Free 6.5 Grendel Reload Data

[barrelcactus]

Beyond556.com is no more. It's been gone for several months that I'm aware of.

Arne designed the 45 Raptor and runs 45raptor.com Its a bore thumper for the ar10.

[StoneHendge]

Arne designed the 45 Raptor and runs 45raptor.com Its a ig bore thumper fir the ar10.

The 45 Raptor is so tempting. Because the Rhino's might also contract the Zombievirus. But then I'd have to get a 460XVR to go with it.....

[barrelcactus]

Another interesting aspect of this collected data is how well the loads track the predicted loads in the Optimal Barrel Time (OBT) spreadsheet (except BHW). Not all loads are predicted but many many are especially loads reported by multiple people that are in the 120 to 123gr range. That satern Grendel II especially seem to track the predicted loads for whatever reason. BHW does not most likely do with the poly rifling.

https://docs.google.com/spreadsheets/d/10N3FszBm0JJlLvsFagGwKakcKxE0D5p39L-FmCVPuvM/edit#gid=0

[rabiddawg]

The SAAMI is one option and is not magic.


As it is now the SAAMI is a great option as long as your not one of the unlucky ones with stuck bullets like have been reported on here over and over.

To be fair the bastardized chambers are not magic either. And they certainly Are Not immune to sticking bullets.

Like Drillboss said, the confusion created by all the other chamber and bolts was/is frustrating and could/should have been avoided.

However, my biggest issue is that business owners chose to take advantage of another business owners hard work and investment. And some even had the nerve to use "Grendel" in their name. I have a little more respect for Les Baer for having confidence enough to use his own name.

[barrelcactus]

To be fair the bastardized chambers are not magic either. And they certainly Are Not immune to sticking bullets.

Like Drillboss said, the confusion created by all the other chamber and bolts was/is frustrating and could/should have been avoided.

However, my biggest issue is that business owners chose to take advantage of another business owners hard work and investment. And some even had the nerve to use "Grendel" in their name. I have a little more respect for Les Baer for having confidence enough to use his own name.

No a standard parallel chamber is not magic its just a standard throat (not bastardized that thinking is the problem by the way) you have to find the powder that a particular bullet likes. The data suggests if the bullet has a large jump then look to an extruded powder but thats not always as CFE223 seems to work well. Having a longer jump like the original chamber and 264LBC which is .120 does however make it immune to bullets getting stuck for factory ammo and ammo loaded withing SAAMI specs as the bullet will not get stuck in the lands. A short chamber is very accurate BUT can be problematic as thread after thread after thread after thread has shown. There are different ways to skin a cat be open. When the Grendel was designed they didn't have these modern extruded powders and designed around what they had to get good groups. Things have changed now. Its ok for someone to use a slightly different chamber like a 264LBC or GII. Choices are normal and ok the Grendel is growing rapidly. Precision for example makes a good mid spec chamber and i have only seen one bullet stuck issue reported on ar15.com. Maybe the reamer was a bit to worn?

[rickOshay]

Another interesting aspect of this collected data is how well the loads track the predicted loads in the Optimal Barrel Time (OBT) spreadsheet (except BHW). Not all loads are predicted but many many are especially loads reported by multiple people that are in the 120 to 123gr range. That satern Grendel II especially seem to track the predicted loads for whatever reason. BHW does not most likely do with the poly rifling.

https://docs.google.com/spreadsheets...uvM/edit#gid=0

Thanks for sharing this.

The text at the top of the sheet makes the disclaimer:
"The following is software generated loading predictions using the Optimal Bullet Time (OBT) method. Some of these predictions are right on the money but some maybe way off. Use this as a reference but work up a load as normal. This is not load data this is just a prediction do not just load the predictions. Predictions are formulated with an assumed 70 degrees F. The data is for a 22in Satern Grendel II with 5R 1/8 rifling."

So, I'm curious, what advantage does this spreadsheet provide the reloader? If it really can't be used as a predictor, why not just use the published load data and work us as usual?

BTW - does Craig know you're sharing this data over here?

[barrelcactus]

The data is free and is allowed to be shared all over thats the point. One of the guys has a relationship with Sierra and they provided a selection of bullets to a group on the facebook page. They have a selection of SAAMI, 264LBC and Grendel II barrels so the spreadsheet should get filled in more with more Sierra loads.

