Bolt not quite closing all the way

[bohawg]

Morning everyone, tried out the new rifle this weekend. My son was in military and very familiar w/ AR's. He has a couple of different set ups he uses for hog hunting so he went along to help me out. He suggested we shoot a couple boxes of cheap ammo to begin with and then try the Hornady blacks. We shot Wolf 100 grain fmj and it shot and cycled well. " even grouped well". Then we tried the Hornady ammo and bolt wouldn't close. Finally got one to load right and when it fires it cylced good. It's the initial 1st round that you close w/ charging handle that won't completely close. Pro 2 A tactical upper w/ 18" barrel. A close friend of
mine recommended it to me, he has run 300 plus rounds thru his w/out issue. I think it's Built w/ mostly BCA components. My son says i just need to keep shooting it and then clean it. Cheaper upper may a little rough? Anyone ever have this happen? Thx, "Bo"

[A5BLASTER]

If it doesn't close when you drop the bcg with the charging handle just use the forward assist.

It may smooth out after some use. My 16 inch still does that from time to time but just with wolf fmj ammo.

Long as it runs properly and isn't over/under gassed I wouldn't worrie bout it to much, just drive it home with the forward assist and enjoy your rifle.

[lazyengineer]

New AR's often need a break-in, as indicated above. Also, for whatever reason, the 6.5 Grendel has really significant magazine drag, and takes noticeably more force to push the round forward and out of the magazine. Meaning your bolt loses more energy running a Grendel, compared to a 5.56. That too should get better with break-in and as the magazine lips smooth up on the inside.

Also, on a final note, it's not clear in your post, but make sure you do a full release/drop of the bolt. If you ride the bolt charging handle at all, it probably won't have enough force to cycle on a new gun. Lock the bolt back, and release it using the lever, for maximum force to strip and close.

[bohawg]

Thx for replies. In reference to the forward assist, we got on it pretty hard. My son finally took the rifle muzzle up and hit the butt stock on the ground while pulling charging handle back to clear the chamber. Then we kept trying as mentioned in last post, w/ full release of bolt. Our concern was the smaller 100 grain rounds cycled w/ no issue. The larger 123 grain was when the bolt wouldn't close. Now, At the end of the day, the 123's would cycle from clip. We shot 3 boxes of break in ammo and 1 box of the Hornady 123's. Came home and my son cleaned the bore and took bcg out and cleand upper also. I'm hoping that may help. Will shoot it again this weekend. My son agrees w/ you that it will need a break in period to smooth out.

[A5BLASTER]

Thx for replies. In reference to the forward assist, we got on it pretty hard. My son finally took the rifle muzzle up and hit the butt stock on the ground while pulling charging handle back to clear the chamber. Then we kept trying as mentioned in last post, w/ full release of bolt. Our concern was the smaller 100 grain rounds cycled w/ no issue. The larger 123 grain was when the bolt wouldn't close. Now, At the end of the day, the 123's would cycle from clip. We shot 3 boxes of break in ammo and 1 box of the Hornady 123's. Came home and my son cleaned the bore and took bcg out and cleand upper also. I'm hoping that may help. Will shoot it again this weekend. My son agrees w/ you that it will need a break in period to smooth out.

Take 2 of those rounds, use calibers and get each rounds measurment.

Then take one round and try to chamber it, if it does it again like you stated, pull the round out and remeasure it and lock at the bullet for land marks.

If the round is longer or much shorter. Stop shooting it and contact the company you purchased it from you may have a short throated barrel.

Anouther test is to take the upper off, remove the bcg place a round in the chamber, press it in with a finger till it stops, turn it muzzle up. If it doesn't drop free or takes a few hard taps to the upper to get the round to drop free.

Contact the company you got it from and see if they will inspect and possible replace it. Sounds like it could be short throated.

[bohawg]

10-4, Will do!

[A5BLASTER]

10-4, Will do!

It maybe possible it is just a break in issue but never hurts to check and be sure it isn't short.

Also if you should need to remove the barrel from the upper that would be a good time to lapp the reciver face and if need be bed the barrel when you reinstall it.

Lapping the reciver face will make it be square and put equal pressure on all the bolt lugs.

