AR-Stoner 6.5 Grendel barrel short chambered.

[45r]

My chamber won't go above 2.170 COL with 85 grain sierra HP's without being too far.
I think that will be good enough .I'm going to seat them at 2.160 since they cycle easy at that length.
If I seated them farther out they wouldn't be in the neck enough to me.
I'm not worried about my chamber.
I think the 123 SST's won't be seated too deep when I try them.

[XcountryRider]

Lets start another thread on ways to polish the throat!!

[adrenaline junkie]

Lets start another thread on ways to polish the throat!!

I would think that it wouldnt be too hard to use the measurements from saami grendel print, to make a rod with the shape of the throat on the end, and with that in a drill, using some lapping compound, to resurface the throat and polish it pretty easily. Or maybe not use a drill, just spin it with your fingers. Wouldnt take too long with different lapping compound grits.

[hydrotech]

I thought of polishing my throat but After talking to my buddy today who shoots bench rest and Fclass at big piney and st louis in MO... he said he thought the scratches I was seeing on bullets were not from the lands....he did say he thought the chamber was short or tight and that the bullet was probably pressed against the walls of the throat...he said shoot the shit out of it and let it open up...he also said if it was his rifle he would have it rethroated because I reload...he said he'd buy a 6.5 throater or let his gunsmith rethroat it and get rid of the compound throat and cut it to so I could seat my SST's at the maximum my mags will allow....I'm not going to shoot matches...just hunt...but I plan to just shoot a bunch first.

[45r]

You can get firelapping kits from Midway and polish up the throat.
I've thought about using my beartooth kit and get some 600 grit to go with the 320 that came with it.
I think Midway has 130 grain long shank bullets to use with the kit.

[65man]

So what is answer to all this from Stoner then?

+1 so until now we still dont have any clear answer.
no second hand info from satern.
No answer for reamer use in Liberty Barrel & the hand lanp barrel (spartan barrel?).
since for some of us we just want to shoot it using factory ammo with out any modification

[explorecaves]

I thought of polishing my throat but After talking to my buddy today who shoots bench rest and Fclass at big piney and st louis in MO... he said he thought the scratches I was seeing on bullets were not from the lands....he did say he thought the chamber was short or tight and that the bullet was probably pressed against the walls of the throat...he said shoot the shit out of it and let it open up...he also said if it was his rifle he would have it rethroated because I reload...he said he'd buy a 6.5 throater or let his gunsmith rethroat it and get rid of the compound throat and cut it to so I could seat my SST's at the maximum my mags will allow....I'm not going to shoot matches...just hunt...but I plan to just shoot a bunch first.

This sounds like your buddy obviously doesn't know the first thing about the grendel chamber. The compound throat allows a round to not require being perfectly centered to the lands. This gives you freedom from the extra variance inherrant in autoloaders while still giving you a precision platform.

[XcountryRider]

+1 so until now we still dont have any clear answer.
no second hand info from satern.
No answer for reamer use in Liberty Barrel & the hand lanp barrel (spartan barrel?).
since for some of us we just want to shoot it using factory ammo with out any modification

I'm pretty sure everyone can shoot factory ammo from hornady and wolf without issues. As we saw one example needed the chamber polished when shooting aa ammo.

[MikeGideon]

This sounds like your buddy obviously doesn't know the first thing about the grendel chamber. The compound throat allows a round to not require being perfectly centered to the lands. This gives you freedom from the extra variance inherrant in autoloaders while still giving you a precision platform.

It's a different animal, that's for sure. In terms of pressure, I view it more like a forcing cone in a revolver. I don't have one of the Liberty barrels, but my Shilen is pretty short too. Still, I can provide enough finger pressure with the Hornady OAL gauge to get the bullet in far enough. I have to pop it back out with a dowell, but there are no nicks in the jacket from the lands. All I have is a bunch of 123g Scenars. I have no intentions of Tubbing a hand lapped barrel, and will just shoot it and look for pressure signs.

