either too fat, or too long, and the lugs are not going fully into battery.
 
Blue68f100 said:
Factory ammo or reloads?

Beating the bolt open tells me the ammo is out of spec. Shoulder not in the correct position and /or bullet jammed into rifling.

Normally when you get a click and no bang, the bolt is not fully closed. This prevents the hammer from hitting the FP as it should.

Will your gun load off the magazine, and fire, lock the bolt back?

Did you check the head space of the chamber when you assembled the gun. I know from experience depending on which side of the tolerance things are at, when assembled it's out of spec.

Which part of the country are you in?
Click to expand...
I'm in Tennessee, Rockwood. The ammo is factory generic stuff. Prior to getting the adjustable gas block I was getting off two rounds and the third would get pick up but not into battery. It "seemed" like the bolt was moving too fast? Hence the adjustable gas block. I do reload .308 but for this build I wanted to stick to factory to eliminate
Slamfire said:
Let me add, did you use cartridge head space gauges in setting up your sizing dies?

View attachment 988972

View attachment 988973

For a gas gun, I recommend small base dies, as you want the cases sized as closely as possible to factory dimensions. And then, you set up the dies with these cartridge head space gauges, and size to gauge minimum.

It is my opinion, your cases are either too fat, or too long, and the lugs are not going fully into battery.
Click to expand...

any other errors.
Wouldn't putting the round into battery by use of the charging handle fully seat the round? Thanks guys!
 
gun'sRgood said:
I'm in Tennessee, Rockwood. The ammo is factory generic stuff. Prior to getting the adjustable gas block I was getting off two rounds and the third would get pick up but not into battery. It "seemed" like the bolt was moving too fast? Hence the adjustable gas block. I do reload .308 but for this build I wanted to stick to factory to eliminate


any other errors.
Wouldn't putting the round into battery by use of the charging handle fully seat the round? Thanks guys!
Click to expand...

Just like I did not know you were using factory ammunition, I don't exactly know what your AR10 looks like. If it has the typical forward assist, those don't have a lot of camming power.

However, not firing with factory ammunition, the best thing to do is call the manufacturer, assuming it is under warranty. A new rifle should fire factory ammunition.
 
You said Generic Ammo, Is this reloads? If so you need to run it through a case gauge and see if it fits the gauge. To me it sounds like the ammo may be out of spec. Since you reload, load some up that you know is in spec, Shoulder in the right position, bullet not into lands etc........
 
ar10.jpg twin pins.jpg
The lower pin is the problem. The right pic is the build. Can head space change from torque value on barrel nut? There's about 50# on this one.
 
Head space is distance from the bolt face to the chamber shoulder position with the bolt locked into to barrel extension nut. The ejectors in general all have way more spring than what is needed. But that does not impact head spacing. If you can remove the 1/16" pin that hold the ejector, make sure it's not binding. It's recommended to check head space with the ejector and extractor removed from the bolt. Best to use a bolt service tool, makes it easy to remove the pin, since it loads up the ejector spring so it's not pushing on the pin.

You need to do some checking:

Have you swapped bolts to see if one works in the other? The ejector pin can be pushed in with a punch (will be hard) or just use a piece of brass under the extractor and see if it moves easily. The ejector will launch a piece of brass 10-15' with little effort. I always trim 1 coil off the spring so it does not beat the brass up during the ejector, since I reload.

At this case you need to check the chamber to make sure it's in spec with the Go/NoGo gauges. I would also use a cartridge gauge and check to ammo too to make sure it's in spec with relation to shoulder position. You can do a quick test with the ammo. Place on in the chamber and press it in with your fingers, till it stops. Then tilt the barrel up, it should fall out freely on it's own with no help. If it sticks you may need to use a cleaning rod to remove. Then paint the bullet and brass with a marker and inset again. Knock back out and see where the marker rubbed off. If no marks found it may be the shoulder position is too far forward, not sized properly. The bullet may have little cut marks on it if into the rifling. It's possible the barrel did not get the chamber reamed properly. Head space on bolts can vary as much as 0.003", the chamber 0.005"? (difference between go and nogo). Tolerance stacking can throw miss matched components out of spec.
 
gun'sRgood said:
The lower pin is the problem. The right pic is the build. Can head space change from torque value on barrel nut?
Click to expand...

Lower firing pin? What is the measured protrusion? Looks about half or 2/3 of the top one.

Headspace cannot change from barrel torque on an AR type platform. It can change from swapping bolts, but not bolt carriers.
 
