Downloading 6.5 Creedmoor to 6.5 Grendel power

[lazyengineer]

I have a project where I want to do some experimenting with this. Going way below book minimum on your own can be cause problems. Curious if anyone else has any experiences or thoughts here?

[outbreaker]

Problems I have seen in other calibers.

1. Allows for the throwing of a double charge ( any caliber that has less than 50% capacity powder charge)
2. Powder charge is away from the primer and does not ignite causing the bullet to lodge in the barrel (several cowboy pistol loads)
3. Gas builds in the barrel and causes a secondary ignition that is more energetic than the primary (300 win mag)

If you are going to do this I would move to a powder that is bulky and slow that will still allow for 80% case capacity fill.

[biodsl]

I've heard Trailboss is used for such things. https://hodgdon.com/wp-content/uploads/2...ds-r_p.pdf

[Harpoon1]

I have a project where I want to do some experimenting with this. Going way below book minimum on your own can be cause problems. Curious if anyone else has any experiences or thoughts here?

Trail Boss or H4895. I use Trail Boss with a 243 and the (60% rule) with H4895 in the Creedmoor, for no real reason other than that’s how it worked out with the powder I had available at the time. Either one would work with both cartridges.

You can go crazy low with trail boss. I never took H4895 to its lower limits. The ES/SD were lousy, and didn’t pursue it much, although I didn’t try many different primers.

My WAG would be that a max charge of TB would be very close to Grendel speeds in the Creedmoor, depending on the projectile weight. Do NOT try to compress TB to squeeze out anymore performance, it gets real spikey very quickly.

Shooter World Buffalo Rifle is supposed to a universal reduced load powder also but I can’t get them to answer my emails and the load data for it’s use is very thin.

[lazyengineer]

Thanks, I have some 4895 I may try then.

I didn't know if fast powder, might be the way to go. People do this with pistol powder for ultra light loads in fact. I have some LT32, wich is pretty fast. But can't find any 6.5 CM data of any kind with that one.

[lazyengineer]

Trail Boss or H4895. I use Trail Boss with a 243 and the (60% rule) with H4895 in the Creedmoor, for no real reason other than that’s how it worked out with the powder I had available at the time. Either one would work with both cartridges.

You can go crazy low with trail boss. I never took H4895 to its lower limits. The ES/SD were lousy, and didn’t pursue it much, although I didn’t try many different primers.

My WAG would be that a max charge of TB would be very close to Grendel speeds in the Creedmoor, depending on the projectile weight. Do NOT try to compress TB to squeeze out anymore performance, it gets real spikey very quickly.

Shooter World Buffalo Rifle is supposed to a universal reduced load powder also but I can’t get them to answer my emails and the load data for it’s use is very thin.

and here we go - asked and answered. 123 gr bullets at Grendel speeds. Thanks.


from
https://rifleshooter.com/2017/08/6-5-cre...d-142-smk/

[tdbru]

LE,
Hodgdon website has instructions for reduced loads with Trailboss and H4895 only.

H4895 lowest is 60% of max if i recall correctly.

I can't remember what Trailboss directions are off the top of my head.

Go to Hodgdon website and review the reduced loads they list.

-tdbru

[Harpoon1]

That’s an interesting chart.

Just for reference, I can get 2650 out of my Howa Grendel 20” HB with 33 grns of Lever and a123 ELD-M ! According to the chart, their 26” Creedmoor test gun needed 33 grns of H4895 for the same speed. Wow!

[biodsl]

That’s an interesting chart.

Just for reference, I can get 2650 out of my Howa Grendel 20” HB with 33 grns of Lever and a123 ELD-M ! According to the chart, their 26” Creedmoor test gun needed 33 grns of H4895 for the same speed. Wow!

Think this is due to efficiency of burn?

[grayfox]

I've shot some 120-123 class bullets in my creed, looking for ~2700 or a bit less, successfully.
No recoil or kick much to them.
Not with H4895 (had none of that at the time), but using for example, I4166. And the 120 pro hunter or 123 sst.
Nice thing about I4166 is it still has some temp stability and i takes up some room in the brass, ~94% load by my grt estimates.
The pro hunter, which is stubbier, also took up some room. Thing you want is room taken up much as possible so powder doesn't shift around or give squirrely MVs.
I got MV's in the 2600's for them.
and the 120 Eldm too.
This was from a 20" barrel in 6.5 CM. I just did a quick load reduction in my grt in this down to ~36 gr powder and grt said it was still ok, ~2570 MV or so. Not sure how much lower I would go.

Hodgdon says you can go down to 60% load in H4895 but performance at those levels can be quirky and inconsistent, I tried a few one time and the MV's were more variable than I liked. So I up-charged it some for better more reliable response. So be aware of that.

