Cast Bullets for 6.5 Grendel in AR-15?

[kcofohio]

I'm looking seriously at getting an upper in the 6.5 Grendel. It would be a new cartridge to me. Trying to get all the ducks in a row.

I did a search on different .266" molds. The Noe 266-126 looks to be a top candidate.
https://noebulletmolds.com/site/sho...n-ao3/266-126-fn-ao3-2-cavity-pb-6-5-grendel/

They offer a flat-base and gas check base.

The upper I'm looking at is a 20" with a 1:8 twist.

My question is, using Hi-Tek powdered coating, would I still need the gas check for up to 2400 fps. For target shooting purposes. I'm hoping these would be good for 100-200 yds.

 

[AJC1]

I would say no but if I had any issues I would back down the charge and see if I could find a slower load that worked well. I powdercoat not hi tech so I dont know how they compare directly. Getting one with gas checks would require less experimentation and may give you better velosity ranges at the added cost. My big bullets dont move that fast or operate at that high of a pressure. Hopefully more ar guys will help...

 

[kcofohio]

Well, I came across another interesting looking mold for 6.5mm.
http://arsenalmolds.com/257-bullet-spitzer

But I'm wondering if 85 gr. is too light for a 1:8 twist barrel.

 

[AJC1]

Well, I came across another interesting looking mold for 6.5mm.
http://arsenalmolds.com/257-bullet-spitzer

But I'm wondering if 85 gr. is too light for a 1:8 twist barrel.

When shooting lead I stay heavy for caliber to slow down the bullet and still carry a good amount of energy. The lighter you go the faster the bullet goes most times and the harder the lead would be. I would be looking over 100gr.

 

[kcofohio]

When shooting lead I stay heavy for caliber to slow down the bullet and still carry a good amount of energy. The lighter you go the faster the bullet goes most times and the harder the lead would be. I would be looking over 100gr.

AJC1, thanks! Kind of had a feeling of that. It's just that the Arsenal mold looked to have a good profile.
Guess I will keep my focus on the Noe mold.

 

[AJC1]

I found some 140 load data... it may help. I only found sweed data in my lyman cast manual. I shoot sweed so that's the limit of my 6.5 experience

 

[forrest r]

When shooting hv cast/coated bullets I look for 2 things.

Bullets with a gc
Bullets that are at least 70% supported by the bore.

While heavy bullet might be good for slower velocities they have a lot of issues with hv/high pressure loads. Things like rotational torque come into play.

 

[kcofohio]

When shooting hv cast/coated bullets I look for 2 things.

Bullets with a gc
Bullets that are at least 70% supported by the bore.

While heavy bullet might be good for slower velocities they have a lot of issues with hv/high pressure loads. Things like rotational torque come into play.

So I'm thinking that a slower burning powder like R15 or CFE223 may work better than IMR4198 or R7?

 

[AJC1]

So I'm thinking that a slower burning powder like R15 or CFE223 may work better than IMR4198 or R7?

What is best to drive the bullet is going to be moderated on what works your gas system the best. Magnum pistol and fast rifle seems to work best in 300 bo for shooting suppressed subs. Having an adjustable gas block changes the usable options as well. Develop a test load with a powder you have and then see what indications you have. I have a jug of tac so I start most loads testing with that if its acceptable. Then I try arcomp and varget.

 

[jmorris]

I don’t load cast in my Grendel but do for other calibers. My smallest 100-200 yard groups were fired using jacketed bullets but I guess just shooting at something makes it a target and lead will certainly do that.

 

[kcofohio]

I don’t load cast in my Grendel but do for other calibers. My smallest 100-200 yard groups were fired using jacketed bullets but I guess just shooting at something makes it a target and lead will certainly do that.

With getting into a new to me cartridge and caliber, and the situation of the market, I'd like to have options in bullets. Of course, accumulating brass may be a hurdle too.

 

[forrest r]

Doesn't matter if the rifle cycles or not to begin with.

