Bergara HMR heavy bolt lift when hot.

ssteve

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Jan 8, 2011
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So I purchased a new HMR in 6.5cm. Just put the first 140 rounds through it. I was shooting only Norma 130gr match. The rifle shot great, consistent 3/4” groups without wind, when I did my part etc etc add excuses. Gun shot good imo. When I got to the last 20rnds of the day I decided to put some heat into it to see what the barrel would do. Shot a string of 20 pretty fast and at about round 12-13 I started getting heavy bolt lift. Velocity stayed pretty constant at about 2790-2810. I shot the last 5 into a group and they were at about 1”-1 1/4” and all had fairly heavy bolt lift but the brass showed no signs of pressure or any issues.

Is this normal? My frame of reference is a 700 sps tac and some other hunting rifles that were all a lot looser tolerance rifles.
 
A little more break in time it'll probably loosen up. Only time I've had sticky bolt on a bergara was with hornady superformance which was way too hot. I've been told that hornady brass is soft tho. Havent had an issue with norma. No scratches or anything on cases to indicate a bur in chamber? Primers still flat and in place? Look at case neck and see if its sticking in the chamber.
 
No signs of any abnormalities on the brass at all. Primers, necks, body etc, it all looked perfect.

I just went out yesterday and put another 60 rounds through it. I got some heat into it to see if it would happen again but nothing this time. Everything felt fine, managed several groups in the .600" range and couldnt be happier with the gun.

I am wondering if it could be some type of fouling, oils from the factory etc that were in the chamber and when I cleaned the gun it resolved the issue?
 
No signs of any abnormalities on the brass at all. Primers, necks, body etc, it all looked perfect.

I just went out yesterday and put another 60 rounds through it. I got some heat into it to see if it would happen again but nothing this time. Everything felt fine, managed several groups in the .600" range and couldnt be happier with the gun.

I am wondering if it could be some type of fouling, oils from the factory etc that were in the chamber and when I cleaned the gun it resolved the issue?


If you don't clean the rifle first, the oil they put on as a preservative can actually cause a rifle to show pressure signs. Same if you put a too much oil in a chamber then shoot the rifle.
 
No I didn't but I didn't look super close at comparing the soot between them. I was mostly looking for cracks, scratches, measured cases etc.
 
I shoot surpressed a lot and noticed that after long strings they would start to get tight bolt lift and feel over pressured. Along with that I noticed the shoot on the shoulders. A good chamber clean and I havent been able to replicate the issue.
I also noticed that sometimes chambering could be tough and saw the bullet would be scored so I gave it a deep cleaning to scrub out a carbon ring and now my bullets dont get marked. So im gonna attribute the pressure to just soot coating the chamber and cleaning it alleviated the issue.
 
Awesome, I'll have to pay closer attention to it next time I run a bunch of rounds through it. What are you using to clean the chamber?
 
Awesome, I'll have to pay closer attention to it next time I run a bunch of rounds through it. What are you using to clean the chamber?


I am now using boretch c4 carbon and c2 copper, it was on sale after I ran out of hoppes9. Sinclair bore guide and a tipton carbon fiber rod. I figure that combination is the least likely to drag a rod across the barrel that many claim to be why cleaning is bad.

I do the bore and chamber at the same time since I already have it all out.
-Ill soak a patch with the c4 carbon, send it through, soak a second and send it through again. Only the couple minutes it takes to unscrew the jag, extract the rod and then re put it all together between them.
-Then Ill take that patch, load it up with carbon cleaner again and just insert it enough so that leaves the bore guide and the saturated patch is physically sitting in the throat on where the carbon ring develops ensuring that it is getting the chemicals on it. Ill then leave it sitting for a half hour maybe? Long enough to go away and do something else before coming back to it for a good soak.
-Ill then take an old bronze brush and run it down the bore a time or two and then Ill short stroke the throat to take and use that mechanical action to more forcefully remove the hopefully chemically weakened carbon ring. I tried to use just patches initially but I still got marks on the bullet, not so after the brush.
-A dry patch or two to clear the bore of the carbon and then Ill just take a bit of paper towel to swab the chamber without pushing it too deep, stick it in a bit and just twirl it lightly to wipe the walls down. Even with a bore guide some of that crap still gets back in the chamber and the paper towel can remove a bunch of it quicker than a small patch or two at a time.
-Then Ill to a couple passes with the copper remover. My rod and jags arent solvent proof so theyll turn blue even with no copper present but a couple passes witha light soak should be more than adequate. Then a pass or two witht he bronze brush for some more mechanical action.
-After than some dry patches to get it all out, an oil patch or two to try and flush it a tad and then another dry patch to remove the surplus oil from the bore.

So thats my long drawn out steps for a relatively simple process. I think its the short stroking of the throat with the bronze that gets rid of the carbon ring primarily.
I really only do this every... I want to say 3-400 but in actually looking at how often I clean and how many bags and boxes of bullets Im going through Id say 6-700 rounds in between is more likely. I put it off until the target tells me to but thats never really happened; its been the chambering thats telling me when I need to clean.

I also like the idea of wipe out being safe for long term exposure and just spraying the bore and leaving it over night but wipeout wasnt on sale when I needed it.