Looks like I have some bullet pulling to do.

I'm getting issues with excessive pressure in a 6.5/06 AI I'm loading for. I've been starting at the suggested "start" and I'm getting sticky bolts. I was thinking at one point since the round is sticky going in due to the crush fit, maybe its not pressure. 2 grains below max I blew a primer the other day. I was shooting a 120 gr barnes TSX. I've been also getting excessive pressure with the 125 gr Partition.

I was thinking that I'm seating the bullet pretty deep because this rifle has a shorter throat. The TSX is seated .045 from the lands with a COL of 3.165. It was suggested to me by another fellow that possibly there is too much neck tension. I've measured the rest of those loads and the neck diametre is .291??

I'm going to continue with the developement but I'm just going to start much lower of course. My question is why this is happening? Velocity represents the pressure btw. I hit the 3400 fps when I blew the primer. I broke 3300 with the 125 gr Partition. I'm looking for 3100 to 3200 fps with the TSX. I'm going to start at 55.0 gr of H 4831. I blew the primer at 60.0 gr.

Boiler,

I'd get that throat reamed out or look at going to a faster powder which will build up pressure quicker... but also velocity... so you don't have to push it up that far to get usable velocity....

good luck
cheers
seafire

6.5/06 AI is overbore - go with the slowest burning powders available, such as Hodgdon H870, Hodgdon Retumbo, 1MR7878, Vihtavuori N560, Ramshot Magnum (Big Boy), Accurate MAGPRO, and Alliant Reloder-25. With a 24" barrel and a Nosler 125 NPT you should be able to get ~3250 fps and not exceed ~65,000 PSI. Primers usually blow at >75-80,000 PSI.

Your throat is OK - just don't jam the bullet into the lands, because it can cause excessive pressure. Also, "stiff" all copper bullets and the like can be tricky to load. Barnes recommends you seat them well off the lands, even up to 0.050" from the lands. The coated TSX bullets are more foregiving in my experience. The Nosler NPT is your best bet.

IMR 4350 was giving me excessive pressure with the 125 gr Partition. It was suggested that the powder was too fast and I should try RL 22 and H4831??

What do you mean by reaming out the throat? Taking it to a smith and reaming out the rifle's throat? Are there other alternatives like turning/reaming the cartridge neck?

Am I running into this problem because the neck is getting too thick? I sized down 270 Win brass. It seemed to be the consensus on here that 270 brass was the way to go and no one had neck tension problems.

Mmm...One week til mulies open.

As a quick check see if a bullet will slide into a fired case. Your neck may be too smallwhich will really raise pressure. A too short neck will act the same way. Try chambering a sized empty case to check.
Good luck!

What is the diameter of your chamber's neck?? Measure your fired brass, and figure .001-.0015 springback on the brass. Alternatively, you can have a chamber cast made - although some people claim the cerrosafe continues to shrink, in which case you need to measure the neck diameter immediately after the cast is removed from the chamber.

You need at least .002" clearance between chamber neck diameter and diameter of loaded rounds.

I personally don't think a short throat is your problem. After all, you can measure for your bullet seating depth and seat accordingly. Besides, seating bullets into the lands rarely raises pressure to the degree you are seeing.

Finally, if you are really running of options to try, have your bore slugged to make sure the bore diameter is as expected. Oh, and by the way, make sure you use the right caliber bullets as well...

- mike

you might retry this starting with .25-06 brass.

In addition to checking that a bullet will easily enter a fired neck make sure that the cases are not too long for the chamber at the mouth.

Usually AI's shorten the case but if you made them from 270's!

I had a case stick this summer. Its been hotter than ever.