If it was me I'd start out with soft lead alloys and pistol powders to see what the rifle can do. A chronograph is always a good thing. You should be able to get to the 1800fps+ range with the soft alloy/pistol powders. This establishes a base line for what you're doing. From there use slower burning powders until the bullet/groups fail. Then work on the alloy to see if the groups tighten back up. If the groups tighten up do keep increasing the powder. If the groups don't tighten up with the harder alloys keep trying slower powders until you use your slowest powder.

When the groups open up and you can no longer bring them back thru alloy or powder changes you'll of reached the max of the rifle or bullet design.

A strong bullet design that is 70%+ supported by the bore is a must for hv/high pressure rounds in hp rifles.
MP silhouette bullet, It's 1" long weighs 175gr and .750" of the bullet is .308" in diameter or larger (.310") or 75% of the bullet is supported by the bore.


The band on the front of the bullet (line) is where the nose starts to taper down from the .308" body. The line in the center of the bullet is where the .308" body starts and goes to the left line at the nose. The back of the bullet has a gc shank and the 2 drive bands are .310". The bullet tapers down from .310" at the front of the front drive band to .308" at the center line. The drive bands and gc are .310" and are supported in the 308w case. The 310" to .308" tapered part of the bullet is fully supported by the throat of the chamber. The .308" bullet body is locked into the lands and is fully supported by the bbl. The mp silhouette bullet.


That bullet will easily do 2" 10-shot groups @ 100yds/2600fps+

Something else to think about:
It's a good idea to use fillers with the rifle powders in the hv cases. I use 1/4" to 3/8" square pieces of lofted dacron or poly batting. I also loft/pull/expand the squares of the dacron/poly even further. This keep the powder back in the case where it should be, by the primer with loads that are less then 85% load density.
https://www.walmart.com/ip/Fairfield-45-x-60-Poly-Fil-Extra-Loft-Batting-1-Each/17808678

Using this filler will also protect the base of the bullet. A plain based bullet with the dacron filler used to fill the case and protect the bullet's base.


Same bullet/load but this time no dacron filler was used.


Anyway start low and work up to get all the bugs worked out of casting/sizing/oal's/etc. If you can't get the rifle/bullet combo to groups @ 1600fps/1800fps then all the testing in the world doesn't matter at +/- 2400fps.

 

[kcofohio]

Doesn't matter if the rifle cycles or not to begin with.

If it was me I'd start out with soft lead alloys and pistol powders to see what the rifle can do. A chronograph is always a good thing. You should be able to get to the 1800fps+ range with the soft alloy/pistol powders. This establishes a base line for what you're doing. From there use slower burning powders until the bullet/groups fail. Then work on the alloy to see if the groups tighten back up. If the groups tighten up do keep increasing the powder. If the groups don't tighten up with the harder alloys keep trying slower powders until you use your slowest powder.

When the groups open up and you can no longer bring them back thru alloy or powder changes you'll of reached the max of the rifle or bullet design.

A strong bullet design that is 70%+ supported by the bore is a must for hv/high pressure rounds in hp rifles.
MP silhouette bullet, It's 1" long weighs 175gr and .750" of the bullet is .308" in diameter or larger (.310") or 75% of the bullet is supported by the bore.
View attachment 973285

The band on the front of the bullet (line) is where the nose starts to taper down from the .308" body. The line in the center of the bullet is where the .308" body starts and goes to the left line at the nose. The back of the bullet has a gc shank and the 2 drive bands are .310". The bullet tapers down from .310" at the front of the front drive band to .308" at the center line. The drive bands and gc are .310" and are supported in the 308w case. The 310" to .308" tapered part of the bullet is fully supported by the throat of the chamber. The .308" bullet body is locked into the lands and is fully supported by the bbl. The mp silhouette bullet.
View attachment 973286

