I would certainly bump farther! And make sure the body is getting pushed in.
Then test the brass case before loading in chamber.
Aka close the bolt and make sure it chambers easy before loading
Hard bolt lift but not every time
- Thread starter Nomad88
- Start date
Then test the brass case before loading in chamber.
Aka close the bolt and make sure it chambers easy before loading
Well, ya got one now. All guns behave different. Where did you get that load?
The barrel isn't fast, It's the fire cracking in the barrel that's causing your pressure to rise a lot, hence the reason for your high velocities. The fire cracking grabs the bullet and greatly increases the pressure. Take some abrasives and completely clean the barrel, I'll almost guarantee your rounds will come out slower afterward. You might also be developing a carbon ring.
Dolomite
Silver $$ Contributor
Could be new brass thats being fire formed with a hot load can cause bolt thrust with the short headspace. Did you have a hard bolt close? Was the bullet into the lands?
Normally you don’t have to bump shoulders on virgin brass or even 1x fired brass as it’s not fully formed to the chamber. May take 2-3 firings, chamber the new brass and the bolt without the firing pin should drop easily, now try with a fired case if it drops easily don’t bump the shoulder when sizing. When the bolt doesn’t drop freely that’s when you start bumping the shoulders. Alex wheeler has a good video on how to determine headspace on his website.
New brass or factory rounds, sounds like the headspace is long which could be giving you false pressure signs due to bolt thrust.
Normally you don’t have to bump shoulders on virgin brass or even 1x fired brass as it’s not fully formed to the chamber. May take 2-3 firings, chamber the new brass and the bolt without the firing pin should drop easily, now try with a fired case if it drops easily don’t bump the shoulder when sizing. When the bolt doesn’t drop freely that’s when you start bumping the shoulders. Alex wheeler has a good video on how to determine headspace on his website.
New brass or factory rounds, sounds like the headspace is long which could be giving you false pressure signs due to bolt thrust.
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I took the firing pin out and put a new piece of brass in, the bolt handle didnt drop all the way down on its own, but i had to very lightly push it down. I got 2 different factory loads, they were the same. So, I assume that is good.
I took a previously loaded round from the batch I was firing first that gave me issues, and the bolt handle is noticeably harder to push down and close.
If you research it, the charges I was trying, and have ran for years, many, MANY people run without issue. Ive used those charge weights for 10+ years.
With the brass that I was using being tight in the chamber, could that cause "pressure" signs when there wouldnt be any if I resized the brass?
I have adjusted my sizing die and current brass locks up much better.
Dolomite
Silver $$ Contributor
If the bolt doesn’t drop on a virgin piece of brass it could be you have a short headspace chamber. Depending on how hot the load is the brass has no room to grow which could cause pressure issues or heavy bolt lift. Sounds like you have to bump the shoulders on a new piece of brass to avoid pressure issues either that drop the load slightly to accommodate virgin cases and then work up the load once fired. Hunting rounds I would guess you want enough shoulder bump to prevent any issues with dust or dirt.
I have Forster dies, not Redding as I said earlier. With the Hornady gauge, a fired piece of brass measures 1.560
I sized brass to 1.557, and then bottomed out my die and it will size down to 1.550. The bolt closes the same with it at 1.557 and 1.550. Doesn’t drop freely but takes very little to get it to drop. Wouldn’t the ejectors cause some tension?
With the firing pin in, on a empty chamber, it has a slightly tighter feel to close than some guns I’ve had.
Hoping this new rifle isn’t a problem.
Dolomite
Silver $$ Contributor
Remove the ejector to see if that makes a difference. Some others may know but I don't think a heavy ejector spring will cause issues with heavy bolt lift.
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Schippergreg
Silver $$ Contributor
Remove the ejector when checking shoulder bump with the stripped bolt method.
Update:
Loaded 5 rounds from 40.4-41.4
Instead of being 20 thou off the lands, I seated to 2.800 oal
Zero issues with bolt lift, no ejector marks on the brass on any of the cases and 41.4 shot very well.
Middle group is the 41.4. Far left impact was off a cold bore. I’ll take this.
MV average 2764 with a ES of 12 and SD of 4.4
Loaded 5 rounds from 40.4-41.4
Instead of being 20 thou off the lands, I seated to 2.800 oal
Zero issues with bolt lift, no ejector marks on the brass on any of the cases and 41.4 shot very well.
Middle group is the 41.4. Far left impact was off a cold bore. I’ll take this.
MV average 2764 with a ES of 12 and SD of 4.4
Ruger15151
F-Class Shooter (6BRA and WIN 284)
My 6.5 CM shoots great with 42.3 gr of H4350. Were you fire forming new brass? That can cause what looks like pressure signs because the case doesn't expand quick enough to grab the case so it slams against the bolt.
Also, is there any chance you have moisture or something wet in the chamber.T hat will cause issue like you are seeing as well.
Also, is there any chance you have moisture or something wet in the chamber.T hat will cause issue like you are seeing as well.
Ruger15151
F-Class Shooter (6BRA and WIN 284)
2825 fps is exactly what I get with 42.3 grains of H4350. I have no signs of pressure at that charge.
Good deal
Glad you got it off of that unsafe edge, looks good. Where is your new overall length, touch or in the lands some?
I’ll have to check again but I think at 2.800 oal is jumping 40-50thou
Another update:
Tried a different sizing die with virgin brass.
Hornady match die with SAC bushing.
I loaded 2 groups without the expander in and 2 with. Both with bushing.
10 at 2.81 and 10 at 2.82, 5 of each with/without expander. Same powder charge, of 41.5gr H4350
The 2.81 loads are both on left, Top groups are without expander. Both groups are with. I had a stiff bolt lift and light ejector marks on the last load, which is weird to me.
Why would that be? I also have them on factory brass but no stiff bolt lift.
Tried a different sizing die with virgin brass.
Hornady match die with SAC bushing.
I loaded 2 groups without the expander in and 2 with. Both with bushing.
10 at 2.81 and 10 at 2.82, 5 of each with/without expander. Same powder charge, of 41.5gr H4350
The 2.81 loads are both on left, Top groups are without expander. Both groups are with. I had a stiff bolt lift and light ejector marks on the last load, which is weird to me.
Why would that be? I also have them on factory brass but no stiff bolt lift.
esromvre1
Silver $$ Contributor
Too HOT even taking in to account the vergin break did not fit your chamber correctly.
Definite high pressure as indicated by severe swipe marks.
Old Navy
Gold $$ Contributor
If the bolt closes smoothly on a round but is stiff to open, especially if I see the ejector mark, I quit shooting. Period!
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