6mm rem AI for compitition?

[1000yardstare]

CanusLS..........the best way to get the proper throat dimension on a reamer is to send a dummy round to the reamer manufacturer with the bullet seated to the depth you want.

The maker has way better gauges than you and me and can dial the dimensions into the CNC machine.

I also send an unseated bullet and an empty fired case along with the dummy round.

Just make sure there are no live primers in the cases or you will run seriously afoul of the HazMat laws.

 

[CanusLatransSnpr]

Thanks 1000! I wasn't sure how all that went but now I have an idea. Don't have any bullets or brass as of yet so I can't quite set all that up. I won't be able to send them a fired round either, since I don't have a 6mm A.I. What I will probably do is just give Manson Reamers a call and have them send me the prints for all their 6mm A.I. reamers and make a decision on which reamer I want. This isn't going to be a competition gun, just critter slayer , so I don't think I need to be real fussy about it. Just find one thats throated close to what I want and run it! Thanks again for the help!

Mike

 

[frnkeore]

Mike,
For bullets under 90 gr, I think the standard .100 ball seat length will do (thats just one of the great things the 6 has, is a good ball seat and long neck). I would change the throat taper to 1.5 deg from the Rem's 3 deg.

1000yard and others, do you ever set your 30" barrels back? If not, why? does the barrel erode more that 2-3" in front of the chamber?

Lastly, how many use Win. 257 Roberts case's to fire form 6AI's?

I just got my 6AI and haven't taken it to the range yet. I do have a Rem 6mm, so I already had brass. I fire formed with 12.5 gr 4756 and a case full of corn meal with a grease wad. Primers stayed and shoulders pushed out to full capacity (i'm sure they will iron out a little more with full pressure). I had three 7x57 Norma's that I ran into a 243 die untill they crushed fit and fired them the same way. The Norma's had full length necks after firing, where the Rem and Win fired to 2.2". Is that common with that brass? The Rem's and Win's had been fired a few times in the standard chamber.

Frank

 

[WyleWD]

Everyone has pretty well covered the need for a tight chamber crush fit, brass woes (or strategies), and relatively short barrel life.

I can give testament to all the above. Had one that shot lights out for about 700 total rounds. The obvious applies here of course. If you shoot a lot of 10-15 shot in a row flights, the barrel most likely will not last very long at all. And as sure as the sun rises accuracy begins to waiver after about 5 - 7 shots when the barrel gets HOT.

I rebarreled to a 6-284 and wa$ a happier fellow for it. Won more matche$ with it.

The only item that I can see the others missed is that your name will change to Jesus at the ranges you shoot at. That is what everyone said when I shot mine with that muzzle break on it anyway. That thing will make your scull reverberate if it is anything like the one I had. No one wanted to sit near it when it went off.

Not trying to talk ya out of it....... let us know how it all turns out. WD

 

[CanusLatransSnpr]

Thanks Frank! I'll have to see if Manson has a reamer with .100" thoat and what taper it is. Does changing the throat taper to 1.5 degrees from 3 degrees slow the erosion process? Just trying to figure out the reason for doing so thats all! Thanks!

Mike

 

[frnkeore]

Mike,
All I can tell you about the 1.5 deg throat is that the bench rester's have been using that angle since at least the early 90's. I saw it on the 6 PPC drawing's back then at Hendrickson's reamer shop and that same angle is still used today in match reamers. So, it still seems to work.

Maybe someone the forum has the reasoning for it and how it came about.

Frank

 

[Steve Blair]

When the .308 Winchester was introduced in 1952, it had a 1.5° leade where the .30-'06 had a 3° leade. Many people attribute the .308's accuracy advantage to the leade angle instead of cartridge superiority.

There may have been cartridge chamberings before the .308 that used 1.5° leade but I have no knowledge of them.

 

[CanusLatransSnpr]

Thanks guys! I never even thought that it may have something to do with accuracy rather than throat erosion. Like I said, I was just wondering why, wasn't trying to be difficult or anything. If it is proven that a 1.5 deg leade is more accurate than a 3 deg leade then by all means thats what I want. I need any help I can get ! Thanks!

Mike

 

[1000yardstare]

frnkeore.............thought about using .257 Rob brass to create a false shoulder when necking down to ensure proper headspace but only .257 Rob brass I could find was Rem so went with 6mm Win brass.

My old 30 inch 6AI barrel is currently in the hands of its maker, MacLennon. He is going to bore scope it. If only the throat is eroded he will cut 2 inches off the chamber end and re-chamber with a 6mm Super LR reamer that I got from PT&G. He will also recrown. If the whole bore is toast he will make me a new 6mm barrel. Hopefully the 6SLR gives me longer barrel life. Will be using Lapua .243 brass which I can get from a Toronto supplier at a very good price.

In Canadian F Class we shoot in twos or threes, alternating shots, which would allow the barrels to cool somewhat between shots. And average daily temps would be lower than in the U.S. So our barrels are not subjected to single string fire in extreme temps like you would get south of the border. This probably gives us as much as 50% longer barrel life.

My 6AI brass is now necked up to 6.5x57AI for a new rifle that another `smith is working on.

 

[GWY]

First, I'd like to say that the information on this thread has been great and I'd like to again thank everyone for sharing their knowledge on this subject.

Regarding barrel life and throat erosion, has anyone used H1000? I know the 6CM shooters are claiming upwards of 3000 rounds or more of accurate barrel life. Their reasoning is that since H1000 has a slower burn rate, it burns "cooler" so there is less heat on the barrel's steel. Additionally, they say the slower H1000 results in the pressure curve being more evenly distributed over more of the length of the barrel instead of being concentrated in the throat.