That bullet will easily do 2" 10-shot groups @ 100yds/2600fps+

Something else to think about:
It's a good idea to use fillers with the rifle powders in the hv cases. I use 1/4" to 3/8" square pieces of lofted dacron or poly batting. I also loft/pull/expand the squares of the dacron/poly even further. This keep the powder back in the case where it should be, by the primer with loads that are less then 85% load density.
https://www.walmart.com/ip/Fairfield-45-x-60-Poly-Fil-Extra-Loft-Batting-1-Each/17808678

Using this filler will also protect the base of the bullet. A plain based bullet with the dacron filler used to fill the case and protect the bullet's base.
View attachment 973287

Same bullet/load but this time no dacron filler was used.
View attachment 973288

Anyway start low and work up to get all the bugs worked out of casting/sizing/oal's/etc. If you can't get the rifle/bullet combo to groups @ 1600fps/1800fps then all the testing in the world doesn't matter at +/- 2400fps.

I will keep this in mind when I get to that point.

 

[Kaldor]

@kcofohio
Some great advice here
Stay with a heavy bullet, use a GC, dont expect super high velocities, and a good coating of HiTek will get you to about 2000 FPS without leading Id bet.

 

[John#2]

When shooting hv cast/coated bullets I look for 2 things.

Bullets with a gc
Bullets that are at least 70% supported by the bore.

While heavy bullet might be good for slower velocities they have a lot of issues with hv/high pressure loads. Things like rotational torque come into play.

So, you’re saying avoid bore-riding molds so the lands have enough material to grip thereby reducing the risk of stripping the bullet?

 

[Swampman]

Well, I came across another interesting looking mold for 6.5mm.
http://arsenalmolds.com/257-bullet-spitzer

But I'm wondering if 85 gr. is too light for a 1:8 twist barrel.

Maybe I'm missing something here, but my main issue with that mold is that it's designed to throw a .258" bullet and 6.5 Grendel has a groove diameter of .264".

Are you planning to paper patch?

 

[kcofohio]

Maybe I'm missing something here, but my main issue with that mold is that it's designed to throw a .258" bullet and 6.5 Grendel has a groove diameter of .264".

Are you planning to paper patch?

You are correct, this is the bullet for 6.5;
http://arsenalmolds.com/products?product_id=193
The original link list 6.5 grendel for the bullet design, but a different mold size is there if I would have been paying attention.

This bullet design has been effectively used with the .250/3000 Savage - 256 Winchester Magnum - 256 Newton - 25/06 Remington 25/35 Winchester - 25 Remington - 25 WSSM - 257 Roberts 257 Roberts Ackley 257 Weatherby Magnum - 6.5mm Johnson - 6.5/284 6.5mm Creedmoor - 6.5mm Grendel - 6.5 x 50mm Arisaka - 6.5 x 52mm Mannlicher-Carcano - 6.5 x 53mmR Mannlicher - 6.5 x 54mm Mannlicher Schoenaver - 6.5 x 55mm - 6.5 x 57 Mauser 6.5 x 68mm Von Hofe Express

 

[AJC1]

Have you considered measuring your distance to the lands and selecting a bullet or design that gives you the desired jump or jump range. Obviously a round nose designs can get you much closer on deep throat barrels. If your really motivated you could search designs here....
http://www.accuratemolds.com/catalog.php?page=1#catalog-anchor

 

[Swampman]

A strong bullet design that is 70%+ supported by the bore is a must for hv/high pressure rounds in hp rifles.
MP silhouette bullet, It's 1" long weighs 175gr and .750" of the bullet is .308" in diameter or larger (.310") or 75% of the bullet is supported by the bore.

I think you're confusing bore diameter with groove diameter.

Nominal bore diameter for .30 caliber/7.62mm barrels is .3 inch, thus a .300" bullet IS supported by the bore. Unfortunately it won't take the rifling worth a damn or hit anything much past mud slingin' range. To do that it takes a groove filling bullet (or maybe even a couple of thousandths over groove diameter for cast).

