Fireforming: Critical to seat bullet into lands ?

[Mirage]

Have 100 W/W cases to load / fireform for .250 AI for an Encore. This obviously precludes seating bullet into lands as per Nosler manual. Is this really required, particularly for a tight chambered gun? Fred Smith (Bullberry) tells me that his AI chambers are cut extra tight for almost nil headspace (thought he said .5~ 1 mil!).

Seat to factory COL, try for 10 mils off


Mirage

[jhm]

For fireforming all you are trying to do is get the brass to expand to your chamber and that will happen weather your bullet is on or off the lands, after you fireform and resize then trim to length you can seat the bullet just of the lands.    JIM

[dave375hh]

You can use a .264 dia expander to expand the necks, then partial size the necks to create a false shoulder. Just size the neck untill it will just chamber, and it leaves a raised band at the base of the neck. Just fireing loaded rounds won't completely fireform the cases because the fireing pin will push the case foreward and would leave the rim to shoulder short. You need to hold the case back against the breach face. that's what seating a bullet into the rifleing does.

[onesonek]

If the chamber is tight, you shouldn't have to worry about it. I have a 6mmAi with a slightly longer throat. I have shot factory loads in it with no problems.

[Catfish]

For fire forming I would recomand that you just load good hot loads for the parent case. I like to work with 500 rounds of brass at a time and work up a good varmient load and then go hunting, but for 100 rounds you probibly be through 1/2 of your brass befor you find the best load so I would recomand you just pick a load and go to the range and have fun. When you get home you can trim cases ect., then start working up a load for the imp. case.

[riddleofsteel]

Actually you do not even need a bullet to fireform a case. I often fireform cases in my 6.5-.284 by necking down a .284 case to 6.5. Then I put in a light load of quick burning powder similar to a .38 special load. Top off the remaining volume in the case with unsalted corn meal or dry grits. Seal the top with a plug of hot wax or even a toilet paper wad. When you fire the load the case is held against the bolt head by the extractor. The case shoulder will be forced forward to meet the shoulder on the chamber and the neck will blow out to the chamber lead neck diameter.
Clean the cases up and trim them to the proper length. For my rifle, on the first full power loading, I just run the newly formed case up into the die far enough to neck size the round only.
Load the round with a full power loading and shoot it for target, sight in, ect. Accuracy and velocity will be normal as the case is already formed. I usually only hunt with rounds that are full length resized but I often shoot neck sized only rounds for target use.
This method works well and I have a gunsmith friend that set up an old RCBS Rock Chucker press to fireform cases. He loads the rounds as I have described but instead of blowing all that stuff down his barrel he built a striker device to set off the round while in the loading die with the ram is all the way closed. The pressure escapes thru the hole at the top of the die and the case is fireformed. Plus no barrel or gun to clean. This forming die/press is mounted horizontally with a sheet metal shield over the end to prevent hot escaping gases from hurting anyone in the shop. This works really well with a custom die cut by RCBS for your chamber. You can get one by sending them a fired case. That way you are still firefroming to your individual chamber.

[Catfish]

When fire forming AI rounds all you have to do is to fire the parent round in an AI chamber. Bullberry chambers, especially wildcats, are usually thight neck and you may have trouble loading the rounds in the chamber, if you do, do not fire them as the presure will be extreem! If they chamber easily just fire them and you`ll have AI cases. If your going to load your own parent round work up to max. loads with them and form with max. loads, you`ll get better formed cases, and don`t worry about the bullet not being in the lands.

[roper]

I'm lucky as I can load at the range so once I get an AI case i can test for powder I want to use then once I find a pretty good load for the AI I just drop powder depending on case capacity about 2/6 grs and normally that will be a pretty good load to fireform.  I don't seat any bullets into the lands when fireforming a good load will normally blow the case out also that first case gives me my seating depth for the  AI case and that what I set my dies for on the fireform load.  I do alot of research on the AI caliber before I have one build and have bullet and about what powder I want to use.  This years project were a 22-250AI and 6mmremAI neither are for high volume shooting the 22-250AI is a light walk around rifle for the high country rock chuck out here in Co so may only need 50 the 6mmremAI is a LR pd rifle so only need 100rds.  Well good luck.