[barrelcactus]

The data is not Craigs its only being compiled by Craig (and a few others have input permission) but its free and open the promise is that it will always be free and never sold.

[IceAxe]

Barrelcactus, Thanks for posting I like using the QL predictions as a starting point and adjusting for refinement. I have found OBT to be helpful on finding useable nodes. By using that data, I am generally close, so it saves a lot of powder and bullets in the ladder development. Thanks again.

[barrelcactus]

Barrelcactus, Thanks for posting I like using the QL predictions as a starting point and adjusting for refinement. I have found OBT to be helpful on finding useable nodes. By using that data, I am generally close, so it saves a lot of powder and bullets in the ladder development. Thanks again.

How close have you found the predictions to be? Seems like they are on the money in the 120-125gr range but not so much going up or down from there.

[barrelcactus]

Thanks for sharing this.

The text at the top of the sheet makes the disclaimer:
"The following is software generated loading predictions using the Optimal Bullet Time (OBT) method. Some of these predictions are right on the money but some maybe way off. Use this as a reference but work up a load as normal. This is not load data this is just a prediction do not just load the predictions. Predictions are formulated with an assumed 70 degrees F. The data is for a 22in Satern Grendel II with 5R 1/8 rifling."

So, I'm curious, what advantage does this spreadsheet provide the reloader? If it really can't be used as a predictor, why not just use the published load data and work us as usual?

BTW - does Craig know you're sharing this data over here?

Rick is does predict very well with Satern 5R rifling with the longer throat in the 120-123gr range. It will not tell you though what powder is best to use though. It would be stupid just to load up in your rifle though but if you knew were the accurate load was most likely to be you could drop the increments from .3 to .1 approaching the sweet spot. Its more powderful when combined with the real world data spreadsheet when you look at predicted loads for specific barrel length then see what the real world results are. If they match thats a double confirmation that its going to be good. All bets are off with BHW though they are a different animal.

[IceAxe]

How close have you found the predictions to be? Seems like they are on the money in the 120-125gr range but not so much going up or down from there.

All I have loaded for the Grendel are the Sierra 120 Pro Hunter and the Hornady 120 SST

[rickOshay]

Can someone explain why this OBT data only works for some bullet weights and not others; some rifling and not others; some chambers and not others ?

Is it also affected by barrel contour? Fluting? Muzzle devices?

[barrelcactus]

Can someone explain why this OBT data only works for some bullet weights and not others; some rifling and not others; some chambers and not others ?

Is it also affected by barrel contour? Fluting? Muzzle devices?

You can tweak Quick Load for specific rifling profiles so this spreadsheet is created with that rifling tuned in for saterns 5R button. Why it works for a Grendel II so well? Maybe because its a conventional chamber design pressure builds at more predictable levels. A short throat may throw it off. Why it does not work so good at the lower or upper ranges but is right on for the 120 to 125 range i don't know. OBT requires good data from quickload to work. OBT theory is sound QL sometimes is not. Its not effected by contour as its timing the bullet exit. Its timing the exit of the bullet to avoid the pressure wave at the muzzle which travels at a known speed its an acoustic wave and not effected by contour. Contour determines who accurate the node is not where or powder increment which deterimes where the node is. It also is not effected by a break. How OBT works should be directed to Chris Long the engineer who discovered it (chris@the-long-family.com). DO you have a working copy of Quick Load? If so tweak it for your rifling you'll need to measure it. Then use this program with quickload http://castboolits.gunloads.com/show...kLOAD-OBT-Tool. It will give you the optimal bullet exit time in milli seconds that represents an accuracy node. You then find the load in quickload that gives one of the predicted barrel times. Thats the predicted accuracy node. Like i said i have no idea why quickload sucks for the 100gr and below and nails it for the 120 to 125gr range of bullets. Its still close for the 130gr bullets usually within .5gr. If your barrel has been lapped it will run slower and that will throw off quickload. It does not predict the higher end barrel like Lilja and JP for that reason there speeds are slower than the liberty barrels. I should say it will get within .5gr though for those barrels just not right on the .1gr that it does for liberty barrels. Quickload and OBT will give you multiple accuracy nodes as well and they will shift with barrel length.

[barrelcactus]

This is what Quickload predicts for the 123gr Amax/SST. Do these loads look familiar? They should they have been shared over and over in peoples real world results. If its not right on its close.