I still plan to measure my buddy's Stoner barrel, just to satisfy my own curiosity. I don't mind Tubbing a barrel that hasn't been lapped. I have done a couple of mine.

[woohoo]

The compound throat allows a round to not require being perfectly centered to the lands. This gives you freedom from the extra variance inherrant in autoloaders while still giving you a precision platform.

Is it working in the Liberty barrels?

[explorecaves]

Is it working in the Liberty barrels?

Sounds like it is with factory ammo.... but I think I read that the throat is only polished with 180 grit? Hence the short loadings initially till a few rounds are sent through it to knock down the high points. A little flitz may be in order for some?

[hydrotech]

This sounds like your buddy obviously doesn't know the first thing about the grendel chamber. The compound throat allows a round to not require being perfectly centered to the lands. This gives you freedom from the extra variance inherrant in autoloaders while still giving you a precision platform.

He shoots F-class bolt actions...so no he doesnt' mess with auto loaders...but I don't like short chambers. You can agree or Disagree with me but i want to shoot my bullets loaded to the max the mags will allow them...I am disappointed my chamber will not allow this...maybe ill get used to it after shooting a while and like what I see...if not I am going rethroat it so I can load longer and maximize the case capacity....Im not interested in shooting tight groups for super accuracy. Im interested in blowing holes through deer, pigs, coyotes. more powder the better the chances of that happening at longer ranges.

[JASmith]

The last 50 fps in velocity is effectively irrelevant in the hunting environment. Volume 1 discusses that and Volume 2 covers the question extensively.

You will also see a bunch of success stories in this forum by folks using 14.5" and shorter barrels. Adding 0.2" to one's cartridge length adds very little even compared to an inch or two change of barrel length.

While there are those who would cheerfully tell one to ream that throat, one really needs to be sure of the intended result and the consequences of having done it.

If one reloads, shooting the rifle a bunch is an option. Again this practice shooting does not depend on getting the last FPS out the muzzle.

Also, the throat polishing thread is uncovering a nice collection of techniques.

[Shivesy]

My McGowen barrel was sent to me with a short chamber. When I would go to eject a unfired round from the chamber, sometimes I would pull the bullet from the case. This was common with 2 barrels I purchased from them at the same time. I sent them back to Dan and he could never mimic the problem, even with my bolt, magazine and factory A-Max rounds. They had the barrels for over 3 months and when I did get them back, they did the same thing. Go figure.
At that time I rented a PTG uni-throater reamer from 4-D rentals in MT. This is a "do it yourself" tool that worked for me. I don't shoot competition and use my AR Grendel for killing purposes only. This method probably isn't for everybody but I am satified with the results.

[bwaites]

After 46 pages and more than 400 posts, some historical perspective may be useful. I have generally avoided comment, because I don't have one of these barrels and can't really check what everyone is doing and using to measure. During development of the Grendel, it was discovered that it was difficult to find a chamber that would shoot consistently. This was complicated by the desire to be able to use a significant number of the wide range of bullets available for the caliber. Bill Alexander, especially, wanted to be able to use bullets ranging all the way from 80 to at least 123 grains, or possibly even 140 grains. Over time, it was decided that the case capacity really wasn't sufficient to drive bullets above 130 grains, except in certain lower velocity scenarios.

While chambers could be found that would be very accurate with some loads and some bullets, other loads would be radically inconsistent. This is simply a characteristic of any standard chamber shooting bullets with radically different ogives. It is why long range competitors work so hard to find the ideal bullet for their rifle and barrel. Using ogives from traditional 6.5 caliber round nosed bullets to long, sleek VLD designs, to super light varmint bullets in the same chamber and hoping that they will all be accurate is a very tall order: Add in that you are going to try to do it with a relatively small case for the 6.5 caliber, restricted to magazine length of 2.26", and a relatively weak action compared to those used previously and
the issue became complicated very rapidly.

