over pressure?

TheNewGunnut

TheNewGunnut

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so i finally got my Stw out to the range this past weekend and i found that the bolt was having a hard time lifting properly (say the last 5% required force to open) after shooting. i've been searching the net looking for a remedy and most of what im finding for this is saying its and extractor issue but the local gun smith i spoke to has decided its over pressure from my hand loads..

the recipe im using is from the https://load-data.nosler.com/load-data/7mm-shooting-times-westerner-stw/ . With my powder (H1000) the range given is 74gr-78gr with a 175gr sbt, my load is 74gr w/175gr sbt. which should be well within the safe range...

i'm not ruling out over pressure as the cause i'm just looking for advice on where to go from here
 
Do you lube the locking lugs? What do the primers look like on a fired case. Is it possible that you have a tight necked chamber, and may need to neck turn your brass? How far are you seating the bullets off the lands?
 
yes my locking lugs have been lubed, aside from lines running lengthwise down the case of "shiny" brass the cases look normal as do the primers, no bulging etc. as for how far off the lands I'm seating i have no idea, I'm not doing precision shooting at all so I've just been using the SAAMI guidelines for over all length...

while testing with fired brass i am finding that some of the 8mm rem mag brass that's been necked down for stw isn't chambering very well and is very tight. i had 2 that actually got stuck in the chamber and had to be tapped out. That's when the gunsmith said its over pressure and wont discuss anything else. which seems fair but as i said before i should be well within the safe pressure....
 
If the neck can't expand to release the bullets then there will be more pressure, measure the neck of a loaded factory shell and one of your loaded handloads, if the handload is significantly bigger this would be the cause of the seeming over pressure you are experiencing.
 
I'll see what I can measure my hand loada and see what they look like, ill have to check between my 8mm cases and my stw cases though as factory loads are a ##### to find and are super expensive ($120+) would there be any other symptoms from the neck being to tight that would help pin point it?
 
take a fired case from your rifle and see if a new bullet will just drop in the neck. If it does then neck thicknes is ok ,if the bullet does not just drop right in then your case necks will have to be turned.
 
There could be a thicker portion of brass near the bottom of the neck of the 8mm reformed brass, seating the bullet deep enough in the neck to that thicker "donut" could potentially create excess pressure, may need to inside neck ream if that is the problem. If you look inside the neck you may see a noticeable donut in there just above the shoulder/neck junction.
Seating the bullets farther out if there is room in the mag & throat could help too if that's the issue, keep the base of the bullet above the thicker part of the neck, if reaming isn't an option.
No idea if that's the issue but I've ran into that reforming brass before, especially when reforming to a shorter cartrige.
 
I had worked with a friend on a family rifle that had been unused for 30 years. Very hard to open bolt with "start" level hand loads. Fired one factory shell and just about did not get bolt open. With my bore scope found what looked like corrosion pitting in the neck area of the chamber - I believe under firing pressure, the brass was wanting to "flow" into those pits and "lock" the case. Careful polishing with oil and steel wool helped, but did not cure the issue - buddy had the neck reamed by gunsmith in the "city" and problem went away.

You do not say what type of rifle. Designs like Mauser and Winchester will have bolt lugs riding on a flat surface for at least last half of the bolt movement. So, for at least half of bolt opening movement, the bolt body does not move rearward at all - all extraction occurring in last 40% or so of the bolt lift. Enfield designs, like the No.1 and No.4, the P14 and M1917, have helical breech - the bolt continues to move forward right until bolt handle stops going down, and in reverse, starts reverse movement almost as soon as the bolt handle is lifted. So if first part of your bolt handle lifting movement is "okay", depending on what your design is, may not have started to extract yet.
 
Dump those reload and start over at 70 grains.
Are you using the same components as the data ? Same bullet - same primer - same brand of case ? There is more to load data than just the powder charge. Brass are not all created equal - neck thickness vary as is capacity. There is quite a difference in volume from one brand to the other.
There is also the CBTO of your gun. Your load might be too long for your chamber - free bore.

As stated above - a sticky bolt mean you are way way over pressure.
 
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It could be the type of brass you are using. I reload for a 350 Rem Mag and HSM brass is always sticky bolt lift while RP brass with exact same powder charge, bullet and primer is never sticky.
 
It doesn't matter what the book load is. You're loading for your rifle using your components. Maybe your chamber is tighter than the test rifle for the book, or maybe your brass is softer. Maybe your brass is from a different lot and has less capacity. Your rifle is telling you your loads are too hot... back off 2-3 grs.
 
