Help with weird pressure signs

[GB213]

Hello,
Long time lurker here, never posted, but I have a problem that I can't figure out. I am doing load development tests in my 6.5x47. I am starting off w/ 37g of RX15 and going up .2g every 5 rounds. This is behind a 123g lapua. Temp is 52 degrees.
O.k. everything is find, some great groups, no pressure signs. I get to 38.2g and decide to clean. I fire 1st load of 38.4 and bolt is more than sticky, I need to get up and pull to unload. The case has clear ejector mark on it, primer looks o.k, didn't notice heavy recoil.
I think this is strange because nothing leading up to this. I say a pray and fire another 38.4, this time a little stinky, but nothing like before. Case is o.k.
After 39g I clean again, and guess what 1st round of 39.2 same thing. I ran the rest of the way up to 39.6, with no problems.
What could cause this. I don't think that there was anything left in the barrel, It was only 5-7min of cleaning, so I don't think the barrel could of cooled down that much.
Anyways does anyone know what could be happening?

 

[cav has been]

Re: Help with weird pressure signs

OIl,solvent or other slippy/slidey stuff in chamber. Case didn't get a good grip on chamber walls, bolt had to take all the pressure, instant hard bolt lift. Definitely bad form.

 

[Victor N TN]

Re: Help with weird pressure signs

Did you think to relube the bolt lugs after cleaning? Dry lugs are a lot like you describe.

 

[GB213]

Re: Help with weird pressure signs

Pimpgun, that maybe it, thing is it has never happen before. I was using a bore guide, but sometimes that can leave stuff in the chamber.
Victor, I was using the Brownells action magic on bolt lugs, I checked it was there.
Thanks for the help

 

[cav has been]

Re: Help with weird pressure signs

With that short of a cycle time (5-7 mins) maybe the solvent didn't have time to evaporate? I don't know your normal procedure, I almost never clean during range session, especially during load development, most especially when only changing powder charge. Just saying if your normal cleaning is at home and rifle stands over night, maybe chamber dries out. Best of luck! Steve