Over time, Bill noted that both the Swedish Mauser in 6.5x55 and the Lee Enfield had great reputations for being accurate with multiple different bullets and that they both had a "Non-standard" compound throat, dating from a time when machining standards weren't quite as easy to maintain in the days before CAD/CAM design and manufacturing. They were sloppy compared to todays designs for super accurate, tight chambers, but both provided very good accuracy. In reality, the Grendel chamber is a direct lineage to those military rifles in regards to the design.

That throat had a shallow .5 degree throat, which served to effectively center the bullet because that angle starts where people would expect normal freebore in a standard chamber. This creates a very slight engagement, but does not significantly increase pressures. However, it should NOT create enough engagement that the cartridge cannot be retracted with only minimal force. Factory cartridges should not create any difficulty in a properly cut chamber. Factory ammo is repeatedly checked against hard standards during manufacture, and should not create issues in ANY properly cut SAAMI chamber. Those standards used by manufacturers mimic a minimal tolerance SAAMI chamber. You might see a tiny "rub" on a polished bullet, but you shouldn't see anything else, and there certainly shouldn't be significant abrasions.

In thoughtful consideration, its not hard to figure out that maintaining equipment to cut those angles probably isn't the easiest thing in the world, and its probably at least part of the reason that we don't see barrels for the Grendel from every barrel maker. In addition, trying to push a lot of barrels through gets constricted in maintaining that equipment.

I have a couple concerns in that I've read that "the same reamer he has always used" is being used to cut these chambers. I hope that means the SAME DESIGN, and not the same, actual reamer. Reamers wear pretty quickly, and standard reamers are generally good for 150-200 barrels. Exceptionally high quality reamers with special coatings may go twice that. (WooHoo might be able to give us a better idea, but thats what the gunsmiths I know tell me.) But the tolerances to maintain a chamber are small. I read somewhere here that PTG uses +/- .001 for their reamers. IF you start with a minimum chamber reamer, and you are .001 under, that chamber is NOT a SAAMI chamber. It might be a SAAMI chamber design, but its below the minimums, and thus not an actual SAAMI chamber. Every barrel you then cut becomes smaller and smaller, if only by .0001 at a time. None of those barrels are SAAMI chambers.

If ANY SAAMI factory ammunition is not fitting, you can be sure that you have a chamber issue. If you want to fire polish it out, or polish with a throat polish of some kind, that is up to you. However, I believe that a manufacturer should give you what you paid for, and if it doesn't, then you should send the barrel back for evaluation. I don't understand the "I'll break it in and then factory ammo will fit" train of thought. What if it doesn't? And the idea of loading special ammunition for the short chamber and other ammunition for the other SAAMI chambers is crazy! That's the VERY REASON you take a cartridge design to SAAMI, to standardize it! We call chambers that aren't SAAMI wildcats!

Steve Satern certainly knows how to make barrels, and he knows how to fix them if they are a problem. He is, by all accounts, an honorable man, and will do whatever it takes to make it right, I recommend that we let him have time to do so.

[XcountryRider]

My McGowen barrel was sent to me with a short chamber. When I would go to eject a unfired round from the chamber, sometimes I would pull the bullet from the case. This was common with 2 barrels I purchased from them at the same time. I sent them back to Dan and he could never mimic the problem, even with my bolt, magazine and factory A-Max rounds. They had the barrels for over 3 months and when I did get them back, they did the same thing. Go figure.
At that time I rented a PTG uni-throater reamer from 4-D rentals in MT. This is a "do it yourself" tool that worked for me. I don't shoot competition and use my AR Grendel for killing purposes only. This method probably isn't for everybody but I am satified with the results.

What ammo was getting stuck?

