Results: Cutting a 7mm-08 Barrel From 26" to 20"

[Another Casual]

In my opinion, there's not enough threads with data from cutting down barrels!

I cut down my 26" 7mm-08 barrel to 20". I tested 7 loads before and after and wanted to share the data. Bullets and powders were picked based on what I have on hand. ***Disclaimer, all loads were max in my rifle and should not be attempted***

Why 20"? I figured it would be a good balance between too long to hunt with the can and too short to be tolerable from a noise perspective.

	Speer 130gr	50.2g H4350	Lost	Speer 145	48.0g H4350	Lost	Interlock 139	48.0g H4350	Lost	162 ELD-M	45.0g H4350	Lost	150 SPFB	45.9g IMR4451	Lost	162 ELD-M	45.1g IMR4451	Lost	162 ELD-M	46.0g IMR4831	Lost
	26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"
1	3126	2993		2986	2865		2972	2855		2730	2649		2765	2705		2710	2622		2660	2587
2	3108	2995		2980	2870		2974	2847		2717	2653		2820	2677		2688	2610		2660	2595
3	3126	2990		2980	2871		2982	2858		2723	2658		2772	2684		2731	2594		2648	2584
AVG	3120	2993	127	2982	2869	113	2976	2853	123	2723	2653	70	2786	2689	97	2710	2609	101	2656	2589	67
SD	10	3		3	3		5	6		7	5		30	15		22	14		7	6
ES	18	5		6	6		10	11		13	9		55	28		43	28		12	11

Average Lost: 100 FPS
Average per Inch: 16.63 FPS

Sadly my rifle prefers much lower charge weights than the max, but the FPS lost per inch was less than I expected. The difference in velocity won't be missed as the rifle is much more enjoyable to shoot with a silencer on it now and the speeds are still quite good. In many cases the choice in powder will have a larger impact on the velocity than having cut down the barrel. I still need to pick up some of the more traditional 7mm-08 powders to try, once supply improves.

 

[bamban]

I did not record the data. I cut my 700 VFSS 308 from its original 26 to 20 and then a month ago I further cut amd threaded to 16-1/2. Velocity drop from 20 to 16-1/2 is about 100 FPS as well. 16-1/2 with FA762SS attached the length is 24. Very handy for short range hunting.

 

[BillLarson]

In my opinion, there's not enough threads with data from cutting down barrels!

I cut down my 26" 7mm-08 barrel to 20". I tested 7 loads before and after and wanted to share the data. Bullets and powders were picked based on what I have on hand. ***Disclaimer, all loads were max in my rifle and should not be attempted***

Why 20"? I figured it would be a good balance between too long to hunt with the can and too short to be tolerable from a noise perspective.

	Speer 130gr	50.2g H4350	Lost	Speer 145	48.0g H4350	Lost	Interlock 139	48.0g H4350	Lost	162 ELD-M	45.0g H4350	Lost	150 SPFB	45.9g IMR4451	Lost	162 ELD-M	45.1g IMR4451	Lost	162 ELD-M	46.0g IMR4831	Lost
	26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"		26"	20"
1	3126	2993		2986	2865		2972	2855		2730	2649		2765	2705		2710	2622		2660	2587
2	3108	2995		2980	2870		2974	2847		2717	2653		2820	2677		2688	2610		2660	2595
3	3126	2990		2980	2871		2982	2858		2723	2658		2772	2684		2731	2594		2648	2584
AVG	3120	2993	127	2982	2869	113	2976	2853	123	2723	2653	70	2786	2689	97	2710	2609	101	2656	2589	67
SD	10	3		3	3		5	6		7	5		30	15		22	14		7	6
ES	18	5		6	6		10	11		13	9		55	28		43	28		12	11

Average Lost: 100 FPS
Average per Inch: 16.63 FPS

Sadly my rifle prefers much lower charge weights than the max, but the FPS lost per inch was less than I expected. The difference in velocity won't be missed as the rifle is much more enjoyable to shoot with a silencer on it now and the speeds are still quite good. In many cases the choice in powder will have a larger impact on the velocity than having cut down the barrel. I still need to pick up some of the more traditional 7mm-08 powders to try, once supply improves.

Dam good write up..................
Thank You....

 

[John Klingenberg]

Great post, thank you.

 

[JKennedy]

Interesting information, easy to follow…thanks! SD & ES are lower in most cases with 20" barrel. Thoughts on reason for this?

 

[JAYgs8163]

Looks like average lost was about 120 ft per second. Not to bad at all. Very good info. Thanks

 

[Jonoton]

Great real-world data!
Thank you for the effort

 

[john k]

very interesting information and detailed results. Can't imagine not being satisfied with the results. Would be interesting to see what type of effect slower burning powders with the heavier bullets would yield or faster burning powders with the lighter bullets would yield. Great subject to stir the reloading mind. Thanks

 

[xsn10s]

I have to concur that was an excellent write up! Thanks for sharing. I also agree a shorter barrel is handy. I find my 22" 30-06 FWT very handy for future reference.

 

[HRM Johnny]

Excellent information. Thank you for posting this.. We are in your debt.

 

[LVJ76]

Thanks for the info, that's very helpful. Not the loss in fps I would've thought.

 

[hydehunter]

you might try a faster burning powder, my 30.06 only lost 33fps with a 150 gr Power Hammer Bullet using IMR8208 powder and it was cut from 24"to 18" very happy with the results

 

[436]

I see the concept of heavier bullets in the same loads holds true to the least amount of velocity loss between the barrel lengths.
Very good write-up. Cheers.

 

[UncleDano]

Nicely documented information, thank you very much!