From SAAMI:
BORE DIAMETER
Rifled barrels: the minor interior diameter of a barrel which is the diameter of a circle formed by the tops of the lands.
https://saami.org/glossary/bore-diameter/

 

[forrest r]

Yes swampman I should be saying groove diameter, thank you for correcting this!!!!

 

[forrest r]

So, you’re saying avoid bore-riding molds so the lands have enough material to grip thereby reducing the risk of stripping the bullet?

Yes, you nailed it!!!!

Bore riding bullets have their place but that design was never designed for high pressure/hv loads. The other thing to avoid is bullets that don't have a strong nose or a long unsupported nose. Pointy nosed bullets tend to have issues. Playing around with a cramer bullet cast from a 2-cavity mold. 1 cavity is a sp, the other cavity is a hp version of the same bullet. Because of the hp pin the hp bullet now has a flat nose.


The sp bullet is 60% supported. The hp bullet is 66% supported. A target from 3 years ago with both bullets doing 2450fps+ 10-shot groups @ 100yds.

 

[forrest r]

@kcofohio
Some great advice here
Stay with a heavy bullet, use a GC, dont expect super high velocities, and a good coating of HiTek will get you to about 2000 FPS without leading Id bet.

I see this all the time and have no idea why things like "a good coating of HiTek will get you to about 2000 FPS without leading" this keep getting posted???

2000fps is child's play for a coated bullet. Back in 2013 I was testing coated bullets looking for an alloy for hunting. A cast bullet that was not lube/temp dependent appealed to me. As you can see the lower velocity bullets shattered and the 2300fps bullet bent. That 230gr/50,000+psi load/bullet has an alloy I still use to this day.


The pc coating stays on and has to mechanically be stripped off.
The pc coating does not fail causing leading

Some coating will actually start to scorch/burn when driven too hard from friction. When I started pushing pc'd bullets over 2700fps I started seeing this in the bbl.


Simple enough to fix, I simply tumble lube the pc'd bullets with 45/45/10 or give them a light coat of johnson's paste wax.

Anyway you don't get leading from a coated bullet unless there is a mechanical issue like the coating got scrapped off during seating the bullet. Crimping too much cutting ("cutting") thru the coating. Scraping the coating off from edges in the chamber or rough spots in the bbl, etc.

 

[HankC]

I shoot 308 powder/polymer coated cast bullets ( no gas check) in my bolt guns at reduced load, I would say max is 1500 fps. Smoke a lot above 1500 fps and don't group well. Gas check can push to higher fps.

 

[kcofohio]

Have you considered measuring your distance to the lands and selecting a bullet or design that gives you the desired jump or jump range. Obviously a round nose designs can get you much closer on deep throat barrels. If your really motivated you could search designs here....
http://www.accuratemolds.com/catalog.php?page=1#catalog-anchor

I'm not to that point yet. But thanks for the link.

 

[Kaldor]

I see this all the time and have no idea why things like "a good coating of HiTek will get you to about 2000 FPS without leading" this keep getting posted???

2000fps is child's play for a coated bullet. Back in 2013 I was testing coated bullets looking for an alloy for hunting. A cast bullet that was not lube/temp dependent appealed to me. As you can see the lower velocity bullets shattered and the 2300fps bullet bent. That 230gr/50,000+psi load/bullet has an alloy I still use to this day.
View attachment 973409

The pc coating stays on and has to mechanically be stripped off.
The pc coating does not fail causing leading

Some coating will actually start to scorch/burn when driven too hard from friction. When I started pushing pc'd bullets over 2700fps I started seeing this in the bbl.
View attachment 973410

Simple enough to fix, I simply tumble lube the pc'd bullets with 45/45/10 or give them a light coat of johnson's paste wax.

Anyway you don't get leading from a coated bullet unless there is a mechanical issue like the coating got scrapped off during seating the bullet. Crimping too much cutting ("cutting") thru the coating. Scraping the coating off from edges in the chamber or rough spots in the bbl, etc.

Good info. I really wish I had the time to get more into casting. Someday when my kids are grown and gone