[sundowner]

It sounds like headspace issue , had that happen when the headspace was off on some of my reloads , check with manufacturer .

[BCHunter]

There are 4 common issues that may cause this.
1) new gun everything is tight needs to break/wear in not lubed well enough.
2) short chamber bullet is hitting lands and not fitting.
3 ) im- proper headspace this can be with the brass out of spec in your chamber,usually more common with reloads then factory ammo. Or the headspace of the bolt can be wrong for your chamber. Several threads on this topic.
4)extractor, it's common on grendels for the extractor to have teeth on edges and not be beveled correctly, as well as the ejector spring too be too stiff. There are several threads on easy modifications to correct this yourself..

Its likely you have several of this issues going on,...but most of them are relatively easy to resolve

[bohawg]

1st of all thx again for your input. I very much appreciate the fact you guys took time to try to help me figure this out. My son sent me a link to AR15.com where another Grendel owner was having the exact same issue w/ a high dollar barrel! When he started testing different bullet lengths he discovered that Hornady 123 SST would chamber correctly and cycle. My son just came by w/ 2 boxes of 123 SST's that a friend gave him for me to try. I loaded up 3 mags and pulled charging handle back and bolt slammed shut like it should! Emptied all 3 mags w/ charging handle w/ no issues, not one jammed. The ELD's have to be longer. I guess this tells us I have a " short throat issue". I will shoot the SST's for now and try to decide what I need to do. I may just buy another " better quality barrel or complete upper" and be done w/ it.

[bj139]

On a new barrel, there is sometimes a dried preservative in the chamber. Clean with a bronze brush and solvent until clean.
I had a few new barrels that were gunked up.

[FRB6.5]

I'd say contact the vendor OP and see if they will repair or replace it. They say 100% satisfaction on their site, may as well see if they live up to it.

[brian y]

Take 2 of those rounds, use calibers and get each rounds measurment.

Then take one round and try to chamber it, if it does it again like you stated, pull the round out and remeasure it and lock at the bullet for land marks.

If the round is longer or much shorter. Stop shooting it and contact the company you purchased it from you may have a short throated barrel.

Anouther test is to take the upper off, remove the bcg place a round in the chamber, press it in with a finger till it stops, turn it muzzle up. If it doesn't drop free or takes a few hard taps to the upper to get the round to drop free.

Contact the company you got it from and see if they will inspect and possible replace it. Sounds like it could be short throated.

I am bumping this thread as this is the problem I am having with my latest build, I bought an expensive barrel and matching bolt back in February and finally took delivery of it in November, Put it together and took it out for its first to day and it shot very nice and accurate.
I tried taking the upper off, remove the bcg place a round in the chamber, press it in with a finger till it stops, turn it muzzle up. If it doesn't drop free or takes a few hard taps to the upper to get the round to drop free. Hornaday Black and SST would not drop out I had to rod them to remove them,
Federal Gold Medal Berger 6.5 Grendel Ammo 130 GrFederal Gold Medal Berger 6.5 Grendel Ammo 130 Grain would drop out with a little effort, Should I keep shooting it and see if it improves it is accurate or do I break it down and send it back,

[Klem]

Brian,

You've got me thinking this is like when I reload for 9mm handgun. I take the barrel out and use it as a 'rifle gauge'. I hold it upright, drop the loaded round in, place my thumb over the base and give a gentle press; this to simulate going into battery. The turn it upside down and see if it drops out freely. Factory rounds always do. Reloads will only di that if I size the bejeezus out of the case. I have learnt that just because it doesn;t fall out freely doesn't mean it's not going to cycle. As long as my I can pinch it back out reasonably easily it is going to function.

In your case it would be the chamber being tight, not the ammo, and as long as the bolt goes completely into battery it is safe to fire (bearing in mind an AR is not supposed to fire unless in battery, but there are degrees of being in battery). If that chamber gets filthy it won't be as forgiving as if there's plenty of slop around the case....but in theory it should actually aid accuracy being held tightly and concentrically to the bore. As long as bullets are not getting pulled when pulling back on the handle, the gun cycles fine when fired, and the bolt goes completely into battery under it's own steam then I would look at the accuracy and decide whether it's a keeper or not.

[BluntForceTrauma]

I think Klem's advice makes sense, as well.