Wild velocity spreads?!?

[LEG_X]

Good morning all, I am in need of some serious help and assistance! I’m going to apologize up front for the length that I believe this post will be, sorry.

My basic problem is that I’m having difficulty (read extremely wild velocity spreads) working up a load for a 6.5CM with 140 RDFs and H4350.

Let me preface this by saying that I’ve been reloading for about 5 years for the 6.5 SLR and the 6.5CM to shoot local comps here in AZ. I’m not new to it but I’m sure there’s plenty I can learn.

Ok, the basics...

Barreled action is a stock R700 heavy barrel at 24”. Stock is McMillian ATR, Trigger is a Timney Calvin Elite 2-stage. I’m using a Magnetospeed Sporter that was recently tuned up by the factory. Brass is once fired Prime, primers are standard CCI large rifle. Scale is Hornady’s version of ChargeMaster with a Dandy trickler.

My first load ladder was done using IMR 4451 which looked promising...

39.0 - 2569
39.5 - 2708
40.0 - 2936??
40.5 - 2666
41.0 - 2660
41.5 - 2757*
42.0 - 2753*
42.5 - 2778
43.0 - 2801
43.5 - 2834

Everything looks ok except 40.0, but a decent node at 41.5 - 42.0. But I only have the 1# of 4451. And I have 8# of H4350.

So I basically do the same ladder except with H4350...

39.0, 2500
39.5, 2610
40.0, 2596
40.5, 2613
41.0, 3126!!!
41.5, 2722
42.0, 2750
42.5, 3221!!!
43.0, 2831
43.5, 3291!!!
44.0, 3394!!!

I didn’t actually believe what I was seeing so I started over at 40.5...

40.5, 2679
41.0, 2702
41.5, 3410!!!!
42.0, 3191!!!!
42.5, 2809
43.0, 3072!!!!
43.5, 2876
44.0, 3206!!!!

When I first started reloading for the SLR I was going all out for speed. So I learned very early what to look for as signs and symptoms of high pressure. There was faint ejector marks on all the 3K+ rounds but no swipe and no sticky bolt???

So then I wondered if my scale was reading wrong. I went and zero’d it, again. Then backed that up with a RCBS 5-10 balance. It was a couple tenths off above and below but nothing ridiculous. I zero’d the balance and used it for my repeat loads...

40.5, 2674
41.0, 3342!!!!!
41.5, 2750
42.0, 2771
42.5, 2781
43.0, 2867
43.5, 3229!!!!!
44.0, 3692 WTF?!?!?

At this point I’m stumped, what am I missing?? Any help or ideas would be greatly appreciated. Or maybe I should just buy more 4451?

Thank you much in advance!!

 

[spife7980]

Seems to me that your chrono is slipping or you have the sensitivity turned up way too high.

 

[Wheres-Waldo]

Seems to me that your chrono is slipping or you have the sensitivity turned up way too high.

Agree’d, I’d be looking at the chronograph first.

If those readings were accurate, you’d have known it with felt recoil, brass flowing into the ejector, blown primers, very hard extraction.

 

[Steel head]

I concur with the above opinions.

 

[Supersubes]

What they said ^

 

[Steel head]

 

[LEG_X]

Copy that all, thank you. I’ll check the sensitivity on my Magnetospeed and try again. ??

 

[LEG_X]

Just a quick follow up on this thread... I went out this morning and reshot the 8 string loads twice, once on Regular setting and once at H1 setting (previously was on H2). The Regular setting had 4 no read loads but the H1 picked up all 8 with no problem. Apparently that was the problem.
So thank you all very much for your help and guidance, it is much appreciated!!

 

[Sirshredalot]

Also consider your light source. Ive found that with led lights and a cardboard backer my results are much more consistent.

Shred

 

[spife7980]

Also consider your light source. Ive found that with led lights and a cardboard backer my results are much more consistent.

Shred

Huh?

 

[Sirshredalot]

Light sources have caused me problems with my chronograph...especially indirect light.

I use led towers/sun shades with a 3ft square of carboard clamped on top of them to block as much indirect light as i can so that the chrono only sees one specific light source.

Shooting in the morning outside would cause my light source to move(sun) ... also trees filtering light could cause issues.

The chrono needs a consistent light source.

This is really useful for shooting indoors too with multiple sources of overhead lighting and has improved my results.

Maybe my chrono is more finicky than others, but this works for me.

Shred

 

[SupressYourself]

He's got a Magnetospeed. Lighting is irrelevant.

I'd look at your spacing between the bore and the bayonet. It should be like 1/4 inch. The V3 kit comes with a little aluminum bar to check, not sure about the sporter. The only time I've had to mess with the sensitivity is if I couldn't quite get the spacing right for a particular barrel.

 

[spife7980]

Light sources have caused me problems with my chronograph...especially indirect light.

I use led towers/sun shades with a 3ft square of carboard clamped on top of them to block as much indirect light as i can so that the chrono only sees one specific light source.

Shooting in the morning outside would cause my light source to move(sun) ... also trees filtering light could cause issues.

The chrono needs a consistent light source.

This is really useful for shooting indoors too with multiple sources of overhead lighting and has improved my results.

Maybe my chrono is more finicky than others, but this works for me.

Shred

Well it in no way applies to this situation

 

[LEG_X]

I do have a .25” dowel in my pack that I use for spacing confirmation. I went back out again today to test 4 5-shot loads, not a single failure to read or wild number. I truly think it was the sensitivity.

 

[spife7980]

I do have a .25” dowel in my pack that I use for spacing confirmation. I went back out again today to test 4 5-shot loads, not a single failure to read or wild number. I truly think it was the sensitivity.

Yep, its a lesson almost all of us have probably learned in the first trip or two out fiddling with the magneato.

Higher doesnt necessarily mean better... unless you just like seeing those wild numbers.
I was amazed when after messing around in the settings one of my 300bo subs was clocked going 4k fps