Blue68f100 said:
Head space is distance from the bolt face to the chamber shoulder position with the bolt locked into to barrel extension nut. The ejectors in general all have way more spring than what is needed. But that does not impact head spacing. If you can remove the 1/16" pin that hold the ejector, make sure it's not binding. It's recommended to check head space with the ejector and extractor removed from the bolt. Best to use a bolt service tool, makes it easy to remove the pin, since it loads up the ejector spring so it's not pushing on the pin.

You need to do some checking:

Have you swapped bolts to see if one works in the other? The ejector pin can be pushed in with a punch (will be hard) or just use a piece of brass under the extractor and see if it moves easily. The ejector will launch a piece of brass 10-15' with little effort. I always trim 1 coil off the spring so it does not beat the brass up during the ejector, since I reload.

At this case you need to check the chamber to make sure it's in spec with the Go/NoGo gauges. I would also use a cartridge gauge and check to ammo too to make sure it's in spec with relation to shoulder position. You can do a quick test with the ammo. Place on in the chamber and press it in with your fingers, till it stops. Then tilt the barrel up, it should fall out freely on it's own with no help. If it sticks you may need to use a cleaning rod to remove. Then paint the bullet and brass with a marker and inset again. Knock back out and see where the marker rubbed off. If no marks found it may be the shoulder position is too far forward, not sized properly. The bullet may have little cut marks on it if into the rifling. It's possible the barrel did not get the chamber reamed properly. Head space on bolts can vary as much as 0.003", the chamber 0.005"? (difference between go and nogo). Tolerance stacking can throw miss matched components out of spec.
Click to expand...
I did swap bolts. The Black Rain bolt hits the upper in the new build. Please see pic. IMG_1332.jpg
That mark just above the black mark on that cleaning rod is where the other bolt hits. This may have started when I was using a different ammo. With low stock, I went to a white box type of ammo. I've never taken a pin out of a bolt. Any University of U tube to go watch? Thanks. And why would the Black Rain not fit this upper?
 
Hey all you helpful people! I took apart my first and second BCG's. That's not why I here. but thanks for the brain power. So I took the black rain lower and put it on the new build. I pulled a few rounds to check primer hits. The black rain hits the primer just fine. So hammer spring? This is a Geisselle two stage. But a weak hammer spring seems to make sense? What would you suggest? Call Geisselle? I've got a few trigger parts. Do AR 15 and 10's share parts on triggers?
 
That indicates a head space difference between the bolts. One is positioning the bolt back farther so it's not getting full contact on the FP.

Most AR-10, AR-15 use the same ignition parts. Some AR-10's have a larger pin size.
 
When put the black rain lower onto the build upper it fires. So the bolt is working? I'm now thinking trigger?
 
gun'sRgood said:
View attachment 988989 View attachment 989054
The lower pin is the problem. The right pic is the build. Can head space change from torque value on barrel nut? There's about 50# on this one.
Click to expand...

In all of your swapping did you only swap the bolt keeping the BCG as built?

There is a spec on the BCG as to where the hammer comes up through to impact the FP. The area on the bottom used to cock the hammer.

Did you use any shims on the barrel to align the gas port? If so where are they located? If shims were used and placed between the barrel extension nut and Upper it moves the barrel further out. This could cause a BCG to hit the upper housing depending on spec tolerance.
 
Blue68f100 said:
In all of your swapping did you only swap the bolt keeping the BCG as built?

There is a spec on the BCG as to where the hammer comes up through to impact the FP. The area on the bottom used to cock the hammer.

Did you use any shims on the barrel to align the gas port? If so where are they located? If shims were used and placed between the barrel extension nut and Upper it moves the barrel further out. This could cause a BCG to hit the upper housing depending on spec tolerance.
Click to expand...
Thx, I will try the swap as you suggest. The BCG hits the new upper, but I did not think of trying just the bolt and pin. Thx, I did try swapping triggers. Nope. Also plan on looking at barrel and nut shims. Thanks buddy!
 
The BCG should not be hitting the upper. If so it is preventing the bolt from fully closing, going forward. That needs to be addressed.

There is currently 2 different specs out for the AR-10. The differences is the bolt and barrel. They are not compatible with each other.
 
Blue68f100 said:
There is currently 2 different specs out for the AR-10. The differences is the bolt and barrel. They are not compatible with each other.
Click to expand...

I've not found that to be a problem. I used an Aero Precision (DPMS spec) barrel on a Spikes Tactical (LR 308 spec) upper with no issues. Also using an Aero Precision bolt carrier group in the same build.
AR-10 (Armalite spec) and LR 308 (DPMS spec) uppers and lowers are incompatible, but that is obvious when you look at them. Low and high profile upper receiver rails differ by 1/16" in height, but will work with railed forends of either height, although it will look odd. There are three different barrel nuts threads - 1-5/16" x 18, 1-7/16" x 18, and 1-7/16" x 16. That will dictate the forend that you use to some degree because a lot of them use a proprietary barrel nut that may not be available in all thread pitches..
 
