6.5 Grendel PTG Reamer

[arnie]

If im reading the measurements right ,the throat goes from .2644 down to .2617 ?? That's not possible or you would be swaging a .264 bullet down to .261 before it enters a barrel that's groove diameter should be .264 .

[BjornF16]

If im reading the measurements right ,the throat goes from .2644 down to .2617 ?? That's not possible or you would be swaging a .264 bullet down to .261 before it enters a barrel that's groove diameter should be .264 .

Arnie,

The bore is .264", but the lands are .256".

So the lands are being trimmed at 1.5 degree angle to the diameter that is less than .264".

[arnie]

Ok ,that makes since .

[FlatsFlite]

2.212 + 0.035 would put you at ~2.247, which is the approximate COL of factory Amax. I think another 0.010 to 0.015 to keep factory ammo out of the lands would be ideal. The 123gr Amax doesn't seem to mind a jump.

I have an older cut-rifled Satern where the 123gr Amax is touching the lands at ~2.262, which has worked very well with ~2.250 COL.

Factory 123gr Amax (2.245) loaded into my liberty barrel measure 2.238 when extracted. I still have not fired it yet, depending on what Satern decides to do.

[Sputnik]

Factory 123gr Amax (2.245) loaded into my liberty barrel measure 2.238 when extracted.

That is what I measured m 16 inch Liberty barrel as well. It has been over two weeks now since Satern posted a response. What does that mean? Are they conferring with their legal staff as to see what to say as an explaination? I wonder what they will offer for future barrel sales. Barrels offered with their "old" Saami chambers or "new" Saami barrels reamed out with an adaptation to accept factory ammo, or both? I hope they get the new reamer soon so I can get my barrel adapted.

[driven]

Factory 123gr Amax (2.245) loaded into my liberty barrel measure 2.238 when extracted. I still have not fired it yet, depending on what Satern decides to do.

I also have a Liberty barrel purchased from Midway. I'm seeing similar measurements with my factory A-max ammunition. I did install the barrel and shot 20 rounds before being made aware of the short throat. Primers showed cratering and I had one pierced. Next, I hand loaded 20 of the 123gr A-Max with a moderate load (listed at 2200fps, but I did not chrono) just touching the lands. I saw no pressure signs with this load. Accuracy looked good.
So I've been trying to decide if I want to try and polish the bore to possibly gain a little free bore or send it to Satern to get the throat modified. Do we know if the modification will be a Grendel spec throat or parallel throat?

[Tedward]

I also have a Liberty barrel purchased from Midway. I'm seeing similar measurements with my factory A-max ammunition. I did install the barrel and shot 20 rounds before being made aware of the short throat. Primers showed cratering and I had one pierced. Next, I hand loaded 20 of the 123gr A-Max with a moderate load (listed at 2200fps, but I did not chrono) just touching the lands. I saw no pressure signs with this load. Accuracy looked good.
So I've been trying to decide if I want to try and polish the bore to possibly gain a little free bore or send it to Satern to get the throat modified. Do we know if the modification will be a Grendel spec throat or parallel throat?

since you have some rounds thru it did the OAL get better? Have you checked a factory round OAL, then inserted and extract it the check the OAL since you ran some ammo thru it? I just wonder if using it helped the OAL with factory ammo, like did it brake in some???

[driven]

since you have some rounds thru it did the OAL get better? Have you checked a factory round OAL, then inserted and extract it the check the OAL since you ran some ammo thru it? I just wonder if using it helped the OAL with factory ammo, like did it brake in some???

Here is what I've seen with my barrel:
Before shooting I cleaned the barrel. The factory A-Max appeared to chamber normally, with the bolt closing easily in the competed upper.
After firing I did check OAL on my factory rounds and they are at 2.245". Carefully chambering one leaves light marks from the lands. Cleaned barrel.
After firing my hand loads a factory round still has land markings but they look a bit lighter than initially seen. This may be from smoothing out the lands as a normal result of breaking in the barrel.

[Tedward]

Here is what I've seen with my barrel:
Before shooting I cleaned the barrel. The factory A-Max appeared to chamber normally, with the bolt closing easily in the competed upper.
After firing I did check OAL on my factory rounds and they are at 2.245". Carefully chambering one leaves light marks from the lands. Cleaned barrel.
After firing my hand loads a factory round still has land markings but they look a bit lighter than initially seen. This may be from smoothing out the lands as a normal result of breaking in the barrel.

Great info, that is what I was looking for. I'm seeing the same thing but wanted another person to post there findings. If people would do the same measuring before and after, we might just determine it is a brake in process needed for a Grendel Chamber that is not hand lapped. Yes other calibers might not need this due to there throat geometry but this is a Grendel and it is unique.

[Sputnik]

I am just glad that there is a way to make everyone happy and satisfied. Whether you keep it as is, or return it for scraping, it was is still a great deal and you can't buy this education!

[Tedward]

I am just glad that there is a way to make everyone happy and satisfied. Whether you keep it as is, or return it for scraping, it was is still a great deal and you can't buy this education!

I think even people who thought they knew almost everything with the Grendel are learning more too. This is an educational forum with a lot of people who have first hand experience and knowledge so I think the more the cartridge gets into peoples hands, new issues will arise and if it is discussed proactively, this forum will help resolve the fellow Grendels issues and sometimes before they occur.