[lazyengineer]

I've shot some 120-123 class bullets in my creed, looking for ~2700 or a bit less, successfully.
No recoil or kick much to them.
Not with H4895 (had none of that at the time), but using for example, I4166. And the 120 pro hunter or 123 sst.
Nice thing about I4166 is it still has some temp stability and i takes up some room in the brass, ~94% load by my grt estimates.
The pro hunter, which is stubbier, also took up some room. Thing you want is room taken up much as possible so powder doesn't shift around or give squirrely MVs.
I got MV's in the 2600's for them.
and the 120 Eldm too.
This was from a 20" barrel in 6.5 CM. I just did a quick load reduction in my grt in this down to ~36 gr powder and grt said it was still ok, ~2570 MV or so. Not sure how much lower I would go.

Hodgdon says you can go down to 60% load in H4895 but performance at those levels can be quirky and inconsistent, I tried a few one time and the MV's were more variable than I liked. So I up-charged it some for better more reliable response. So be aware of that.

Thanks for the reply, always good to get more experiences. I will say, I use MP580 surplus, which is reportedly very similar to IMR 4166. It's a good powder and I've run a lot of 140 gr creedmoor with it, at Creedmoor level power. But I will say, it can be sensative to void space (it's fast for Creedmoor, so you generally don't have a very full case), and with small rifle primer brass, that very load would give me lots of hang-fires. That gives me pause on using it with more void that this project would have, even with large rifle primed brass. It's a bit tangential, because is 4166 really the same as MP380, etc? But the good news, is I have a can of H4895 a guy at work just gave to me as "can you get rid of this?" hand-off, only a couple weeks ago. To which, I said sure, I can dispose of that for you.
The 2017 publication table above, reports pretty remarkable accuracy for such a large void-space his reduced loads must have had - which is encouraging.

[jbmarshtx]

I used 28.5gr H4895 with the 108 scenar for high power silhouette in my 6.5 creedmoor. I don't know velocities, but it was accurate enough for my use which was as far as 375m/400y.

Oddly that's close to the same as an over max listed load I use for the 100/108s in my grendel bolt action.

[kmon]

4895 can get you there and has been used for years in reduced loads, Hodgdon has instructions for reduced loads, I never have loaded for the Creedmoor but we did workup an accurate load for the 7mm-08 with 120gr Nose BT at Grendel velocities for a friends kids. Worked well on deer and was sub MOA in their rifle.

[Fess]

Another powder that is commonly used in reduced loads is Accurate 5744. I have seen factory recommendations to use as little as 40% case capacity. If you do a search, just be aware that the powder has had several names, like XMP 5744 and AA 5744.

[Fess]

In addition, here is an article on 6.5 Creedmoor reduced loads using H4895. It shows velocities and accuracy in his rifle for Sierra 123 and 142 SMK's at various loadings from 60% to 100% capacity.
https://rifleshooter.com/2017/08/6-5-cre...d-142-smk/

[Old Bob]

I used to use SR 4759 for cast bullets in 30-06, 7.62x54R & 8mm Mauser. It was good for reduced loads with jacketed bullets as well. I also used it in a black powder duplex load (10grs 4759 under 45grs FF black powder) in my 45-70 Rolling Block. Unfortunately IMR (Hodgdon) doesn't make it anymore. I still have half a can. I switched to AA5744 when the 4759 was discontinued. IMR 4227 might work out OK for reduced loads. Even Alliant 2400 might work as well. A lot of the cast bullet shooters at our rifle club switched to it when the 4759 was dropped. Find a cast bullet reloading manual for powder suggestions & data...

[lazyengineer]

Thanks for the replies. Here's what I intend to hit the range with tomorrow:


Lot date # powder charge bullet brasss primer OAL Crimp

65-115 8/15/21 11 Hodgdon 4895 29.0 Hornady SST 129 Federal CCI250 2.682 Heavy Roll
65-116 8/15/21 11 Hodgdon 4895 30.0 Hornady SST 129 Federal CCI250 2.682 Heavy Roll
65-117 8/15/21 11 Hodgdon 4895 31.0 Hornady SST 129 Federal CCI250 2.682 Heavy Roll
65-118 8/15/21 11 Hodgdon 4895 33.0 Sierra Varm 85 Federal CCI250 2.488 No


Will fire out of an MDRx. Which is a 6.5CM gas operated bullpup. It also flexes with heavy loads, and gives horizontal stringing, but doesn't in the .223 chamberings. The experiment is to see if downgraded closer to Grendel power, can I eliminate the occasional horizontal stringing and slinging. (while such can also be shooter error, unlikely as this appears to be a common MDRx issue).

[kmon]

Accurate listed reduced loads with 5744 for years in their printed manuals and I used them for kids loads as well. Harder to find that data now though.

[StoneHendge]

LE, I'd be willing to wager that any stringing is due to the bull pup trigger mechanism and lock time.

The easiest way to get Grendel velocities out of a CM would be to lop a foot or so off the barrel. Not recommended with a bullpup though!

[Draftpick]

That’s an interesting chart.

Just for reference, I can get 2650 out of my Howa Grendel 20” HB with 33 grns of Lever and a123 ELD-M ! According to the chart, their 26” Creedmoor test gun needed 33 grns of H4895 for the same speed. Wow!

Bigger case less PSI, also shows the efficiency of the Grendel case