Blue68f100 said:
The BCG should not be hitting the upper. If so it is preventing the bolt from fully closing, going forward. That needs to be addressed.

There is currently 2 different specs out for the AR-10. The differences is the bolt and barrel. They are not compatible with each other.
Click to expand...

What a tangled weave the OP presents. Have to keep pulling on the threads to find out that he is swapping parts out assuming that they are all interchangeable.


“It ain’t what you don’t know that gets you into trouble, its what you know for sure that just ain’t so.”

Not only is there no law that all AR10 parts have to be fully interchangeable between all manufacturer's, they will sue if someone copies their "fit". They don't want you using someone else's part in their assemblies, they want you to use their parts in their pieces.

So the problem is, the OP is building some sort of a parts gun and finding that not everything fits together they way he wants.

The best solution for the OP is to figure out what is not working, or find a gunsmith who can make all the pieces work.
 
Slamfire said:
What a tangled weave the OP presents. Have to keep pulling on the threads to find out that he is swapping parts out assuming that they are all interchangeable.


“It ain’t what you don’t know that gets you into trouble, its what you know for sure that just ain’t so.”

Not only is there no law that all AR10 parts have to be fully interchangeable between all manufacturer's, they will sue if someone copies their "fit". They don't want you using someone else's part in their assemblies, they want you to use their parts in their pieces.

So the problem is, the OP is building some sort of a parts gun and finding that not everything fits together they way he wants.

The best solution for the OP is to figure out what is not working, or find a gunsmith who can make all the pieces work.
Click to expand...
I agree with you. It's just that I want to be the person who eventually figures it out. I've learned more from the problems with this build than the dozen or so AR15's I've worked on. I can not thank you guys enough for the help, direction and generosity of your time. Thanks guys!
 
gun'sRgood said:
I agree with you. It's just that I want to be the person who eventually figures it out. I've learned more from the problems with this build than the dozen or so AR15's I've worked on. I can not thank you guys enough for the help, direction and generosity of your time. Thanks guys!
Click to expand...

I do wish you the best of luck. Things made from parts that are not 100% interchangeable can be very frustrating. Do expect to bust something. We learn more from our failures than our successes. There is a vast amount of material on the web, and always check out YouTube. Someone has encountered the problem of fitting a AR 10 bolt before. I was so luckily to find lots of videos on how to completely disassemble and reassemble a Ruger MKII, and install a trigger and sear. I would never have figured that out by myself.
 
Blue68f100 said:
The BCG should not be hitting the upper. If so it is preventing the bolt from fully closing, going forward. That needs to be addressed.

There is currently 2 different specs out for the AR-10. The differences is the bolt and barrel. They are not compatible with each other.
Click to expand...
Thank you for all of your time. Very meaning full. I have interchanged every part of the black rains' build with the green build. Part by part and in combinations. I also tried putting the complete black rain lower on the green upper. Always the same lite FP strike. The only part that will not interchange is the black rains' BC. I marked the PF head and tried several hammer strikes with each trigger. Both ended up with only a slight pick up of the FP's head. I added a patch of duct tape to the head of the FP and it works just fine. Any way and with any of the parts. I am pretty sure that this method is not in the Gunsmiths Handbook. If I could, please look at the attached las7.jpg last3.jpg last 2.jpg pics and let me know if there's something you might see that I am missing. Thank you. All the beer and BBQ at any time.
 
Can't tell by the the photo of the lower. A quick check to see if the hammer pin location is close to spec is see if the hammer face is forward of the front well face. The face of the hammer should be close in alignment with bolt lock catch. Another words the hammer face over hangs the forward face of the well.

PM sent.
 
Blue68f100 said:
Can't tell by the the photo of the lower. A quick check to see if the hammer pin location is close to spec is see if the hammer face is forward of the front well face. The face of the hammer should be close in alignment with bolt lock catch. Another words the hammer face over hangs the forward face of the well.

PM sent.
Click to expand...
Will check, This gun used to shoot. I've tried a two stage Geissele and a drop in. Thanks for the infor and direction!
 
BBBBill said:
Correct me if I am wrong, but I have yet to see where you actually measured headspace, cartridge dimensions, and the firing pin protrusion.
Click to expand...
I'm am ignorant in how to measure head space. Cartridge dimensions: I've been pulling apart different factory ammo that this gun used to shoot. Keeping the shell and primer. I do have rather nice measuring tool such as Starrett calipers and micrometers. I'll go back to the university of U Tube for some education. Thanks for the advice. I'll take all that I can get.
 
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