IMR Enduron 4551 & 4166 - 6.5CM & .223

[Ejcb]

Hello all,

Looking to develop some loads with the following components, for a pair of Tikka Tac A1s in 6.5CM and .223

6.5CM - Virgin Lapua SR Brass, CC450 Primers, IMR 4551, Hornady 147 ELD-M

.223 - Virgin Lapua SR Brass, CC450 Primers, IMR 4166, Hornady 80 ELD-M

Cant find a great deal of load data, although the 4451 has been suggested as a 4350 replacement, and the 4166 to be similar to Varget.

Many thanks!

[henryo]

Hodgdon website has the data:

(Note the COAL on the 223/80gr)

Would be interested to know how you get on with the 4166 as I've loaded some up for a .204 Ruger/39gr and I thought the grain size was massive.

Ta

H

[Ejcb]

Many thanks!

Ive measured my cartridge base to lands of my rifle being 1.815 inches

I’m going to try a 0.050 jump as some have had good luck doing so with the ELDM, resulting in my COAL being 2.378.

If I were to follow the data COL of 2.550, the 80 ELDM would be jammed 0.060 into the lands.

I appreciate there’s a line between reducing case capacity / increasing cartridge pressure as more projectile is seated into the case, however I feel the jam above would be the most significant culprit with regards to pressure.

Not sure how to proceed?

[henryo]

If it helps there is also data for the 82gr Berg with more or less the same charges at a shorter COAL:

Can't tell you how to load your ammo but I think you have a fair margin - the 'max load' is standard commercial 55kpsi but Lapua brass + CCI 450 will take closer to 5.56 levels (60kpsi).

Best thing to do is string a few over a chronograph to see where you are - every gun is different

If it works for you at 50''' jump then go for it

[KABOOM]

6 hours ago, Ejcb said:

Many thanks!

Ive measured my cartridge base to lands of my rifle being 1.815 inches

I’m going to try a 0.050 jump as some have had good luck doing so with the ELDM, resulting in my COAL being 2.378.

If I were to follow the data COL of 2.550, the 80 ELDM would be jammed 0.060 into the lands.

I appreciate there’s a line between reducing case capacity / increasing cartridge pressure as more projectile is seated into the case, however I feel the jam above would be the most significant culprit with regards to pressure.

Not sure how to proceed?

I tend not to jam into the lands and I don't worry about compressed loads, follow data and increase charge in 10ths

[KABOOM]

5 hours ago, henryo said:

If it helps there is also data for the 82gr Berg with more or less the same charges at a shorter COAL:

Can't tell you how to load your ammo but I think you have a fair margin - the 'max load' is standard commercial 55kpsi but Lapua brass + CCI 450 will take closer to 5.56 levels (60kpsi).

Best thing to do is string a few over a chronograph to see where you are - every gun is different

If it works for you at 50''' jump then go for it

yes the chronograph is the handloaders best friend indeed I seat about where I don't get engraving on the ogive or when it fits the magazine, I shoot some bolt guns others farquarson type single shots.

 

[Ejcb]

Hi guys,

Managed to to test the 4451 / CCI450 / 147 ELDM / Lapua 6.5CM SRP brass combo at bisley.

I used a magnetospeed v3 on my 24" Tikka Tac A1 using an MK Machining mount, so the chrono wasn't attached to my barrel.

The wind 10 to 20 MPH from all angles, air and ammo temp was 21C, measured with a kestrel and laser thermometer respectively.

All loads grouped well despite the wind, so I focused on SD/ED and will shoot for groups another day in more favourable conditions.

The below 40.6 grain load had excellent figures, but is quite slow - however Tikka barrels can be known to be slow, however given the relatively warm ammo temperature of 21C, on a more common, cooler day I may see a lower MV, although the IMR Enduron range are meant to be relatively temperature insensitive - ( https://precisionrifleblog.com/2016/06/19/powder-temp-stability-hodgdon-extreme-vs-imr-enduron/#:~:text=That%20is%20very%2C%20very%20low,to%20large%20swings%20in%20temperature. - approx 68 FPS from -3 to 60C)

Unfortunately the other shots of the below series were not recorded, however they grouped very nicely at 600 and seem to have good SD/ES.

I did however notice some marks on the Lapua brass after their first firing, I am unsure whether this is brass wipe or smear from the virgin brass on the bolt face during fireforming, from bolt unlock and cartridge extraction, or from excessive pressure. 

In the picture below the 41.2 load cartridges have been arranged to place the ejector marks at the 6 o'clock position.

What are your thoughts?

 

[Leeman]

To me I would say that is a pressure sign clear as day, especially as you seem to have a corresponding mark at 1 o'clock presumably from the extractor.    You could chamber a virgin case and see if the ejector is making any marks that may indicate it is not compressing fully into it's recess and marking the brass but I think that is unlikely as you would feel it on chambering a round.   I've not used the powder you list but I've used the same case/bullet/primer combination with both N550 and N160 and didn't see ejector marks until I was running a fair bit faster (30" barrel) than you list.  Maybe try a slower burning powder, but the ELD bullet is so long, unless the rifle is throated for it you will be loosing powder capacity especially if you're at mag length, having said that I wouldn't have a clue what mag length is for the Tikka but just checked and my loaded rounds with the 147 ELD were 3.054" OAL

[Triffid]

This article goes into pressure signs.

https://www.primalrights.com/library/articles/understanding-pressure

"Ejector ring is basically ejector wipe, without the wipe!  With ejector ring, you can see the imprint of the ejector relief in the bolt face, but the brass is not subsequently smeared upon extraction.  This can be due to the case rotating with the bolt as the bolt is rotated rather than the case being stuck in place.  A false positive reading of ejector ring can be caused by sharp or jagged edges on the ejector relief.  Some polishing compound and or light filing can usually take care of this. "

Triffid

[Richie88]

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