I don't have any experience with a 6.5-06AI, but I do have a 25-06AI and a 264 Win Mag 26" barrel. The velocities you are having trouble with are not easy to get with my .264 Win Mag. which I believe has more case capacity. On the surface it would seem to me you are pushing this round too far. Where did you get your data?

quote:

Originally posted by rick243:
I don't have any experience with a 6.5-06AI, but I do have a 25-06AI and a 264 Win Mag 26" barrel. The velocities you are having trouble with are not easy to get with my .264 Win Mag. which I believe has more case capacity. On the surface it would seem to me you are pushing this round too far. Where did you get your data?

Rick243, this seems the norm with the "AI" followers. 3,300'/sec with a 125 Partition is about the absolute max with a .264 magnum.....

I got data from Huntington years ago about a .243 superrockchucker that was totally out of line as well....Never came close to what velocity was published.

I had a simuliar problem recently and it near drove me to drink...

I solved it by starting with new brass and full length resizing the new stuff before ever shooting it, presto prolem solved...I have seen this happen on several ocassions...

Yes on a standard chamber but this is an AI and we assume fireformed cases are used. Still Ray may be right and that because the loads are too hot in the first place the AI brass needs to be FL sized in AI die.

If you don't have an AI Fl die then start over and keep the loads lighter.

I can scratch off several of the suggested reasons.

Bullets are definitely sliding into a fired case with ease.

I'm not seated into the lands. I use a Stoney Point Chamber All and I've darkened a bullet with no rifling marks.

I've measured the fired case necks at .296, that’s without springback estimated.

Cases are not too long but a few are well under the suggested trim length for 6.5/06 in the manuals. This problem however is not isolated to just those cases. I've checked.

I've used Load Tech data, Stevespages data for the 6.5/280 Improved and I've used 6.5/06 data out of manuals. It seemed that the first batch of loads I shot after the initial fire forming were ok, a few sticky bolts MAYBE?? Not quite sure on that because I had a few rounds that were not chambering with ease. I summed it up to the "crush fit".

I'm definitely pushing too hard but is it too hard by average? I know all chambers are different but how do these numbers look?

I started to get pressure signs with 53.0 gr of IMR 4350 with the 125 gr Nosler Part. I actually started a little higher but returned to the range with it reduced to this and was dumfounded that I continued to get pressure, albeit reduced. Data from Stevespages.

Looking back I have to correct myself. I blew the primer with 61.0 gr of H4831. Signs of pressure at 59.0 gr though. Data from Load Tech.

I only FL size and I have the 6.5/06 AI RCBS FL die.

I'm thinking that the Barnes bullets have to go but still the 125 Partition was giving me issues.

I have some Hornady 140 gr Interbonds I'm picking up at the bus depot today. This was the bullet used to fire form and during the process I was able to put 14 out of 15 into an inch. Velocities were only 2600 fps but I'm going to work the load ladder and see where the pressure starts.

I'm most curious to compare where max sits with their rifles in this chambering in weight of powder charge. I've asked before but people have given me velocities and psi. I don’t matter to me if I can't use as much powder as the data suggests. I'll get the velocities. If there is a problem with this rifle though, I'll have to get it looked at. Very bad timing though.

boilerroom:
I am pushing the 120 grain bullet at about 3175 to 3200 fps, in my 6.5-06. This I am getting with 54/IMR4831/Sierra 120 SP. I suffer the same symptoms as you when I get over this powder charge. I am not shooting an AI so you may be able to get a little more velocity than me, but I have had to watch closely, especially in the heat for pressure problems.

I used one guys suggested load with IMR4064, and when I finally got the bolt open, the case looked like it would accept a 209 shotgun primer. Try something close to the load above and se if you get the same problem, if you do I am lost.


Jerry

I had a problem like this with a 243 once. In my instance, the once fired cases were on the long end of the range and my chamber neck on the short. There was just enough that when I cammed the bolt shut, (lots of "feel" as you describe) the case mouth was being slightly crimped into the bullet.
The fired case looked like a 6mm belted magnum with a shotgun primer sized hole, just as you describe. Careful trimming was the answer.