[BjornF16]

From Shivesy's thread:

I have 2 Grendel barrels made by McGowen Barrels and I am having issues with them both. Actually I purchased 3 of them but 1 of the 3 seems to be okay. The issue I am having with 1 particular barrel is that I am pulling the bullet away from the unspent cartride when I use the charging handle to unload my rifle. The other barrel can be tough when removing the round but not to the point of pulling bullets from the case. Now this is a little tricky and I will try to explain myself better. I can hand cycle a 10 round mag for both barrels for example and all goes well and everything is fine. Now when I hunt and shoot lets say 5 of the 10 rounds and put the rifle on safe, then drop my magazine with 4 rounds left, here's where the problem starts. I have one more round left in the chamber. This round can be difficult to extract. I have actually pulled the bullet from the case a few times. Sometimes is worse than others. I am using factory grade Hornady A-max or SST 123 gr. ammo. No reloads at all.
I have sent the 2 barrels back to McGowen along with a 10 round mag, 10 SST rounds and a bolt approx. 2 weeks ago and today finally taked with their gunsmith who manufactured these barrels. He says that he used a 6.5 Grendel PTG reamer and the barrels are within specs and he could not duplicate my problem. He seems to be lost at what to do and so do I. He suggested that I have a ammo issue. I disagreed but anyway McGowen suggested that I send more ammo so they can do further test. Any suggestions??

Unless the tooling is measured and inspected against the correct drawing with tolerances included you can only say that you think you have a correct chamber. The alternative is to employ Replicast compound to examine the chamber directly. Cerrosafe while widely used is not the best choice as it does move slightly. Measurement needs to be with an optical tooling comparator. Calipers or even a micrometer will not let you resolve angles or determine any barreling that might be present.

Bingo!!!! Just hung up the phone with Dave at PTG. (Pacific Tool and Gauge) They made the reamer for the Grendel that McGowen used on our barrels. Dave stated that the Grendel reamers are made to SAMMI specs but the specs drawings are wrong in his opinion. To tight of tolerance. Dave also stated that he has heard of many many case of bullets being torn from the case when this reamer is used. When the barrel throat gets just the slightest of carbon fouling in it the bullet sticks. As soon as I said Grendel reamer Dave new exactly what I was talking about. The Grendel is a double throated reamer and he said to use a .264 LBC reamer and that reamer works just fine and much better with the Hornady Grendel ammo because this reamer uses a parallel throat. *Dave also stated that one could use a uni throat reamer and that reamer would open the throat a bit and probably solve the problem I am having.

The SAAMI spec reamer has plenty of clearance, it was designed to be extremely tolerant of bullet design, to the extent that many accuse it of being a machine gun chamber. The tolerance for the reamer is not specified within SAAMI only the minimum chamber size. The tolerance is the toolmakers descision.

The chamber is set to allow the guns to run excessively dirty and the carbon fouling deposits have clearance.

Hornady ammunition and the 123 Amax was designed for the Grendel chamber. Hornady is the SAAMI sponsor for the Grendel.

You have just found that you do not have a (correct) Grendel SAAMI chamber.

Shocker!...it wasn't AA factory ammo. Things that make you go "Hmmmm"

BTW, didn't Steve Satern say he was using a PTG reamer?

[txgunner00]

....Im not interested in shooting tight groups for super accuracy. Im interested in blowing holes through deer, pigs, coyotes. more powder the better the chances of that happening at longer ranges.

For this purpose just load what works and shoot. A .1% increase in case capacity will give you no advantage. I understand the mind games we play with ourselves trying to squeeze every ounce of performance out of our equipment BUT, at then end of the day, it makes little to no difference in the real world.

[txgunner00]

After 46 pages and more than 400 posts, some historical perspective may be useful. I have generally avoided comment, because I don't have one of these barrels and can't really check what everyone is doing and using to measure. During development of the Grendel, it was discovered that it was difficult to find a chamber that would shoot consistently. This was complicated by the desire to be able to use a significant number of the wide range of bullets available for the caliber. Bill Alexander, especially, wanted to be able to use bullets ranging all the way from 80 to at least 123 grains, or possibly even 140 grains. Over time, it was decided that the case capacity really wasn't sufficient to drive bullets above 130 grains, except in certain lower velocity scenarios.

