Sendero 300 Ultra Velocities

[tjbill]

Three of us just bought Sendero SFII's in 300 Ultra and are working up 200gr Accubond loads. This morning we shot loads from 89 - 92 grains of Reloader 25. Accuracy was good across the board, but velocities from the chronograph were not IMHO. We averaged velocities from 2820 to 3030 with the various loads. We had expected to be somewhere close to 3150 or 3200 with the 92 grain loads. One of us used another chronograph a couple of days ago and averaged 3170 with 90 grains. Are we getting bad readings from this chronograph or both? All three of us loaded our own ammo on our own equipment.

 

[DIRTY 30 RUM]

What CG are you using? I have not loaded for 200 gr but my 185 vlds run @ 3380 fps with Retumbo and 215 primers. The gun is factory as well. I also run over an Oehler 35. If you have some Retumbo laying around, I would give it a try, it seems to be more consistent when the you are 90+ % load density.

 

[stxhunter]

mine shots 3135fts with 95.5 gr retumbo 200gr accubond

 

[jmden]

Numbers from 300 RUM w/ 26" tube from loads the past few years:

1. 200g Swift A-frame and 94.4g RE-25 - just under 3100--max I was comfortable with in this combo--loaded to fit stock magazine

2. 180g Nosler Accubond and 96.3g Retumbo - 3300fps - good load, very accurate in my rifle - bullet seated to lands - went to Wyatt's mag box

3. 200g Nosler Accubond and 109g US869 (temp sensitive) - 3200fps in colder temps - seated .010 from lands - quite accurate, but larger ES than I'd like

4. 240g SMK and 104 to 104.5 g US869 - 3000fps - seated to lands - quite accurate and quite possibly the best long range hammer for the Ultra with stock 1 in 10 twist barrel

These velocities are over an Oehler 33 at a local range. Same chrono that a world champ and still currently competing 1000yd Palma shooter uses, so I'm hoping they are accurate numbers. Sounds like one of your chronos might be a bit off?

Good luck finding your load.

 

[sniper2]

TJBill

I have had real good luck with A8700 both accuracy and velocity with the 200 ab.

 

[tjbill]

Thanks for the replies. We were using an older Chrony and in reading the manual it seems that it doesn't work great in cold conditions. It was about 30 degrees, so maybe this had something to do with it.

 

[NWdan]

Sendero 300 RUM

This is my first post but I've been viewing the site for a few months and all of the information is great. I have one of the three new Senderos tjbill mentioned in the original post. I loaded a few rounds today and ran them through a friends Chrony and here are my results with Rem brass, Fed 215 Large Rifle Mag primers, and RL25:

91g - 3017fps, 1st shot clean barrel; 2969 2nd shot

94g - 3204 & 3160.

91 grains shoots .55" 3 shot in my rifle but can't get too excited about 3000 fps in the Ultra. I haven't really shot 94 for groups yet, but no pressure signs today at about 41 degress F. I'm a little disappointed with the 40-50fps ES and tjbill and I talked about trying some Retumbo as others have mentioned. Anyone else had issues with RL25 ES? Thanks

 

[Fotis]

My Beta Master Chrony registers 3147 fps with 200 AB and 92 gr RL 25.

 

[Varmint Hunter]

I'm not clear as to how you conducted your comparisons. You used 3 different rifles, 3 different people loading ammo @ 3 different locations w/different equiptment, and shot over 2 different chronographs.

That's enough variables to account for all kinds of results.

I had an occasion to shoot the same load, from the same rifle, on the same day, through 2 different chronographs. The results were a consistent 100 ft/sec different. The Chrony always gave readings of 100 ft/sec faster than my Oehler 35P even when I put the Chrony directly behind the Oehler and fired a single bullet over both chronographs. This was on a mid-summer day with temperatures @ 70-80 degrees.

I was concerned enough about this discrepency to ship my Oehler 35 and the screens back to the company to verify the instruments accuracy. Oehler stated that it would be "nearly" impossible for the Oehler to be off that much because it has 3 screens and 2 clocks by which it verifies the velocity. They tested the unit anyway and determined that it was very accurate, consistent, and well within their tolerances.

I can only assume that the Chrony was consistently inaccurate and the data derived while using that chronograph would be highly unreliable. However, it belongs to my buddy who continues to use it and relies on its output.

 

[NWdan]

Thanks for your thoughts. It has been a little confusing trying to track three different setups, however the only difference we know of in our loads is that tjbill is using Nosler brass. I'm thinking the results I got yesterday with the Betta Master Chrony are pretty accurate and are close to what others here have experienced. I'd love to shoot the 200 AB with that 94g load of RL25 at 3200 but the large (40fps) ES has me worried for long range work. If the weather breaks soon and I can shoot at 500 yards I should be able to tell based on verticle dispersion. If it really is that large I'd like to cut that down (try different primers, or ?)but am not sure where to start. What do others feel is an acceptable ES for 1000 yards?

POP - I'm wondering if you recall what your ES was with your 92g RL25 load with the 200 g Accubonds?

One other thing - we've all noticed in our Senderos that if we try to load 3 cartridges into the magazine the first round chambered tends to want to jump up and get out of alignment with the bolt face, sometimes trying to bind. We're thinking we'll have to settle for two rounds in the magazine while hunting. I was wondering if the Wyatt box magazine others mentioned here would help with that. Not to mention it would be a step in the right direction towards the .338 Edge.

 

[280AIman]

load some Rotumbo and i think you'll be suprised i use only this powder in my 30-378 and my 338-378Wby magnums and it is a very consistent powder and it has been my experiance that it will show a 70-100fps increase in velocity over other powders.

 

[jmden]

"I was wondering if the Wyatt box magazine others mentioned here would help with that. "

I can only get 2 down with the Wyatt's controlled center feed box.