Define "sticky bolt" as it relates to pressure signs

[dk-1]

I was working up a load with H4350/140 VLD (260) today. I had left off last fall at 43 grains, but with the shortages and all, I found a good load using RL22. So, revisiting H4350, I had a start load of 43 grains and worked up to 43.9 where I stopped due to flattened primer. It's too bad because that load grouped .200 MOA at almost 2900 FPS!!!

Anyway, seems like all of my loads had somewhat of a sticky bolt. The bolt lifted just fine, but it stuck a bit when I went to pull the bolt back to eject the round. The 43 grain load, sticky bolt, was almost non existent. The higher the charge the more pronounced it was. No ejector marks at all, only slightly flattened primers on the 43.9 grain charge.

I assume this is the start of max pressure and I need to back it down a bit....
Today's conditions:
94* temp
14% RH
29.59 BP

I think I will try 42.8 next, that should keep me around 2800 FPS and in the .3-.4 range.

 

[RyeDaddy]

Sticky bolt is something I haven't seen much, when present it was accompanied by primers that were either flat or starting to flatten. When I experienced stick, it was on bolt lift, not extraction. Some reading on the internet showed that bolt lift technique that you employ can affect whether you see it on lift or extraction. I've read that lifting the bolt slowly can cause you to notice difficulty on pulling the bolt back if you're overpressure, whereas a sharp quick bolt lift will show the sticky bolt there and less on the pull-back. Don't know if that's true because I haven't tested it, but I do lift the handle hard and fast, hope that makes sense.

I would say you are over pressure. How are the primer pockets, looser to ANY noticeable degree than before they were fired? 2900 FPS is way fast for a 260 with 140's at any barrel length. You're also seeing what is presumably sticky bolt lift(which could also be a dirty chamber) and flattening primers starting.

I was just posting on someone else's thread tonight: 42.5-42.9 grains of H4350 with 140's in a 260 works in every damn 260 I've seen. (I've owned 2, and shot 2 others regularly) Read around, 42.8 is the universal sweet spot. I'd roll with that, seeig that it seems to work in your rifle as well. If you need more speed, you may just need a new cartridge choice. On that note, that 6.5 4S(6.5SAUM) that GAP has been messing with sure looks like a WINNER, 140's at 3100+ with 3k+ barrel life? Whoa!

 

[ksthomas]

dk-1,

Need to bear in mind that case configuration, shoulder angle and body taper all play a role in the "feel" of the bolt lift. As a rule, anytime you get resistance in lifting the bolt, you're over pressure. In some cases, like manu of the Ackley Improved or the Gibbs family, you will have a much harder time getting the bolt to stick. Doesn't mean there's no pressure there, just that one of your primary indicators is now unavailable to the handloader. With many of these, if you get the bolt to stick, you're so far past proof pressure loads . . . you get the idea. RyeDaddy give you some good advice here, and I'd second it as well. Back it off a bit, watch the other pressure indicators (including your velocity) and don't push this one that hard.

 

[Tripwire]

Is there ANY case lube residue at all on your brass, is there any gun oil at all in the chamber?

If you are asking for a definition of sticky bolt then you haven't been around reloading very long.

Your pressure could be fine but a case with any amount of lube on it will give pressure like signs.

Rule it out if nothing else.

My two cents, for what it's worth.......

 

[dk-1]

Thanks for the info guys. Just for the record, I have only been handloading for about two years now. Only worked one other load up near max and the signs there were sticky bolt LIFT and slightly flattened primers. With that said, I shot my load with RL22 (known performing load in this rifle) before and after testing these loads today with H4350 to maintain a baseline (shooter and chrony). I did not experience the bolt stick with that load. I'll try 42.8 and 42.6 tomorrow.

The reason for this post was because I always interpreted it as sticky bolt LIFT.

Further info, bbl is 23 inch krieger 5r 1:8 twist, chambered in 260 .295 neck, .060 freebore (pt&g tight match reamer)..... Remington brass, br2, 140 VLD, 2.206 CBTO, 2.864 coal.

On all of the fired brass I was able to slide a bullet down into the case, so no real doughnut.

 

[khw9mm]

Interesting topic. I had similar issues as far as not being able to pull the bolt back using 43.2gr of 4350 and 142smk.

Cleaned the chamber and have no problems now.