While chambers could be found that would be very accurate with some loads and some bullets, other loads would be radically inconsistent. This is simply a characteristic of any standard chamber shooting bullets with radically different ogives. It is why long range competitors work so hard to find the ideal bullet for their rifle and barrel. Using ogives from traditional 6.5 caliber round nosed bullets to long, sleek VLD designs, to super light varmint bullets in the same chamber and hoping that they will all be accurate is a very tall order: Add in that you are going to try to do it with a relatively small case for the 6.5 caliber, restricted to magazine length of 2.26", and a relatively weak action compared to those used previously and
the issue became complicated very rapidly.

Over time, Bill noted that both the Swedish Mauser in 6.5x55 and the Lee Enfield had great reputations for being accurate with multiple different bullets and that they both had a "Non-standard" compound throat, dating from a time when machining standards weren't quite as easy to maintain in the days before CAD/CAM design and manufacturing. They were sloppy compared to todays designs for super accurate, tight chambers, but both provided very good accuracy. In reality, the Grendel chamber is a direct lineage to those military rifles in regards to the design.

That throat had a shallow .5 degree throat, which served to effectively center the bullet because that angle starts where people would expect normal freebore in a standard chamber. This creates a very slight engagement, but does not significantly increase pressures. However, it should NOT create enough engagement that the cartridge cannot be retracted with only minimal force. Factory cartridges should not create any difficulty in a properly cut chamber. Factory ammo is repeatedly checked against hard standards during manufacture, and should not create issues in ANY properly cut SAAMI chamber. Those standards used by manufacturers mimic a minimal tolerance SAAMI chamber. You might see a tiny "rub" on a polished bullet, but you shouldn't see anything else, and there certainly shouldn't be significant abrasions.

In thoughtful consideration, its not hard to figure out that maintaining equipment to cut those angles probably isn't the easiest thing in the world, and its probably at least part of the reason that we don't see barrels for the Grendel from every barrel maker. In addition, trying to push a lot of barrels through gets constricted in maintaining that equipment.

I have a couple concerns in that I've read that "the same reamer he has always used" is being used to cut these chambers. I hope that means the SAME DESIGN, and not the same, actual reamer. Reamers wear pretty quickly, and standard reamers are generally good for 150-200 barrels. Exceptionally high quality reamers with special coatings may go twice that. (WooHoo might be able to give us a better idea, but thats what the gunsmiths I know tell me.) But the tolerances to maintain a chamber are small. I read somewhere here that PTG uses +/- .001 for their reamers. IF you start with a minimum chamber reamer, and you are .001 under, that chamber is NOT a SAAMI chamber. It might be a SAAMI chamber design, but its below the minimums, and thus not an actual SAAMI chamber. Every barrel you then cut becomes smaller and smaller, if only by .0001 at a time. None of those barrels are SAAMI chambers.

If ANY SAAMI factory ammunition is not fitting, you can be sure that you have a chamber issue. If you want to fire polish it out, or polish with a throat polish of some kind, that is up to you. However, I believe that a manufacturer should give you what you paid for, and if it doesn't, then you should send the barrel back for evaluation. I don't understand the "I'll break it in and then factory ammo will fit" train of thought. What if it doesn't? And the idea of loading special ammunition for the short chamber and other ammunition for the other SAAMI chambers is crazy! That's the VERY REASON you take a cartridge design to SAAMI, to standardize it! We call chambers that aren't SAAMI wildcats!

Steve Satern certainly knows how to make barrels, and he knows how to fix them if they are a problem. He is, by all accounts, an honorable man, and will do whatever it takes to make it right, I recommend that we let him have time to do so.

You, Sir, are wise and noble.

[hydrotech]

interesting post Bjorn!