[NugginFutz]

Great info, that is what I was looking for. I'm seeing the same thing but wanted another person to post there findings. If people would do the same measuring before and after, we might just determine it is a brake in process needed for a Grendel Chamber that is not hand lapped. Yes other calibers might not need this due to there throat geometry but this is a Grendel and it is unique.

Tedward,

I would like to clarify the point you're making, in that last comment. Not every Grendel chamber needs to be hand lapped - far from it. The sample of barrels with this issue is quite small, considering how many Grendels are out there. It is not a function of the chamber design, but rather a function of how a particular reamer was designed.

So, when you say "other calibers may not need (lapping)" because their throat geometry is different than the Grendel's, the implication is that a Grendel would need lapping. This is simply not the case. I am sure you did not mean to imply that all Grendels need to be lapped, and wanted to make certain that point is clear.

[Tedward]

Tedward,

I would like to clarify the point you're making, in that last comment. Not every Grendel chamber needs to be hand lapped - far from it. The sample of barrels with this issue is quite small, considering how many Grendels are out there. It is not a function of the chamber design, but rather a function of how a particular reamer was designed.

So, when you say "other calibers may not need (lapping)" because their throat geometry is different than the Grendel's, the implication is that a Grendel would need lapping. This is simply not the case. I am sure you did not mean to imply that all Grendels need to be lapped, and wanted to make certain that point is clear.

Yes that is true and I am not trying to imply anything. If the reamer manufacture makes there reamer in the throat area on the low end of tolerances, +/-.000 and does not decide to go on the +.001 or +.002 side, that lapping may be needed or a tight throat is likely to be present till it is broke in or wears some. I think, and it is just me saying this, for good practice the reamer manufacture might want to make there reamers on the + side so if and when the reamer does wear .001, it will still cut to the minimum of .000. Again just a point I would have never thought about until this topic came up.

Maybe some reamer manufacturers noticed this a long time ago and do make their Grendel reamers to the +.002 of the tolerance to maintain the SAAMI chamber spec or what ever it is and not have the issue we have seen. Maybe being proactive from past issues. Don't know, just a thought.

[Walter]

The reamer was made wrong. The throat is to short. There should be a recall. SAMMI spec ammo should never touch the lands of a SAMMI chamber. There should be a free bore of .020 in all most all cases. End of story.

[woohoo]

Yes that is true and I am not trying to imply anything. If the reamer manufacture makes there reamer in the throat area on the low end of tolerances, +/-.000 and does not decide to go on the +.001 or +.002 side, that lapping may be needed or a tight throat is likely to be present till it is broke in or wears some. I think, and it is just me saying this, for good practice the reamer manufacture might want to make there reamers on the + side so if and when the reamer does wear .001, it will still cut to the minimum of .000. Again just a point I would have never thought about until this topic came up.

Maybe some reamer manufacturers noticed this a long time ago and do make their Grendel reamers to the +.002 of the tolerance to maintain the SAAMI chamber spec or what ever it is and not have the issue we have seen. Maybe being proactive from past issues. Don't know, just a thought.

If the reamer drawing was sent in like the min SAAMI spec drawing the person sending it did not take into account the PTGs tolerances. PTG will grind the reamers to the customers specs right or wrong.
If Satern just called up and said send me a Grendel reamer then PTG did grind it wrong.
At this point only Satern or PTG know if the drawing was wrong or the reamer was ground wrong.
It may be a little trouble but sounds like Satern is taking care of the issue...betting it wont happen again.

[45r]

My chamber will cycle dummy rounds with the 123 SST's at COL 2.238 and no scratches or scrapes on bullets.
No problem with crimp space if I want to crimp.
My chamber seems OK to me.

[Walter]

45r have you measured the distance to the lands with the ammo you are using? What is your freebore? If you dont know you dont know.

[45r]

Don't want to know.
The rifle shoots real good.
I must have got lucky with my barrel.
I like a snug chamber.
By the time I get all my load work done the throat will be well broken in.
I'm pretty sure I'll be able to get some real good groups with the sst's.
Wish the snow would let up so I can get the chrono out and see how fast they go.
I'm only 7 thou short of factory ammo so there shouldn't be any worries about the compound throat.

[Tedward]

If the reamer drawing was sent in like the min SAAMI spec drawing the person sending it did not take into account the PTGs tolerances. PTG will grind the reamers to the customers specs right or wrong.
If Satern just called up and said send me a Grendel reamer then PTG did grind it wrong.
At this point only Satern or PTG know if the drawing was wrong or the reamer was ground wrong.
It may be a little trouble but sounds like Satern is taking care of the issue...betting it wont happen again.

Ok, I take your word on that. I have no clue what they got or have so I just hope its resolved.

[Lead Chucker]

Hey Tedward I put my dads 16" stoner together on the 5th and have fired 10 rounds of 90gn TNT hand loads down it to function check it. I couldn't load them to the 2.200" as the hand book calls for. I had to load them to 2.185" to keep them off the lands and give them a little jump, I just fired them to check function and adjust the adjustable gas block. I know a dummy round with 123gn amax was just barley touching lands at 2.235" before ever fired. I will measure today with the same dummy round and see if the throat smoothed out any and lengthed the throat.
I do have another stoner barrel though that has a real short throat that needs to go back for a throat reaming. It measures 2.212" with the same dummy round with the 123gn amax and it has 130 rounds down it.