260AI...picture heavy

[LongRange]

how much above did you go?

[Dewey7271]

2 gr

[LongRange]

thanks Dewey...im going to run up a little higher than that unless i start flattening primers...i want this brass to last awhile LOL...if the 4831 starts getting hot before i see what im looking for ive got some H1000 and RL25 i might try...ive shot both powders in the standard 260 and both are VERY accurate but slow...im thinking with 3gs more capacity and a mild mag primer it should be interesting.

ive got the last 77 rounds loaded up to fire form...neck tension is at .007 and i set these so they will be jammed .020 so that should take care of the FTFs i think...im also going to load up the 24 FFd cases at 48.5g and play with seating starting at .002 jammed and work out from there...

[Dewey7271]

That should work.
Can't wait to see how it shoots for you.

[WinnieTheBoom]

I'm sure I missed it but what will the difference in overall length be once you have a load worked up? Or should it stay about the same as the .260?

[LongRange]

the case OAL(trim length) i run in my 260 is 2.028 and before fire forming these cases were there...after FFing they are actually shorter at 2.015-2.017 but thats before i have neck sized them so they will most likely end up around 2.020 or so...if your talking about COAL it is 2.906 touching the lands with a 142g SMK.


fixed the COAL.

[WinnieTheBoom]

Are you running them through .308 mags? Just curious about being able to keep it as a repeater, though it doesn't sound like you've had any issues with seating depth up until now, so I wouldn't expect that you've run into any problems with it.

[LongRange]

im not sure on the mag part as this rifle was a 110BA 300wm when new...the 260 cases fit and hold in the mag but dont feed to well because of the length of the mag...i think Dewey is mag feeding and may be able to answer better than i can.

[LongRange]

come to think about it ill have to try feeding with the AI'd cases they may feed better than the standard 260 cases...ill get back to that after i try.

[Dewey7271]

Mines in a LA and I run right at 2.88. There is definitely a gap or space in the mag but they feed very easily. Zero issues after probably 650 or so. I have not modified from where it was originally. Mine was originally a 30-06.

[WinnieTheBoom]

OK that's what I was wondering about. COAL around 2.9 is getting pretty tight in a .308 mag. LR let us know what you find with the AI'd cases, but it sounds like the ticket might be the '06/.270 length mags.

[LongRange]

so are they the same for the BA models? i believe they are aics mags.

[WinnieTheBoom]

They should all be Accurate Mags. The .300 win mag boxes are around 3.7" iirc and I believe that they use the same one for the .30-06 as well. So in that case you shouldn't have any feeding problems. Dewey might be able to take a measurement of his, but I'd be willing to bet that it's close to the same as the mags that you're using now.

[LongRange]

thanks Winnie ill get back to this after i try feeding...i never feed from the mag so ive never paid much attention to it.

[BarrelBurner]

Hey Longrange, I saw the issues you noted with FTF and jamming the bullets. Not sure if you already know this about the AI chambering or not, but an AI chamber is actually shorter than the standard chamber by about .004 as I recall. That said your headspace is slightly crushing the shoulder on a standard case when the bolt is closed. Basically a standard go gage is an AI no go gage. If you are head spaced properly you shouldn't need to jam bullets to fireform and should eliminate the FTF issues. Hopefully this helps if you weren't already up to speed on this.

[LongRange]

Hey Longrange, I saw the issues you noted with FTF and jamming the bullets. Not sure if you already know this about the AI chambering or not, but an AI chamber is actually shorter than the standard chamber by about .004 as I recall. That said your headspace is slightly crushing the shoulder on a standard case when the bolt is closed. Basically a standard go gage is an AI no go gage. If you are head spaced properly you shouldn't need to jam bullets to fireform and should eliminate the FTF issues. Hopefully this helps if you weren't already up to speed on this.

i was not up to speed on this and thanks for posting...i should have done a little more research...my head space now is probable off(long)by .003 as i used the go gauge but set it tight thinking it would be close...i just ordered an AI head space gauge but in the mean time i will reset the HS with the standard go gauge as the no go.

i did fire form the other 76 cases but had 9 FTFs and the problem with the FTFs was mostly the HS issue but also the sear dragging and having a bunch of crud on it...i cleaned and readjusted the trigger.

[Dewey7271]

Didn't think of that LR, sorry. Bad assumption on my part
Check your PM

Edit: just thought. I got my barrel from Jim also so it should be the same reamer on the brass in the pics.

[LongRange]

Thanks BarrelBurner and Dewey you guys were a lot of help...i fire formed 59 cases this morning and every thing went much better... this barrel does not like the berger hybrids at all...the 142g smks are looking very good so far...ive got some 142s and some 139g lapuas loaded up in the fire formed brass i shot today for tomorrow...i will get this all caught up tomorrow.