Thanks again and regards

GWY

 

[40X Guy]

I tried H1000 in my 6AI under 105 class bullets, my particular combo did not like H1000, and it also lost some velocity. But it may work very well with 115 class bullets.
In my experience RL-22, H4831SC and Viht. N165 are my go to powders with 105's.

As I mentioned previously, I do not worry about throat erosion and premature barrel wear as that is the price you pay for a hot rod. If you build a 6AI, you can rest assured that you will be rebarreling after anywhere from 1000-1500 rounds, YMMV. 1000 yard stare wore his out in 1 season, and mine may be toast by end of 2011 season, but the 6AI is one heck of a fun cartridge!!

Frank

 

[Steve Blair]

Frank is right, push even a standard 6mm and it eats barrels. H1000 seems a little slow. The powders Frank references work well for me and I'll add IMR 7828 SSC. It is slightly slower but a little denser than RL22 or H4831 SC, allowing a full pressure load under 105+. It also provides excellent accuracy.

 

[Elwood]

Re: 6mm rem AI for competition?

A very interesting and timely post as I'm having a 6mm Crusader put together for 300/500/600 F class, although it's not quite a 6mmAI it's as close as you get to it.

On reflection I think if I do this again I will probably go down the 6 AI route next time.

My aim is too get the 115 Dtacs to around 3150-3200, if I can reach the upper end then the ballistics are comparable to my 7WSM, I will be using a Bartlein 30" 5R 1-7.5 barrel, Stiller Vipper action and Ballard low rider stock from Precision Rifle & Tool.

I have Win 6mmRem brass ready to be fire formed ( I see that no one mentions using the cream of wheat method? ) but I'm now looking at RWS brass as I like the idea of being able to make the necks nice and snug, good job I like neck turning! and RWS is as good as Lapua brass.
I ran some unfired RWS over my concentricity gauge and the run out on the necks never went over 2 thou, where as the Win brass went as far as 10 thou, but I guess that will all straighten out when it's fire formed. I did hear that Norma brass can be soft and people have lost cases due to primer pockets after 3 firings, now that would pee me off.

My powder choice will be RL25, VV N560 or H1000, QL tells me that RL25 Will be the velocity king but I don't like the variation it gives me from lot to lot, something I have learnt from my 7WSM, so I really hope that N560 works.

 

[1000yardstare]

Elwood.............I fireform during short range F Class practise. Doesn`t seem to affect accuracy and I am benefiting from wind reading and technique refinement.

Can`t get very excited about COW fireforming. Primers and powder are being used with no return on target reinforcement.

Some brands of COW contain table salt. Have to carefully read the label.

 

[Elwood]

Re: 6mm rem AI for competition?

1000 YS, I hear what you are saying, but here in the UK powder and bullets are expensive to say the least ( we can pay £48 for 100 Berger 7mm 180 vld's, work that one out into Canadian pounds or US dollars ) So my line of thought is if I can use 10 grains or so of pistol powder and some wax, I hopefully will save on barrel life as well as £'s.

You answered my other question in an earlier post, I was curious as to whether you shot strings or relays in Canada, we shoot relays here in the UK as well. I was hoping this was going to give me a barrel life 1600-1800 rounds, seems that might be wishful thinking on my behalf.

Thanks for the tip about salt content in the cream of wheat, I think the same product in the UK is called Semolina.

 

[bozo699]

Elwood,
Very good posts you have written, I built a 22-250 AI one time with a 1:9 to shoot heavier bullets @ long range GHs
with the short barrel life I didn't want to waste it on fire forming then again on load development, so I had my smith take my old barrel and chamber it as well with the AI reamer,( Didn't want to contaminate new barrel )
and used the COW method. I had a bunch of old primers that I wouldn't have used any more for matches or ground hogging anyways, 20+ years old. I don't remember the load but I think about 12 gr of unique. I did not know about the salt,glad I used the old barrel! I fire formed 500 cases in this manner,. Three trips to the gh towns and I am ready for a new barrel I also agree with you about the RWS brass I have somefor my .300wm and have never seen any Lapua or Norma that was any better if as good. Do you know where I can get any for the 6 remington? I would appreciate a address or phone # if you know and are willing to share it with me. Good Luck with your 6mm Crusader.
Wayne.

 

[Elwood]

Wayne, RWS is a trade name of Ruag Ammotec, http://www.ruag.com/Ammotec/Ammotec_Home

Shoot them a email and see if they have any suppliers in the USA.

I did think about using a fire forming barrel, I took a 6BR barrel off the Stiller Viper and thought about having it chambered with the Crusader reamer, however things aren't that simple here in the UK and I couldn't be bothered jumping through the necessary hoops in order to make it happen.

 

[bozo699]

Thank you Elwood, sent them off a email.
Wayne.

 

[CanusLatransSnpr]

Hey folks! Called Manson Reamers the other day and got the specs. on their .244 Rem. A.I. reamer. I hope I am not out of line for posting this. Their reamer has .100" freebore, a 2.5 degree leade, and a .277" neck. This reamer can be obtained with a solid or live pilot. I am thinking this reamer would probably do for a varmint rig with the lighter pills. Can't lie though, would like a little shorter throat and a 1.5 degree leade. The leade angle as recommended by a member earlier in this thread but, I imagine it will work. What do you folks think? Thanks!

Mike

 

[dawgmaster]

Thought I'd put my 2 cents in as well... ;D

One nice thing I found with fireforming the 6AI brass is that the standard 6mmRem rounds can often be quite accurate, so it gives a guy the chance to gopher/ground hog shoot while forming!

I too have had pretty good luck with the WIN brass...right now I'm using R-P brass and its holding up decent, however I've back off on my powder charge.

I've got a 12 twist that shoots 69gr and 80gr Bergers very well.