I think you guys are flirting with disaster, all for a few feet-per-second. I value my eyesight more than that. Maybe I feel this way after having seen a friend accidently fire a 270 round in a 7mm mag rifle. The results of a failed case are the same. He is lucky he can still see. A trip to the hospital to get brass and powder specs picked from his face and he was good as new. Looked like he had a bad case of acne.When you start to see those pressure signs, STOP adding powder. Simple as that.

BoilerRoom,

Will bullets slip easily into the neck of once fired cases (before they are resized)?

Garrett

I have a 6.5 x 55 BJAI that all of a sudden started showing pressure (sticky bolt and loose primers) with a well-used load. It turned-out that two things were at work: 1) fired cases were due for FL resizing and trimming and 2) I had accumulated significant copper fouling. Once these problems were resolved the pressure signs disappeared.

OK,..checked my data for my 6.5-06AI. I run the 140gr a-max right now with plans on the 139gr scenar and 140gr berger next.

First,..although they don't give max load density, RL22 and H4831sc are the best powders I have found for 3 different ackelys.

I have gotten to 51.7gr 4831sc thus far at 3000fps and small change with no pressure. I had run them to 3200fps and primer pockets were gone in 1 firing. They don't show pressure like other chamberings,..so a chrono is a must have tool. Jerry's load data with a 125gr pill being 3.3gr higher with a 15gr lighter pill seems to be right in line with my data and the same powder.

Back the charges down,..remember book charges are for factory stuff,..and a custom/aftermarket barrel often requires MUCH LESS powder to make speed as the lands and grooves are much tighter. I almost NEVER reach a book max with a match barrel/chamber. Even a tight chamber in a factory barrel makes for less powder needed.

If you got to 60.0grs' you are wayyyyyyyy over max.

HTH.

quote:

Originally posted by rick243:
I think you guys are flirting with disaster, all for a few feet-per-second. When you start to see those pressure signs, STOP adding powder. Simple as that.

Amen, except "pressure signs" may not show up until 70,000 - 75,000 psi. Do you really want to run at 70,000 psi, so close to the ragged edge that a change in temperature or a different lot of powder can open up primer pockets?

quote:

Originally posted by N. Garrett:
BoilerRoom,

Will bullets slip easily into the neck of once fired cases (before they are resized)?

Garrett

YES

quote:

Originally posted by DobleTroble:
I have a 6.5 x 55 BJAI that all of a sudden started showing pressure (sticky bolt and loose primers) with a well-used load. It turned-out that two things were at work: 1) fired cases were due for FL resizing and trimming and 2) I had accumulated significant copper fouling. Once these problems were resolved the pressure signs disappeared.

I'n FL sizing and may cases are not due to be trimmed any time soon.

quote:

Originally posted by JustC:
OK,..checked my data for my 6.5-06AI. I run the 140gr a-max right now with plans on the 139gr scenar and 140gr berger next.

First,..although they don't give max load density, RL22 and H4831sc are the best powders I have found for 3 different ackelys.

I have gotten to 51.7gr 4831sc thus far at 3000fps and small change with no pressure. I had run them to 3200fps and primer pockets were gone in 1 firing. They don't show pressure like other chamberings,..so a chrono is a must have tool. Jerry's load data with a 125gr pill being 3.3gr higher with a 15gr lighter pill seems to be right in line with my data and the same powder.

Back the charges down,..remember book charges are for factory stuff,..and a custom/aftermarket barrel often requires MUCH LESS powder to make speed as the lands and grooves are much tighter. I almost NEVER reach a book max with a match barrel/chamber. Even a tight chamber in a factory barrel makes for less powder needed.

If you got to 60.0grs' you are wayyyyyyyy over max.

HTH.

This is what I was affraid of all along and the reason for several other threads I have posted over the last couple of months. I was just looking for data and a reasonable "starting" load to work up from.

Thanks again JustC. Thanks to eveyone else too. All the suggestions given are still part of the learning process.

I'll let you know how things look at the range tonight.