Not clear from your posts - have you actually fired factory loaded cartridges in your rifle, and extraction, etc. was fine? That step very much eliminates a potential problem within your rifle, and directs everything to your loads. Also very worth while to carefully mike (not calliper) your loaded round's external neck diameter - right back to the junction with the shoulder - and compare to the SAAMI drawings for a STW cartridge and chamber - if your re-formed brass has thicker necks, then that can significantly add to pressure, even if your load is a "start" load. SAAMI 2015 - available on the Internet - calls for .3170" as neck diameter on cartridge; it shows .3200" to .3190" for the chamber neck, so .0020" as Minimum clearance.

If you re-read your source of data, should have given you a brand and type of primer, a brand of case, a brand and weight of bullet, etc. as the "recipe" - not just a charge weight of powder. Every item that you change from "their" recipe, makes "their" pressure test results less and less applicable.

And, I will agree with posters above - if factory cartridges fire and extract normally, and your hand loads are "tight" - you are over pressure, by a lot - not a "little bit", but a lot. Be especially "leery" of data from before 1998 - see warning on page 417 of Speer Manual #14 - at that time it became accepted by SAAMI and sane maximum pressures were established. Prior to 1998, there are loads to be found with as much as 20% more breech pressure - it was a "wildcat" - and that is what many "wildcatters" do - load the thing up to 70,000 psi or more and call their invention "wonderful"...
 
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Potashminer said:
Not clear from your posts - have you actually fired factory loaded cartridges in your rifle, and extraction, etc. was fine? That step very much eliminates a potential problem within your rifle, and directs everything to your loads. Also very worth while to carefully mike (not calliper) your loaded round's external neck diameter - right back to the junction with the shoulder - and compare to the SAAMI drawings for a STW cartridge and chamber - if your re-formed brass has thicker necks, then that can significantly add to pressure, even if your load is a "start" load. SAAMI 2015 - available on the Internet - calls for .3170" as neck diameter on cartridge; it shows .3200" to .3190" for the chamber neck, so .0020" as Minimum clearance.

If you re-read your source of data, should have given you a brand and type of primer, a brand of case, a brand and weight of bullet, etc. as the "recipe" - not just a charge weight of powder. Every item that you change from "their" recipe, makes "their" pressure test results less and less applicable.

And, I will agree with posters above - if factory cartridges fire and extract normally, and your hand loads are "tight" - you are over pressure, by a lot - not a "little bit", but a lot. Be especially "leery" of data from before 1998 - at that time it became accepted by SAAMI and sane maximum pressures were established. Prior to 1998, there are loads to be found with as much as 20% more breech pressure - it was a "wildcat" - and that is what many "wildcatters" do - load the thing up to 70,000 psi or more and call their invention "wonderful"...
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unfortunately i don't have factory load to test with but i did have some last year and i found that they were still sticky at the time I attributed it to the a spot on the bolt where a burr had been forming from the recoil i filed it smooth and this is the first rounds i've been able to put through it since then. aside from the specific brand of brass I have been using the primer powder and bullet weight given on the nosler load data webpage which i'm hoping should be up tp date?

i put 6 rounds down range with it before calling it, all were loaded the same except for 4 were in old 8mm rem mag brass one was old FC 7mm stw and 2 were brand new Hornady stw brass i picked up last summer...
 
take a fired case from your rifle and see if a new bullet will just drop in the neck. If it does then neck thicknes is ok ,if the bullet does not just drop right in then your case necks will have to be turned

i tried this with all the cases including actual stw brass and none are dropping right in they get stuck about 1/2 way up the bullet
 
TheNewGunnut i tried this with all the cases including actual stw brass and none are dropping right in they get stuck about 1/2 way up the bullet[/QUOTE said:
THAT is a problem!! Chamber out of spec, brass out of spec, whatever - as poster above said, your loads are overpressure for your rifle and your components!
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300_savage said:
Are you sure it's 7mm stw and not a 270stw?
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there is a 270 STW....???
no im not sure the gun doesnt actually have a caliber stamped on it, and i inherited it so i didnt purchase it. that said it was marked as a 7mm STW on the stock by my grandfather and came with 7mm stw dies and the 8mm brass that was loaded came from him. having said that he passed in the mid 90's so the original loads in that brass are questionable given what potashminer has said but ive already shot them and have reloaded them now.

If its as simple as just backing off my load down to 70gr(the lightest end of the recipe) and i have nothing else to worry about from there then golden im happy. however my concern is that because im not loading "hot" according to the load data i have that the issue maybe being caused by something else
 
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