Thread: Kimber Montana 308 Load Development

Still working on this post chop and A-Tec Forward 45 suppressor. 2 shots touching and 3rd an inch or more flyer.

46.5gn and 47.0gn on a hot afternoon. SD is great. 47gn I would say is at max as one round bolt lift firmed up and QL suggesting near max too. 46.5gn and seating depth change may help.

More mag space would be good...limited to about 2.840 COL.

Haven't read through your entire thread but one thing I have found with my Montana is it builds pressure early and is one of the only rifles I have owned that will not run certain loads using ADI powders at over their book max. The flip side of that is it still achieves the same or better velocities but using less powder.

@Ryan_Songhurst I'm using CFE223...not sure it is an ADI produced one?? Yes I think it approaches max quite quickly. On QL 47gn at 2.800 COL shoots into the read, while 2.840 COL is under max. Yes it is a bit more complex in the real world but my testing indicates 47gn is at or very close to max. This confirms your experience as it is 2gn below book max and is why you should never treat book max as a conservative figure to start from.

Having trouble replicating groups post suppressor. Have made some errors and learnt a bit along the way. I use a Sinclair priming tool...expensive but good kit. Realised I hadn't properly adjusted washers and was putting a slight crush on the primers. Easy fix but ignored it for longer than I should have.

Also got lazy with my hold and realised I could shoot better with the overhand scope hold method. The range practice isn't doing any harm.

Got low on CFE223 so trying RE17 as have plenty. Apparently great with heavy 30 cal bullets so my 168gn LRABs may have been at the lighter end of usability. Started at 47, 47.5 and 48gn with Fed match primers and no pressure signs with speed close to 2600fps.

Today tried 48.5 (2603), 49.0 (2636) and 49.5gn (2640) and again no pressure so will try 50gn and then running out of case to hold it. Groups not there yet...may have to try ELDMs.


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Originally Posted by Tikka7mm08

Quite a difference!


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Greetings Tikka 7mm-08,
A note of caution. The 168 grain ABLR will develop more pressure than the 165 grain Hornady so you will probably need to cut those loads a grain or two. I would use the Nosler on line data if they give loads for CFE 223. The ABLR projectiles are harder due to their construction and run the pressures up faster.
Regards Grandpamac.

Originally Posted by Tikka7mm08

Having trouble replicating groups post suppressor. Have made some errors and learnt a bit along the way. I use a Sinclair priming tool...expensive but good kit. Realised I hadn't properly adjusted washers and was putting a slight crush on the primers. Easy fix but ignored it for longer than I should have.

Also got lazy with my hold and realised I could shoot better with the overhand scope hold method. The range practice isn't doing any harm.

Got low on CFE223 so trying RE17 as have plenty. Apparently great with heavy 30 cal bullets so my 168gn LRABs may have been at the lighter end of usability. Started at 47, 47.5 and 48gn with Fed match primers and no pressure signs with speed close to 2600fps.

Today tried 48.5 (2603), 49.0 (2636) and 49.5gn (2640) and again no pressure so will try 50gn and then running out of case to hold it. Groups not there yet...may have to try ELDMs.


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Greetings Again Tikka 7mm - 08,
A max of 47 grains looks reasonable for CFE 223 and the 168 grain ABLR as you have found. The 168 grain HPBT Sierra is also is much softer than the ABLR. Nosler does not list either of the powders you have used but its best velocity is about 2,800 with powders I have seen here. Your 2,700 plus with CFE looks about what you would expect. As you have found RL17 is too slow for the .308. CFE 223 is a spherical powder and is not made by ADI. I found that AR2208 and AR2206H worked well in the .308 and Nosler got good results as well.
Regards Grandpamac.

I'll see how the RL17 50gn load goes (if it works great because I have a lot of RL17 that I no longer use for anything). It isn't giving up much to CFE223 and I feel that 46gn is max for that powder in my rifle for brass life. I like the ABLR because it also has a good BC, but to TBH I struggled to get it going in my 260AI and it is a fussy projectile. It is the length of the 168gn ABLR that really drives the pressure up....it is longer than similar bullets.

The weather has not played ball for testing loads but the wind finally dropped this morning.

I thought 50gn RE17 might hit a spike as powder is half way up case neck but no pressure signs in terms of bolt lift etc and pleasing accuracy with a slight breeze in play. This with 168gn LRABs.







I then tried some 168gn NosBTs over 46.5gn CFE223. These shot much better than the 168gn LRABs over the same powder:





I also tried some Sierra 165 gamechangers but these did not group so well.

So LRABs with RE17 and BTs with CFE223 seem to be a good landing point.

Comparing the loads there is not much between them: at 600y the BT needs 15.24 MOA and the LRAB 14.76 MOA. The energy respectively is 1110 ft/lbs vs 1187 ft/lbs. The BT minimum speed for expansion is 1800fps and it is just below this at 600y while the LRAB only requires 1300fps (these are manufacturer claims).

Pity I forgot to arm the chrony for one of the BT loads but I suspect it is pretty low SD same as RE17.

400y group then a couple of spares shot at 600y off the spartan...not adjusted for crosswind. Scope is 2-10x. 168BTs.

Final check in low light on range. BTs are devasting.

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Similar size to a whitetail, so a good yest


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Haha, check was on the range...Mr Hare just happened to hop into sight.

Managed to bag a buck on Stewart Is. trip. The 168gn went straight through and would probably try a much lighter bullet next time. It was an unexpected 'long range' shot too at 350ish yards.

Originally Posted by Tikka7mm08

Managed to bag a buck on Stewart Is. trip. The 168gn went straight through and would probably try a much lighter bullet next time. It was an unexpected 'long range' shot too at 350ish yards.


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Nice mate