[LongRange]

well ive had a crash course on the 260AI the last few days and have learned a few things....first was the head space issue. now as ive said ive been thinking about doing a 260AI for a long time and have read a lot of info in that time but failed to understand that the 260AI head space is approximately .004 shorter than a standard 260.
so when i head spaced the barrel i used the standard go gauge but set it so that the bolt would close with a hard crush but wouldnt lock all the way down...this obviously didnt work out to well as it caused several FTFs and $56 bucks worth of brass.

after talking with Dewey and getting some measurements from him i reset the head space yesterday morning and prep'd 50 more pieces of brass and fired them yesterday and according to all the measurements im .002 short which is fine for now as i have a gauge on the way and will reset again when it gets here.

now another issue is the redding body die i ordered is long...even when i set the die with a hard over cam it does not touch the shoulders on the formed cases...even on the first cases i shot which are about .004 to .006 longer than the cases i formed yesterday...i was going to buy a set of competition shell holders but their $50 bucks +or-...i can have my smith trim the die cheaper so ill drop it off to him tomorrow.

while fire forming cases yesterday morning(with no FTFs)i found this barrel does not like the 140g berger hybrids..AT ALL..i shot 25 rounds with them from slightly jammed to .030 off the lands and the groups were so bad that it had me wondering if something was loose or if my scope finally gave way.
next i shot 142g SMKs seated the same as above and at .015 to .025 i had some impressive groups for fire forming brass and at all seating depths the 142s grouped way better than the bergers.
today ive got some 142s loaded at 48.5g of H4831sc and seated from .002 jammed to .030 off as well as some 139g lapuas loaded and seated the same in the fire formed brass so today will be the day i find out if the 260AI is here to stay...if i get the claimed speeds(or close since im working with a barrel that has 3000 rounds through it)and it is accurate and most of all consistent i will order a reamer and a throater from PT&G on monday and have barrel that was on this rifle set back and threaded for the break.

ive read a few posts(not here)about guys claiming they are getting close to AI speed while fire forming with the same load im using...well im not sure how because i clocked 10 rounds yesterday over the magneto speed(awesome chrony)and they were from 2840 to 2851...this is from a compressed load with a mag primer.

the case on the left is one i FF'd yesterday after resetting the head space...the case on the right is one i FF'd friday...the first 100 cases are stretched pretty bad so i doubt ill be using them again....



now here is something i figured out when i was preping the 50 cases yesterday morning...ive been using a piece of rubber wrapped around the cases to uniform primer pockets which works well but is still hard on the fingers as you guys that do this know...as i was uniforming PPs i was thinking theres got to be a easier way....so i grabbed a case and went out to the garage to see what i could find...there was a piece of parker 3/8s rubber hose sticking out from under my tool box(ding)i grabbed it and the case fit very tight into the hose...i went back in to test it and its the cats A$$!!! NO MORE SORE FINGERS...so you guys uniforming primer pockets with a drill type uniformer...do yourselves a favor...run down to your local auto parts with a case and buy a 6" piece of rubber hose that fits the case real tight...at some point the rubber wont grip as well but you can just cut a little off or clean it with alcohol.



i will post some target pics a little later today and some more thoughts on all of this.

[LongRange]

the best two groups with the 140g berger hybrids...





the 142g SMks....

[Dewey7271]

FF sometimes yields a little slower than you're going to see with the full loads. I'd be pretty surprised if that Sierra load isn't around the mid 2900s.

[LongRange]

if it shoots that fast and as accurate as the .015 and .020 FFing loads ill be talking to Kiff monday morning.

im guessing your load at mag length is compressed? because mine touching the lands at 2.924 is and at .025 off it gets pretty crunchy LOL.

[BarrelBurner]

I wouldn't necessarily discard those longer cases being you jammed the bullets when you did the FF. That should Have prevented stretching at the case head, you just moved the shoulder a little farther forward which you should be able Tom set back once you straighten out the die situation.

FWIW, I had the same situation on a set of RCBS dies. I used a "Smith" brand diamond bench stone (knife sharpening stone) and took .012 off the bottom of the die and problem solved. You could do the same off the top of the shell holder as well. Those stones are $30 which is likely less than a visit to the GS.

[Dewey7271]

Yessir. They're compressed a bit.

[LongRange]

I wouldn't necessarily discard those longer cases being you jammed the bullets when you did the FF. That should Have prevented stretching at the case head, you just moved the shoulder a little farther forward which you should be able Tom set back once you straighten out the die situation.

FWIW, I had the same situation on a set of RCBS dies. I used a "Smith" brand diamond bench stone (knife sharpening stone) and took .012 off the bottom of the die and problem solved. You could do the same off the top of the shell holder as well. Those stones are $30 which is likely less than a visit to the GS.

im in pretty good with the smith ive been using so i think he will do it for free...if not i have a new stone on my bench.
im going to try and bump the shoulder back and see what happens before i toss them...if it dont work no biggie ive got 250 more to play with...if it were lapua id be a little more concerned LOL.

Yessir. They're compressed a bit.

i figured...have you tried H4350? if yes what was the max charge you ran?